Merge branch 'DRTVWR-519' into DRTVWR-552-cache-360

# Conflicts:
#	indra/newview/app_settings/settings.xml

22 files changed, 5412 insertions, 0 deletions

diff --git a/indra/llfilesystem/CMakeLists.txt b/indra/llfilesystem/CMakeLists.txt
new file mode 100644
index 0000000000..09c4c33ebf
--- /dev/null
+++ b/indra/llfilesystem/CMakeLists.txt
@@ -0,0 +1,99 @@
+# -*- cmake -*-
+
+project(llfilesystem)
+
+include(00-Common)
+include(LLCommon)
+include(UnixInstall)
+
+include_directories(
+    ${LLCOMMON_INCLUDE_DIRS}
+    ${LLCOMMON_SYSTEM_INCLUDE_DIRS}
+    )
+
+set(llfilesystem_SOURCE_FILES
+    lldir.cpp
+    lldiriterator.cpp
+    lllfsthread.cpp
+    lldiskcache.cpp
+    llfilesystem.cpp
+    )
+
+set(llfilesystem_HEADER_FILES
+    CMakeLists.txt
+    lldir.h
+    lldirguard.h
+    lldiriterator.h
+    lllfsthread.h
+    lldiskcache.h
+    llfilesystem.h
+    )
+
+if (DARWIN)
+  LIST(APPEND llfilesystem_SOURCE_FILES lldir_utils_objc.mm)
+  LIST(APPEND llfilesystem_SOURCE_FILES lldir_utils_objc.h)
+  LIST(APPEND llfilesystem_SOURCE_FILES lldir_mac.cpp)
+  LIST(APPEND llfilesystem_HEADER_FILES lldir_mac.h)
+endif (DARWIN)
+
+if (LINUX)
+  LIST(APPEND llfilesystem_SOURCE_FILES lldir_linux.cpp)
+  LIST(APPEND llfilesystem_HEADER_FILES lldir_linux.h)
+
+  if (INSTALL)
+    set_source_files_properties(lldir_linux.cpp
+                                PROPERTIES COMPILE_FLAGS
+                                "-DAPP_RO_DATA_DIR=\\\"${APP_SHARE_DIR}\\\""
+                                )
+  endif (INSTALL)
+endif (LINUX)
+
+if (WINDOWS)
+  LIST(APPEND llfilesystem_SOURCE_FILES lldir_win32.cpp)
+  LIST(APPEND llfilesystem_HEADER_FILES lldir_win32.h)
+endif (WINDOWS)
+
+set_source_files_properties(${llfilesystem_HEADER_FILES}
+                            PROPERTIES HEADER_FILE_ONLY TRUE)
+
+list(APPEND llfilesystem_SOURCE_FILES ${llfilesystem_HEADER_FILES})
+
+add_library (llfilesystem ${llfilesystem_SOURCE_FILES})
+
+set(cache_BOOST_LIBRARIES
+    ${BOOST_FILESYSTEM_LIBRARY}
+    ${BOOST_SYSTEM_LIBRARY}
+    )
+
+target_link_libraries(llfilesystem
+    ${LLCOMMON_LIBRARIES}
+    ${cache_BOOST_LIBRARIES}
+    )
+
+if (DARWIN)
+  include(CMakeFindFrameworks)
+  find_library(COCOA_LIBRARY Cocoa)
+  target_link_libraries(llfilesystem ${COCOA_LIBRARY})
+endif (DARWIN)
+
+
+# Add tests
+if (LL_TESTS)
+    include(LLAddBuildTest)
+    # UNIT TESTS
+    SET(llfilesystem_TEST_SOURCE_FILES
+    lldiriterator.cpp
+    )
+
+    set_source_files_properties(lldiriterator.cpp
+    PROPERTIES
+    LL_TEST_ADDITIONAL_LIBRARIES "${cache_BOOST_LIBRARIES}"
+    )
+    LL_ADD_PROJECT_UNIT_TESTS(llfilesystem "${llfilesystem_TEST_SOURCE_FILES}")
+
+    # INTEGRATION TESTS
+    set(test_libs llmath llcommon llfilesystem ${LLCOMMON_LIBRARIES} ${WINDOWS_LIBRARIES})
+
+    # TODO: Some of these need refactoring to be proper Unit tests rather than Integration tests.
+    LL_ADD_INTEGRATION_TEST(lldir "" "${test_libs}")
+endif (LL_TESTS)
diff --git a/indra/llfilesystem/lldir.cpp b/indra/llfilesystem/lldir.cpp
new file mode 100644
index 0000000000..69b23f9cf8
--- /dev/null
+++ b/indra/llfilesystem/lldir.cpp
@@ -0,0 +1,1141 @@
+/** 
+ * @file lldir.cpp
+ * @brief implementation of directory utilities base class
+ *
+ * $LicenseInfo:firstyear=2002&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+
+#if !LL_WINDOWS
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <errno.h>
+#else
+#include <direct.h>
+#endif
+
+#include "lldir.h"
+
+#include "llerror.h"
+#include "lltimer.h"	// ms_sleep()
+#include "lluuid.h"
+
+#include "lldiriterator.h"
+#include "stringize.h"
+#include "llstring.h"
+#include <boost/filesystem.hpp>
+#include <boost/foreach.hpp>
+#include <boost/range/begin.hpp>
+#include <boost/range/end.hpp>
+#include <boost/assign/list_of.hpp>
+#include <boost/bind.hpp>
+#include <boost/ref.hpp>
+#include <algorithm>
+
+using boost::assign::list_of;
+using boost::assign::map_list_of;
+
+#if LL_WINDOWS
+#include "lldir_win32.h"
+LLDir_Win32 gDirUtil;
+#elif LL_DARWIN
+#include "lldir_mac.h"
+LLDir_Mac gDirUtil;
+#else
+#include "lldir_linux.h"
+LLDir_Linux gDirUtil;
+#endif
+
+LLDir *gDirUtilp = (LLDir *)&gDirUtil;
+
+/// Values for findSkinnedFilenames(subdir) parameter
+const char
+	*LLDir::XUI      = "xui",
+	*LLDir::TEXTURES = "textures",
+	*LLDir::SKINBASE = "";
+
+static const char* const empty = "";
+std::string LLDir::sDumpDir = "";
+
+LLDir::LLDir()
+:	mAppName(""),
+	mExecutablePathAndName(""),
+	mExecutableFilename(""),
+	mExecutableDir(""),
+	mAppRODataDir(""),
+	mOSUserDir(""),
+	mOSUserAppDir(""),
+	mLindenUserDir(""),
+	mOSCacheDir(""),
+	mCAFile(""),
+	mTempDir(""),
+	mDirDelimiter("/"), // fallback to forward slash if not overridden
+	mLanguage("en"),
+	mUserName("undefined")
+{
+}
+
+LLDir::~LLDir()
+{
+}
+
+std::vector<std::string> LLDir::getFilesInDir(const std::string &dirname)
+{
+    //Returns a vector of fullpath filenames.
+
+#ifdef LL_WINDOWS // or BOOST_WINDOWS_API
+    boost::filesystem::path p(utf8str_to_utf16str(dirname));
+#else
+    boost::filesystem::path p(dirname);
+#endif
+
+    std::vector<std::string> v;
+    
+    if (exists(p))
+    {
+        if (is_directory(p))
+        {
+            boost::filesystem::directory_iterator end_iter;
+            for (boost::filesystem::directory_iterator dir_itr(p);
+                 dir_itr != end_iter;
+                 ++dir_itr)
+            {
+                if (boost::filesystem::is_regular_file(dir_itr->status()))
+                {
+                    v.push_back(dir_itr->path().filename().string());
+                }
+            }
+        }
+    }
+    return v;
+}   
+            
+S32 LLDir::deleteFilesInDir(const std::string &dirname, const std::string &mask)
+{
+	S32 count = 0;
+	std::string filename; 
+	std::string fullpath;
+	S32 result;
+
+	// File masks starting with "/" will match nothing, so we consider them invalid.
+	if (LLStringUtil::startsWith(mask, getDirDelimiter()))
+	{
+		LL_WARNS() << "Invalid file mask: " << mask << LL_ENDL;
+		llassert(!"Invalid file mask");
+	}
+
+	LLDirIterator iter(dirname, mask);
+	while (iter.next(filename))
+	{
+		fullpath = add(dirname, filename);
+
+		if(LLFile::isdir(fullpath))
+		{
+			// skipping directory traversal filenames
+			count++;
+			continue;
+		}
+
+		S32 retry_count = 0;
+		while (retry_count < 5)
+		{
+			if (0 != LLFile::remove(fullpath))
+			{
+				retry_count++;
+				result = errno;
+				LL_WARNS() << "Problem removing " << fullpath << " - errorcode: "
+						<< result << " attempt " << retry_count << LL_ENDL;
+
+				if(retry_count >= 5)
+				{
+					LL_WARNS() << "Failed to remove " << fullpath << LL_ENDL ;
+					return count ;
+				}
+
+				ms_sleep(100);
+			}
+			else
+			{
+				if (retry_count)
+				{
+					LL_WARNS() << "Successfully removed " << fullpath << LL_ENDL;
+				}
+				break;
+			}			
+		}
+		count++;
+	}
+	return count;
+}
+
+U32 LLDir::deleteDirAndContents(const std::string& dir_name)
+{
+    //Removes the directory and its contents.  Returns number of files deleted.
+	
+	U32 num_deleted = 0;
+
+	try
+	{
+#ifdef LL_WINDOWS // or BOOST_WINDOWS_API
+		boost::filesystem::path dir_path(utf8str_to_utf16str(dir_name));
+#else
+		boost::filesystem::path dir_path(dir_name);
+#endif
+
+	   if (boost::filesystem::exists (dir_path))
+	   {
+	      if (!boost::filesystem::is_empty (dir_path))
+		  {   // Directory has content
+		     num_deleted = boost::filesystem::remove_all (dir_path);
+		  }
+		  else
+		  {   // Directory is empty
+		     boost::filesystem::remove (dir_path);
+		  }
+	   }
+	}
+	catch (boost::filesystem::filesystem_error &er)
+	{ 
+		LL_WARNS() << "Failed to delete " << dir_name << " with error " << er.code().message() << LL_ENDL;
+	} 
+	return num_deleted;
+}
+
+const std::string LLDir::findFile(const std::string &filename, 
+						   const std::string& searchPath1, 
+						   const std::string& searchPath2, 
+						   const std::string& searchPath3) const
+{
+	std::vector<std::string> search_paths;
+	search_paths.push_back(searchPath1);
+	search_paths.push_back(searchPath2);
+	search_paths.push_back(searchPath3);
+	return findFile(filename, search_paths);
+}
+
+const std::string LLDir::findFile(const std::string& filename, const std::vector<std::string> search_paths) const
+{
+	std::vector<std::string>::const_iterator search_path_iter;
+	for (search_path_iter = search_paths.begin();
+		search_path_iter != search_paths.end();
+		++search_path_iter)
+	{
+		if (!search_path_iter->empty())
+		{
+			std::string filename_and_path = (*search_path_iter);
+			if (!filename.empty())
+			{
+				filename_and_path += getDirDelimiter() + filename;
+			}
+			if (fileExists(filename_and_path))
+			{
+				return filename_and_path;
+			}
+		}
+	}
+	return "";
+}
+
+
+const std::string &LLDir::getExecutablePathAndName() const
+{
+	return mExecutablePathAndName;
+}
+
+const std::string &LLDir::getExecutableFilename() const
+{
+	return mExecutableFilename;
+}
+
+const std::string &LLDir::getExecutableDir() const
+{
+	return mExecutableDir;
+}
+
+const std::string &LLDir::getWorkingDir() const
+{
+	return mWorkingDir;
+}
+
+const std::string &LLDir::getAppName() const
+{
+	return mAppName;
+}
+
+const std::string &LLDir::getAppRODataDir() const
+{
+	return mAppRODataDir;
+}
+
+const std::string &LLDir::getOSUserDir() const
+{
+	return mOSUserDir;
+}
+
+const std::string &LLDir::getOSUserAppDir() const
+{
+	return mOSUserAppDir;
+}
+
+const std::string &LLDir::getLindenUserDir() const
+{
+	if (mLindenUserDir.empty())
+	{
+		LL_DEBUGS() << "getLindenUserDir() called early, we don't have the user name yet - returning empty string to caller" << LL_ENDL;
+	}
+
+	return mLindenUserDir;
+}
+
+const std::string& LLDir::getChatLogsDir() const
+{
+	return mChatLogsDir;
+}
+
+void LLDir::setDumpDir( const std::string& path )
+{
+    LLDir::sDumpDir = path;
+    if (LLStringUtil::endsWith(sDumpDir, mDirDelimiter))
+    {
+        sDumpDir.erase(sDumpDir.size() - mDirDelimiter.size());
+    }
+}
+
+const std::string &LLDir::getDumpDir() const
+{
+    if (sDumpDir.empty() )
+    {
+        LLUUID uid;
+        uid.generate();
+        
+        sDumpDir = gDirUtilp->getExpandedFilename(LL_PATH_LOGS, "")
+                    + "dump-" + uid.asString();
+
+        dir_exists_or_crash(sDumpDir);  
+    }
+
+	return LLDir::sDumpDir;
+}
+
+bool LLDir::dumpDirExists() const
+{
+    return !sDumpDir.empty();
+}
+
+const std::string &LLDir::getPerAccountChatLogsDir() const
+{
+	return mPerAccountChatLogsDir;
+}
+
+const std::string &LLDir::getTempDir() const
+{
+	return mTempDir;
+}
+
+const std::string  LLDir::getCacheDir(bool get_default) const
+{
+	if (mCacheDir.empty() || get_default)
+	{
+		if (!mDefaultCacheDir.empty())
+		{	// Set at startup - can't set here due to const API
+			return mDefaultCacheDir;
+		}
+		
+		std::string res = buildSLOSCacheDir();
+		return res;
+	}
+	else
+	{
+		return mCacheDir;
+	}
+}
+
+// Return the default cache directory
+std::string LLDir::buildSLOSCacheDir() const
+{
+	std::string res;
+	if (getOSCacheDir().empty())
+	{
+		if (getOSUserAppDir().empty())
+		{
+			res = "data";
+		}
+		else
+		{
+			res = add(getOSUserAppDir(), "cache");
+		}
+	}
+	else
+	{
+		res = add(getOSCacheDir(), "SecondLife");
+	}
+	return res;
+}
+
+
+
+const std::string &LLDir::getOSCacheDir() const
+{
+	return mOSCacheDir;
+}
+
+
+const std::string &LLDir::getCAFile() const
+{
+	return mCAFile;
+}
+
+const std::string &LLDir::getDirDelimiter() const
+{
+	return mDirDelimiter;
+}
+
+const std::string& LLDir::getDefaultSkinDir() const
+{
+	return mDefaultSkinDir;
+}
+
+const std::string &LLDir::getSkinDir() const
+{
+	return mSkinDir;
+}
+
+const std::string &LLDir::getUserDefaultSkinDir() const
+{
+    return mUserDefaultSkinDir;
+}
+
+const std::string &LLDir::getUserSkinDir() const
+{
+	return mUserSkinDir;
+}
+
+const std::string LLDir::getSkinBaseDir() const
+{
+	return mSkinBaseDir;
+}
+
+const std::string &LLDir::getLLPluginDir() const
+{
+	return mLLPluginDir;
+}
+
+const std::string &LLDir::getUserName() const
+{
+	return mUserName;
+}
+
+static std::string ELLPathToString(ELLPath location)
+{
+	typedef std::map<ELLPath, const char*> ELLPathMap;
+#define ENT(symbol) (symbol, #symbol)
+	static const ELLPathMap sMap = map_list_of
+		ENT(LL_PATH_NONE)
+		ENT(LL_PATH_USER_SETTINGS)
+		ENT(LL_PATH_APP_SETTINGS)
+		ENT(LL_PATH_PER_SL_ACCOUNT) // returns/expands to blank string if we don't know the account name yet
+		ENT(LL_PATH_CACHE)
+		ENT(LL_PATH_CHARACTER)
+		ENT(LL_PATH_HELP)
+		ENT(LL_PATH_LOGS)
+		ENT(LL_PATH_TEMP)
+		ENT(LL_PATH_SKINS)
+		ENT(LL_PATH_TOP_SKIN)
+		ENT(LL_PATH_CHAT_LOGS)
+		ENT(LL_PATH_PER_ACCOUNT_CHAT_LOGS)
+		ENT(LL_PATH_USER_SKIN)
+		ENT(LL_PATH_LOCAL_ASSETS)
+		ENT(LL_PATH_EXECUTABLE)
+		ENT(LL_PATH_DEFAULT_SKIN)
+		ENT(LL_PATH_FONTS)
+		ENT(LL_PATH_LAST)
+	;
+#undef ENT
+
+	ELLPathMap::const_iterator found = sMap.find(location);
+	if (found != sMap.end())
+		return found->second;
+	return STRINGIZE("Invalid ELLPath value " << location);
+}
+
+std::string LLDir::getExpandedFilename(ELLPath location, const std::string& filename) const
+{
+	return getExpandedFilename(location, "", filename);
+}
+
+std::string LLDir::getExpandedFilename(ELLPath location, const std::string& subdir, const std::string& filename) const
+{
+	return getExpandedFilename(location, "", subdir, filename);
+}
+
+std::string LLDir::getExpandedFilename(ELLPath location, const std::string& subdir1, const std::string& subdir2, const std::string& in_filename) const
+{
+	std::string prefix;
+	switch (location)
+	{
+	case LL_PATH_NONE:
+		// Do nothing
+		break;
+
+	case LL_PATH_APP_SETTINGS:
+		prefix = add(getAppRODataDir(), "app_settings");
+		break;
+	
+	case LL_PATH_CHARACTER:
+		prefix = add(getAppRODataDir(), "character");
+		break;
+		
+	case LL_PATH_HELP:
+		prefix = "help";
+		break;
+		
+	case LL_PATH_CACHE:
+		prefix = getCacheDir();
+		break;
+		
+    case LL_PATH_DUMP:
+        prefix=getDumpDir();
+        break;
+            
+	case LL_PATH_USER_SETTINGS:
+		prefix = add(getOSUserAppDir(), "user_settings");
+		break;
+
+	case LL_PATH_PER_SL_ACCOUNT:
+		prefix = getLindenUserDir();
+		if (prefix.empty())
+		{
+			// if we're asking for the per-SL-account directory but we haven't
+			// logged in yet (or otherwise don't know the account name from
+			// which to build this string), then intentionally return a blank
+			// string to the caller and skip the below warning about a blank
+			// prefix.
+			LL_DEBUGS("LLDir") << "getLindenUserDir() not yet set: "
+							   << ELLPathToString(location)
+							   << ", '" << subdir1 << "', '" << subdir2 << "', '" << in_filename
+							   << "' => ''" << LL_ENDL;
+			return std::string();
+		}
+		break;
+		
+	case LL_PATH_CHAT_LOGS:
+		prefix = getChatLogsDir();
+		break;
+		
+	case LL_PATH_PER_ACCOUNT_CHAT_LOGS:
+		prefix = getPerAccountChatLogsDir();
+		if (prefix.empty())
+		{
+			// potentially directory was not set yet
+			// intentionally return a blank string to the caller
+			LL_DEBUGS("LLDir") << "Conversation log directory is not yet set" << LL_ENDL;
+			return std::string();
+		}
+		break;
+
+	case LL_PATH_LOGS:
+		prefix = add(getOSUserAppDir(), "logs");
+		break;
+
+	case LL_PATH_TEMP:
+		prefix = getTempDir();
+		break;
+
+	case LL_PATH_TOP_SKIN:
+		prefix = getSkinDir();
+		break;
+
+	case LL_PATH_DEFAULT_SKIN:
+		prefix = getDefaultSkinDir();
+		break;
+
+	case LL_PATH_USER_SKIN:
+		prefix = getUserSkinDir();
+		break;
+
+	case LL_PATH_SKINS:
+		prefix = getSkinBaseDir();
+		break;
+
+	case LL_PATH_LOCAL_ASSETS:
+		prefix = add(getAppRODataDir(), "local_assets");
+		break;
+
+	case LL_PATH_EXECUTABLE:
+		prefix = getExecutableDir();
+		break;
+		
+	case LL_PATH_FONTS:
+		prefix = add(getAppRODataDir(), "fonts");
+		break;
+		
+	default:
+		llassert(0);
+	}
+
+	if (prefix.empty())
+	{
+		LL_WARNS() << ELLPathToString(location)
+				<< ", '" << subdir1 << "', '" << subdir2 << "', '" << in_filename
+				<< "': prefix is empty, possible bad filename" << LL_ENDL;
+	}
+
+	std::string expanded_filename = add(prefix, subdir1, subdir2);
+	if (expanded_filename.empty() && in_filename.empty())
+	{
+		return "";
+	}
+	// Use explicit concatenation here instead of another add() call. Callers
+	// passing in_filename as "" expect to obtain a pathname ending with
+	// mDirSeparator so they can later directly concatenate with a specific
+	// filename. A caller using add() doesn't care, but there's still code
+	// loose in the system that uses std::string::operator+().
+	expanded_filename += mDirDelimiter;
+	expanded_filename += in_filename;
+
+	LL_DEBUGS("LLDir") << ELLPathToString(location)
+					   << ", '" << subdir1 << "', '" << subdir2 << "', '" << in_filename
+					   << "' => '" << expanded_filename << "'" << LL_ENDL;
+	return expanded_filename;
+}
+
+std::string LLDir::getBaseFileName(const std::string& filepath, bool strip_exten) const
+{
+	std::size_t offset = filepath.find_last_of(getDirDelimiter());
+	offset = (offset == std::string::npos) ? 0 : offset+1;
+	std::string res = filepath.substr(offset, std::string::npos);
+	if (strip_exten)
+	{
+		offset = res.find_last_of('.');
+		if (offset != std::string::npos &&
+		    offset != 0) // if basename STARTS with '.', don't strip
+		{
+			res = res.substr(0, offset);
+		}
+	}
+	return res;
+}
+
+std::string LLDir::getDirName(const std::string& filepath) const
+{
+	std::size_t offset = filepath.find_last_of(getDirDelimiter());
+	S32 len = (offset == std::string::npos) ? 0 : offset;
+	std::string dirname = filepath.substr(0, len);
+	return dirname;
+}
+
+std::string LLDir::getExtension(const std::string& filepath) const
+{
+	if (filepath.empty())
+		return std::string();
+	std::string basename = getBaseFileName(filepath, false);
+	std::size_t offset = basename.find_last_of('.');
+	std::string exten = (offset == std::string::npos || offset == 0) ? "" : basename.substr(offset+1);
+	LLStringUtil::toLower(exten);
+	return exten;
+}
+
+std::string LLDir::findSkinnedFilenameBaseLang(const std::string &subdir,
+											   const std::string &filename,
+											   ESkinConstraint constraint) const
+{
+	// This implementation is basically just as described in the declaration comments.
