IQA-463: Add error logging for certain LLFile operations.

Attempting to debug an observed LLFile::remove() failure, I was floored to
find that remove() made no attempt whatsoever to report its lack of success!
Add warnif() function to log errno text in platform-dependent way. Support the
notion that for some functions, certain errno values are acceptable -- e.g. we
expect stat() to frequently hit ENOENT -- and need not be logged.
Add commented-out Windows-specific logic to try to provide further information
in the case of EACCES ("Permission denied," e.g. another process has the file
open). To use, enable the code block, download handle.exe and turn on DEBUG
logging for LLFile. handle.exe can be obtained from:
http://technet.microsoft.com/en-us/sysinternals/bb896655

1 files changed, 163 insertions, 24 deletions

diff --git a/indra/llcommon/llfile.cpp b/indra/llcommon/llfile.cpp
index c32a776c3f..c51d042a3d 100644
--- a/indra/llcommon/llfile.cpp
+++ b/indra/llcommon/llfile.cpp
@@ -1,4 +1,4 @@
-/** 
+/**
  * @file llfile.cpp
  * @author Michael Schlachter
  * @date 2006-03-23
@@ -8,60 +8,194 @@
  * $LicenseInfo:firstyear=2006&license=viewerlgpl$
  * 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 <windows.h>
+#include <stdlib.h>                 // Windows errno
+#else
+#include <errno.h>
 #endif
 
 #include "linden_common.h"
 #include "llfile.h"
 #include "llstring.h"
 #include "llerror.h"
+#include "stringize.h"
 
 using namespace std;
 
+static std::string empty;
+
+// Many of the methods below use OS-level functions that mess with errno. Wrap
+// variants of strerror() to report errors.
+
+#if LL_WINDOWS
+// On Windows, use strerror_s().
+std::string strerr(int errn)
+{
+	char buffer[256];
+	strerror_s(buffer, errn);       // infers sizeof(buffer) -- love it!
+	return buffer;
+}
+
+#else
+// On Posix we want to call strerror_r(), but alarmingly, there are two
+// different variants. The one that returns int always populates the passed
+// buffer (except in case of error), whereas the other one always returns a
+// valid char* but might or might not populate the passed buffer. How do we
+// know which one we're getting? Define adapters for each and let the compiler
+// select the applicable adapter.
+
+// strerror_r() returns char*
+std::string message_from(int /*orig_errno*/, const char* /*buffer*/, size_t /*bufflen*/,
+						 const char* strerror_ret)
+{
+	return strerror_ret;
+}
+
+// strerror_r() returns int
+std::string message_from(int orig_errno, const char* buffer, size_t bufflen,
+						 int strerror_ret)
+{
+	if (strerror_ret == 0)
+	{
+		return buffer;
+	}
+	// Here strerror_r() has set errno. Since strerror_r() has already failed,
+	// seems like a poor bet to call it again to diagnose its own error...
+	int stre_errno = errno;
+	if (stre_errno == ERANGE)
+	{
+		return STRINGIZE("strerror_r() can't explain errno " << orig_errno
+						 << " (" << bufflen << "-byte buffer too small)");
+	}
+	if (stre_errno == EINVAL)
+	{
+		return STRINGIZE("unknown errno " << orig_errno);
+	}
+	// Here we don't even understand the errno from strerror_r()!
+	return STRINGIZE("strerror_r() can't explain errno " << orig_errno
+					 << " (error " << stre_errno << ')');
+}
+
+std::string strerr(int errn)
+{
+	char buffer[256];
+	// Select message_from() function matching the strerror_r() we have on hand.
+	return message_from(errn, buffer, sizeof(buffer),
+						strerror_r(errn, buffer, sizeof(buffer)));
+}
+#endif	// ! LL_WINDOWS
+
+// On either system, shorthand call just infers global 'errno'.
+std::string strerr()
+{
+	return strerr(errno);
+}
+
+int warnif(const std::string& desc, const std::string& filename, int rc, int accept=0)
+{
+	if (rc < 0)
+	{
+		// Capture errno before we start emitting output
+		int errn = errno;
+		// For certain operations, a particular errno value might be
+		// acceptable -- e.g. stat() could permit ENOENT, mkdir() could permit
+		// EEXIST. Don't warn if caller explicitly says this errno is okay.
+		if (errn != accept)
+		{
+			LL_WARNS("LLFile") << "Couldn't " << desc << " '" << filename
+							   << "' (errno " << errn << "): " << strerr(errn) << LL_ENDL;
+		}
+#if 0 && LL_WINDOWS                 // turn on to debug file-locking problems
+		// If the problem is "Permission denied," maybe it's because another
+		// process has the file open. Try to find out.
+		if (errn == EACCES)         // *not* EPERM
+		{
+			// Only do any of this stuff (before LL_ENDL) if it will be logged.
+			LL_DEBUGS("LLFile") << empty;
+			const char* TEMP = getenv("TEMP");
+			if (! TEMP)
+			{
+				LL_CONT << "No $TEMP, not running 'handle'";
+			}
+			else
+			{
+				std::string tf(TEMP);
+				tf += "\\handle.tmp";
+				// http://technet.microsoft.com/en-us/sysinternals/bb896655
+				std::string cmd(STRINGIZE("handle \"" << filename
+										  // "openfiles /query /v | fgrep -i \"" << filename
+										  << "\" > \"" << tf << '"'));
+				LL_CONT << cmd;
+				if (system(cmd.c_str()) != 0)
+				{
+					LL_CONT << "\nDownload 'handle.exe' from http://technet.microsoft.com/en-us/sysinternals/bb896655";
+				}
+				else
+				{
+					std::ifstream inf(tf);
+					std::string line;
+					while (std::getline(inf, line))
+					{
+						LL_CONT << '\n' << line;
+					}
+				}
+				LLFile::remove(tf);
+			}
+			LL_CONT << LL_ENDL;
+		}
+#endif  // LL_WINDOWS hack to identify processes holding file open
+	}
+	return rc;
+}
+
 // static
 int	LLFile::mkdir(const std::string& dirname, int perms)
 {
-#if LL_WINDOWS	
+#if LL_WINDOWS
 	// permissions are ignored on Windows
 	std::string utf8dirname = dirname;
 	llutf16string utf16dirname = utf8str_to_utf16str(utf8dirname);
-	return _wmkdir(utf16dirname.c_str());
+	int rc = _wmkdir(utf16dirname.c_str());
 #else
-	return ::mkdir(dirname.c_str(), (mode_t)perms);
+	int rc = ::mkdir(dirname.c_str(), (mode_t)perms);
 #endif
+	// We often use mkdir() to ensure the existence of a directory that might
+	// already exist. Don't spam the log if it does.
+	return warnif("mkdir", dirname, rc, EEXIST);
 }
 
