/**
 * @file llfile.cpp
 * @author Michael Schlachter
 * @date 2006-03-23
 * @brief Implementation of cross-platform POSIX file buffer and c++
 * stream classes.
 *
 * $LicenseInfo:firstyear=2006&license=viewerlgpl$
 * 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
 * $/LicenseInfo$
 */

#include "linden_common.h"
#include "llfile.h"
#include "llstring.h"
#include "llerror.h"
#include "stringize.h"

#if LL_WINDOWS
#include "llwin32headers.h"
#include <stdlib.h>                 // Windows errno
#include <vector>
#else
#include <errno.h>
#endif

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;
}

typedef std::basic_ios<char,std::char_traits < char > > _Myios;

#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;
            // would be nice to use LLDir for this, but dependency goes the
            // wrong way
            const char* TEMP = LLFile::tmpdir();
            if (! (TEMP && *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
    // permissions are ignored on Windows
    std::string utf8dirname = dirname;
    llutf16string utf16dirname = utf8str_to_utf16str(utf8dirname);
    int rc = _wmkdir(utf16dirname.c_str());
#else
    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. There is no known case in which we want to call out as
    // an error the requested directory already existing.
    if (rc < 0 && errno == EEXIST)
    {
        // this is not the error you want, move along
        return 0;
    }
    // anything else might be a problem
    return warnif("mkdir", dirname, rc, EEXIST);
}

// static
int LLFile::rmdir(const std::string& dirname)
{
#if LL_WINDOWS
    // permissions are ignored on Windows
    std::string utf8dirname = dirname;
    llutf16string utf16dirname = utf8str_to_utf16str(utf8dirname);
    int rc = _wrmdir(utf16dirname.c_str());
#else
    int rc = ::rmdir(dirname.c_str());
#endif
    return warnif("rmdir", dirname, rc);
}

// static
LLFILE* LLFile::fopen(const std::string& filename, const char* mode)    /* Flawfinder: ignore */
{
#if LL_WINDOWS
    std::string utf8filename = filename;
    std::string utf8mode = std::string(mode);
    llutf16string utf16filename = utf8str_to_utf16str(utf8filename);
    llutf16string utf16mode = utf8str_to_utf16str(utf8mode);
    return _wfopen(utf16filename.c_str(),utf16mode.c_str());
#else
    return ::fopen(filename.c_str(),mode);  /* Flawfinder: ignore */
#endif
}

LLFILE* LLFile::_fsopen(const std::string& filename, const char* mode, int sharingFlag)
{
#if LL_WINDOWS
    std::string utf8filename = filename;
    std::string utf8mode = std::string(mode);
    llutf16string utf16filename = utf8str_to_utf16str(utf8filename);
    llutf16string utf16mode = utf8str_to_utf16str(utf8mode);
    return _wfsopen(utf16filename.c_str(),utf16mode.c_str(),sharingFlag);
#else
    llassert(0);//No corresponding function on non-windows
    return NULL;
#endif
}

int LLFile::close(LLFILE * file)
{
    int ret_value = 0;
    if (file)
    {
        ret_value = fclose(file);
    }
    return ret_value;
}

std::string LLFile::getContents(const std::string& filename)
{
    LLFILE* fp = fopen(filename, "rb"); /* Flawfinder: ignore */
    if (fp)
    {
        fseek(fp, 0, SEEK_END);
        U32 length = ftell(fp);
        fseek(fp, 0, SEEK_SET);

        std::vector<char> buffer(length);
        size_t nread = fread(buffer.data(), 1, length, fp);
        fclose(fp);

        return std::string(buffer.data(), nread);
    }

    return LLStringUtil::null;
}

int LLFile::remove(const std::string& filename, int supress_error)
{
#if LL_WINDOWS
    std::string utf8filename = filename;
    llutf16string utf16filename = utf8str_to_utf16str(utf8filename);
    int rc = _wremove(utf16filename.c_str());
#else
    int rc = ::remove(filename.c_str());
#endif
    return warnif("remove", filename, rc, supress_error);
}

int LLFile::rename(const std::string& filename, const std::string& newname, int supress_error)
{
#if LL_WINDOWS
    std::string utf8filename = filename;
    std::string utf8newname = newname;
    llutf16string utf16filename = utf8str_to_utf16str(utf8filename);
    llutf16string utf16newname = utf8str_to_utf16str(utf8newname);
    int rc = _wrename(utf16filename.c_str(),utf16newname.c_str());
#else
    int rc = ::rename(filename.c_str(),newname.c_str());
#endif
    return warnif(STRINGIZE("rename to '" << newname << "' from"), filename, rc, supress_error);
}

bool LLFile::copy(const std::string& from, const std::string& to)
{
    bool copied = false;
    LLFILE* in = LLFile::fopen(from, "rb");     /* Flawfinder: ignore */
    if (in)
    {
        LLFILE* out = LLFile::fopen(to, "wb");      /* Flawfinder: ignore */
        if (out)
        {
            char buf[16384];        /* Flawfinder: ignore */
            size_t readbytes;
            bool write_ok = true;
            while(write_ok && (readbytes = fread(buf, 1, 16384, in))) /* Flawfinder: ignore */
            {
                if (fwrite(buf, 1, readbytes, out) != readbytes)
                {
                    LL_WARNS("LLFile") << "Short write" << LL_ENDL;
                    write_ok = false;
                }
            }
            if ( write_ok )
            {
                copied = true;
            }
            fclose(out);
        }
        fclose(in);
    }
    return copied;
}