+	std::vector<std::string> found(findSkinnedFilenames(subdir, filename, constraint));
+	if (found.empty())
+	{
+		return "";
+	}
+	return found.front();
+}
+
+std::string LLDir::findSkinnedFilename(const std::string &subdir,
+									   const std::string &filename,
+									   ESkinConstraint constraint) const
+{
+	// This implementation is basically just as described in the declaration comments.
+	std::vector<std::string> found(findSkinnedFilenames(subdir, filename, constraint));
+	if (found.empty())
+	{
+		return "";
+	}
+	return found.back();
+}
+
+// This method exists because the two code paths for
+// findSkinnedFilenames(ALL_SKINS) and findSkinnedFilenames(CURRENT_SKIN) must
+// generate the list of candidate pathnames in identical ways. The only
+// difference is in the body of the inner loop.
+template <typename FUNCTION>
+void LLDir::walkSearchSkinDirs(const std::string& subdir,
+							   const std::vector<std::string>& subsubdirs,
+							   const std::string& filename,
+							   const FUNCTION& function) const
+{
+	BOOST_FOREACH(std::string skindir, mSearchSkinDirs)
+	{
+		std::string subdir_path(add(skindir, subdir));
+		BOOST_FOREACH(std::string subsubdir, subsubdirs)
+		{
+			std::string full_path(add(subdir_path, subsubdir, filename));
+			if (fileExists(full_path))
+			{
+				function(subsubdir, full_path);
+			}
+		}
+	}
+}
+
+// ridiculous little helper function that should go away when we can use lambda
+inline void push_back(std::vector<std::string>& vector, const std::string& value)
+{
+	vector.push_back(value);
+}
+
+typedef std::map<std::string, std::string> StringMap;
+// ridiculous little helper function that should go away when we can use lambda
+inline void store_in_map(StringMap& map, const std::string& key, const std::string& value)
+{
+	map[key] = value;
+}
+
+std::vector<std::string> LLDir::findSkinnedFilenames(const std::string& subdir,
+													 const std::string& filename,
+													 ESkinConstraint constraint) const
+{
+	// Recognize subdirs that have no localization.
+	static const std::set<std::string> sUnlocalized = list_of
+		("")                        // top-level directory not localized
+		("textures")                // textures not localized
+	;
+
+	LL_DEBUGS("LLDir") << "subdir '" << subdir << "', filename '" << filename
+					   << "', constraint "
+					   << ((constraint == CURRENT_SKIN)? "CURRENT_SKIN" : "ALL_SKINS")
+					   << LL_ENDL;
+
+	// Build results vector.
+	std::vector<std::string> results;
+	// Disallow filenames that may escape subdir
+	if (filename.find("..") != std::string::npos)
+	{
+		LL_WARNS("LLDir") << "Ignoring potentially relative filename '" << filename << "'" << LL_ENDL;
+		return results;
+	}
+
+	// Cache the default language directory for each subdir we've encountered.
+	// A cache entry whose value is the empty string means "not localized,
+	// don't bother checking again."
+	static StringMap sLocalized;
+
+	// Check whether we've already discovered if this subdir is localized.
+	StringMap::const_iterator found = sLocalized.find(subdir);
+	if (found == sLocalized.end())
+	{
+		// We have not yet determined that. Is it one of the subdirs "known"
+		// to be unlocalized?
+		if (sUnlocalized.find(subdir) != sUnlocalized.end())
+		{
+			// This subdir is known to be unlocalized. Remember that.
+			found = sLocalized.insert(StringMap::value_type(subdir, "")).first;
+		}
+		else
+		{
+			// We do not recognize this subdir. Investigate.
+			std::string subdir_path(add(getDefaultSkinDir(), subdir));
+			if (fileExists(add(subdir_path, "en")))
+			{
+				// defaultSkinDir/subdir contains subdir "en". That's our
+				// default language; this subdir is localized.
+				found = sLocalized.insert(StringMap::value_type(subdir, "en")).first;
+			}
+			else if (fileExists(add(subdir_path, "en-us")))
+			{
+				// defaultSkinDir/subdir contains subdir "en-us" but not "en".
+				// Set as default language; this subdir is localized.
+				found = sLocalized.insert(StringMap::value_type(subdir, "en-us")).first;
+			}
+			else
+			{
+				// defaultSkinDir/subdir contains neither "en" nor "en-us".
+				// Assume it's not localized. Remember that assumption.
+				found = sLocalized.insert(StringMap::value_type(subdir, "")).first;
+			}
+		}
+	}
+	// Every code path above should have resulted in 'found' becoming a valid
+	// iterator to an entry in sLocalized.
+	llassert(found != sLocalized.end());
+
+	// Now -- is this subdir localized, or not? The answer determines what
+	// subdirectories we check (under subdir) for the requested filename.
+	std::vector<std::string> subsubdirs;
+	if (found->second.empty())
+	{
+		// subdir is not localized. filename should be located directly within it.
+		subsubdirs.push_back("");
+	}
+	else
+	{
+		// subdir is localized, and found->second is the default language
+		// directory within it. Check both the default language and the
+		// current language -- if it differs from the default, of course.
+		subsubdirs.push_back(found->second);
+		if (mLanguage != found->second)
+		{
+			subsubdirs.push_back(mLanguage);
+		}
+	}
+
+	// The process we use depends on 'constraint'.
+	if (constraint != CURRENT_SKIN) // meaning ALL_SKINS
+	{
+		// ALL_SKINS is simpler: just return every pathname generated by
+		// walkSearchSkinDirs(). Tricky bit: walkSearchSkinDirs() passes its
+		// FUNCTION the subsubdir as well as the full pathname. We just want
+		// the full pathname.
+		walkSearchSkinDirs(subdir, subsubdirs, filename,
+						   boost::bind(push_back, boost::ref(results), _2));
+	}
+	else                            // CURRENT_SKIN
+	{
+		// CURRENT_SKIN turns out to be a bit of a misnomer because we might
+		// still return files from two different skins. In any case, this
+		// value of 'constraint' means we will return at most two paths: one
+		// for the default language, one for the current language (supposing
+		// those differ).
+		// It is important to allow a user to override only the localization
+		// for a particular file, for all viewer installs, without also
+		// overriding the default-language file.
+		// It is important to allow a user to override only the default-
+		// language file, for all viewer installs, without also overriding the
+		// applicable localization of that file.
+		// Therefore, treat the default language and the current language as
+		// two separate cases. For each, capture the most-specialized file
+		// that exists.
+		// Use a map keyed by subsubdir (i.e. language code). This allows us
+		// to handle the case of a single subsubdirs entry with the same logic
+		// that handles two. For every real file path generated by
+		// walkSearchSkinDirs(), update the map entry for its subsubdir.
+		StringMap path_for;
+		walkSearchSkinDirs(subdir, subsubdirs, filename,
+						   boost::bind(store_in_map, boost::ref(path_for), _1, _2));
+		// Now that we have a path for each of the default language and the
+		// current language, copy them -- in proper order -- into results.
+		// Don't drive this by walking the map itself: it matters that we
+		// generate results in the same order as subsubdirs.
+		BOOST_FOREACH(std::string subsubdir, subsubdirs)
+		{
+			StringMap::const_iterator found(path_for.find(subsubdir));
+			if (found != path_for.end())
+			{
+				results.push_back(found->second);
+			}
+		}
+	}
+
+	LL_DEBUGS("LLDir") << empty;
+	const char* comma = "";
+	BOOST_FOREACH(std::string path, results)
+	{
+		LL_CONT << comma << "'" << path << "'";
+		comma = ", ";
+	}
+	LL_CONT << LL_ENDL;
+
+	return results;
+}
+
+std::string LLDir::getTempFilename() const
+{
+	LLUUID random_uuid;
+	std::string uuid_str;
+
+	random_uuid.generate();
+	random_uuid.toString(uuid_str);
+
+	return add(getTempDir(), uuid_str + ".tmp");
+}
+
+// static
+std::string LLDir::getScrubbedFileName(const std::string uncleanFileName)
+{
+	std::string name(uncleanFileName);
+	const std::string illegalChars(getForbiddenFileChars());
+	// replace any illegal file chars with and underscore '_'
+	for( unsigned int i = 0; i < illegalChars.length(); i++ )
+	{
+		int j = -1;
+		while((j = name.find(illegalChars[i])) > -1)
+		{
+			name[j] = '_';
+		}
+	}
+	return name;
+}
+
+std::string LLDir::getDumpLogsDirPath(const std::string &file_name)
+{
+    return gDirUtilp->getExpandedFilename(LL_PATH_LOGS, "dump_logs", file_name);
+}
+
+// static
+std::string LLDir::getForbiddenFileChars()
+{
+	return "\\/:*?\"<>|";
+}
+
+void LLDir::setLindenUserDir(const std::string &username)
+{
+	// if the username isn't set, that's bad
+	if (!username.empty())
+	{
+		// some platforms have case-sensitive filesystems, so be
+		// utterly consistent with our firstname/lastname case.
+		std::string userlower(username);
+		LLStringUtil::toLower(userlower);
+		LLStringUtil::replaceChar(userlower, ' ', '_');
+		mLindenUserDir = add(getOSUserAppDir(), userlower);
+	}
+	else
+	{
+		LL_ERRS() << "NULL name for LLDir::setLindenUserDir" << LL_ENDL;
+	}
+
+	dumpCurrentDirectories();	
+}
+
+void LLDir::setChatLogsDir(const std::string &path)
+{
+	if (!path.empty() )
+	{
+		mChatLogsDir = path;
+	}
+	else
+	{
+		LL_WARNS() << "Invalid name for LLDir::setChatLogsDir" << LL_ENDL;
+	}
+}
+
+void LLDir::updatePerAccountChatLogsDir()
+{
+	mPerAccountChatLogsDir = add(getChatLogsDir(), mUserName);
+}
+
+void LLDir::setPerAccountChatLogsDir(const std::string &username)
+{
+	// if both first and last aren't set, assume we're grabbing the cached dir
+	if (!username.empty())
+	{
+		// some platforms have case-sensitive filesystems, so be
+		// utterly consistent with our firstname/lastname case.
+		std::string userlower(username);
+		LLStringUtil::toLower(userlower);
+		LLStringUtil::replaceChar(userlower, ' ', '_');
+
+		mUserName = userlower;
+		updatePerAccountChatLogsDir();
+	}
+	else
+	{
+		LL_ERRS() << "NULL name for LLDir::setPerAccountChatLogsDir" << LL_ENDL;
+	}
+}
+
+void LLDir::setSkinFolder(const std::string &skin_folder, const std::string& language)
+{
+	LL_DEBUGS("LLDir") << "Setting skin '" << skin_folder << "', language '" << language << "'"
+					   << LL_ENDL;
+	mSkinName = skin_folder;
+	mLanguage = language;
+
+	// This method is called multiple times during viewer initialization. Each
+	// time it's called, reset mSearchSkinDirs.
+	mSearchSkinDirs.clear();
+
+	// base skin which is used as fallback for all skinned files
+	// e.g. c:\program files\secondlife\skins\default
+	mDefaultSkinDir = getSkinBaseDir();
+	append(mDefaultSkinDir, "default");
+	// This is always the most general of the search skin directories.
+	addSearchSkinDir(mDefaultSkinDir);
+
+	mSkinDir = getSkinBaseDir();
+	append(mSkinDir, skin_folder);
+	// Next level of generality is a skin installed with the viewer.
+	addSearchSkinDir(mSkinDir);
+
+	// user modifications to skins, current and default
+	// e.g. c:\documents and settings\users\username\application data\second life\skins\dazzle
+	mUserSkinDir = getOSUserAppDir();
+	append(mUserSkinDir, "skins");
+	mUserDefaultSkinDir = mUserSkinDir;
+	append(mUserDefaultSkinDir, "default");
+	append(mUserSkinDir, skin_folder);
+	// Next level of generality is user modifications to default skin...
+	addSearchSkinDir(mUserDefaultSkinDir);
+	// then user-defined skins.
+	addSearchSkinDir(mUserSkinDir);
+}
+
+void LLDir::addSearchSkinDir(const std::string& skindir)
+{
+	if (std::find(mSearchSkinDirs.begin(), mSearchSkinDirs.end(), skindir) == mSearchSkinDirs.end())
+	{
+		LL_DEBUGS("LLDir") << "search skin: '" << skindir << "'" << LL_ENDL;
+		mSearchSkinDirs.push_back(skindir);
+	}
+}
+
+std::string LLDir::getSkinFolder() const
+{
+	return mSkinName;
+}
+
+std::string LLDir::getLanguage() const
+{
+	return mLanguage;
+}
+
+bool LLDir::setCacheDir(const std::string &path)
+{
+	if (path.empty() )
+	{
+		// reset to default
+		mCacheDir = "";
+		return true;
+	}
+	else
+	{
+		LLFile::mkdir(path);
+		std::string tempname = add(path, "temp");
+		LLFILE* file = LLFile::fopen(tempname,"wt");
+		if (file)
+		{
+			fclose(file);
+			LLFile::remove(tempname);
+			mCacheDir = path;
+			return true;
+		}
+		return false;
+	}
+}
+
+void LLDir::dumpCurrentDirectories(LLError::ELevel level)
+{
+	LL_VLOGS(level, "AppInit","Directories") << "Current Directories:" << LL_ENDL;
+
+	LL_VLOGS(level, "AppInit", "Directories") << "  CurPath:               " << getCurPath() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  AppName:               " << getAppName() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  ExecutableFilename:    " << getExecutableFilename() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  ExecutableDir:         " << getExecutableDir() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  ExecutablePathAndName: " << getExecutablePathAndName() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  WorkingDir:            " << getWorkingDir() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  AppRODataDir:          " << getAppRODataDir() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  OSUserDir:             " << getOSUserDir() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  OSUserAppDir:          " << getOSUserAppDir() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  LindenUserDir:         " << getLindenUserDir() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  TempDir:               " << getTempDir() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  CAFile:                " << getCAFile() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  SkinBaseDir:           " << getSkinBaseDir() << LL_ENDL;
+	LL_VLOGS(level, "AppInit", "Directories") << "  SkinDir:               " << getSkinDir() << LL_ENDL;
+}
+
+void LLDir::append(std::string& destpath, const std::string& name) const
+{
+	// Delegate question of whether we need a separator to helper method.
+	SepOff sepoff(needSep(destpath, name));
+	if (sepoff.first)               // do we need a separator?
+	{
+		destpath += mDirDelimiter;
+	}
+	// If destpath ends with a separator, AND name starts with one, skip
+	// name's leading separator.
+	destpath += name.substr(sepoff.second);
+}
+
+LLDir::SepOff LLDir::needSep(const std::string& path, const std::string& name) const
+{
+	if (path.empty() || name.empty())
+	{
+		// If either path or name are empty, we do not need a separator
+		// between them.
+		return SepOff(false, 0);
+	}
+	// Here we know path and name are both non-empty. But if path already ends
+	// with a separator, or if name already starts with a separator, we need
+	// not add one.
+	std::string::size_type seplen(mDirDelimiter.length());
+	bool path_ends_sep(path.substr(path.length() - seplen) == mDirDelimiter);
+	bool name_starts_sep(name.substr(0, seplen) == mDirDelimiter);
+	if ((! path_ends_sep) && (! name_starts_sep))
+	{
+		// If neither path nor name brings a separator to the junction, then
+		// we need one.
+		return SepOff(true, 0);
+	}
+	if (path_ends_sep && name_starts_sep)
+	{
+		// But if BOTH path and name bring a separator, we need not add one.
+		// Moreover, we should actually skip the leading separator of 'name'.
+		return SepOff(false, (unsigned short)seplen);
+	}
+	// Here we know that either path_ends_sep or name_starts_sep is true --
+	// but not both. So don't add a separator, and don't skip any characters:
+	// simple concatenation will do the trick.
+	return SepOff(false, 0);
+}
+
+void dir_exists_or_crash(const std::string &dir_name)
+{
+#if LL_WINDOWS
+	// *FIX: lame - it doesn't do the same thing on windows. not so
+	// important since we don't deploy simulator to windows boxes.
+	LLFile::mkdir(dir_name, 0700);
+#else
+	struct stat dir_stat;
+	if(0 != LLFile::stat(dir_name, &dir_stat))
+	{
+		S32 stat_rv = errno;
+		if(ENOENT == stat_rv)
+		{
+		   if(0 != LLFile::mkdir(dir_name, 0700))		// octal
+		   {
+			   LL_ERRS() << "Unable to create directory: " << dir_name << LL_ENDL;
+		   }
+		}
+		else
+		{
+			LL_ERRS() << "Unable to stat: " << dir_name << " errno = " << stat_rv
+				   << LL_ENDL;
+		}
+	}
+	else
+	{
+		// data_dir exists, make sure it's a directory.
+		if(!S_ISDIR(dir_stat.st_mode))
+		{
+			LL_ERRS() << "Data directory collision: " << dir_name << LL_ENDL;
+		}
+	}
+#endif
+}
diff --git a/indra/llfilesystem/lldir.h b/indra/llfilesystem/lldir.h
new file mode 100644
index 0000000000..b9a046ba33
--- /dev/null
+++ b/indra/llfilesystem/lldir.h
@@ -0,0 +1,278 @@
+/**  
+ * @file lldir.h
+ * @brief Definition of directory utilities class
+ *
+ * $LicenseInfo:firstyear=2000&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#ifndef LL_LLDIR_H
+#define LL_LLDIR_H
+
+// these numbers are read from settings_files.xml, so we need to be explicit
+typedef enum ELLPath
+{
+	LL_PATH_NONE = 0,
+	LL_PATH_USER_SETTINGS = 1,
+	LL_PATH_APP_SETTINGS = 2,	
+	LL_PATH_PER_SL_ACCOUNT = 3, // returns/expands to blank string if we don't know the account name yet
+	LL_PATH_CACHE = 4,	
+	LL_PATH_CHARACTER = 5,	
+	LL_PATH_HELP = 6,		
+	LL_PATH_LOGS = 7,
+	LL_PATH_TEMP = 8,
+	LL_PATH_SKINS = 9,
+	LL_PATH_TOP_SKIN = 10,
+	LL_PATH_CHAT_LOGS = 11,
+	LL_PATH_PER_ACCOUNT_CHAT_LOGS = 12,
+	LL_PATH_USER_SKIN = 14,
+	LL_PATH_LOCAL_ASSETS = 15,
+	LL_PATH_EXECUTABLE = 16,
+	LL_PATH_DEFAULT_SKIN = 17,
+	LL_PATH_FONTS = 18,
+    LL_PATH_DUMP = 19,
+	LL_PATH_LAST
+} ELLPath;
+
+/// Directory operations
+class LLDir
+{
+ public:
+	LLDir();
+	virtual ~LLDir();
+
+	// app_name - Usually SecondLife, used for creating settings directories
+	// in OS-specific location, such as C:\Documents and Settings
+	// app_read_only_data_dir - Usually the source code directory, used
+	// for test applications to read newview data files.
+	virtual void initAppDirs(const std::string &app_name, 
+		const std::string& app_read_only_data_dir = "") = 0;
+
+	virtual S32 deleteFilesInDir(const std::string &dirname, const std::string &mask);
+    U32 deleteDirAndContents(const std::string& dir_name);
+    std::vector<std::string> getFilesInDir(const std::string &dirname);
+// pure virtual functions
+	virtual std::string getCurPath() = 0;
+	virtual bool fileExists(const std::string &filename) const = 0;
+
+	const std::string findFile(const std::string& filename, const std::vector<std::string> filenames) const; 
+	const std::string findFile(const std::string& filename, const std::string& searchPath1 = "", const std::string& searchPath2 = "", const std::string& searchPath3 = "") const;
+
+	virtual std::string getLLPluginLauncher() = 0; // full path and name for the plugin shell
+	virtual std::string getLLPluginFilename(std::string base_name) = 0; // full path and name to the plugin DSO for this base_name (i.e. 'FOO' -> '/bar/baz/libFOO.so')
+
+	const std::string &getExecutablePathAndName() const;	// Full pathname of the executable
+	const std::string &getAppName() const;			// install directory under progams/ ie "SecondLife"
+	const std::string &getExecutableDir() const;	// Directory where the executable is located
+	const std::string &getExecutableFilename() const;// Filename of .exe
+	const std::string &getWorkingDir() const; // Current working directory
+	const std::string &getAppRODataDir() const;	// Location of read-only data files
+	const std::string &getOSUserDir() const;		// Location of the os-specific user dir
+	const std::string &getOSUserAppDir() const;	// Location of the os-specific user app dir
+	const std::string &getLindenUserDir() const;	// Location of the Linden user dir.
+	const std::string &getChatLogsDir() const;	// Location of the chat logs dir.
+	const std::string &getDumpDir() const;	// Location of the per-run dump dir.
+	bool              dumpDirExists() const;
+	const std::string &getPerAccountChatLogsDir() const;	// Location of the per account chat logs dir.
+	const std::string &getTempDir() const;			// Common temporary directory
+	const std::string  getCacheDir(bool get_default = false) const;	// Location of the cache.
+	const std::string &getOSCacheDir() const;		// location of OS-specific cache folder (may be empty string)
+	const std::string &getCAFile() const;			// File containing TLS certificate authorities
+	const std::string &getDirDelimiter() const;	// directory separator for platform (ie. '\' or '/' or ':')
+	const std::string &getDefaultSkinDir() const;	// folder for default skin. e.g. c:\program files\second life\skins\default
+	const std::string &getSkinDir() const;		// User-specified skin folder.