 // static
 int	LLFile::rmdir(const std::string& dirname)
 {
-#if LL_WINDOWS	
+#if LL_WINDOWS
 	// permissions are ignored on Windows
 	std::string utf8dirname = dirname;
 	llutf16string utf16dirname = utf8str_to_utf16str(utf8dirname);
-	return _wrmdir(utf16dirname.c_str());
+	int rc = _wrmdir(utf16dirname.c_str());
 #else
-	return ::rmdir(dirname.c_str());
+	int rc = ::rmdir(dirname.c_str());
 #endif
+	return warnif("rmdir", dirname, rc);
 }
 
 // static
@@ -108,10 +242,11 @@ int	LLFile::remove(const std::string& filename)
 #if	LL_WINDOWS
 	std::string utf8filename = filename;
 	llutf16string utf16filename = utf8str_to_utf16str(utf8filename);
-	return _wremove(utf16filename.c_str());
+	int rc = _wremove(utf16filename.c_str());
 #else
-	return ::remove(filename.c_str());
+	int rc = ::remove(filename.c_str());
 #endif
+	return warnif("remove", filename, rc);
 }
 
 int	LLFile::rename(const std::string& filename, const std::string& newname)
@@ -121,10 +256,11 @@ int	LLFile::rename(const std::string& filename, const std::string& newname)
 	std::string utf8newname = newname;
 	llutf16string utf16filename = utf8str_to_utf16str(utf8filename);
 	llutf16string utf16newname = utf8str_to_utf16str(utf8newname);
-	return _wrename(utf16filename.c_str(),utf16newname.c_str());
+	int rc = _wrename(utf16filename.c_str(),utf16newname.c_str());
 #else
-	return ::rename(filename.c_str(),newname.c_str());
+	int rc = ::rename(filename.c_str(),newname.c_str());
 #endif
+	return warnif(STRINGIZE("rename to '" << newname << "' from"), filename, rc);
 }
 
 int	LLFile::stat(const std::string& filename, llstat* filestatus)
@@ -132,23 +268,26 @@ int	LLFile::stat(const std::string& filename, llstat* filestatus)
 #if LL_WINDOWS
 	std::string utf8filename = filename;
 	llutf16string utf16filename = utf8str_to_utf16str(utf8filename);
-	return _wstat(utf16filename.c_str(),filestatus);
+	int rc = _wstat(utf16filename.c_str(),filestatus);
 #else
-	return ::stat(filename.c_str(),filestatus);
+	int rc = ::stat(filename.c_str(),filestatus);
 #endif
+	// We use stat() to determine existence (see isfile(), isdir()).
+	// Don't spam the log if the subject pathname doesn't exist.
+	return warnif("stat", filename, rc, ENOENT);
 }
 
 bool LLFile::isdir(const std::string& filename)
 {
 	llstat st;
-	
+
 	return stat(filename, &st) == 0 && S_ISDIR(st.st_mode);
 }
 
 bool LLFile::isfile(const std::string& filename)
 {
 	llstat st;
-	
+
 	return stat(filename, &st) == 0 && S_ISREG(st.st_mode);
 }
 
@@ -260,7 +399,7 @@ void llifstream::open(const std::string& _Filename,	/* Flawfinder: ignore */
 	ios_base::openmode _Mode,
 	int _Prot)
 {	// open a C stream with specified mode
-	
+
 	LLFILE* filep = LLFile::_Fiopen(_Filename,_Mode | ios_base::in, _Prot);
 	if(filep == NULL)
 	{
@@ -280,7 +419,7 @@ bool llifstream::is_open() const
 	return false;
 }
 llifstream::~llifstream()
-{	
+{
 	if (_ShouldClose)
 	{
 		close();
@@ -309,7 +448,7 @@ bool llofstream::is_open() const
 
 void llofstream::open(const std::string& _Filename,	/* Flawfinder: ignore */
 	ios_base::openmode _Mode,
-	int _Prot)	
+	int _Prot)
 {	// open a C stream with specified mode
 
 	LLFILE* filep = LLFile::_Fiopen(_Filename,_Mode | ios_base::out, _Prot);
@@ -340,14 +479,14 @@ void llofstream::close()
 
 llofstream::llofstream(const std::string& _Filename,
 	std::ios_base::openmode _Mode,
-	int _Prot) 
+	int _Prot)
 		: std::basic_ostream<char,std::char_traits < char > >(NULL,true),_Filebuffer(NULL),_ShouldClose(false)
 {	// construct with named file and specified mode
 	open(_Filename, _Mode , _Prot);	/* Flawfinder: ignore */
 }
 
 llofstream::~llofstream()
-{	
+{
 	// destroy the object
 	if (_ShouldClose)
 	{