Re: [FFmpeg-devel] [PATCH 1/3] fftools: Stop using av_fopen_utf8

["Martin Storsjö" <martin@martin.st>]

On Sat, 21 May 2022, Soft Works wrote:

>> -----Original Message-----
>> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of Martin
>> Storsjö
>> Sent: Friday, May 20, 2022 11:13 PM
>> To: ffmpeg-devel@ffmpeg.org
>> Subject: [FFmpeg-devel] [PATCH 1/3] fftools: Stop using av_fopen_utf8
>>
>> Provide a header based inline reimplementation of it.
>>
>> Using av_fopen_utf8 doesn't work outside of the libraries when built
>> with MSVC as shared libraries (in the default configuration, where
>> each DLL gets a separate statically linked CRT).
>> ---
>>  fftools/ffmpeg_opt.c |  3 +-
>>  fftools/fopen_utf8.h | 71 ++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 73 insertions(+), 1 deletion(-)
>>  create mode 100644 fftools/fopen_utf8.h
>>
>> diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
>> index 47e8b9b7bd..a5cd989d35 100644
>> --- a/fftools/ffmpeg_opt.c
>> +++ b/fftools/ffmpeg_opt.c
>> @@ -28,6 +28,7 @@
>>  #endif
>>
>>  #include "ffmpeg.h"
>> +#include "fopen_utf8.h"
>>  #include "cmdutils.h"
>>  #include "opt_common.h"
>>
>> @@ -1882,7 +1883,7 @@ static OutputStream *new_video_stream(OptionsContext
>> *o, AVFormatContext *oc, in
>>                      video_enc->stats_in = logbuffer;
>>                  }
>>                  if (video_enc->flags & AV_CODEC_FLAG_PASS1) {
>> -                    f = av_fopen_utf8(logfilename, "wb");
>> +                    f = fopen_utf8(logfilename, "wb");
>>                      if (!f) {
>>                          av_log(NULL, AV_LOG_FATAL,
>>                                 "Cannot write log file '%s' for pass-1
>> encoding: %s\n",
>> diff --git a/fftools/fopen_utf8.h b/fftools/fopen_utf8.h
>> new file mode 100644
>> index 0000000000..db57fcaec4
>> --- /dev/null
>> +++ b/fftools/fopen_utf8.h
>> @@ -0,0 +1,71 @@
>> +/*
>> + * This file is part of FFmpeg.
>> + *
>> + * FFmpeg 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; either
>> + * version 2.1 of the License, or (at your option) any later version.
>> + *
>> + * FFmpeg 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 FFmpeg; if not, write to the Free Software
>> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-
>> 1301 USA
>> + */
>> +
>> +#ifndef FFTOOLS_FOPEN_UTF8_H
>> +#define FFTOOLS_FOPEN_UTF8_H
>> +
>> +#include <stdio.h>
>> +
>> +/* The fopen_utf8 function here is essentially equivalent to
>> av_fopen_utf8,
>> + * except that it doesn't set O_CLOEXEC, and that it isn't exported
>> + * from a different library. (On Windows, each DLL might use a different
>> + * CRT, and FILE* handles can't be shared across them.) */
>> +
>> +#ifdef _WIN32
>> +#include "libavutil/wchar_filename.h"
>> +
>> +static inline FILE *fopen_utf8(const char *path_utf8, const char *mode)
>> +{
>> +    wchar_t *path_w, *mode_w;
>> +    FILE *f;
>> +
>> +    /* convert UTF-8 to wide chars */
>> +    if (utf8towchar(path_utf8, &path_w)) /* This sets errno on error. */
>> +        return NULL;
>> +    if (!path_w)
>> +        goto fallback;
>> +
>> +    if (utf8towchar(mode, &mode_w))
>> +        return NULL;
>> +    if (!mode_w) {
>> +        /* If failing to interpret the mode string as utf8, it is an
>> invalid
>> +         * parameter. */
>> +        av_freep(&path_w);
>> +        errno = EINVAL;
>> +        return NULL;
>> +    }
>> +
>> +    f = _wfopen(path_w, mode_w);
>> +    av_freep(&path_w);
>> +    av_freep(&mode_w);
>> +
>> +    return f;
>> +fallback:
>> +    /* path may be in CP_ACP */
>> +    return fopen(path_utf8, mode);
>> +}
>> +
>> +#else
>> +
>> +static inline FILE *fopen_utf8(const char *path, const char *mode)
>> +{
>> +    return fopen(path, mode);
>> +}
>> +#endif
>> +
>> +#endif /* FFTOOLS_FOPEN_UTF8_H */
>> --
>
> LGTM. (all three)
>
> Tested with VS project build (full static linkage, though).

I discussed this with Anton on irc, and he was ok with the patchset too, 
so I pushed it now.

// Martin
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