+	const std::string &getUserDefaultSkinDir() const; // dir with user modifications to default skin
+	const std::string &getUserSkinDir() const;		// User-specified skin folder with user modifications. e.g. c:\documents and settings\username\application data\second life\skins\curskin
+	const std::string getSkinBaseDir() const;		// folder that contains all installed skins (not user modifications). e.g. c:\program files\second life\skins
+	const std::string &getLLPluginDir() const;		// Directory containing plugins and plugin shell
+	const std::string &getUserName() const;
+
+	// Expanded filename
+	std::string getExpandedFilename(ELLPath location, const std::string &filename) const;
+	std::string getExpandedFilename(ELLPath location, const std::string &subdir, const std::string &filename) const;
+	std::string getExpandedFilename(ELLPath location, const std::string &subdir1, const std::string &subdir2, const std::string &filename) const;
+
+	// Base and Directory name extraction
+	std::string getBaseFileName(const std::string& filepath, bool strip_exten = false) const;
+	std::string getDirName(const std::string& filepath) const;
+	std::string getExtension(const std::string& filepath) const; // Excludes '.', e.g getExtension("foo.wav") == "wav"
+
+	// these methods search the various skin paths for the specified file in the following order:
+	// getUserSkinDir(), getUserDefaultSkinDir(), getSkinDir(), getDefaultSkinDir()
+	/// param value for findSkinnedFilenames(), explained below
+	enum ESkinConstraint { CURRENT_SKIN, ALL_SKINS };
+	/**
+	 * Given a filename within skin, return an ordered sequence of paths to
+	 * search. Nonexistent files will be filtered out -- which means that the
+	 * vector might be empty.
+	 *
+	 * @param subdir Identify top-level skin subdirectory by passing one of
+	 * LLDir::XUI (file lives under "xui" subtree), LLDir::TEXTURES (file
+	 * lives under "textures" subtree), LLDir::SKINBASE (file lives at top
+	 * level of skin subdirectory).
+	 * @param filename Desired filename within subdir within skin, e.g.
+	 * "panel_login.xml". DO NOT prepend (e.g.) "xui" or the desired language.
+	 * @param constraint Callers perform two different kinds of processing.
+	 * When fetching a XUI file, for instance, the existence of @a filename in
+	 * the specified skin completely supercedes any @a filename in the default
+	 * skin. For that case, leave the default @a constraint=CURRENT_SKIN. The
+	 * returned vector will contain only
+	 * ".../<i>current_skin</i>/xui/en/<i>filename</i>",
+	 * ".../<i>current_skin</i>/xui/<i>current_language</i>/<i>filename</i>".
+	 * But for (e.g.) "strings.xml", we want a given skin to be able to
+	 * override only specific entries from the default skin. Any string not
+	 * defined in the specified skin will be sought in the default skin. For
+	 * that case, pass @a constraint=ALL_SKINS. The returned vector will
+	 * contain at least ".../default/xui/en/strings.xml",
+	 * ".../default/xui/<i>current_language</i>/strings.xml",
+	 * ".../<i>current_skin</i>/xui/en/strings.xml",
+	 * ".../<i>current_skin</i>/xui/<i>current_language</i>/strings.xml".
+	 */
+	std::vector<std::string> findSkinnedFilenames(const std::string& subdir,
+												  const std::string& filename,
+												  ESkinConstraint constraint=CURRENT_SKIN) const;
+	/// Values for findSkinnedFilenames(subdir) parameter
+	static const char *XUI, *TEXTURES, *SKINBASE;
+	/**
+	 * Return the base-language pathname from findSkinnedFilenames(), or
+	 * the empty string if no such file exists. Parameters are identical to
+	 * findSkinnedFilenames(). This is shorthand for capturing the vector
+	 * returned by findSkinnedFilenames(), checking for empty() and then
+	 * returning front().
+	 */
+	std::string findSkinnedFilenameBaseLang(const std::string &subdir,
+											const std::string &filename,
+											ESkinConstraint constraint=CURRENT_SKIN) const;
+	/**
+	 * Return the "most localized" pathname from findSkinnedFilenames(), or
+	 * the empty string if no such file exists. Parameters are identical to
+	 * findSkinnedFilenames(). This is shorthand for capturing the vector
+	 * returned by findSkinnedFilenames(), checking for empty() and then
+	 * returning back().
+	 */
+	std::string findSkinnedFilename(const std::string &subdir,
+									const std::string &filename,
+									ESkinConstraint constraint=CURRENT_SKIN) const;
+
+	// random filename in common temporary directory
+	std::string getTempFilename() const;
+
+    static std::string getDumpLogsDirPath(const std::string &file_name = "");
+
+	// For producing safe download file names from potentially unsafe ones
+	static std::string getScrubbedFileName(const std::string uncleanFileName);
+	static std::string getForbiddenFileChars();
+    void setDumpDir( const std::string& path );
+
+
+	virtual void setChatLogsDir(const std::string &path);		// Set the chat logs dir to this user's dir
+	virtual void setPerAccountChatLogsDir(const std::string &username);		// Set the per user chat log directory.
+	virtual void setLindenUserDir(const std::string &username);		// Set the linden user dir to this user's dir
+	virtual void setSkinFolder(const std::string &skin_folder, const std::string& language);
+	virtual std::string getSkinFolder() const;
+	virtual std::string getLanguage() const;
+	virtual bool setCacheDir(const std::string &path);
+	virtual void updatePerAccountChatLogsDir();
+
+	virtual void dumpCurrentDirectories(LLError::ELevel level = LLError::LEVEL_DEBUG);
+
+	// Utility routine
+	std::string buildSLOSCacheDir() const;
+
+	/// Append specified @a name to @a destpath, separated by getDirDelimiter()
+	/// if both are non-empty.
+	void append(std::string& destpath, const std::string& name) const;
+	/// Variadic form: append @a name0 and @a name1 and arbitrary other @a
+	/// names to @a destpath, separated by getDirDelimiter() as needed.
+	template <typename... NAMES>
+	void append(std::string& destpath, const std::string& name0, const std::string& name1,
+				const NAMES& ... names) const
+	{
+		// In a typical recursion case, we'd accept (destpath, name0, names).
+		// We accept (destpath, name0, name1, names) because it's important to
+		// delegate the two-argument case to the non-template implementation.
+		append(destpath, name0);
+		append(destpath, name1, names...);
+	}
+
+	/// Append specified @a names to @a path, separated by getDirDelimiter()
+	/// as needed. Return result, leaving @a path unmodified.
+	template <typename... NAMES>
+	std::string add(const std::string& path, const NAMES& ... names) const
+	{
+		std::string destpath(path);
+		append(destpath, names...);
+		return destpath;
+	}
+
+protected:
+	// Does an add() or append() call need a directory delimiter?
+	typedef std::pair<bool, unsigned short> SepOff;
+	SepOff needSep(const std::string& path, const std::string& name) const;
+	// build mSearchSkinDirs without adding duplicates
+	void addSearchSkinDir(const std::string& skindir);
+
+	// Internal to findSkinnedFilenames()
+	template <typename FUNCTION>
+	void walkSearchSkinDirs(const std::string& subdir,
+							const std::vector<std::string>& subsubdirs,
+							const std::string& filename,
+							const FUNCTION& function) const;
+
+	std::string mAppName;               // install directory under progams/ ie "SecondLife"   
+	std::string mExecutablePathAndName; // full path + Filename of .exe
+	std::string mExecutableFilename;    // Filename of .exe
+	std::string mExecutableDir;	 	 // Location of executable
+	std::string mWorkingDir;	 	 // Current working directory
+	std::string mAppRODataDir;			 // Location for static app data
+	std::string mOSUserDir;			 // OS Specific user directory
+	std::string mOSUserAppDir;			 // OS Specific user app directory
+	std::string mLindenUserDir;		 // Location for Linden user-specific data
+	std::string mPerAccountChatLogsDir;		 // Location for chat logs.
+	std::string mChatLogsDir;		 // Location for chat logs.
+	std::string mCAFile;				 // Location of the TLS certificate authority PEM file.
+	std::string mTempDir;
+	std::string mCacheDir;			// cache directory as set by user preference
+	std::string mDefaultCacheDir;	// default cache diretory
+	std::string mOSCacheDir;		// operating system cache dir
+	std::string mDirDelimiter;
+	std::string mSkinName;           // caller-specified skin name
+	std::string mSkinBaseDir;			// Base for skins paths.
+	std::string mDefaultSkinDir;			// Location for default skin info.
+	std::string mSkinDir;			// Location for current skin info.
+	std::string mUserDefaultSkinDir;		// Location for default skin info.
+	std::string mUserSkinDir;			// Location for user-modified skin info.
+	// Skin directories to search, most general to most specific. This order
+	// works well for composing fine-grained files, in which an individual item
+	// in a specific file overrides the corresponding item in more general
+	// files. Of course, for a file-level search, iterate backwards.
+	std::vector<std::string> mSearchSkinDirs;
+	std::string mLanguage;              // Current viewer language
+	std::string mLLPluginDir;			// Location for plugins and plugin shell
+    static std::string sDumpDir;            // Per-run crash report subdir of log directory.
+	std::string mUserName;				// Current user name
+};
+
+void dir_exists_or_crash(const std::string &dir_name);
+
+extern LLDir *gDirUtilp;
+
+#endif // LL_LLDIR_H
diff --git a/indra/llfilesystem/lldir_linux.cpp b/indra/llfilesystem/lldir_linux.cpp
new file mode 100644
index 0000000000..80ad05345a
--- /dev/null
+++ b/indra/llfilesystem/lldir_linux.cpp
@@ -0,0 +1,269 @@
+/** 
+ * @file lldir_linux.cpp
+ * @brief Implementation of directory utilities for linux
+ *
+ * $LicenseInfo:firstyear=2002&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+
+#include "lldir_linux.h"
+#include "llerror.h"
+#include "llrand.h"
+#include "llstring.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <glob.h>
+#include <pwd.h>
+
+
+static std::string getCurrentUserHome(char* fallback)
+{
+	const uid_t uid = getuid();
+	struct passwd *pw;
+
+	pw = getpwuid(uid);
+	if ((pw != NULL) && (pw->pw_dir != NULL))
+	{
+		return pw->pw_dir;
+	}
+
+	LL_INFOS() << "Couldn't detect home directory from passwd - trying $HOME" << LL_ENDL;
+	auto home_env = LLStringUtil::getoptenv("HOME");
+	if (home_env)
+	{
+		return *home_env;
+	}
+	else
+	{
+		LL_WARNS() << "Couldn't detect home directory!  Falling back to " << fallback << LL_ENDL;
+		return fallback;
+	}
+}
+
+
+LLDir_Linux::LLDir_Linux()
+{
+	mDirDelimiter = "/";
+	mCurrentDirIndex = -1;
+	mCurrentDirCount = -1;
+	mDirp = NULL;
+
+	char tmp_str[LL_MAX_PATH];	/* Flawfinder: ignore */ 
+	if (getcwd(tmp_str, LL_MAX_PATH) == NULL)
+	{
+		strcpy(tmp_str, "/tmp");
+		LL_WARNS() << "Could not get current directory; changing to "
+				<< tmp_str << LL_ENDL;
+		if (chdir(tmp_str) == -1)
+		{
+			LL_ERRS() << "Could not change directory to " << tmp_str << LL_ENDL;
+		}
+	}
+
+	mExecutableFilename = "";
+	mExecutablePathAndName = "";
+	mExecutableDir = tmp_str;
+	mWorkingDir = tmp_str;
+#ifdef APP_RO_DATA_DIR
+	mAppRODataDir = APP_RO_DATA_DIR;
+#else
+	mAppRODataDir = tmp_str;
+#endif
+    std::string::size_type build_dir_pos = mExecutableDir.rfind("/build-linux-");
+    if (build_dir_pos != std::string::npos)
+    {
+		// ...we're in a dev checkout
+		mSkinBaseDir = mExecutableDir.substr(0, build_dir_pos) + "/indra/newview/skins";
+		LL_INFOS() << "Running in dev checkout with mSkinBaseDir "
+		 << mSkinBaseDir << LL_ENDL;
+    }
+    else
+    {
+		// ...normal installation running
+		mSkinBaseDir = mAppRODataDir + mDirDelimiter + "skins";
+    }	
+
+	mOSUserDir = getCurrentUserHome(tmp_str);
+	mOSUserAppDir = "";
+	mLindenUserDir = "";
+
+	char path [32];	/* Flawfinder: ignore */ 
+
+	// *NOTE: /proc/%d/exe doesn't work on FreeBSD. But that's ok,
+	// because this is the linux implementation.
+
+	snprintf (path, sizeof(path), "/proc/%d/exe", (int) getpid ()); 
+	int rc = readlink (path, tmp_str, sizeof (tmp_str)-1);	/* Flawfinder: ignore */ 
+	if ( (rc != -1) && (rc <= ((int) sizeof (tmp_str)-1)) )
+	{
+		tmp_str[rc] = '\0'; //readlink() doesn't 0-terminate the buffer
+		mExecutablePathAndName = tmp_str;
+		char *path_end;
+		if ((path_end = strrchr(tmp_str,'/')))
+		{
+			*path_end = '\0';
+			mExecutableDir = tmp_str;
+			mWorkingDir = tmp_str;
+			mExecutableFilename = path_end+1;
+		}
+		else
+		{
+			mExecutableFilename = tmp_str;
+		}
+	}
+
+	mLLPluginDir = mExecutableDir + mDirDelimiter + "llplugin";
+
+	// *TODO: don't use /tmp, use $HOME/.secondlife/tmp or something.
+	mTempDir = "/tmp";
+}
+
+LLDir_Linux::~LLDir_Linux()
+{
+}
+
+// Implementation
+
+
+void LLDir_Linux::initAppDirs(const std::string &app_name,
+							  const std::string& app_read_only_data_dir)
+{
+	// Allow override so test apps can read newview directory
+	if (!app_read_only_data_dir.empty())
+	{
+		mAppRODataDir = app_read_only_data_dir;
+		mSkinBaseDir = add(mAppRODataDir, "skins");
+	}
+	mAppName = app_name;
+
+	std::string upper_app_name(app_name);
+	LLStringUtil::toUpper(upper_app_name);
+
+	auto app_home_env(LLStringUtil::getoptenv(upper_app_name + "_USER_DIR"));
+	if (app_home_env)
+	{
+		// user has specified own userappdir i.e. $SECONDLIFE_USER_DIR
+		mOSUserAppDir = *app_home_env;
+	}
+	else
+	{
+		// traditionally on unixoids, MyApp gets ~/.myapp dir for data
+		mOSUserAppDir = mOSUserDir;
+		mOSUserAppDir += "/";
+		mOSUserAppDir += ".";
+		std::string lower_app_name(app_name);
+		LLStringUtil::toLower(lower_app_name);
+		mOSUserAppDir += lower_app_name;
+	}
+
+	// create any directories we expect to write to.
+
+	int res = LLFile::mkdir(mOSUserAppDir);
+	if (res == -1)
+	{
+		LL_WARNS() << "Couldn't create app user dir " << mOSUserAppDir << LL_ENDL;
+		LL_WARNS() << "Default to base dir" << mOSUserDir << LL_ENDL;
+		mOSUserAppDir = mOSUserDir;
+	}
+
+	res = LLFile::mkdir(getExpandedFilename(LL_PATH_LOGS,""));
+	if (res == -1)
+	{
+		LL_WARNS() << "Couldn't create LL_PATH_LOGS dir " << getExpandedFilename(LL_PATH_LOGS,"") << LL_ENDL;
+	}
+	
+	res = LLFile::mkdir(getExpandedFilename(LL_PATH_USER_SETTINGS,""));
+	if (res == -1)
+	{
+		LL_WARNS() << "Couldn't create LL_PATH_USER_SETTINGS dir " << getExpandedFilename(LL_PATH_USER_SETTINGS,"") << LL_ENDL;
+	}
+
+	res = LLFile::mkdir(getExpandedFilename(LL_PATH_CACHE,""));
+	if (res == -1)
+	{
+		LL_WARNS() << "Couldn't create LL_PATH_CACHE dir " << getExpandedFilename(LL_PATH_CACHE,"") << LL_ENDL;
+	}
+
+	mCAFile = getExpandedFilename(LL_PATH_EXECUTABLE, "ca-bundle.crt");
+}
+
+U32 LLDir_Linux::countFilesInDir(const std::string &dirname, const std::string &mask)
+{
+	U32 file_count = 0;
+	glob_t g;
+
+	std::string tmp_str;
+	tmp_str = dirname;
+	tmp_str += mask;
+	
+	if(glob(tmp_str.c_str(), GLOB_NOSORT, NULL, &g) == 0)
+	{
+		file_count = g.gl_pathc;
+
+		globfree(&g);
+	}
+
+	return (file_count);
+}
+
+std::string LLDir_Linux::getCurPath()
+{
+	char tmp_str[LL_MAX_PATH];	/* Flawfinder: ignore */ 
+	if (getcwd(tmp_str, LL_MAX_PATH) == NULL)
+	{
+		LL_WARNS() << "Could not get current directory" << LL_ENDL;
+		tmp_str[0] = '\0';
+	}
+	return tmp_str;
+}
+
+
+bool LLDir_Linux::fileExists(const std::string &filename) const
+{
+	struct stat stat_data;
+	// Check the age of the file
+	// Now, we see if the files we've gathered are recent...
+	int res = stat(filename.c_str(), &stat_data);
+	if (!res)
+	{
+		return TRUE;
+	}
+	else
+	{
+		return FALSE;
+	}
+}
+
+
+/*virtual*/ std::string LLDir_Linux::getLLPluginLauncher()
+{
+	return gDirUtilp->getExecutableDir() + gDirUtilp->getDirDelimiter() +
+		"SLPlugin";
+}
+
+/*virtual*/ std::string LLDir_Linux::getLLPluginFilename(std::string base_name)
+{
+	return gDirUtilp->getLLPluginDir() + gDirUtilp->getDirDelimiter() +
+		"lib" + base_name + ".so";
+}
diff --git a/indra/llfilesystem/lldir_linux.h b/indra/llfilesystem/lldir_linux.h
new file mode 100644
index 0000000000..e83a020ba4
--- /dev/null
+++ b/indra/llfilesystem/lldir_linux.h
@@ -0,0 +1,64 @@
+/** 
+ * @file lldir_linux.h
+ * @brief Definition of directory utilities class for linux
+ *
+ * $LicenseInfo:firstyear=2000&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#if !LL_LINUX
+#error This header must not be included when compiling for any target other than Linux. Consider including lldir.h instead.
+#endif // !LL_LINUX
+
+#ifndef LL_LLDIR_LINUX_H
+#define LL_LLDIR_LINUX_H
+
+#include "lldir.h"
+
+#include <dirent.h>
+#include <errno.h>
+
+class LLDir_Linux : public LLDir
+{
+public:
+	LLDir_Linux();
+	virtual ~LLDir_Linux();
+
+	/*virtual*/ void initAppDirs(const std::string &app_name,
+		const std::string& app_read_only_data_dir);
+
+	virtual std::string getCurPath();
+	virtual U32 countFilesInDir(const std::string &dirname, const std::string &mask);
+	/*virtual*/ bool fileExists(const std::string &filename) const;
+
+	/*virtual*/ std::string getLLPluginLauncher();
+	/*virtual*/ std::string getLLPluginFilename(std::string base_name);
+
+private:
+	DIR *mDirp;
+	int mCurrentDirIndex;
+	int mCurrentDirCount;
+	std::string mCurrentDir;
+};
+
+#endif // LL_LLDIR_LINUX_H
+
+
diff --git a/indra/llfilesystem/lldir_mac.cpp b/indra/llfilesystem/lldir_mac.cpp
new file mode 100644
index 0000000000..3bc4ee844e
--- /dev/null
+++ b/indra/llfilesystem/lldir_mac.cpp
@@ -0,0 +1,205 @@
+/** 
+ * @file lldir_mac.cpp
+ * @brief Implementation of directory utilities for Mac OS X
+ *
+ * $LicenseInfo:firstyear=2002&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */ 
+
+#if LL_DARWIN
+
+#include "linden_common.h"
+
+#include "lldir_mac.h"
+#include "llerror.h"
+#include "llrand.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <glob.h>
+#include <boost/filesystem.hpp>
+#include "lldir_utils_objc.h"
+
+// --------------------------------------------------------------------------------
+
+static bool CreateDirectory(const std::string &parent, 
+                            const std::string &child,
+                            std::string *fullname)
+{
+    
+    boost::filesystem::path p(parent);
+    p /= child;
+    
+    if (fullname)
+        *fullname = std::string(p.string());
+    
+    if (! boost::filesystem::create_directory(p))
+    {
+        return (boost::filesystem::is_directory(p));
+    }
+    return true;
+}
+
+// --------------------------------------------------------------------------------
+
+LLDir_Mac::LLDir_Mac()
+{
+	mDirDelimiter = "/";
+
+    const std::string     secondLifeString = "SecondLife";
+    
+    std::string *executablepathstr = getSystemExecutableFolder();
+
+    //NOTE:  LLINFOS/LLERRS will not output to log here.  The streams are not initialized.
+    
+	if (executablepathstr)
+	{
+		// mExecutablePathAndName
+		mExecutablePathAndName = *executablepathstr;
+        
+        boost::filesystem::path executablepath(*executablepathstr);
+        
+# ifndef BOOST_SYSTEM_NO_DEPRECATED
+#endif
+        mExecutableFilename = executablepath.filename().string();
+        mExecutableDir = executablepath.parent_path().string();
+		
+		// mAppRODataDir
+        std::string *resourcepath = getSystemResourceFolder();
+        mAppRODataDir = *resourcepath;
+		
+		// *NOTE: When running in a dev tree, use the copy of
+		// skins in indra/newview/ rather than in the application bundle.  This
+		// mirrors Windows dev environment behavior and allows direct checkin
+		// of edited skins/xui files. JC
+		
+		// MBW -- This keeps the mac application from finding other things.
+		// If this is really for skins, it should JUST apply to skins.
