[FFmpeg-devel] [PATCH v7 0/3] Support long file names on Windows

[ffmpegagent <ffmpegagent@gmail.com>]

This patchset adds support for long file and directory paths on Windows. The
implementation follows the same logic that .NET is using internally, with
the only exception that it doesn't expand short path components in 8.3
format. .NET does this as the same function is also used for other purposes,
but in our case, that's not required. Short (8.3) paths are working as well
with the extended path prefix, even when longer than 260.

Successfully tested:

 * Regular paths wth drive letter
 * Regular UNC paths
 * Long paths wth drive letter
 * Long paths wth drive letter and forward slashes
 * Long UNC paths
 * Prefixed paths wth drive letter
 * Prefixed UNC paths

I have kept the individual functions separate on purpose, to make it easy to
compare with the .NET impl. (compilers should inlinie those anyway)

v2

 * wchar_filename: Improve comments and function documentation
 * os_support: adjust defines to use win32_stat

v3

 * removed length check in path_is_extended()
 * added path_is_device_path() check in add_extended_prefix()
 * add_extended_prefix(): clarified doc and add checks
 * clarified string allocation length calculation
 * replaced 260 with MAX_PATH
 * removed redundant checks after normalization

v4

 * rebased. no changes

v5

 * resolved the ugly struct duplication
 * compatible with _USE_32BIT_TIME_T

v6

 * wchar_filename.h: added links to .NET source code
 * wchar_filename.h: free allocations on error
 * os_support.hs: use clean and safe way to redirect stat() calls

v7

 * os_support.h: remapped fstat with win32_stat structure
 * os_support.h: use int64_t for some members
 * avformat/file: remove _WIN32 condition

softworkz (3):
  avutil/wchar_filename,file_open: Support long file names on Windows
  avformat/os_support: Support long file names on Windows
  avformat/file: remove _WIN32 condition

 libavformat/file.c         |   4 -
 libavformat/os_support.h   | 106 ++++++++++++++++------
 libavutil/file_open.c      |   2 +-
 libavutil/wchar_filename.h | 180 +++++++++++++++++++++++++++++++++++++
 4 files changed, 262 insertions(+), 30 deletions(-)


base-commit: 6076dbcb55d0c9b6693d1acad12a63f7268301aa
Published-As: https://github.com/ffstaging/FFmpeg/releases/tag/pr-ffstaging-28%2Fsoftworkz%2Fsubmit_long_filenames-v7
Fetch-It-Via: git fetch https://github.com/ffstaging/FFmpeg pr-ffstaging-28/softworkz/submit_long_filenames-v7
Pull-Request: https://github.com/ffstaging/FFmpeg/pull/28

Range-diff vs v6:

 1:  960aa795ff = 1:  960aa795ff avutil/wchar_filename,file_open: Support long file names on Windows
 2:  6f8d400db7 ! 2:  7751335906 avformat/os_support: Support long file names on Windows
     @@ libavformat/os_support.h
      +        short          st_uid;     /* user ID of owner */
      +        short          st_gid;     /* group ID of owner */
      +        _dev_t         st_rdev;    /* device ID (if special file) */
     -+        long           st_size;    /* total size, in bytes */
     -+        time_t         st_atime;   /* time of last access */
     -+        time_t         st_mtime;   /* time of last modification */
     -+        time_t         st_ctime;   /* time of last status change */
     ++        int64_t        st_size;    /* total size, in bytes */
     ++        int64_t        st_atime;   /* time of last access */
     ++        int64_t        st_mtime;   /* time of last modification */
     ++        int64_t        st_ctime;   /* time of last status change */
      +    };
      +
       #  ifdef fstat
       #   undef fstat
       #  endif
     +-#  define fstat(f,s) _fstati64((f), (s))
     ++#  define fstat win32_fstat
     + #endif /* defined(_WIN32) */
     + 
     + 
      @@ libavformat/os_support.h: static inline int win32_##name(const char *filename_utf8) \
           wchar_t *filename_w;                                  \
           int ret;                                              \
     @@ libavformat/os_support.h: DEF_FS_FUNCTION(unlink, _wunlink, _unlink)
      +    return ret;
      +fallback:
      +    return _access(filename_utf8, par);
     ++}
     ++
     ++static inline void copy_stat(struct _stati64 *winstat, struct win32_stat *par)
     ++{
     ++    par->st_dev   = winstat->st_dev;
     ++    par->st_ino   = winstat->st_ino;
     ++    par->st_mode  = winstat->st_mode;
     ++    par->st_nlink = winstat->st_nlink;
     ++    par->st_uid   = winstat->st_uid;
     ++    par->st_gid   = winstat->st_gid;
     ++    par->st_rdev  = winstat->st_rdev;
     ++    par->st_size  = winstat->st_size;
     ++    par->st_atime = winstat->st_atime;
     ++    par->st_mtime = winstat->st_mtime;
     ++    par->st_ctime = winstat->st_ctime;
       }
       
      -DEF_FS_FUNCTION2(access, _waccess, _access, int)
      -DEF_FS_FUNCTION2(stat, _wstati64, _stati64, struct stat*)
     -+static inline int win32_stat(const char *filename_utf8, struct stat *par)
     ++static inline int win32_stat(const char *filename_utf8, struct win32_stat *par)
      +{
     ++    struct _stati64 winstat = { 0 };
      +    wchar_t *filename_w;
      +    int ret;
     -+    struct _stati64 winstat = { 0 };
      +
      +    if (get_extended_win32_path(filename_utf8, &filename_w))
      +        return -1;
     @@ libavformat/os_support.h: DEF_FS_FUNCTION(unlink, _wunlink, _unlink)
      +    } else
      +        ret = _stat64(filename_utf8, &winstat);
      +
     -+    par->st_dev   = winstat.st_dev;
     -+    par->st_ino   = winstat.st_ino;
     -+    par->st_mode  = winstat.st_mode;
     -+    par->st_nlink = winstat.st_nlink;
     -+    par->st_uid   = winstat.st_uid;
     -+    par->st_gid   = winstat.st_gid;
     -+    par->st_rdev  = winstat.st_rdev;
     -+    par->st_size  = winstat.st_size;
     -+    par->st_atime = winstat.st_atime;
     -+    par->st_mtime = winstat.st_mtime;
     -+    par->st_ctime = winstat.st_ctime;
     ++    copy_stat(&winstat, par);
     ++
     ++    return ret;
     ++}
     ++
     ++static inline int win32_fstat(int fd, struct win32_stat *par)
     ++{
     ++    struct _stati64 winstat = { 0 };
     ++    int ret;
     ++
     ++    ret = _fstat64(fd, &winstat);
     ++
     ++    copy_stat(&winstat, par);
      +
      +    return ret;
      +}
 -:  ---------- > 3:  0522fc2315 avformat/file: remove _WIN32 condition

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