int LLFile::stat(const std::string& filename, llstat* filestatus)
{
#if LL_WINDOWS
    std::string utf8filename = filename;
    llutf16string utf16filename = utf8str_to_utf16str(utf8filename);
    int rc = _wstat(utf16filename.c_str(),filestatus);
#else
    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);
}

const char *LLFile::tmpdir()
{
    static std::string utf8path;

    if (utf8path.empty())
    {
        char sep;
#if LL_WINDOWS
        sep = '\\';

        std::vector<wchar_t> utf16path(MAX_PATH + 1);
        GetTempPathW(static_cast<DWORD>(utf16path.size()), &utf16path[0]);
        utf8path = ll_convert_wide_to_string(&utf16path[0]);
#else
        sep = '/';

        utf8path = LLStringUtil::getenv("TMPDIR", "/tmp/");
#endif
        if (utf8path[utf8path.size() - 1] != sep)
        {
            utf8path += sep;
        }
    }
    return utf8path.c_str();
}


/***************** Modified file stream created to overcome the incorrect behaviour of posix fopen in windows *******************/

#if LL_WINDOWS

LLFILE *    LLFile::_Fiopen(const std::string& filename,
        std::ios::openmode mode)
{   // open a file
    static const char *mods[] =
    {   // fopen mode strings corresponding to valid[i]
    "r", "w", "w", "a", "rb", "wb", "wb", "ab",
    "r+", "w+", "a+", "r+b", "w+b", "a+b",
    0};
    static const int valid[] =
    {   // valid combinations of open flags
        ios_base::in,
        ios_base::out,
        ios_base::out | ios_base::trunc,
        ios_base::out | ios_base::app,
        ios_base::in | ios_base::binary,
        ios_base::out | ios_base::binary,
        ios_base::out | ios_base::trunc | ios_base::binary,
        ios_base::out | ios_base::app | ios_base::binary,
        ios_base::in | ios_base::out,
        ios_base::in | ios_base::out | ios_base::trunc,
        ios_base::in | ios_base::out | ios_base::app,
        ios_base::in | ios_base::out | ios_base::binary,
        ios_base::in | ios_base::out | ios_base::trunc
            | ios_base::binary,
        ios_base::in | ios_base::out | ios_base::app
            | ios_base::binary,
    0};

    LLFILE *fp = 0;
    int n;
    ios_base::openmode atendflag = mode & ios_base::ate;
    ios_base::openmode norepflag = mode & ios_base::_Noreplace;

    if (mode & ios_base::_Nocreate)
        mode |= ios_base::in;   // file must exist
    mode &= ~(ios_base::ate | ios_base::_Nocreate | ios_base::_Noreplace);
    for (n = 0; valid[n] != 0 && valid[n] != mode; ++n)
        ;   // look for a valid mode

    if (valid[n] == 0)
        return (0); // no valid mode
    else if (norepflag && mode & (ios_base::out | ios_base::app)
        && (fp = LLFile::fopen(filename, "r")) != 0)    /* Flawfinder: ignore */
        {   // file must not exist, close and fail
        fclose(fp);
        return (0);
        }
    else if (fp != 0 && fclose(fp) != 0)
        return (0); // can't close after test open
// should open with protection here, if other than default
    else if ((fp = LLFile::fopen(filename, mods[n])) == 0)  /* Flawfinder: ignore */
        return (0); // open failed

    if (!atendflag || fseek(fp, 0, SEEK_END) == 0)
        return (fp);    // no need to seek to end, or seek succeeded

    fclose(fp); // can't position at end
    return (0);
}

#endif /* LL_WINDOWS */


#if LL_WINDOWS
/************** input file stream ********************************/

llifstream::llifstream() {}

// explicit
llifstream::llifstream(const std::string& _Filename, ios_base::openmode _Mode):
    std::ifstream(utf8str_to_utf16str( _Filename ).c_str(),
                  _Mode | ios_base::in)
{
}

void llifstream::open(const std::string& _Filename, ios_base::openmode _Mode)
{
    std::ifstream::open(utf8str_to_utf16str(_Filename).c_str(),
                        _Mode | ios_base::in);
}


/************** output file stream ********************************/


llofstream::llofstream() {}

// explicit
llofstream::llofstream(const std::string& _Filename, ios_base::openmode _Mode):
    std::ofstream(utf8str_to_utf16str( _Filename ).c_str(),
                  _Mode | ios_base::out)
{
}

void llofstream::open(const std::string& _Filename, ios_base::openmode _Mode)
{
    std::ofstream::open(utf8str_to_utf16str( _Filename ).c_str(),
                        _Mode | ios_base::out);
}

/************** helper functions ********************************/

std::streamsize llifstream_size(llifstream& ifstr)
{
    if(!ifstr.is_open()) return 0;
    std::streampos pos_old = ifstr.tellg();
    ifstr.seekg(0, ios_base::beg);
    std::streampos pos_beg = ifstr.tellg();
    ifstr.seekg(0, ios_base::end);
    std::streampos pos_end = ifstr.tellg();
    ifstr.seekg(pos_old, ios_base::beg);
    return pos_end - pos_beg;
}

std::streamsize llofstream_size(llofstream& ofstr)
{
    if(!ofstr.is_open()) return 0;
    std::streampos pos_old = ofstr.tellp();
    ofstr.seekp(0, ios_base::beg);
    std::streampos pos_beg = ofstr.tellp();
    ofstr.seekp(0, ios_base::end);
    std::streampos pos_end = ofstr.tellp();
    ofstr.seekp(pos_old, ios_base::beg);
    return pos_end - pos_beg;
}

#endif  // LL_WINDOWS