+        
+		std::string::size_type build_dir_pos = mExecutableDir.rfind("/build-darwin-");
+		if (build_dir_pos != std::string::npos)
+		{
+			// ...we're in a dev checkout
+			mSkinBaseDir = mExecutableDir.substr(0, build_dir_pos)
+				+ "/indra/newview/skins";
+			LL_INFOS() << "Running in dev checkout with mSkinBaseDir "
+				<< mSkinBaseDir << LL_ENDL;
+		}
+		else
+		{
+			// ...normal installation running
+			mSkinBaseDir = mAppRODataDir + mDirDelimiter + "skins";
+		}
+		
+		// mOSUserDir
+        std::string *appdir = getSystemApplicationSupportFolder();
+        std::string rootdir;
+
+        //Create root directory
+        if (CreateDirectory(*appdir, secondLifeString, &rootdir))
+        {
+            
+            // Save the full path to the folder
+            mOSUserDir = rootdir;
+            
+            // Create our sub-dirs
+            CreateDirectory(rootdir, std::string("data"), NULL);
+            CreateDirectory(rootdir, std::string("logs"), NULL);
+            CreateDirectory(rootdir, std::string("user_settings"), NULL);
+            CreateDirectory(rootdir, std::string("browser_profile"), NULL);
+        }
+    
+		//mOSCacheDir
+        std::string *cachedir =  getSystemCacheFolder();
+
+        if (cachedir)
+		
+		{
+            mOSCacheDir = *cachedir;
+            //TODO:  This changes from ~/Library/Cache/Secondlife to ~/Library/Cache/com.app.secondlife/Secondlife.  Last dir level could go away.
+            CreateDirectory(mOSCacheDir, secondLifeString, NULL);
+		}
+		
+		// mOSUserAppDir
+		mOSUserAppDir = mOSUserDir;
+		
+		// mTempDir
+        //Aura 120920 boost::filesystem::temp_directory_path() not yet implemented on mac. :(
+        std::string *tmpdir = getSystemTempFolder();
+        if (tmpdir)
+        {
+            
+            CreateDirectory(*tmpdir, secondLifeString, &mTempDir);
+            if (tmpdir) delete tmpdir;
+        }
+		
+		mWorkingDir = getCurPath();
+
+		mLLPluginDir = mAppRODataDir + mDirDelimiter + "llplugin";
+	}
+}
+
+LLDir_Mac::~LLDir_Mac()
+{
+}
+
+// Implementation
+
+
+void LLDir_Mac::initAppDirs(const std::string &app_name,
+							const std::string& app_read_only_data_dir)
+{
+	// Allow override so test apps can read newview directory
+	if (!app_read_only_data_dir.empty())
+	{
+		mAppRODataDir = app_read_only_data_dir;
+		mSkinBaseDir = add(mAppRODataDir, "skins");
+	}
+	mCAFile = add(mAppRODataDir, "ca-bundle.crt");
+}
+
+std::string LLDir_Mac::getCurPath()
+{
+	return boost::filesystem::path( boost::filesystem::current_path() ).string();
+}
+
+
+
+bool LLDir_Mac::fileExists(const std::string &filename) const
+{
+    return boost::filesystem::exists(filename);
+}
+
+
+/*virtual*/ std::string LLDir_Mac::getLLPluginLauncher()
+{
+	return gDirUtilp->getAppRODataDir() + gDirUtilp->getDirDelimiter() +
+		"SLPlugin.app/Contents/MacOS/SLPlugin";
+}
+
+/*virtual*/ std::string LLDir_Mac::getLLPluginFilename(std::string base_name)
+{
+	return gDirUtilp->getLLPluginDir() + gDirUtilp->getDirDelimiter() +
+		base_name + ".dylib";
+}
+
+
+#endif // LL_DARWIN
diff --git a/indra/llfilesystem/lldir_mac.h b/indra/llfilesystem/lldir_mac.h
new file mode 100644
index 0000000000..558727ebbc
--- /dev/null
+++ b/indra/llfilesystem/lldir_mac.h
@@ -0,0 +1,56 @@
+/** 
+ * @file lldir_mac.h
+ * @brief Definition of directory utilities class for Mac OS X
+ *
+ * $LicenseInfo:firstyear=2000&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */ 
+
+#if !LL_DARWIN
+#error This header must not be included when compiling for any target other than Mac OS. Consider including lldir.h instead.
+#endif // !LL_DARWIN
+
+#ifndef LL_LLDIR_MAC_H
+#define LL_LLDIR_MAC_H
+
+#include "lldir.h"
+
+#include <dirent.h>
+
+class LLDir_Mac : public LLDir
+{
+public:
+	LLDir_Mac();
+	virtual ~LLDir_Mac();
+
+	/*virtual*/ void initAppDirs(const std::string &app_name,
+		const std::string& app_read_only_data_dir);
+
+	virtual std::string getCurPath();
+	virtual bool fileExists(const std::string &filename) const;
+
+	/*virtual*/ std::string getLLPluginLauncher();
+	/*virtual*/ std::string getLLPluginFilename(std::string base_name);
+};
+
+#endif // LL_LLDIR_MAC_H
+
+
diff --git a/indra/llfilesystem/lldir_utils_objc.h b/indra/llfilesystem/lldir_utils_objc.h
new file mode 100644
index 0000000000..12019c4284
--- /dev/null
+++ b/indra/llfilesystem/lldir_utils_objc.h
@@ -0,0 +1,43 @@
+/** 
+ * @file lldir_utils_objc.h
+ * @brief Definition of directory utilities class for Mac OS X
+ *
+ * $LicenseInfo:firstyear=2020&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2020, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */ 
+
+#if !LL_DARWIN
+#error This header must not be included when compiling for any target other than Mac OS. Consider including lldir.h instead.
+#endif // !LL_DARWIN
+
+#ifndef LL_LLDIR_UTILS_OBJC_H
+#define LL_LLDIR_UTILS_OBJC_H
+
+#include <iostream>
+
+std::string* getSystemTempFolder();
+std::string* getSystemCacheFolder();
+std::string* getSystemApplicationSupportFolder();
+std::string* getSystemResourceFolder();
+std::string* getSystemExecutableFolder();
+
+
+#endif // LL_LLDIR_UTILS_OBJC_H
diff --git a/indra/llfilesystem/lldir_utils_objc.mm b/indra/llfilesystem/lldir_utils_objc.mm
new file mode 100644
index 0000000000..da55a2f897
--- /dev/null
+++ b/indra/llfilesystem/lldir_utils_objc.mm
@@ -0,0 +1,108 @@
+/** 
+ * @file lldir_utils_objc.mm
+ * @brief Cocoa implementation of directory utilities for Mac OS X
+ *
+ * $LicenseInfo:firstyear=2020&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2020, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */ 
+#if LL_DARWIN
+
+//WARNING:  This file CANNOT use standard linden includes due to conflicts between definitions of BOOL
+
+#include "lldir_utils_objc.h"
+#import <Cocoa/Cocoa.h>
+
+std::string* getSystemTempFolder()
+{
+    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+    NSString * tempDir = NSTemporaryDirectory();
+    if (tempDir == nil)
+        tempDir = @"/tmp";
+    std::string *result = ( new std::string([tempDir UTF8String]) );
+    [pool release];
+    
+    return result;
+}
+
+//findSystemDirectory scoped exclusively to this file. 
+std::string* findSystemDirectory(NSSearchPathDirectory searchPathDirectory,
+                                   NSSearchPathDomainMask domainMask)
+{
+    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+    
+    std::string *result = nil;
+    NSString *path = nil;
+    
+    // Search for the path
+    NSArray* paths = NSSearchPathForDirectoriesInDomains(searchPathDirectory,
+                                                         domainMask,
+                                                         YES);
+    if ([paths count])
+    {
+        path = [paths objectAtIndex:0];
+        //HACK:  Always attempt to create directory, ignore errors.
+        NSError *error = nil;
+
+        [[NSFileManager defaultManager] createDirectoryAtPath:path withIntermediateDirectories:YES attributes:nil error:&error];
+
+        
+        result = new std::string([path UTF8String]);        
+    }
+    [pool release];
+    return result;
+}
+
+std::string* getSystemExecutableFolder()
+{
+    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+
+    NSString *bundlePath = [[NSBundle mainBundle] executablePath];
+    std::string *result = (new std::string([bundlePath UTF8String]));  
+    [pool release];
+
+    return result;
+}
+
+std::string* getSystemResourceFolder()
+{
+    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+
+    NSString *bundlePath = [[NSBundle mainBundle] resourcePath];
+    std::string *result = (new std::string([bundlePath UTF8String]));
+    [pool release];
+    
+    return result;
+}
+
+std::string* getSystemCacheFolder()
+{
+    return findSystemDirectory (NSCachesDirectory,
+                                NSUserDomainMask);
+}
+
+std::string* getSystemApplicationSupportFolder()
+{
+    return findSystemDirectory (NSApplicationSupportDirectory,
+                                NSUserDomainMask);
+    
+}
+
+#endif // LL_DARWIN
diff --git a/indra/llfilesystem/lldir_win32.cpp b/indra/llfilesystem/lldir_win32.cpp
new file mode 100644
index 0000000000..b3b3afb37e
--- /dev/null
+++ b/indra/llfilesystem/lldir_win32.cpp
@@ -0,0 +1,452 @@
+/** 
+ * @file lldir_win32.cpp
+ * @brief Implementation of directory utilities for windows
+ *
+ * $LicenseInfo:firstyear=2002&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#if LL_WINDOWS
+
+#include "linden_common.h"
+
+#include "lldir_win32.h"
+#include "llerror.h"
+#include "llstring.h"
+#include "stringize.h"
+#include "llfile.h"
+#include <shlobj.h>
+#include <fstream>
+
+#include <direct.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+// Utility stuff to get versions of the sh
+#define PACKVERSION(major,minor) MAKELONG(minor,major)
+DWORD GetDllVersion(LPCTSTR lpszDllName);
+
+namespace
+{ // anonymous
+    enum class prst { INIT, OPEN, SKIP } state = prst::INIT;
+    // This is called so early that we can't count on static objects being
+    // properly constructed yet, so declare a pointer instead of an instance.
+    std::ofstream* prelogf = nullptr;
+
+    void prelog(const std::string& message)
+    {
+        boost::optional<std::string> prelog_name;
+
+        switch (state)
+        {
+        case prst::INIT:
+            // assume we failed, until we succeed
+            state = prst::SKIP;
+
+            prelog_name = LLStringUtil::getoptenv("PRELOG");
+            if (! prelog_name)
+                // no PRELOG variable set, carry on
+                return;
+            prelogf = new llofstream(*prelog_name, std::ios_base::app);
+            if (! (prelogf && prelogf->is_open()))
+                // can't complain to anybody; how?
+                return;
+            // got the log file open, cool!
+            state = prst::OPEN;
+            (*prelogf) << "========================================================================"
+                       << std::endl;
+            // fall through, don't break
+
+        case prst::OPEN:
+            (*prelogf) << message << std::endl;
+            break;
+
+        case prst::SKIP:
+            // either PRELOG isn't set, or we failed to open that pathname
+            break;
+        }
+    }
+} // anonymous namespace
+
+#define PRELOG(expression) prelog(STRINGIZE(expression))
+
+LLDir_Win32::LLDir_Win32()
+{
+	// set this first: used by append() and add() methods
+	mDirDelimiter = "\\";
+
+	WCHAR w_str[MAX_PATH];
+	// Application Data is where user settings go. We rely on $APPDATA being
+	// correct.
+	auto APPDATA = LLStringUtil::getoptenv("APPDATA");
+	if (APPDATA)
+	{
+		mOSUserDir = *APPDATA;
+	}
+	PRELOG("APPDATA='" << mOSUserDir << "'");
+	// On Windows, we could have received a plain-ASCII pathname in which
+	// non-ASCII characters have been munged to '?', or the pathname could
+	// have been badly encoded and decoded such that we now have garbage
+	// instead of a valid path. Check that mOSUserDir actually exists.
+	if (mOSUserDir.empty() || ! fileExists(mOSUserDir))
+	{
+		PRELOG("APPDATA does not exist");
+		//HRESULT okay = SHGetFolderPath(NULL, CSIDL_APPDATA, NULL, 0, w_str);
+		wchar_t *pwstr = NULL;
+		HRESULT okay = SHGetKnownFolderPath(FOLDERID_RoamingAppData, 0, NULL, &pwstr);
+		PRELOG("SHGetKnownFolderPath(FOLDERID_RoamingAppData) returned " << okay);
+		if (SUCCEEDED(okay) && pwstr)
+		{
+			// But of course, only update mOSUserDir if SHGetKnownFolderPath() works.
+			mOSUserDir = ll_convert_wide_to_string(pwstr);
+			// Not only that: update our environment so that child processes
+			// will see a reasonable value as well.
+			_wputenv_s(L"APPDATA", pwstr);
+			// SHGetKnownFolderPath() contract requires us to free pwstr
+			CoTaskMemFree(pwstr);
+			PRELOG("mOSUserDir='" << mOSUserDir << "'");
+		}
+	}
+
+	// We want cache files to go on the local disk, even if the
+	// user is on a network with a "roaming profile".
+	//
+	// On Vista this is:
+	//   C:\Users\James\AppData\Local
+	//
+	// We used to store the cache in AppData\Roaming, and the installer
+	// cleans up that version on upgrade.  JC
+	auto LOCALAPPDATA = LLStringUtil::getoptenv("LOCALAPPDATA");
+	if (LOCALAPPDATA)
+	{
+		mOSCacheDir = *LOCALAPPDATA;
+	}
+	PRELOG("LOCALAPPDATA='" << mOSCacheDir << "'");
+	// Windows really does not deal well with pathnames containing non-ASCII
+	// characters. See above remarks about APPDATA.
+	if (mOSCacheDir.empty() || ! fileExists(mOSCacheDir))
+	{
+		PRELOG("LOCALAPPDATA does not exist");
+		//HRESULT okay = SHGetFolderPath(NULL, CSIDL_LOCAL_APPDATA, NULL, 0, w_str);
+		wchar_t *pwstr = NULL;
+		HRESULT okay = SHGetKnownFolderPath(FOLDERID_LocalAppData, 0, NULL, &pwstr);
+		PRELOG("SHGetKnownFolderPath(FOLDERID_LocalAppData) returned " << okay);
+		if (SUCCEEDED(okay) && pwstr)
+		{
+			// But of course, only update mOSCacheDir if SHGetKnownFolderPath() works.
+			mOSCacheDir = ll_convert_wide_to_string(pwstr);
+			// Update our environment so that child processes will see a
+			// reasonable value as well.
+			_wputenv_s(L"LOCALAPPDATA", pwstr);
+			// SHGetKnownFolderPath() contract requires us to free pwstr
+			CoTaskMemFree(pwstr);
+			PRELOG("mOSCacheDir='" << mOSCacheDir << "'");
+		}
+	}
+
+	if (GetTempPath(MAX_PATH, w_str))
+	{
+		if (wcslen(w_str))	/* Flawfinder: ignore */ 
+		{
+			w_str[wcslen(w_str)-1] = '\0'; /* Flawfinder: ignore */ // remove trailing slash
+		}
+		mTempDir = utf16str_to_utf8str(llutf16string(w_str));
+
+		if (mOSUserDir.empty())
+		{
+			mOSUserDir = mTempDir;
+		}
+
+		if (mOSCacheDir.empty())
+		{
+			mOSCacheDir = mTempDir;
+		}
+	}
+	else
+	{
+		mTempDir = mOSUserDir;
+	}
+
+/*==========================================================================*|
+	// Now that we've got mOSUserDir, one way or another, let's see how we did
+	// with our environment variables.
+	{
+		auto report = [this](std::ostream& out){
+			out << "mOSUserDir  = '" << mOSUserDir  << "'\n"
+				<< "mOSCacheDir = '" << mOSCacheDir << "'\n"
+				<< "mTempDir    = '" << mTempDir    << "'" << std::endl;
+		};
+		int res = LLFile::mkdir(mOSUserDir);
+		if (res == -1)
+		{
+			// If we couldn't even create the directory, just blurt to stderr
+			report(std::cerr);
+		}
+		else
+		{
+			// successfully created logdir, plunk a log file there
+			std::string logfilename(add(mOSUserDir, "lldir.log"));
+			std::ofstream logfile(logfilename.c_str());
+			if (! logfile.is_open())
+			{
+				report(std::cerr);
+			}
+			else
+			{
+				report(logfile);
+			}
+		}
+	}
+|*==========================================================================*/
+
+//	fprintf(stderr, "mTempDir = <%s>",mTempDir);
+
+	// Set working directory, for LLDir::getWorkingDir()
+	GetCurrentDirectory(MAX_PATH, w_str);
+	mWorkingDir = utf16str_to_utf8str(llutf16string(w_str));
+
+	// Set the executable directory
+	S32 size = GetModuleFileName(NULL, w_str, MAX_PATH);
+	if (size)
+	{
+		w_str[size] = '\0';
+		mExecutablePathAndName = utf16str_to_utf8str(llutf16string(w_str));
+		S32 path_end = mExecutablePathAndName.find_last_of('\\');
+		if (path_end != std::string::npos)
+		{
+			mExecutableDir = mExecutablePathAndName.substr(0, path_end);
+			mExecutableFilename = mExecutablePathAndName.substr(path_end+1, std::string::npos);
+		}
+		else
+		{
+			mExecutableFilename = mExecutablePathAndName;
+		}
+
+	}
+	else
+	{
+		fprintf(stderr, "Couldn't get APP path, assuming current directory!");
+		mExecutableDir = mWorkingDir;
+		// Assume it's the current directory
+	}
+
+	// mAppRODataDir = ".";	
+
+	// Determine the location of the App-Read-Only-Data
+	// Try the working directory then the exe's dir.
+	mAppRODataDir = mWorkingDir;	
+
+
+//	if (mExecutableDir.find("indra") == std::string::npos)
+	
+	// *NOTE:Mani - It is a mistake to put viewer specific code in
+	// the LLDir implementation. The references to 'skins' and 
+	// 'llplugin' need to go somewhere else.
+	// alas... this also gets called during static initialization 
+	// time due to the construction of gDirUtil in lldir.cpp.
+	if(! LLFile::isdir(add(mAppRODataDir, "skins")))
+	{
+		// What? No skins in the working dir?
+		// Try the executable's directory.
+		mAppRODataDir = mExecutableDir;
+	}
+
+//	LL_INFOS() << "mAppRODataDir = " << mAppRODataDir << LL_ENDL;
+
+	mSkinBaseDir = add(mAppRODataDir, "skins");
+
+	// Build the default cache directory
+	mDefaultCacheDir = buildSLOSCacheDir();
+	
+	// Make sure it exists
+	int res = LLFile::mkdir(mDefaultCacheDir);
+	if (res == -1)
+	{
+		LL_WARNS() << "Couldn't create LL_PATH_CACHE dir " << mDefaultCacheDir << LL_ENDL;
+	}
+
+	mLLPluginDir = add(mExecutableDir, "llplugin");
+}
+
+LLDir_Win32::~LLDir_Win32()
+{
+}
+
+// Implementation
+
+void LLDir_Win32::initAppDirs(const std::string &app_name,
+							  const std::string& app_read_only_data_dir)
+{
+	// Allow override so test apps can read newview directory
+	if (!app_read_only_data_dir.empty())
+	{
+		mAppRODataDir = app_read_only_data_dir;
+		mSkinBaseDir = add(mAppRODataDir, "skins");
+	}
+	mAppName = app_name;
+	mOSUserAppDir = add(mOSUserDir, app_name);
+
+	int res = LLFile::mkdir(mOSUserAppDir);
+	if (res == -1)
+	{
+		LL_WARNS() << "Couldn't create app user dir " << mOSUserAppDir << LL_ENDL;
+		LL_WARNS() << "Default to base dir" << mOSUserDir << LL_ENDL;
+		mOSUserAppDir = mOSUserDir;
+	}
+	//dumpCurrentDirectories();
+
+	res = LLFile::mkdir(getExpandedFilename(LL_PATH_LOGS,""));
+	if (res == -1)
+	{
+		LL_WARNS() << "Couldn't create LL_PATH_LOGS dir " << getExpandedFilename(LL_PATH_LOGS,"") << LL_ENDL;
+	}
+
+	res = LLFile::mkdir(getExpandedFilename(LL_PATH_USER_SETTINGS,""));
+	if (res == -1)
+	{
+		LL_WARNS() << "Couldn't create LL_PATH_USER_SETTINGS dir " << getExpandedFilename(LL_PATH_USER_SETTINGS,"") << LL_ENDL;
+	}
+
+	res = LLFile::mkdir(getExpandedFilename(LL_PATH_CACHE,""));
+	if (res == -1)
+	{
+		LL_WARNS() << "Couldn't create LL_PATH_CACHE dir " << getExpandedFilename(LL_PATH_CACHE,"") << LL_ENDL;
+	}
+
+	mCAFile = getExpandedFilename( LL_PATH_EXECUTABLE, "ca-bundle.crt" );
+}
+
+U32 LLDir_Win32::countFilesInDir(const std::string &dirname, const std::string &mask)
+{
+	HANDLE count_search_h;
+	U32 file_count;
+
+	file_count = 0;
+
+	WIN32_FIND_DATA FileData;
+
+	llutf16string pathname = utf8str_to_utf16str(dirname);
+	pathname += utf8str_to_utf16str(mask);
+	
+	if ((count_search_h = FindFirstFile(pathname.c_str(), &FileData)) != INVALID_HANDLE_VALUE)   
+	{
+		file_count++;
+
+		while (FindNextFile(count_search_h, &FileData))
+		{
+			file_count++;
+		}
+		   
+		FindClose(count_search_h);
+	}
+
+	return (file_count);
+}
+
+std::string LLDir_Win32::getCurPath()
+{
+	WCHAR w_str[MAX_PATH];
+	GetCurrentDirectory(MAX_PATH, w_str);
+
+	return utf16str_to_utf8str(llutf16string(w_str));
+}
+
+
+bool LLDir_Win32::fileExists(const std::string &filename) const
+{
+	llstat stat_data;
+	// Check the age of the file
+	// Now, we see if the files we've gathered are recent...
+	int res = LLFile::stat(filename, &stat_data);
+	if (!res)
+	{
+		return TRUE;
+	}
+	else
+	{
+		return FALSE;
+	}
+}
+
+
+/*virtual*/ std::string LLDir_Win32::getLLPluginLauncher()
+{
+	return gDirUtilp->getExecutableDir() + gDirUtilp->getDirDelimiter() +
+		"SLPlugin.exe";
+}
+
+/*virtual*/ std::string LLDir_Win32::getLLPluginFilename(std::string base_name)
+{
+	return gDirUtilp->getLLPluginDir() + gDirUtilp->getDirDelimiter() +
+		base_name + ".dll";
+}
+
+
+#if 0
+// Utility function to get version number of a DLL
+
+#define PACKVERSION(major,minor) MAKELONG(minor,major)
+
+DWORD GetDllVersion(LPCTSTR lpszDllName)
+{
+
+    HINSTANCE hinstDll;
+    DWORD dwVersion = 0;
+
+    hinstDll = LoadLibrary(lpszDllName);	/* Flawfinder: ignore */ 
+	
+    if(hinstDll)
+    {
+        DLLGETVERSIONPROC pDllGetVersion;
+
+        pDllGetVersion = (DLLGETVERSIONPROC) GetProcAddress(hinstDll, "DllGetVersion");
+
+/*Because some DLLs might not implement this function, you
+  must test for it explicitly. Depending on the particular 
+  DLL, the lack of a DllGetVersion function can be a useful
+  indicator of the version.
+*/
+        if(pDllGetVersion)
+        {
+            DLLVERSIONINFO dvi;
+            HRESULT hr;
+
+            ZeroMemory(&dvi, sizeof(dvi));
+            dvi.cbSize = sizeof(dvi);
+
+            hr = (*pDllGetVersion)(&dvi);
+
+            if(SUCCEEDED(hr))
+            {
+                dwVersion = PACKVERSION(dvi.dwMajorVersion, dvi.dwMinorVersion);
+            }
+        }
+        
+        FreeLibrary(hinstDll);
+    }
+    return dwVersion;
+}
+#endif
+
+#endif
+
+
diff --git a/indra/llfilesystem/lldir_win32.h b/indra/llfilesystem/lldir_win32.h
new file mode 100644
index 0000000000..450efaf9da
--- /dev/null
+++ b/indra/llfilesystem/lldir_win32.h
@@ -0,0 +1,59 @@
+/** 
+ * @file lldir_win32.h
+ * @brief Definition of directory utilities class for windows
+ *
+ * $LicenseInfo:firstyear=2000&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#if !LL_WINDOWS
+#error This header must not be included when compiling for any target other than Windows. Consider including lldir.h instead.
+#endif // !LL_WINDOWS
+
+#ifndef LL_LLDIR_WIN32_H
+#define LL_LLDIR_WIN32_H
+
+#include "lldir.h"
+
+class LLDir_Win32 : public LLDir
+{
+public:
+	LLDir_Win32();
+	virtual ~LLDir_Win32();
+
+	/*virtual*/ void initAppDirs(const std::string &app_name,
+		const std::string& app_read_only_data_dir);
+
+	/*virtual*/ std::string getCurPath();
+	/*virtual*/ U32 countFilesInDir(const std::string &dirname, const std::string &mask);
+	/*virtual*/ bool fileExists(const std::string &filename) const;
+
+	/*virtual*/ std::string getLLPluginLauncher();
+	/*virtual*/ std::string getLLPluginFilename(std::string base_name);
+
+private:
+	void* mDirSearch_h;
+	llutf16string mCurrentDir;
+};
+
+#endif // LL_LLDIR_WIN32_H
+
+
diff --git a/indra/llfilesystem/lldirguard.h b/indra/llfilesystem/lldirguard.h
new file mode 100644
index 0000000000..37b9e9b83e
--- /dev/null
+++ b/indra/llfilesystem/lldirguard.h
@@ -0,0 +1,72 @@
+/** 
+ * @file lldirguard.h
+ * @brief Protect working directory from being changed in scope.
+ *
+ * $LicenseInfo:firstyear=2009&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#ifndef LL_DIRGUARD_H
+#define LL_DIRGUARD_H
+
+#include "linden_common.h"
+#include "llerror.h"
+
+#if LL_WINDOWS
+class LLDirectoryGuard
+{
+public:
+	LLDirectoryGuard()
+	{
+		mOrigDirLen = GetCurrentDirectory(MAX_PATH, mOrigDir);
+	}
+
+	~LLDirectoryGuard()
+	{
+		mFinalDirLen = GetCurrentDirectory(MAX_PATH, mFinalDir);
+		if ((mOrigDirLen!=mFinalDirLen) ||
+			(wcsncmp(mOrigDir,mFinalDir,mOrigDirLen)!=0))
+		{
+			// Dir has changed
+			std::string mOrigDirUtf8 = utf16str_to_utf8str(llutf16string(mOrigDir));
+			std::string mFinalDirUtf8 = utf16str_to_utf8str(llutf16string(mFinalDir));
+			LL_INFOS() << "Resetting working dir from " << mFinalDirUtf8 << " to " << mOrigDirUtf8 << LL_ENDL;
+			SetCurrentDirectory(mOrigDir);
+		}
+	}
+
+private:
+	TCHAR mOrigDir[MAX_PATH];
+	DWORD mOrigDirLen;
+	TCHAR mFinalDir[MAX_PATH];
+	DWORD mFinalDirLen;
+};
+#else // No-op outside Windows.
+class LLDirectoryGuard
+{
+public:
+	LLDirectoryGuard() {}
+	~LLDirectoryGuard() {}
+};
+#endif 
+
+
+#endif
diff --git a/indra/llfilesystem/lldiriterator.cpp b/indra/llfilesystem/lldiriterator.cpp
new file mode 100644
index 0000000000..f57bf4ebc6
--- /dev/null
+++ b/indra/llfilesystem/lldiriterator.cpp
@@ -0,0 +1,243 @@
+/**
+ * @file lldiriterator.cpp
+ * @brief Iterator through directory entries matching the search pattern.
+ *
+ * $LicenseInfo:firstyear=2010&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "lldiriterator.h"
+
+#include "fix_macros.h"
+#include "llregex.h"
+#include <boost/filesystem.hpp>
+
+namespace fs = boost::filesystem;
+
+static std::string glob_to_regex(const std::string& glob);
+
+class LLDirIterator::Impl
+{
+public:
+	Impl(const std::string &dirname, const std::string &mask);
+	~Impl();
+
+	bool next(std::string &fname);
+
+private:
+	boost::regex			mFilterExp;
+	fs::directory_iterator	mIter;
+	bool					mIsValid;
+};
+
+LLDirIterator::Impl::Impl(const std::string &dirname, const std::string &mask)
+	: mIsValid(false)
+{
+#ifdef LL_WINDOWS // or BOOST_WINDOWS_API
+	fs::path dir_path(utf8str_to_utf16str(dirname));
+#else
+	fs::path dir_path(dirname);
+#endif
+
+	bool is_dir = false;
+
+	// Check if path is a directory.
+	try
+	{
+		is_dir = fs::is_directory(dir_path);
+	}
+	catch (const fs::filesystem_error& e)
+	{
+		LL_WARNS() << e.what() << LL_ENDL;
+		return;
+	}
+
+	if (!is_dir)
+	{
+		LL_WARNS() << "Invalid path: \"" << dir_path.string() << "\"" << LL_ENDL;
+		return;
+	}
+
+	// Initialize the directory iterator for the given path.
+	try
+	{
+		mIter = fs::directory_iterator(dir_path);
+	}
+	catch (const fs::filesystem_error& e)
+	{
+		LL_WARNS() << e.what() << LL_ENDL;
+		return;
+	}
+
+	// Convert the glob mask to a regular expression
+	std::string exp = glob_to_regex(mask);
+
+	// Initialize boost::regex with the expression converted from
+	// the glob mask.
+	// An exception is thrown if the expression is not valid.
+	try
+	{
+		mFilterExp.assign(exp);
+	}
+	catch (boost::regex_error& e)
+	{
+		LL_WARNS() << "\"" << exp << "\" is not a valid regular expression: "
+				<< e.what() << LL_ENDL;
+		return;
+	}
+
+	mIsValid = true;
+}
+
+LLDirIterator::Impl::~Impl()
+{
+}
+
+bool LLDirIterator::Impl::next(std::string &fname)
+{
+	fname = "";
+
+	if (!mIsValid)
+	{
+		LL_WARNS() << "The iterator is not correctly initialized." << LL_ENDL;
+		return false;
+	}
+
+	fs::directory_iterator end_itr; // default construction yields past-the-end
+	bool found = false;
+
+	// Check if path is a directory.
+	try
+	{
+		while (mIter != end_itr && !found)
+		{
+			boost::smatch match;
+			std::string name = mIter->path().filename().string();
+			found = ll_regex_match(name, match, mFilterExp);
+			if (found)
+			{
+				fname = name;
+			}
+
+			++mIter;
+		}
+	}
+	catch (const fs::filesystem_error& e)
+	{
+		LL_WARNS() << e.what() << LL_ENDL;
+	}
+
+	return found;
+}
+
+/**
+Converts the incoming glob into a regex. This involves
+converting incoming glob expressions to regex equivilents and
+at the same time, escaping any regex meaningful characters which
+do not have glob meaning, i.e.
+            .()+|^$ 
+in the input.
+*/
+std::string glob_to_regex(const std::string& glob)
+{
+	std::string regex;
+	regex.reserve(glob.size()<<1);
+	S32 braces = 0;
+	bool escaped = false;
+	bool square_brace_open = false;
+
+	for (std::string::const_iterator i = glob.begin(); i != glob.end(); ++i)
+	{
+		char c = *i;
+
+		switch (c)
+		{
+			case '*':
+				if (glob.begin() == i)
+				{
+					regex+="[^.].*";
+				}
+				else
+				{
+					regex+= escaped ? "*" : ".*";
+				}
+				break;
+			case '?':
+				regex+= escaped ? '?' : '.';
+				break;
+			case '{':
+				braces++;
+				regex+='(';
+				break;
+			case '}':
+				if (!braces)
+				{
+					LL_ERRS() << "glob_to_regex: Closing brace without an equivalent opening brace: " << glob << LL_ENDL;
+				}
+
+				regex+=')';
+				braces--;
+				break;
+			case ',':
+				regex+= braces ? '|' : c;
+				break;
+			case '!':
+				regex+= square_brace_open ? '^' : c;
+				break;
+			case '.': // This collection have different regex meaning
+			case '^': // and so need escaping.
+			case '(': 
+			case ')':
+			case '+':
+			case '|':
+			case '$':
+				regex += '\\'; 
+			default:
+				regex += c;
+				break;
+		}
+
+		escaped = ('\\' == c);
+		square_brace_open = ('[' == c);
+	}
+
+	if (braces)
+	{
+		LL_ERRS() << "glob_to_regex: Unterminated brace expression: " << glob << LL_ENDL;
+	}
+
+	return regex;
+}
+
+LLDirIterator::LLDirIterator(const std::string &dirname, const std::string &mask)
+{
+	mImpl = new Impl(dirname, mask);
+}
+
+LLDirIterator::~LLDirIterator()
+{
+	delete mImpl;
+}
+
+bool LLDirIterator::next(std::string &fname)
+{
+	return mImpl->next(fname);
+}
diff --git a/indra/llfilesystem/lldiriterator.h b/indra/llfilesystem/lldiriterator.h
new file mode 100644
index 0000000000..0b48be41b3
--- /dev/null
+++ b/indra/llfilesystem/lldiriterator.h
@@ -0,0 +1,87 @@
+/**
+ * @file lldiriterator.h
+ * @brief Iterator through directory entries matching the search pattern.
+ *
+ * $LicenseInfo:firstyear=2010&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#ifndef LL_LLDIRITERATOR_H
+#define LL_LLDIRITERATOR_H
+
+#include "linden_common.h"
+
+/**
+ * Class LLDirIterator
+ *
+ * Iterates through directory entries matching the search pattern.
+ */
+class LLDirIterator
+{
+public:
+	/**
+	 * Constructs LLDirIterator object to search for glob pattern
+	 * matches in a directory.
+	 *
+	 * @param dirname - name of a directory to search in.
+	 * @param mask - search pattern, a glob expression
+	 *
+	 * Wildcards supported in glob expressions:
+	 * --------------------------------------------------------------
+	 * | Wildcard 	| Matches										|
+	 * --------------------------------------------------------------
+	 * | 	* 		|zero or more characters						|
+	 * | 	?		|exactly one character							|
+	 * | [abcde]	|exactly one character listed					|
+	 * | [a-e]		|exactly one character in the given range		|
+	 * | [!abcde]	|any character that is not listed				|
+	 * | [!a-e]		|any character that is not in the given range	|
+	 * | {abc,xyz}	|exactly one entire word in the options given	|
+	 * --------------------------------------------------------------
+	 */
+	LLDirIterator(const std::string &dirname, const std::string &mask);
+
+	~LLDirIterator();
+
+	/**
+	 * Searches for the next directory entry matching the glob mask
+	 * specified upon iterator construction.
+	 * Returns true if a match is found, sets fname
+	 * parameter to the name of the matched directory entry and
+	 * increments the iterator position.
+	 *
+	 * Typical usage:
+	 * <code>
+	 * LLDirIterator iter(directory, pattern);
+	 * if ( iter.next(scanResult) )
+	 * </code>
+	 *
+	 * @param fname - name of the matched directory entry.
+	 * @return true if a match is found, false otherwise.
+	 */
+	bool next(std::string &fname);
+
+protected:
+	class Impl;
+	Impl* mImpl;
+};
+
+#endif //LL_LLDIRITERATOR_H
diff --git a/indra/llfilesystem/lldiskcache.cpp b/indra/llfilesystem/lldiskcache.cpp
new file mode 100644
index 0000000000..ee43a599f7
--- /dev/null
+++ b/indra/llfilesystem/lldiskcache.cpp
@@ -0,0 +1,410 @@
+/**
+ * @file lldiskcache.cpp
+ * @brief The disk cache implementation.
+ *
+ * Note: Rather than keep the top level function comments up
+ * to date in both the source and header files, I elected to
+ * only have explicit comments about each function and variable
+ * in the header - look there for details. The same is true for
+ * description of how this code is supposed to work.
+ *
+ * $LicenseInfo:firstyear=2009&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2020, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+#include "llapp.h"
+#include "llassettype.h"
+#include "lldir.h"
+#include <boost/filesystem.hpp>
+#include <boost/range/iterator_range.hpp>
+#include <chrono>
+
+#include "lldiskcache.h"
+
+LLDiskCache::LLDiskCache(const std::string cache_dir,
+                         const uintmax_t max_size_bytes,
+                         const bool enable_cache_debug_info) :
+    mCacheDir(cache_dir),
+    mMaxSizeBytes(max_size_bytes),
+    mEnableCacheDebugInfo(enable_cache_debug_info)
+{
+    mCacheFilenamePrefix = "sl_cache";
+
+    LLFile::mkdir(cache_dir);
+}
+
+// WARNING: purge() is called by LLPurgeDiskCacheThread. As such it must
+// NOT touch any LLDiskCache data without introducing and locking a mutex!
+
+// Interaction through the filesystem itself should be safe. Let’s say thread
+// A is accessing the cache file for reading/writing and thread B is trimming
+// the cache. Let’s also assume using llifstream to open a file and
+// boost::filesystem::remove are not atomic (which will be pretty much the
+// case).
+
+// Now, A is trying to open the file using llifstream ctor. It does some
+// checks if the file exists and whatever else it might be doing, but has not
+// issued the call to the OS to actually open the file yet. Now B tries to
+// delete the file: If the file has been already marked as in use by the OS,
+// deleting the file will fail and B will continue with the next file. A can
+// safely continue opening the file. If the file has not yet been marked as in
+// use, B will delete the file. Now A actually wants to open it, operation
+// will fail, subsequent check via llifstream.is_open will fail, asset will
+// have to be re-requested. (Assuming here the viewer will actually handle
+// this situation properly, that can also happen if there is a file containing
+// garbage.)
+
+// Other situation: B is trimming the cache and A wants to read a file that is
+// about to get deleted. boost::filesystem::remove does whatever it is doing
+// before actually deleting the file. If A opens the file before the file is
+// actually gone, the OS call from B to delete the file will fail since the OS
+// will prevent this. B continues with the next file. If the file is already
+// gone before A finally gets to open it, this operation will fail and the
+// asset will have to be re-requested.
+void LLDiskCache::purge()
+{
+    if (mEnableCacheDebugInfo)
+    {
+        LL_INFOS() << "Total dir size before purge is " << dirFileSize(mCacheDir) << LL_ENDL;
+    }
+
+    boost::system::error_code ec;
+    auto start_time = std::chrono::high_resolution_clock::now();
+
+    typedef std::pair<std::time_t, std::pair<uintmax_t, std::string>> file_info_t;
+    std::vector<file_info_t> file_info;
+
+#if LL_WINDOWS
+    std::wstring cache_path(utf8str_to_utf16str(mCacheDir));
+#else
+    std::string cache_path(mCacheDir);
+#endif
+    if (boost::filesystem::is_directory(cache_path, ec) && !ec.failed())
+    {
+        for (auto& entry : boost::make_iterator_range(boost::filesystem::directory_iterator(cache_path, ec), {}))
+        {
+            if (boost::filesystem::is_regular_file(entry, ec) && !ec.failed())
+            {
+                if (entry.path().string().find(mCacheFilenamePrefix) != std::string::npos)
+                {
+                    uintmax_t file_size = boost::filesystem::file_size(entry, ec);
+                    if (ec.failed())
+                    {
+                        continue;
+                    }
+                    const std::string file_path = entry.path().string();
+                    const std::time_t file_time = boost::filesystem::last_write_time(entry, ec);
+                    if (ec.failed())
+                    {
+                        continue;
+                    }
+
+                    file_info.push_back(file_info_t(file_time, { file_size, file_path }));
+                }
+            }
+        }
+    }
+
+    std::sort(file_info.begin(), file_info.end(), [](file_info_t& x, file_info_t& y)
+    {
+        return x.first > y.first;
+    });
+
+    LL_INFOS() << "Purging cache to a maximum of " << mMaxSizeBytes << " bytes" << LL_ENDL;
+
+    uintmax_t file_size_total = 0;
+    for (file_info_t& entry : file_info)
+    {
+        file_size_total += entry.second.first;
+
+        std::string action = "";
+        if (file_size_total > mMaxSizeBytes)
+        {
+            action = "DELETE:";
+            boost::filesystem::remove(entry.second.second, ec);
+            if (ec.failed())
+            {
+                LL_WARNS() << "Failed to delete cache file " << entry.second.second << ": " << ec.message() << LL_ENDL;
+            }
+        }
+        else
+        {
+            action = "  KEEP:";
+        }
+
+        if (mEnableCacheDebugInfo)
+        {
+            // have to do this because of LL_INFO/LL_END weirdness
+            std::ostringstream line;
+
+            line << action << "  ";
+            line << entry.first << "  ";
+            line << entry.second.first << "  ";
+            line << entry.second.second;
+            line << " (" << file_size_total << "/" << mMaxSizeBytes << ")";
+            LL_INFOS() << line.str() << LL_ENDL;
+        }
+    }
+
+    if (mEnableCacheDebugInfo)
+    {
+        auto end_time = std::chrono::high_resolution_clock::now();
+        auto execute_time = std::chrono::duration_cast<std::chrono::milliseconds>(end_time - start_time).count();
+        LL_INFOS() << "Total dir size after purge is " << dirFileSize(mCacheDir) << LL_ENDL;
+        LL_INFOS() << "Cache purge took " << execute_time << " ms to execute for " << file_info.size() << " files" << LL_ENDL;
+    }
+}
+
+const std::string LLDiskCache::assetTypeToString(LLAssetType::EType at)
+{
+    /**
+     * Make use of the handy C++17  feature that allows
+     * for inline initialization of an std::map<>
+     */
+    typedef std::map<LLAssetType::EType, std::string> asset_type_to_name_t;
+    asset_type_to_name_t asset_type_to_name =
+    {
+        { LLAssetType::AT_TEXTURE, "TEXTURE" },
+        { LLAssetType::AT_SOUND, "SOUND" },
+        { LLAssetType::AT_CALLINGCARD, "CALLINGCARD" },
+        { LLAssetType::AT_LANDMARK, "LANDMARK" },
+        { LLAssetType::AT_SCRIPT, "SCRIPT" },
+        { LLAssetType::AT_CLOTHING, "CLOTHING" },
+        { LLAssetType::AT_OBJECT, "OBJECT" },
+        { LLAssetType::AT_NOTECARD, "NOTECARD" },
+        { LLAssetType::AT_CATEGORY, "CATEGORY" },
+        { LLAssetType::AT_LSL_TEXT, "LSL_TEXT" },
+        { LLAssetType::AT_LSL_BYTECODE, "LSL_BYTECODE" },
+        { LLAssetType::AT_TEXTURE_TGA, "TEXTURE_TGA" },
+        { LLAssetType::AT_BODYPART, "BODYPART" },
+        { LLAssetType::AT_SOUND_WAV, "SOUND_WAV" },
+        { LLAssetType::AT_IMAGE_TGA, "IMAGE_TGA" },
+        { LLAssetType::AT_IMAGE_JPEG, "IMAGE_JPEG" },
+        { LLAssetType::AT_ANIMATION, "ANIMATION" },
+        { LLAssetType::AT_GESTURE, "GESTURE" },
+        { LLAssetType::AT_SIMSTATE, "SIMSTATE" },
+        { LLAssetType::AT_LINK, "LINK" },
+        { LLAssetType::AT_LINK_FOLDER, "LINK_FOLDER" },
+        { LLAssetType::AT_MARKETPLACE_FOLDER, "MARKETPLACE_FOLDER" },
+        { LLAssetType::AT_WIDGET, "WIDGET" },
+        { LLAssetType::AT_PERSON, "PERSON" },
+        { LLAssetType::AT_MESH, "MESH" },
+        { LLAssetType::AT_SETTINGS, "SETTINGS" },
+        { LLAssetType::AT_UNKNOWN, "UNKNOWN" }
+    };
+
+    asset_type_to_name_t::iterator iter = asset_type_to_name.find(at);
+    if (iter != asset_type_to_name.end())
+    {
+        return iter->second;
+    }
+
+    return std::string("UNKNOWN");
+}
+
+const std::string LLDiskCache::metaDataToFilepath(const std::string id,
+        LLAssetType::EType at,
+        const std::string extra_info)
+{
+    std::ostringstream file_path;
+
+    file_path << mCacheDir;
+    file_path << gDirUtilp->getDirDelimiter();
+    file_path << mCacheFilenamePrefix;
+    file_path << "_";
+    file_path << id;
+    file_path << "_";
+    file_path << (extra_info.empty() ? "0" : extra_info);
+    //file_path << "_";
+    //file_path << assetTypeToString(at); // see  SL-14210 Prune descriptive tag from new cache filenames
+                                          // for details of why it was removed. Note that if you put it
+                                          // back or change the format of the filename, the cache files
+                                          // files will be invalidated (and perhaps, more importantly,
+                                          // never deleted unless you delete them manually).
+    file_path << ".asset";
+
+    return file_path.str();
+}
+
+void LLDiskCache::updateFileAccessTime(const std::string file_path)
+{
+    /**
+     * Threshold in time_t units that is used to decide if the last access time
+     * time of the file is updated or not. Added as a precaution for the concern
+     * outlined in SL-14582  about frequent writes on older SSDs reducing their
+     * lifespan. I think this is the right place for the threshold value - rather
+     * than it being a pref - do comment on that Jira if you disagree...
+     *
+     * Let's start with 1 hour in time_t units and see how that unfolds
+     */
+    const std::time_t time_threshold = 1 * 60 * 60;
+
+    // current time
+    const std::time_t cur_time = std::time(nullptr);
+
+    boost::system::error_code ec;
+#if LL_WINDOWS
+    // file last write time
+    const std::time_t last_write_time = boost::filesystem::last_write_time(utf8str_to_utf16str(file_path), ec);
+    if (ec.failed())
+    {
+        LL_WARNS() << "Failed to read last write time for cache file " << file_path << ": " << ec.message() << LL_ENDL;
+        return;
+    }
+
+    // delta between cur time and last time the file was written
+    const std::time_t delta_time = cur_time - last_write_time;
+
+    // we only write the new value if the time in time_threshold has elapsed
+    // before the last one
+    if (delta_time > time_threshold)
+    {
+        boost::filesystem::last_write_time(utf8str_to_utf16str(file_path), cur_time, ec);
+    }
+#else
+    // file last write time
+    const std::time_t last_write_time = boost::filesystem::last_write_time(file_path, ec);
+    if (ec.failed())
+    {
+        LL_WARNS() << "Failed to read last write time for cache file " << file_path << ": " << ec.message() << LL_ENDL;
+        return;
+    }
+
+    // delta between cur time and last time the file was written
+    const std::time_t delta_time = cur_time - last_write_time;
+
+    // we only write the new value if the time in time_threshold has elapsed
+    // before the last one
+    if (delta_time > time_threshold)
+    {
+        boost::filesystem::last_write_time(file_path, cur_time, ec);
+    }
+#endif
+
+    if (ec.failed())
+    {
+        LL_WARNS() << "Failed to update last write time for cache file " << file_path << ": " << ec.message() << LL_ENDL;
+    }
+}
+
+const std::string LLDiskCache::getCacheInfo()
+{
+    std::ostringstream cache_info;
+
+    F32 max_in_mb = (F32)mMaxSizeBytes / (1024.0 * 1024.0);
+    F32 percent_used = ((F32)dirFileSize(mCacheDir) / (F32)mMaxSizeBytes) * 100.0;
+
+    cache_info << std::fixed;
+    cache_info << std::setprecision(1);
+    cache_info << "Max size " << max_in_mb << " MB ";
+    cache_info << "(" << percent_used << "% used)";
+
+    return cache_info.str();
+}
+
+void LLDiskCache::clearCache()
+{
+    /**
+     * See notes on performance in dirFileSize(..) - there may be
+     * a quicker way to do this by operating on the parent dir vs
+     * the component files but it's called infrequently so it's
+     * likely just fine
+     */
+    boost::system::error_code ec;
+#if LL_WINDOWS
+    std::wstring cache_path(utf8str_to_utf16str(mCacheDir));
+#else
+    std::string cache_path(mCacheDir);
+#endif
+    if (boost::filesystem::is_directory(cache_path, ec) && !ec.failed())
+    {
+        for (auto& entry : boost::make_iterator_range(boost::filesystem::directory_iterator(cache_path, ec), {}))
+        {
+            if (boost::filesystem::is_regular_file(entry, ec) && !ec.failed())
+            {
+                if (entry.path().string().find(mCacheFilenamePrefix) != std::string::npos)
+                {
+                    boost::filesystem::remove(entry, ec);
+                    if (ec.failed())
+                    {
+                        LL_WARNS() << "Failed to delete cache file " << entry << ": " << ec.message() << LL_ENDL;
+                    }
+                }
+            }
+        }
+    }
+}
+
+uintmax_t LLDiskCache::dirFileSize(const std::string dir)
+{
+    uintmax_t total_file_size = 0;
+
+    /**
+     * There may be a better way that works directly on the folder (similar to
+     * right clicking on a folder in the OS and asking for size vs right clicking
+     * on all files and adding up manually) but this is very fast - less than 100ms
+     * for 10,000 files in my testing so, so long as it's not called frequently,
+     * it should be okay. Note that's it's only currently used for logging/debugging
+     * so if performance is ever an issue, optimizing this or removing it altogether,
+     * is an easy win.
+     */
+    boost::system::error_code ec;
+#if LL_WINDOWS
+    std::wstring dir_path(utf8str_to_utf16str(dir));
+#else
+    std::string dir_path(dir);
+#endif
+    if (boost::filesystem::is_directory(dir_path, ec) && !ec.failed())
+    {
+        for (auto& entry : boost::make_iterator_range(boost::filesystem::directory_iterator(dir_path, ec), {}))
+        {
+            if (boost::filesystem::is_regular_file(entry, ec) && !ec.failed())
+            {
+                if (entry.path().string().find(mCacheFilenamePrefix) != std::string::npos)
+                {
+                    uintmax_t file_size = boost::filesystem::file_size(entry, ec);
+                    if (!ec.failed())
+                    {
+                        total_file_size += file_size;
+                    }
+                }
+            }
+        }
+    }
+
+    return total_file_size;
+}
+
+LLPurgeDiskCacheThread::LLPurgeDiskCacheThread() :
+    LLThread("PurgeDiskCacheThread", nullptr)
+{
+}
+
+void LLPurgeDiskCacheThread::run()
+{
+    constexpr std::chrono::seconds CHECK_INTERVAL{60};
+
+    while (LLApp::instance()->sleep(CHECK_INTERVAL))
+    {
+        LLDiskCache::instance().purge();
+    }
+}
diff --git a/indra/llfilesystem/lldiskcache.h b/indra/llfilesystem/lldiskcache.h
new file mode 100644
index 0000000000..1cbd2c58aa
--- /dev/null
+++ b/indra/llfilesystem/lldiskcache.h
@@ -0,0 +1,198 @@
+/**
+ * @file lldiskcache.h
+ * @brief The disk cache implementation declarations.
+ *
+ * @Description:
+ * This code implements a disk cache using the following ideas:
+ * 1/ The metadata for a file can be encapsulated in the filename.
+      The filenames will be composed of the following fields:
+        Prefix:     Used to identify the file as a part of the cache.
+                    An additional reason for using a prefix is that it
+                    might be possible, either accidentally or maliciously
+                    to end up with the cache dir set to a non-cache
+                    location such as your OS system dir or a work folder.
+                    Purging files from that would obviously be a disaster
+                    so this is an extra step to help avoid that scenario.
+        ID:         Typically the asset ID (UUID) of the asset being
+                    saved but can be anything valid for a filename
+        Extra Info: A field for use in the future that can be used
+                    to store extra identifiers - e.g. the discard
+                    level of a JPEG2000 file
+        Asset Type: A text string created from the LLAssetType enum
+                    that identifies the type of asset being stored.
+        .asset      A file extension of .asset is used to help
+                    identify this as a Viewer asset file
+ * 2/ The time of last access for a file can be updated instantly
+ *    for file reads and automatically as part of the file writes.
+ * 3/ The purge algorithm collects a list of all files in the
+ *    directory, sorts them by date of last access (write) and then
+ *    deletes any files based on age until the total size of all
+ *    the files is less than the maximum size specified.
+ * 4/ An LLSingleton idiom is used since there will only ever be
+ *    a single cache and we want to access it from numerous places.
+ * 5/ Performance on my modest system seems very acceptable. For
+ *    example, in testing, I was able to purge a directory of
+ *    10,000 files, deleting about half of them in ~ 1700ms. For
+ *    the same sized directory of files, writing the last updated
+ *    time to each took less than 600ms indicating that this
+ *    important part of the mechanism has almost no overhead.
+ *
+ * $LicenseInfo:firstyear=2009&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2020, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#ifndef _LLDISKCACHE
+#define _LLDISKCACHE
+
+#include "llsingleton.h"
+
+class LLDiskCache :
+    public LLParamSingleton<LLDiskCache>
+{
+    public:
+        /**
+         * Since this is using the LLSingleton pattern but we
+         * want to allow the constructor to be called first
+         * with various parameters, we also invoke the
+         * LLParamSingleton idiom and use it to initialize
+         * the class via a call in LLAppViewer.
+         */
+        LLSINGLETON(LLDiskCache,
+                    /**
+                     * The full name of the cache folder - typically a
+                     * a child of the main Viewer cache directory. Defined
+                     * by the setting at 'DiskCacheDirName'
+                     */
+                    const std::string cache_dir,
+                    /**
+                     * The maximum size of the cache in bytes - Based on the
+                     * setting at 'CacheSize' and 'DiskCachePercentOfTotal'
+                     */
+                    const uintmax_t max_size_bytes,
+                    /**
+                     * A flag that enables extra cache debugging so that
+                     * if there are bugs, we can ask uses to enable this
+                     * setting and send us their logs
+                     */
+                    const bool enable_cache_debug_info);
+
+        virtual ~LLDiskCache() = default;
+
+    public:
+        /**
+         * Construct a filename and path to it based on the file meta data
+         * (id, asset type, additional 'extra' info like discard level perhaps)
+         * Worth pointing out that this function used to be in LLFileSystem but
+         * so many things had to be pushed back there to accomodate it, that I
+         * decided to move it here.  Still not sure that's completely right.
+         */
+        const std::string metaDataToFilepath(const std::string id,
+                                             LLAssetType::EType at,
+                                             const std::string extra_info);
+
+        /**
+         * Update the "last write time" of a file to "now". This must be called whenever a
+         * file in the cache is read (not written) so that the last time the file was
+         * accessed is up to date (This is used in the mechanism for purging the cache)
+         */
+        void updateFileAccessTime(const std::string file_path);
+
+        /**
+         * Purge the oldest items in the cache so that the combined size of all files
+         * is no bigger than mMaxSizeBytes.
+         *
+         * WARNING: purge() is called by LLPurgeDiskCacheThread. As such it must
+         * NOT touch any LLDiskCache data without introducing and locking a mutex!
+         *
+         * Purging the disk cache involves nontrivial work on the viewer's
+         * filesystem. If called on the main thread, this causes a noticeable
+         * freeze.
+         */
+        void purge();
+
+        /**
+         * Clear the cache by removing all the files in the specified cache
+         * directory individually. Only the files that contain a prefix defined
+         * by mCacheFilenamePrefix will be removed.
+         */
+        void clearCache();
+
+        /**
+         * Return some information about the cache for use in About Box etc.
+         */
+        const std::string getCacheInfo();
+
+    private:
+        /**
+         * Utility function to gather the total size the files in a given
+         * directory. Primarily used here to determine the directory size
+         * before and after the cache purge
+         */
+        uintmax_t dirFileSize(const std::string dir);
+
+        /**
+         * Utility function to convert an LLAssetType enum into a
+         * string that we use as part of the cache file filename
+         */
+        const std::string assetTypeToString(LLAssetType::EType at);
+
+    private:
+        /**
+         * The maximum size of the cache in bytes. After purge is called, the
+         * total size of the cache files in the cache directory will be
+         * less than this value
+         */
+        uintmax_t mMaxSizeBytes;
+
+        /**
+         * The folder that holds the cached files. The consumer of this
+         * class must avoid letting the user set this location as a malicious
+         * setting could potentially point it at a non-cache directory (for example,
+         * the Windows System dir) with disastrous results.
+         */
+        std::string mCacheDir;
+
+        /**
+         * The prefix inserted at the start of a cache file filename to
+         * help identify it as a cache file. It's probably not required
+         * (just the presence in the cache folder is enough) but I am
+         * paranoid about the cache folder being set to something bad
+         * like the users' OS system dir by mistake or maliciously and
+         * this will help to offset any damage if that happens.
+         */
+        std::string mCacheFilenamePrefix;
+
+        /**
+         * When enabled, displays additional debugging information in
+         * various parts of the code
+         */
+        bool mEnableCacheDebugInfo;
+};
+
+class LLPurgeDiskCacheThread : public LLThread
+{
+public:
+    LLPurgeDiskCacheThread();
+
+protected:
+    void run() override;
+};
+#endif // _LLDISKCACHE
diff --git a/indra/llfilesystem/llfilesystem.cpp b/indra/llfilesystem/llfilesystem.cpp
new file mode 100644
index 0000000000..4c836c8838
--- /dev/null
+++ b/indra/llfilesystem/llfilesystem.cpp
@@ -0,0 +1,326 @@
+/**
+ * @file filesystem.h
+ * @brief Simulate local file system operations.
+ * @Note The initial implementation does actually use standard C++
+ *       file operations but eventually, there will be another
+ *       layer that caches and manages file meta data too.
+ *
+ * $LicenseInfo:firstyear=2002&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+
+#include "lldir.h"
+#include "llfilesystem.h"
+#include "llfasttimer.h"
+#include "lldiskcache.h"
+
+const S32 LLFileSystem::READ        = 0x00000001;
+const S32 LLFileSystem::WRITE       = 0x00000002;
+const S32 LLFileSystem::READ_WRITE  = 0x00000003;  // LLFileSystem::READ & LLFileSystem::WRITE
+const S32 LLFileSystem::APPEND      = 0x00000006;  // 0x00000004 & LLFileSystem::WRITE
+
+static LLTrace::BlockTimerStatHandle FTM_VFILE_WAIT("VFile Wait");
+
+LLFileSystem::LLFileSystem(const LLUUID& file_id, const LLAssetType::EType file_type, S32 mode)
+{
+    mFileType = file_type;
+    mFileID = file_id;
+    mPosition = 0;
+    mBytesRead = 0;
+    mMode = mode;
+
+    // This block of code was originally called in the read() method but after comments here:
+    // https://bitbucket.org/lindenlab/viewer/commits/e28c1b46e9944f0215a13cab8ee7dded88d7fc90#comment-10537114
+    // we decided to follow Henri's suggestion and move the code to update the last access time here.
+    if (mode == LLFileSystem::READ)
+    {
+        // build the filename (TODO: we do this in a few places - perhaps we should factor into a single function)
+        std::string id;
+        mFileID.toString(id);
+        const std::string extra_info = "";
+        const std::string filename = LLDiskCache::getInstance()->metaDataToFilepath(id, mFileType, extra_info);
+
+        // update the last access time for the file if it exists - this is required
+        // even though we are reading and not writing because this is the
+        // way the cache works - it relies on a valid "last accessed time" for
+        // each file so it knows how to remove the oldest, unused files
+        bool exists = gDirUtilp->fileExists(filename);
+        if (exists)
+        {
+            LLDiskCache::getInstance()->updateFileAccessTime(filename);
+        }
+    }
+}
+
+LLFileSystem::~LLFileSystem()
+{
+}
+
+// static
+bool LLFileSystem::getExists(const LLUUID& file_id, const LLAssetType::EType file_type)
+{
+    std::string id_str;
+    file_id.toString(id_str);
+    const std::string extra_info = "";
+    const std::string filename = LLDiskCache::getInstance()->metaDataToFilepath(id_str, file_type, extra_info);
+
+    llifstream file(filename, std::ios::binary);
+    if (file.is_open())
+    {
+        file.seekg(0, std::ios::end);
+        return file.tellg() > 0;
+    }
+    return false;
+}
+
+// static
+bool LLFileSystem::removeFile(const LLUUID& file_id, const LLAssetType::EType file_type, int suppress_error /*= 0*/)
+{
+    std::string id_str;
+    file_id.toString(id_str);
+    const std::string extra_info = "";
+    const std::string filename =  LLDiskCache::getInstance()->metaDataToFilepath(id_str, file_type, extra_info);
+
+    LLFile::remove(filename.c_str(), suppress_error);
+
+    return true;
+}
+
+// static
+bool LLFileSystem::renameFile(const LLUUID& old_file_id, const LLAssetType::EType old_file_type,
+                              const LLUUID& new_file_id, const LLAssetType::EType new_file_type)
+{
+    std::string old_id_str;
+    old_file_id.toString(old_id_str);
+    const std::string extra_info = "";
+    const std::string old_filename =  LLDiskCache::getInstance()->metaDataToFilepath(old_id_str, old_file_type, extra_info);
+
+    std::string new_id_str;
+    new_file_id.toString(new_id_str);
+    const std::string new_filename =  LLDiskCache::getInstance()->metaDataToFilepath(new_id_str, new_file_type, extra_info);
+
+    // Rename needs the new file to not exist.
+    LLFileSystem::removeFile(new_file_id, new_file_type, ENOENT);
+
+    if (LLFile::rename(old_filename, new_filename) != 0)
+    {
+        // We would like to return FALSE here indicating the operation
+        // failed but the original code does not and doing so seems to
+        // break a lot of things so we go with the flow...
+        //return FALSE;
+        LL_WARNS() << "Failed to rename " << old_file_id << " to " << new_id_str << " reason: "  << strerror(errno) << LL_ENDL;
+    }
+
+    return TRUE;
+}
+
+// static
+S32 LLFileSystem::getFileSize(const LLUUID& file_id, const LLAssetType::EType file_type)
+{
+    std::string id_str;
+    file_id.toString(id_str);
+    const std::string extra_info = "";
+    const std::string filename =  LLDiskCache::getInstance()->metaDataToFilepath(id_str, file_type, extra_info);
+
+    S32 file_size = 0;
+    llifstream file(filename, std::ios::binary);
+    if (file.is_open())
+    {
+        file.seekg(0, std::ios::end);
+        file_size = file.tellg();
+    }
+
+    return file_size;
+}
+
+BOOL LLFileSystem::read(U8* buffer, S32 bytes)
+{
+    BOOL success = FALSE;
+
+    std::string id;
+    mFileID.toString(id);
+    const std::string extra_info = "";
+    const std::string filename =  LLDiskCache::getInstance()->metaDataToFilepath(id, mFileType, extra_info);
+
+    llifstream file(filename, std::ios::binary);
+    if (file.is_open())
+    {
+        file.seekg(mPosition, std::ios::beg);
+
+        file.read((char*)buffer, bytes);
+
+        if (file)
+        {
+            mBytesRead = bytes;
+        }
+        else
+        {
+            mBytesRead = file.gcount();
+        }
+
+        file.close();
+
+        mPosition += mBytesRead;
+        if (mBytesRead)
+        {
+            success = TRUE;
+        }
+    }
+
+    return success;
+}
+
+S32 LLFileSystem::getLastBytesRead()
+{
+    return mBytesRead;
+}
+
+BOOL LLFileSystem::eof()
+{
+    return mPosition >= getSize();
+}
+
+BOOL LLFileSystem::write(const U8* buffer, S32 bytes)
+{
+    std::string id_str;
+    mFileID.toString(id_str);
+    const std::string extra_info = "";
+    const std::string filename =  LLDiskCache::getInstance()->metaDataToFilepath(id_str, mFileType, extra_info);
+
+    BOOL success = FALSE;
+
+    if (mMode == APPEND)
+    {
+        llofstream ofs(filename, std::ios::app | std::ios::binary);
+        if (ofs)
+        {
+            ofs.write((const char*)buffer, bytes);
+
+            mPosition = ofs.tellp(); // <FS:Ansariel> Fix asset caching
+
+            success = TRUE;
+        }
+    }
+    // <FS:Ansariel> Fix asset caching
+    else if (mMode == READ_WRITE)
+    {
+        // Don't truncate if file already exists
+        llofstream ofs(filename, std::ios::in | std::ios::binary);
+        if (ofs)
+        {
+            ofs.seekp(mPosition, std::ios::beg);
+            ofs.write((const char*)buffer, bytes);
+            mPosition += bytes;
+            success = TRUE;
+        }
+        else
+        {
+            // File doesn't exist - open in write mode
+            ofs.open(filename, std::ios::binary);
+            if (ofs.is_open())
+            {
+                ofs.write((const char*)buffer, bytes);
+                mPosition += bytes;
+                success = TRUE;
+            }
+        }
+    }
+    // </FS:Ansariel>
+    else
+    {
+        llofstream ofs(filename, std::ios::binary);
+        if (ofs)
+        {
+            ofs.write((const char*)buffer, bytes);
+
+            mPosition += bytes;
+
+            success = TRUE;
+        }
+    }
+
+    return success;
+}
+
+BOOL LLFileSystem::seek(S32 offset, S32 origin)
+{
+    if (-1 == origin)
+    {
+        origin = mPosition;
+    }
+
+    S32 new_pos = origin + offset;
+
+    S32 size = getSize();
+
+    if (new_pos > size)
+    {
+        LL_WARNS() << "Attempt to seek past end of file" << LL_ENDL;
+
+        mPosition = size;
+        return FALSE;
+    }
+    else if (new_pos < 0)
+    {
+        LL_WARNS() << "Attempt to seek past beginning of file" << LL_ENDL;
+
+        mPosition = 0;
+        return FALSE;
+    }
+
+    mPosition = new_pos;
+    return TRUE;
+}
+
+S32 LLFileSystem::tell() const
+{
+    return mPosition;
+}
+
+S32 LLFileSystem::getSize()
+{
+    return LLFileSystem::getFileSize(mFileID, mFileType);
+}
+
+S32 LLFileSystem::getMaxSize()
+{
+    // offer up a huge size since we don't care what the max is
+    return INT_MAX;
+}
+
+BOOL LLFileSystem::rename(const LLUUID& new_id, const LLAssetType::EType new_type)
+{
+    LLFileSystem::renameFile(mFileID, mFileType, new_id, new_type);
+
+    mFileID = new_id;
+    mFileType = new_type;
+
+    return TRUE;
+}
+
+BOOL LLFileSystem::remove()
+{
+    LLFileSystem::removeFile(mFileID, mFileType);
+
+    return TRUE;
+}
diff --git a/indra/llfilesystem/llfilesystem.h b/indra/llfilesystem/llfilesystem.h
new file mode 100644
index 0000000000..d934a408c2
--- /dev/null
+++ b/indra/llfilesystem/llfilesystem.h
@@ -0,0 +1,78 @@
+/**
+ * @file filesystem.h
+ * @brief Simulate local file system operations.
+ * @Note The initial implementation does actually use standard C++
+ *       file operations but eventually, there will be another
+ *       layer that caches and manages file meta data too.
+ *
+ * $LicenseInfo:firstyear=2002&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#ifndef LL_FILESYSTEM_H
+#define LL_FILESYSTEM_H
+
+#include "lluuid.h"
+#include "llassettype.h"
+#include "lldiskcache.h"
+
+class LLFileSystem
+{
+    public:
+        LLFileSystem(const LLUUID& file_id, const LLAssetType::EType file_type, S32 mode = LLFileSystem::READ);
+        ~LLFileSystem();
+
+        BOOL read(U8* buffer, S32 bytes);
+        S32  getLastBytesRead();
+        BOOL eof();
+
+        BOOL write(const U8* buffer, S32 bytes);
+        BOOL seek(S32 offset, S32 origin = -1);
+        S32  tell() const;
+
+        S32 getSize();
+        S32 getMaxSize();
+        BOOL rename(const LLUUID& new_id, const LLAssetType::EType new_type);
+        BOOL remove();
+
+        static bool getExists(const LLUUID& file_id, const LLAssetType::EType file_type);
+        static bool removeFile(const LLUUID& file_id, const LLAssetType::EType file_type, int suppress_error = 0);
+        static bool renameFile(const LLUUID& old_file_id, const LLAssetType::EType old_file_type,
+                               const LLUUID& new_file_id, const LLAssetType::EType new_file_type);
+        static S32 getFileSize(const LLUUID& file_id, const LLAssetType::EType file_type);
+
+    public:
+        static const S32 READ;
+        static const S32 WRITE;
+        static const S32 READ_WRITE;
+        static const S32 APPEND;
+
+    protected:
+        LLAssetType::EType mFileType;
+        LLUUID  mFileID;
+        S32     mPosition;
+        S32     mMode;
+        S32     mBytesRead;
+//private:
+//    static const std::string idToFilepath(const std::string id, LLAssetType::EType at);
+};
+
+#endif  // LL_FILESYSTEM_H
diff --git a/indra/llfilesystem/lllfsthread.cpp b/indra/llfilesystem/lllfsthread.cpp
new file mode 100644
index 0000000000..be8e83a56f
--- /dev/null
+++ b/indra/llfilesystem/lllfsthread.cpp
@@ -0,0 +1,245 @@
+/** 
+ * @file lllfsthread.cpp
+ * @brief LLLFSThread base class
+ *
+ * $LicenseInfo:firstyear=2001&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+#include "lllfsthread.h"
+#include "llstl.h"
+#include "llapr.h"
+
+//============================================================================
+
+/*static*/ LLLFSThread* LLLFSThread::sLocal = NULL;
+
+//============================================================================
+// Run on MAIN thread
+//static
+void LLLFSThread::initClass(bool local_is_threaded)
+{
+	llassert(sLocal == NULL);
+	sLocal = new LLLFSThread(local_is_threaded);
+}
+
+//static
+S32 LLLFSThread::updateClass(U32 ms_elapsed)
+{
+	sLocal->update((F32)ms_elapsed);
+	return sLocal->getPending();
+}
+
+//static
+void LLLFSThread::cleanupClass()
+{
+	llassert(sLocal != NULL);
+	sLocal->setQuitting();
+	while (sLocal->getPending())
+	{
+		sLocal->update(0);
+	}
+	delete sLocal;
+	sLocal = NULL;
+}
+
+//----------------------------------------------------------------------------
+
+LLLFSThread::LLLFSThread(bool threaded) :
+	LLQueuedThread("LFS", threaded),
+	mPriorityCounter(PRIORITY_LOWBITS)
+{
+	if(!mLocalAPRFilePoolp)
+	{
+		mLocalAPRFilePoolp = new LLVolatileAPRPool() ;
+	}
+}
+
+LLLFSThread::~LLLFSThread()
+{
+	// mLocalAPRFilePoolp cleanup in LLThread
+	// ~LLQueuedThread() will be called here
+}
+
+//----------------------------------------------------------------------------
+
+LLLFSThread::handle_t LLLFSThread::read(const std::string& filename,	/* Flawfinder: ignore */ 
+										U8* buffer, S32 offset, S32 numbytes,
+										Responder* responder, U32 priority)
+{
+	handle_t handle = generateHandle();
+
+	if (priority == 0) priority = PRIORITY_NORMAL | priorityCounter();
+	else if (priority < PRIORITY_LOW) priority |= PRIORITY_LOW; // All reads are at least PRIORITY_LOW
+
+	Request* req = new Request(this, handle, priority,
+							   FILE_READ, filename,
+							   buffer, offset, numbytes,
+							   responder);
+
+	bool res = addRequest(req);
+	if (!res)
+	{
+		LL_ERRS() << "LLLFSThread::read called after LLLFSThread::cleanupClass()" << LL_ENDL;
+	}
+
+	return handle;
+}
+
+LLLFSThread::handle_t LLLFSThread::write(const std::string& filename,
+										 U8* buffer, S32 offset, S32 numbytes,
+										 Responder* responder, U32 priority)
+{
+	handle_t handle = generateHandle();
+
+	if (priority == 0) priority = PRIORITY_LOW | priorityCounter();
+	
+	Request* req = new Request(this, handle, priority,
+							   FILE_WRITE, filename,
+							   buffer, offset, numbytes,
+							   responder);
+
+	bool res = addRequest(req);
+	if (!res)
+	{
+		LL_ERRS() << "LLLFSThread::read called after LLLFSThread::cleanupClass()" << LL_ENDL;
+	}
+	
+	return handle;
+}
+
+//============================================================================
+
+LLLFSThread::Request::Request(LLLFSThread* thread,
+							  handle_t handle, U32 priority,
+							  operation_t op, const std::string& filename,
+							  U8* buffer, S32 offset, S32 numbytes,
+							  Responder* responder) :
+	QueuedRequest(handle, priority, FLAG_AUTO_COMPLETE),
+	mThread(thread),
+	mOperation(op),
+	mFileName(filename),
+	mBuffer(buffer),
+	mOffset(offset),
+	mBytes(numbytes),
+	mBytesRead(0),
+	mResponder(responder)
+{
+	if (numbytes <= 0)
+	{
+		LL_WARNS() << "LLLFSThread: Request with numbytes = " << numbytes << LL_ENDL;
+	}
+}
+
+LLLFSThread::Request::~Request()
+{
+}
+
+// virtual, called from own thread
+void LLLFSThread::Request::finishRequest(bool completed)
+{
+	if (mResponder.notNull())
+	{
+		mResponder->completed(completed ? mBytesRead : 0);
+		mResponder = NULL;
+	}
+}
+
+void LLLFSThread::Request::deleteRequest()
+{
+	if (getStatus() == STATUS_QUEUED)
+	{
+		LL_ERRS() << "Attempt to delete a queued LLLFSThread::Request!" << LL_ENDL;
+	}	
+	if (mResponder.notNull())
+	{
+		mResponder->completed(0);
+		mResponder = NULL;
+	}
+	LLQueuedThread::QueuedRequest::deleteRequest();
+}
+
+bool LLLFSThread::Request::processRequest()
+{
+	bool complete = false;
+	if (mOperation ==  FILE_READ)
+	{
+		llassert(mOffset >= 0);
+		LLAPRFile infile ; // auto-closes
+		infile.open(mFileName, LL_APR_RB, mThread->getLocalAPRFilePool());
+		if (!infile.getFileHandle())
+		{
+			LL_WARNS() << "LLLFS: Unable to read file: " << mFileName << LL_ENDL;
+			mBytesRead = 0; // fail
+			return true;
+		}
+		S32 off;
+		if (mOffset < 0)
+			off = infile.seek(APR_END, 0);
+		else
+			off = infile.seek(APR_SET, mOffset);
+		llassert_always(off >= 0);
+		mBytesRead = infile.read(mBuffer, mBytes );
+		complete = true;
+// 		LL_INFOS() << "LLLFSThread::READ:" << mFileName << " Bytes: " << mBytesRead << LL_ENDL;
+	}
+	else if (mOperation ==  FILE_WRITE)
+	{
+		apr_int32_t flags = APR_CREATE|APR_WRITE|APR_BINARY;
+		if (mOffset < 0)
+			flags |= APR_APPEND;
+		LLAPRFile outfile ; // auto-closes
+		outfile.open(mFileName, flags, mThread->getLocalAPRFilePool());
+		if (!outfile.getFileHandle())
+		{
+			LL_WARNS() << "LLLFS: Unable to write file: " << mFileName << LL_ENDL;
+			mBytesRead = 0; // fail
+			return true;
+		}
+		if (mOffset >= 0)
+		{
+			S32 seek = outfile.seek(APR_SET, mOffset);
+			if (seek < 0)
+			{
+				LL_WARNS() << "LLLFS: Unable to write file (seek failed): " << mFileName << LL_ENDL;
+				mBytesRead = 0; // fail
+				return true;
+			}
+		}
+		mBytesRead = outfile.write(mBuffer, mBytes );
+		complete = true;
+// 		LL_INFOS() << "LLLFSThread::WRITE:" << mFileName << " Bytes: " << mBytesRead << "/" << mBytes << " Offset:" << mOffset << LL_ENDL;
+	}
+	else
+	{
+		LL_ERRS() << "LLLFSThread::unknown operation: " << (S32)mOperation << LL_ENDL;
+	}
+	return complete;
+}
+
+//============================================================================
+
+LLLFSThread::Responder::~Responder()
+{
+}
+
+//============================================================================
diff --git a/indra/llfilesystem/lllfsthread.h b/indra/llfilesystem/lllfsthread.h
new file mode 100644
index 0000000000..58f658f7ba
--- /dev/null
+++ b/indra/llfilesystem/lllfsthread.h
@@ -0,0 +1,147 @@
+/** 
+ * @file lllfsthread.h
+ * @brief LLLFSThread base class
+ *
+ * $LicenseInfo:firstyear=2000&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#ifndef LL_LLLFSTHREAD_H
+#define LL_LLLFSTHREAD_H
+
+#include <queue>
+#include <string>
+#include <map>
+#include <set>
+
+#include "llpointer.h"
+#include "llqueuedthread.h"
+
+//============================================================================
+// Threaded Local File System
+//============================================================================
+
+class LLLFSThread : public LLQueuedThread
+{
+	//------------------------------------------------------------------------
+public:
+	enum operation_t {
+		FILE_READ,
+		FILE_WRITE,
+		FILE_RENAME,
+		FILE_REMOVE
+	};
+
+	//------------------------------------------------------------------------
+public:
+
+	class Responder : public LLThreadSafeRefCount
+	{
+	protected:
+		~Responder();
+	public:
+		virtual void completed(S32 bytes) = 0;
+	};
+
+	class Request : public QueuedRequest
+	{
+	protected:
+		virtual ~Request(); // use deleteRequest()
+		
+	public:
+		Request(LLLFSThread* thread,
+				handle_t handle, U32 priority, 
+				operation_t op, const std::string& filename,
+				U8* buffer, S32 offset, S32 numbytes,
+				Responder* responder);
+
+		S32 getBytes()
+		{
+			return mBytes;
+		}
+		S32 getBytesRead()
+		{
+			return mBytesRead;
+		}
+		S32 getOperation()
+		{
+			return mOperation;
+		}
+		U8* getBuffer()
+		{
+			return mBuffer;
+		}
+		const std::string& getFilename()
+		{
+			return mFileName;
+		}
+		
+		/*virtual*/ bool processRequest();
+		/*virtual*/ void finishRequest(bool completed);
+		/*virtual*/ void deleteRequest();
+		
+	private:
+		LLLFSThread* mThread;
+		operation_t mOperation;
+		
+		std::string mFileName;
+		
+		U8* mBuffer;	// dest for reads, source for writes, new UUID for rename
+		S32 mOffset;	// offset into file, -1 = append (WRITE only)
+		S32 mBytes;		// bytes to read from file, -1 = all
+		S32 mBytesRead;	// bytes read from file
+
+		LLPointer<Responder> mResponder;
+	};
+
+	//------------------------------------------------------------------------
+public:
+	LLLFSThread(bool threaded = TRUE);
+	~LLLFSThread();	
+
+	// Return a Request handle
+	handle_t read(const std::string& filename,	/* Flawfinder: ignore */ 
+				  U8* buffer, S32 offset, S32 numbytes,
+				  Responder* responder, U32 pri=0);
+	handle_t write(const std::string& filename,
+				   U8* buffer, S32 offset, S32 numbytes,
+				   Responder* responder, U32 pri=0);
+	
+	// Misc
+	U32 priorityCounter() { return mPriorityCounter-- & PRIORITY_LOWBITS; } // Use to order IO operations
+	
+	// static initializers
+	static void initClass(bool local_is_threaded = TRUE); // Setup sLocal
+	static S32 updateClass(U32 ms_elapsed);
+	static void cleanupClass();		// Delete sLocal
+
+	
+private:
+	U32 mPriorityCounter;
+	
+public:
+	static LLLFSThread* sLocal;		// Default local file thread
+};
+
+//============================================================================
+
+
+#endif // LL_LLLFSTHREAD_H
diff --git a/indra/llfilesystem/tests/lldir_test.cpp b/indra/llfilesystem/tests/lldir_test.cpp
new file mode 100644
index 0000000000..3cff622a4b
--- /dev/null
+++ b/indra/llfilesystem/tests/lldir_test.cpp
@@ -0,0 +1,767 @@
+/**
+ * @file lldir_test.cpp
+ * @date 2008-05
+ * @brief LLDir test cases.
+ *
+ * $LicenseInfo:firstyear=2008&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+
+#include "llstring.h"
+#include "tests/StringVec.h"
+#include "../lldir.h"
+#include "../lldiriterator.h"
+
+#include "../test/lltut.h"
+#include "stringize.h"
+#include <boost/foreach.hpp>
+#include <boost/assign/list_of.hpp>
+
+using boost::assign::list_of;
+
+// We use ensure_equals(..., vec(list_of(...))) not because it's functionally
+// required, but because ensure_equals() knows how to format a StringVec.
+// Turns out that when ensure_equals() displays a test failure with just
+// list_of("string")("another"), you see 'stringanother' vs. '("string",
+// "another")'.
+StringVec vec(const StringVec& v)
+{
+    return v;
+}
+
+// For some tests, use a dummy LLDir that uses memory data instead of touching
+// the filesystem
+struct LLDir_Dummy: public LLDir
+{
+    /*----------------------------- LLDir API ------------------------------*/
+    LLDir_Dummy()
+    {
+        // Initialize important LLDir data members based on the filesystem
+        // data below.
+        mDirDelimiter = "/";
+        mExecutableDir = "install";
+        mExecutableFilename = "test";
+        mExecutablePathAndName = add(mExecutableDir, mExecutableFilename);
+        mWorkingDir = mExecutableDir;
+        mAppRODataDir = "install";
+        mSkinBaseDir = add(mAppRODataDir, "skins");
+        mOSUserDir = "user";
+        mOSUserAppDir = mOSUserDir;
+        mLindenUserDir = "";
+
+        // Make the dummy filesystem look more or less like what we expect in
+        // the real one.
+        static const char* preload[] =
+        {
+            // We group these fixture-data pathnames by basename, rather than
+            // sorting by full path as you might expect, because the outcome
+            // of each test strongly depends on which skins/languages provide
+            // a given basename.
+            "install/skins/default/colors.xml",
+            "install/skins/steam/colors.xml",
+            "user/skins/default/colors.xml",
+            "user/skins/steam/colors.xml",
+
+            "install/skins/default/xui/en/strings.xml",
+            "install/skins/default/xui/fr/strings.xml",
+            "install/skins/steam/xui/en/strings.xml",
+            "install/skins/steam/xui/fr/strings.xml",
+            "user/skins/default/xui/en/strings.xml",
+            "user/skins/default/xui/fr/strings.xml",
+            "user/skins/steam/xui/en/strings.xml",
+            "user/skins/steam/xui/fr/strings.xml",
+
+            "install/skins/default/xui/en/floater.xml",
+            "install/skins/default/xui/fr/floater.xml",
+            "user/skins/default/xui/fr/floater.xml",
+
+            "install/skins/default/xui/en/newfile.xml",
+            "install/skins/default/xui/fr/newfile.xml",
+            "user/skins/default/xui/en/newfile.xml",
+
+            "install/skins/default/html/en-us/welcome.html",
+            "install/skins/default/html/fr/welcome.html",
+
+            "install/skins/default/textures/only_default.jpeg",
+            "install/skins/steam/textures/only_steam.jpeg",
+            "user/skins/default/textures/only_user_default.jpeg",
+            "user/skins/steam/textures/only_user_steam.jpeg",
+
+            "install/skins/default/future/somefile.txt"
+        };
+        BOOST_FOREACH(const char* path, preload)
+        {
+            buildFilesystem(path);
+        }
+    }
+
+    virtual ~LLDir_Dummy() {}
+
+    virtual void initAppDirs(const std::string& app_name, const std::string& app_read_only_data_dir)
+    {
+        // Implement this when we write a test that needs it
+    }
+
+    virtual std::string getCurPath()
+    {
+        // Implement this when we write a test that needs it
+        return "";
+    }
+
+    virtual U32 countFilesInDir(const std::string& dirname, const std::string& mask)
+    {
+        // Implement this when we write a test that needs it
+        return 0;
+    }
+
+    virtual bool fileExists(const std::string& pathname) const
+    {
+        // Record fileExists() calls so we can check whether caching is
+        // working right. Certain LLDir calls should be able to make decisions
+        // without calling fileExists() again, having already checked existence.
+        mChecked.insert(pathname);
+        // For our simple flat set of strings, see whether the identical
+        // pathname exists in our set.
+        return (mFilesystem.find(pathname) != mFilesystem.end());
+    }
+
+    virtual std::string getLLPluginLauncher()
+    {
+        // Implement this when we write a test that needs it
+        return "";
+    }
+
+    virtual std::string getLLPluginFilename(std::string base_name)
+    {
+        // Implement this when we write a test that needs it
+        return "";
+    }
+
+    /*----------------------------- Dummy data -----------------------------*/
+    void clearFilesystem() { mFilesystem.clear(); }
+    void buildFilesystem(const std::string& path)
+    {
+        // Split the pathname on slashes, ignoring leading, trailing, doubles
+        StringVec components;
+        LLStringUtil::getTokens(path, components, "/");
+        // Ensure we have an entry representing every level of this path
+        std::string partial;
+        BOOST_FOREACH(std::string component, components)
+        {
+            append(partial, component);
+            mFilesystem.insert(partial);
+        }
+    }
+
+    void clear_checked() { mChecked.clear(); }
+    void ensure_checked(const std::string& pathname) const
+    {
+        tut::ensure(STRINGIZE(pathname << " was not checked but should have been"),
+                    mChecked.find(pathname) != mChecked.end());
+    }
+    void ensure_not_checked(const std::string& pathname) const
+    {
+        tut::ensure(STRINGIZE(pathname << " was checked but should not have been"),
+                    mChecked.find(pathname) == mChecked.end());
+    }
+
+    std::set<std::string> mFilesystem;
+    mutable std::set<std::string> mChecked;
+};
+
+namespace tut
+{
+	struct LLDirTest
+        {
+        };
+        typedef test_group<LLDirTest> LLDirTest_t;
+        typedef LLDirTest_t::object LLDirTest_object_t;
+        tut::LLDirTest_t tut_LLDirTest("LLDir");
+
+	template<> template<>
+	void LLDirTest_object_t::test<1>()
+		// getDirDelimiter
+	{
+		ensure("getDirDelimiter", !gDirUtilp->getDirDelimiter().empty());
+	}
+
+	template<> template<>
+	void LLDirTest_object_t::test<2>()
+		// getBaseFileName
+	{
+		std::string delim = gDirUtilp->getDirDelimiter();
+		std::string rawFile = "foo";
+		std::string rawFileExt = "foo.bAr";
+		std::string rawFileNullExt = "foo.";
+		std::string rawExt = ".bAr";
+		std::string rawDot = ".";
+		std::string pathNoExt = "aa" + delim + "bb" + delim + "cc" + delim + "dd" + delim + "ee";
+		std::string pathExt = pathNoExt + ".eXt";
+		std::string dottedPathNoExt = "aa" + delim + "bb" + delim + "cc.dd" + delim + "ee";
+		std::string dottedPathExt = dottedPathNoExt + ".eXt";
+
+		// foo[.bAr]
+
+		ensure_equals("getBaseFileName/r-no-ext/no-strip-exten",
+			      gDirUtilp->getBaseFileName(rawFile, false),
+			      "foo");
+
+		ensure_equals("getBaseFileName/r-no-ext/strip-exten",
+			      gDirUtilp->getBaseFileName(rawFile, true),
+			      "foo");
+
+		ensure_equals("getBaseFileName/r-ext/no-strip-exten",
+			      gDirUtilp->getBaseFileName(rawFileExt, false),
+			      "foo.bAr");
+
+		ensure_equals("getBaseFileName/r-ext/strip-exten",
+			      gDirUtilp->getBaseFileName(rawFileExt, true),
+			      "foo");
+
+		// foo.
+
+		ensure_equals("getBaseFileName/rn-no-ext/no-strip-exten",
+			      gDirUtilp->getBaseFileName(rawFileNullExt, false),
+			      "foo.");
+
+		ensure_equals("getBaseFileName/rn-no-ext/strip-exten",
+			      gDirUtilp->getBaseFileName(rawFileNullExt, true),
+			      "foo");
+
+		// .bAr
+		// interesting case - with no basename, this IS the basename, not the extension.
+
+		ensure_equals("getBaseFileName/e-ext/no-strip-exten",
+			      gDirUtilp->getBaseFileName(rawExt, false),
+			      ".bAr");
+
+		ensure_equals("getBaseFileName/e-ext/strip-exten",
+			      gDirUtilp->getBaseFileName(rawExt, true),
+			      ".bAr");
+
+		// .
+
+		ensure_equals("getBaseFileName/d/no-strip-exten",
+			      gDirUtilp->getBaseFileName(rawDot, false),
+			      ".");
+
+		ensure_equals("getBaseFileName/d/strip-exten",
+			      gDirUtilp->getBaseFileName(rawDot, true),
+			      ".");
+
+		// aa/bb/cc/dd/ee[.eXt]
+
+		ensure_equals("getBaseFileName/no-ext/no-strip-exten",
+			      gDirUtilp->getBaseFileName(pathNoExt, false),
+			      "ee");
+
+		ensure_equals("getBaseFileName/no-ext/strip-exten",
+			      gDirUtilp->getBaseFileName(pathNoExt, true),
+			      "ee");
+
+		ensure_equals("getBaseFileName/ext/no-strip-exten",
+			      gDirUtilp->getBaseFileName(pathExt, false),
+			      "ee.eXt");
+
+		ensure_equals("getBaseFileName/ext/strip-exten",
+			      gDirUtilp->getBaseFileName(pathExt, true),
+			      "ee");
+
+		// aa/bb/cc.dd/ee[.eXt]
+
+		ensure_equals("getBaseFileName/d-no-ext/no-strip-exten",
+			      gDirUtilp->getBaseFileName(dottedPathNoExt, false),
+			      "ee");
+
+		ensure_equals("getBaseFileName/d-no-ext/strip-exten",
+			      gDirUtilp->getBaseFileName(dottedPathNoExt, true),
+			      "ee");
+
+		ensure_equals("getBaseFileName/d-ext/no-strip-exten",
+			      gDirUtilp->getBaseFileName(dottedPathExt, false),
+			      "ee.eXt");
+
+		ensure_equals("getBaseFileName/d-ext/strip-exten",
+			      gDirUtilp->getBaseFileName(dottedPathExt, true),
+			      "ee");
+	}
+
+	template<> template<>
+	void LLDirTest_object_t::test<3>()
+		// getDirName
+	{
+		std::string delim = gDirUtilp->getDirDelimiter();
+		std::string rawFile = "foo";
+		std::string rawFileExt = "foo.bAr";
+		std::string pathNoExt = "aa" + delim + "bb" + delim + "cc" + delim + "dd" + delim + "ee";
+		std::string pathExt = pathNoExt + ".eXt";
+		std::string dottedPathNoExt = "aa" + delim + "bb" + delim + "cc.dd" + delim + "ee";
+		std::string dottedPathExt = dottedPathNoExt + ".eXt";
+
+		// foo[.bAr]
+
+		ensure_equals("getDirName/r-no-ext",
+			      gDirUtilp->getDirName(rawFile),
+			      "");
+
+		ensure_equals("getDirName/r-ext",
+			      gDirUtilp->getDirName(rawFileExt),
+			      "");
+
+		// aa/bb/cc/dd/ee[.eXt]
+
+		ensure_equals("getDirName/no-ext",
+			      gDirUtilp->getDirName(pathNoExt),
+			      "aa" + delim + "bb" + delim + "cc" + delim + "dd");
+
+		ensure_equals("getDirName/ext",
+			      gDirUtilp->getDirName(pathExt),
+			      "aa" + delim + "bb" + delim + "cc" + delim + "dd");
+
+		// aa/bb/cc.dd/ee[.eXt]
+
+		ensure_equals("getDirName/d-no-ext",
+			      gDirUtilp->getDirName(dottedPathNoExt),
+			      "aa" + delim + "bb" + delim + "cc.dd");
+
+		ensure_equals("getDirName/d-ext",
+			      gDirUtilp->getDirName(dottedPathExt),
+			      "aa" + delim + "bb" + delim + "cc.dd");
+	}
+
+	template<> template<>
+	void LLDirTest_object_t::test<4>()
+		// getExtension
+	{
+		std::string delim = gDirUtilp->getDirDelimiter();
+		std::string rawFile = "foo";
+		std::string rawFileExt = "foo.bAr";
+		std::string rawFileNullExt = "foo.";
+		std::string rawExt = ".bAr";
+		std::string rawDot = ".";
+		std::string pathNoExt = "aa" + delim + "bb" + delim + "cc" + delim + "dd" + delim + "ee";
+		std::string pathExt = pathNoExt + ".eXt";
+		std::string dottedPathNoExt = "aa" + delim + "bb" + delim + "cc.dd" + delim + "ee";
+		std::string dottedPathExt = dottedPathNoExt + ".eXt";
+
+		// foo[.bAr]
+
+		ensure_equals("getExtension/r-no-ext",
+			      gDirUtilp->getExtension(rawFile),
+			      "");
+
+		ensure_equals("getExtension/r-ext",
+			      gDirUtilp->getExtension(rawFileExt),
+			      "bar");
+
+		// foo.
+
+		ensure_equals("getExtension/rn-no-ext",
+			      gDirUtilp->getExtension(rawFileNullExt),
+			      "");
+
+		// .bAr
+		// interesting case - with no basename, this IS the basename, not the extension.
+
+		ensure_equals("getExtension/e-ext",
+			      gDirUtilp->getExtension(rawExt),
+			      "");
+
+		// .
+
+		ensure_equals("getExtension/d",
+			      gDirUtilp->getExtension(rawDot),
+			      "");
+
+		// aa/bb/cc/dd/ee[.eXt]
+
+		ensure_equals("getExtension/no-ext",
+			      gDirUtilp->getExtension(pathNoExt),
+			      "");
+
+		ensure_equals("getExtension/ext",
+			      gDirUtilp->getExtension(pathExt),
+			      "ext");
+
+		// aa/bb/cc.dd/ee[.eXt]
+
+		ensure_equals("getExtension/d-no-ext",
+			      gDirUtilp->getExtension(dottedPathNoExt),
+			      "");
+
+		ensure_equals("getExtension/d-ext",
+			      gDirUtilp->getExtension(dottedPathExt),
+			      "ext");
+	}
+
+   std::string makeTestFile( const std::string& dir, const std::string& file )
+   {
+      std::string path = dir + file;
+      LLFILE* handle = LLFile::fopen( path, "w" );
+      ensure("failed to open test file '"+path+"'", handle != NULL );
+      // Harbison & Steele, 4th ed., p. 366: "If an error occurs, fputs
+      // returns EOF; otherwise, it returns some other, nonnegative value."
+      ensure("failed to write to test file '"+path+"'", EOF != fputs("test file", handle) );
+      fclose(handle);
+      return path;
+   }
+
+   std::string makeTestDir( const std::string& dirbase )
+   {
+      int counter;
+      std::string uniqueDir;
+      bool foundUnused;
+      std::string delim = gDirUtilp->getDirDelimiter();
+      
+      for (counter=0, foundUnused=false; !foundUnused; counter++ )
+      {
+         char counterStr[3];
+         sprintf(counterStr, "%02d", counter);
+         uniqueDir = dirbase + counterStr;
+         foundUnused = ! ( LLFile::isdir(uniqueDir) || LLFile::isfile(uniqueDir) );
+      }
+      ensure("test directory '" + uniqueDir + "' creation failed", !LLFile::mkdir(uniqueDir));
+      
+      return uniqueDir + delim; // HACK - apparently, the trailing delimiter is needed...
+   }
+
+   static const char* DirScanFilename[5] = { "file1.abc", "file2.abc", "file1.xyz", "file2.xyz", "file1.mno" };
+
+   void scanTest(const std::string& directory, const std::string& pattern, bool correctResult[5])
+   {
+
+      // Scan directory and see if any file1.* files are found
+      std::string scanResult;
+      int   found = 0;
+      bool  filesFound[5] = { false, false, false, false, false };
+      //std::cerr << "searching '"+directory+"' for '"+pattern+"'\n";
+
+      LLDirIterator iter(directory, pattern);
+      while ( found <= 5 && iter.next(scanResult) )
+      {
+         found++;
+         //std::cerr << "  found '"+scanResult+"'\n";
+         int check;
+         for (check=0; check < 5 && ! ( scanResult == DirScanFilename[check] ); check++)
+         {
+         }
+         // check is now either 5 (not found) or the index of the matching name
+         if (check < 5)
+         {
+            ensure( "found file '"+(std::string)DirScanFilename[check]+"' twice", ! filesFound[check] );
+            filesFound[check] = true;
+         }
+         else // check is 5 - should not happen
+         {
+            fail( "found unknown file '"+scanResult+"'");
+         }
+      }
+      for (int i=0; i<5; i++)
+      {
+         if (correctResult[i])
+         {
+            ensure("scan of '"+directory+"' using '"+pattern+"' did not return '"+DirScanFilename[i]+"'", filesFound[i]);
+         }
+         else
+         {
+            ensure("scan of '"+directory+"' using '"+pattern+"' incorrectly returned '"+DirScanFilename[i]+"'", !filesFound[i]);
+         }
+      }
+   }
+   
+   template<> template<>
+   void LLDirTest_object_t::test<5>()
+      // LLDirIterator::next
+   {
+      std::string delim = gDirUtilp->getDirDelimiter();
+      std::string dirTemp = LLFile::tmpdir();
+
+      // Create the same 5 file names of the two directories
+
+      std::string dir1 = makeTestDir(dirTemp + "LLDirIterator");
+      std::string dir2 = makeTestDir(dirTemp + "LLDirIterator");
+      std::string dir1files[5];
+      std::string dir2files[5];
+      for (int i=0; i<5; i++)
+      {
+         dir1files[i] = makeTestFile(dir1, DirScanFilename[i]);
+         dir2files[i] = makeTestFile(dir2, DirScanFilename[i]);
+      }
+
+      // Scan dir1 and see if each of the 5 files is found exactly once
+      bool expected1[5] = { true, true, true, true, true };
+      scanTest(dir1, "*", expected1);
+
+      // Scan dir2 and see if only the 2 *.xyz files are found
+      bool  expected2[5] = { false, false, true, true, false };
+      scanTest(dir1, "*.xyz", expected2);
+
+      // Scan dir2 and see if only the 1 *.mno file is found
+      bool  expected3[5] = { false, false, false, false, true };
+      scanTest(dir2, "*.mno", expected3);
+
+      // Scan dir1 and see if any *.foo files are found
+      bool  expected4[5] = { false, false, false, false, false };
+      scanTest(dir1, "*.foo", expected4);
+
+      // Scan dir1 and see if any file1.* files are found
+      bool  expected5[5] = { true, false, true, false, true };
+      scanTest(dir1, "file1.*", expected5);
+
+      // Scan dir1 and see if any file1.* files are found
+      bool  expected6[5] = { true, true, false, false, false };
+      scanTest(dir1, "file?.abc", expected6);
+
+      // Scan dir2 and see if any file?.x?z files are found
+      bool  expected7[5] = { false, false, true, true, false };
+      scanTest(dir2, "file?.x?z", expected7);
+
+      // Scan dir2 and see if any file?.??c files are found
+      bool  expected8[5] = { true, true, false, false, false };
+      scanTest(dir2, "file?.??c", expected8);
+      scanTest(dir2, "*.??c", expected8);
+
+      // Scan dir1 and see if any *.?n? files are found
+      bool  expected9[5] = { false, false, false, false, true };
+      scanTest(dir1, "*.?n?", expected9);
+
+      // Scan dir1 and see if any *.???? files are found
+      bool  expected10[5] = { false, false, false, false, false };
+      scanTest(dir1, "*.????", expected10);
+
+      // Scan dir1 and see if any ?????.* files are found
+      bool  expected11[5] = { true, true, true, true, true };
+      scanTest(dir1, "?????.*", expected11);
+
+      // Scan dir1 and see if any ??l??.xyz files are found
+      bool  expected12[5] = { false, false, true, true, false };
+      scanTest(dir1, "??l??.xyz", expected12);
+
+      bool expected13[5] = { true, false, true, false, false };
+      scanTest(dir1, "file1.{abc,xyz}", expected13);
+
+      bool expected14[5] = { true, true, false, false, false };
+      scanTest(dir1, "file[0-9].abc", expected14);
+
+      bool expected15[5] = { true, true, false, false, false };
+      scanTest(dir1, "file[!a-z].abc", expected15);
+
+      // clean up all test files and directories
+      for (int i=0; i<5; i++)
+      {
+         LLFile::remove(dir1files[i]);
+         LLFile::remove(dir2files[i]);
+      }
+      LLFile::rmdir(dir1);
+      LLFile::rmdir(dir2);
+   }
+
+    template<> template<>
+    void LLDirTest_object_t::test<6>()
+    {
+        set_test_name("findSkinnedFilenames()");
+        LLDir_Dummy lldir;
+        /*------------------------ "default", "en" -------------------------*/
+        // Setting "default" means we shouldn't consider any "*/skins/steam"
+        // directories; setting "en" means we shouldn't consider any "xui/fr"
+        // directories.
+        lldir.setSkinFolder("default", "en");
+        ensure_equals(lldir.getSkinFolder(), "default");
+        ensure_equals(lldir.getLanguage(), "en");
+
+        // top-level directory of a skin isn't localized
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::SKINBASE, "colors.xml", LLDir::ALL_SKINS),
+                      vec(list_of("install/skins/default/colors.xml")
+                                 ("user/skins/default/colors.xml")));
+        // We should not have needed to check for skins/default/en. We should
+        // just "know" that SKINBASE is not localized.
+        lldir.ensure_not_checked("install/skins/default/en");
+
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::TEXTURES, "only_default.jpeg"),
+                      vec(list_of("install/skins/default/textures/only_default.jpeg")));
+        // Nor should we have needed to check skins/default/textures/en
+        // because textures is known not to be localized.
+        lldir.ensure_not_checked("install/skins/default/textures/en");
+
+        StringVec expected(vec(list_of("install/skins/default/xui/en/strings.xml")
+                               ("user/skins/default/xui/en/strings.xml")));
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "strings.xml", LLDir::ALL_SKINS),
+                      expected);
+        // The first time, we had to probe to find out whether xui was localized.
+        lldir.ensure_checked("install/skins/default/xui/en");
+        lldir.clear_checked();
+        // Now make the same call again -- should return same result --
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "strings.xml", LLDir::ALL_SKINS),
+                      expected);
+        // but this time it should remember that xui is localized.
+        lldir.ensure_not_checked("install/skins/default/xui/en");
+
+        // localized subdir with "en-us" instead of "en"
+        ensure_equals(lldir.findSkinnedFilenames("html", "welcome.html"),
+                      vec(list_of("install/skins/default/html/en-us/welcome.html")));
+        lldir.ensure_checked("install/skins/default/html/en");
+        lldir.ensure_checked("install/skins/default/html/en-us");
+        lldir.clear_checked();
+        ensure_equals(lldir.findSkinnedFilenames("html", "welcome.html"),
+                      vec(list_of("install/skins/default/html/en-us/welcome.html")));
+        lldir.ensure_not_checked("install/skins/default/html/en");
+        lldir.ensure_not_checked("install/skins/default/html/en-us");
+
+        ensure_equals(lldir.findSkinnedFilenames("future", "somefile.txt"),
+                      vec(list_of("install/skins/default/future/somefile.txt")));
+        // Test probing for an unrecognized unlocalized future subdir.
+        lldir.ensure_checked("install/skins/default/future/en");
+        lldir.clear_checked();
+        ensure_equals(lldir.findSkinnedFilenames("future", "somefile.txt"),
+                      vec(list_of("install/skins/default/future/somefile.txt")));
+        // Second time it should remember that future is unlocalized.
+        lldir.ensure_not_checked("install/skins/default/future/en");
+
+        // When language is set to "en", requesting an html file pulls up the
+        // "en-us" version -- not because it magically matches those strings,
+        // but because there's no "en" localization and it falls back on the
+        // default "en-us"! Note that it would probably still be better to
+        // make the default localization be "en" and allow "en-gb" (or
+        // whatever) localizations, which would work much more the way you'd
+        // expect.
+        ensure_equals(lldir.findSkinnedFilenames("html", "welcome.html"),
+                      vec(list_of("install/skins/default/html/en-us/welcome.html")));
+
+        /*------------------------ "default", "fr" -------------------------*/
+        // We start being able to distinguish localized subdirs from
+        // unlocalized when we ask for a non-English language.
+        lldir.setSkinFolder("default", "fr");
+        ensure_equals(lldir.getLanguage(), "fr");
+
+        // pass merge=true to request this filename in all relevant skins
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "strings.xml", LLDir::ALL_SKINS),
+                      vec(list_of
+                          ("install/skins/default/xui/en/strings.xml")
+                          ("install/skins/default/xui/fr/strings.xml")
+                          ("user/skins/default/xui/en/strings.xml")
+                          ("user/skins/default/xui/fr/strings.xml")));
+
+        // pass (or default) merge=false to request only most specific skin
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "strings.xml"),
+                      vec(list_of
+                          ("user/skins/default/xui/en/strings.xml")
+                          ("user/skins/default/xui/fr/strings.xml")));
+
+        // Our dummy floater.xml has a user localization (for "fr") but no
+        // English override. This is a case in which CURRENT_SKIN nonetheless
+        // returns paths from two different skins.
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "floater.xml"),
+                      vec(list_of
+                          ("install/skins/default/xui/en/floater.xml")
+                          ("user/skins/default/xui/fr/floater.xml")));
+
+        // Our dummy newfile.xml has an English override but no user
+        // localization. This is another case in which CURRENT_SKIN
+        // nonetheless returns paths from two different skins.
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "newfile.xml"),
+                      vec(list_of
+                          ("user/skins/default/xui/en/newfile.xml")
+                          ("install/skins/default/xui/fr/newfile.xml")));
+
+        ensure_equals(lldir.findSkinnedFilenames("html", "welcome.html"),
+                      vec(list_of
+                          ("install/skins/default/html/en-us/welcome.html")
+                          ("install/skins/default/html/fr/welcome.html")));
+
+        /*------------------------ "default", "zh" -------------------------*/
+        lldir.setSkinFolder("default", "zh");
+        // Because strings.xml has only a "fr" override but no "zh" override
+        // in any skin, the most localized version we can find is "en".
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "strings.xml"),
+                      vec(list_of("user/skins/default/xui/en/strings.xml")));
+
+        /*------------------------- "steam", "en" --------------------------*/
+        lldir.setSkinFolder("steam", "en");
+
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::SKINBASE, "colors.xml", LLDir::ALL_SKINS),
+                      vec(list_of
+                          ("install/skins/default/colors.xml")
+                          ("install/skins/steam/colors.xml")
+                          ("user/skins/default/colors.xml")
+                          ("user/skins/steam/colors.xml")));
+
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::TEXTURES, "only_default.jpeg"),
+                      vec(list_of("install/skins/default/textures/only_default.jpeg")));
+
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::TEXTURES, "only_steam.jpeg"),
+                      vec(list_of("install/skins/steam/textures/only_steam.jpeg")));
+
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::TEXTURES, "only_user_default.jpeg"),
+                      vec(list_of("user/skins/default/textures/only_user_default.jpeg")));
+
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::TEXTURES, "only_user_steam.jpeg"),
+                      vec(list_of("user/skins/steam/textures/only_user_steam.jpeg")));
+
+        // CURRENT_SKIN
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "strings.xml"),
+                      vec(list_of("user/skins/steam/xui/en/strings.xml")));
+
+        // pass constraint=ALL_SKINS to request this filename in all relevant skins
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "strings.xml", LLDir::ALL_SKINS),
+                      vec(list_of
+                          ("install/skins/default/xui/en/strings.xml")
+                          ("install/skins/steam/xui/en/strings.xml")
+                          ("user/skins/default/xui/en/strings.xml")
+                          ("user/skins/steam/xui/en/strings.xml")));
+
+        /*------------------------- "steam", "fr" --------------------------*/
+        lldir.setSkinFolder("steam", "fr");
+
+        // pass CURRENT_SKIN to request only the most specialized files
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "strings.xml"),
+                      vec(list_of
+                          ("user/skins/steam/xui/en/strings.xml")
+                          ("user/skins/steam/xui/fr/strings.xml")));
+
+        // pass ALL_SKINS to request this filename in all relevant skins
+        ensure_equals(lldir.findSkinnedFilenames(LLDir::XUI, "strings.xml", LLDir::ALL_SKINS),
+                      vec(list_of
+                          ("install/skins/default/xui/en/strings.xml")
+                          ("install/skins/default/xui/fr/strings.xml")
+                          ("install/skins/steam/xui/en/strings.xml")
+                          ("install/skins/steam/xui/fr/strings.xml")
+                          ("user/skins/default/xui/en/strings.xml")
+                          ("user/skins/default/xui/fr/strings.xml")
+                          ("user/skins/steam/xui/en/strings.xml")
+                          ("user/skins/steam/xui/fr/strings.xml")));
+    }
+
+    template<> template<>
+    void LLDirTest_object_t::test<7>()
+    {
+        set_test_name("add()");
+        LLDir_Dummy lldir;
+        ensure_equals("both empty", lldir.add("", ""), "");
+        ensure_equals("path empty", lldir.add("", "b"), "b");
+        ensure_equals("name empty", lldir.add("a", ""), "a");
+        ensure_equals("both simple", lldir.add("a", "b"), "a/b");
+        ensure_equals("name leading slash", lldir.add("a", "/b"), "a/b");
+        ensure_equals("path trailing slash", lldir.add("a/", "b"), "a/b");
+        ensure_equals("both bring slashes", lldir.add("a/", "/b"), "a/b");
+    }
+}
diff --git a/indra/llfilesystem/tests/lldiriterator_test.cpp b/indra/llfilesystem/tests/lldiriterator_test.cpp
new file mode 100644
index 0000000000..a65e3dada5
--- /dev/null
+++ b/indra/llfilesystem/tests/lldiriterator_test.cpp
@@ -0,0 +1,65 @@
+/**
+ * @file lldiriterator_test.cpp
+ * @date 2011-06
+ * @brief LLDirIterator test cases.
+ *
+ * $LicenseInfo:firstyear=2011&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2011, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.,
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#include "linden_common.h"
+#include "lltut.h"
+#include "../lldiriterator.h"
+
+
+namespace tut
+{
+    
+    struct LLDirIteratorFixture
+    {
+        LLDirIteratorFixture()
+        {
+        }
+    };
+    typedef test_group<LLDirIteratorFixture> LLDirIteratorTest_factory;
+    typedef LLDirIteratorTest_factory::object LLDirIteratorTest_t;
+    LLDirIteratorTest_factory tf("LLDirIterator");
+
+    /*
+    CHOP-662 was originally introduced to deal with crashes deleting files from
+    a directory (VWR-25500). However, this introduced a crash looking for 
+    old chat logs as the glob_to_regex function in lldiriterator wasn't escaping lots of regexp characters
+    */
+    void test_chop_662(void)
+    {
+        //  Check a selection of bad group names from the crash reports 
+        LLDirIterator iter(".","+bad-group-name]+?\?-??.*");
+        LLDirIterator iter1(".","))--@---bad-group-name2((?\?-??.*\\.txt");
+        LLDirIterator iter2(".","__^v--x)Cuide d sua vida(x--v^__?\?-??.*"); 
+    }
+
+    template<> template<>
+	void LLDirIteratorTest_t::test<1>()
+    {
+       test_chop_662();
+    }
+
+}