[FFmpeg-devel] [PATCH] fftools/ffmpeg: rename read_file() to avoid conflict with libass

[Rémi Denis-Courmont]

Le 20 octobre 2022 10:12:28 GMT+03:00, Anton Khirnov <anton at khirnov.net> a écrit :
>libass defines a non-static read_file() symbol, which causes conflicts
>with static linking.
>---
> fftools/ffmpeg.h          | 2 +-
> fftools/ffmpeg_mux_init.c | 4 ++--
> fftools/ffmpeg_opt.c      | 4 ++--
> 3 files changed, 5 insertions(+), 5 deletions(-)
>
>diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
>index 2dcce45741..5966cac60e 100644
>--- a/fftools/ffmpeg.h
>+++ b/fftools/ffmpeg.h
>@@ -702,7 +702,7 @@ void remove_avoptions(AVDictionary **a, AVDictionary *b);
> void assert_avoptions(AVDictionary *m);
> 
> void assert_file_overwrite(const char *filename);
>-char *read_file(const char *filename);
>+char *file_read(const char *filename);
> AVDictionary *strip_specifiers(AVDictionary *dict);
> const AVCodec *find_codec_or_die(const char *name, enum AVMediaType type, int encoder);
> int parse_and_set_vsync(const char *arg, int *vsync_var, int file_idx, int st_idx, int is_global);
>diff --git a/fftools/ffmpeg_mux_init.c b/fftools/ffmpeg_mux_init.c
>index c8b2552104..c77260c24b 100644
>--- a/fftools/ffmpeg_mux_init.c
>+++ b/fftools/ffmpeg_mux_init.c
>@@ -380,7 +380,7 @@ static char *get_ost_filters(OptionsContext *o, AVFormatContext *oc,
>     }
> 
>     if (ost->filters_script)
>-        return read_file(ost->filters_script);
>+        return file_read(ost->filters_script);
>     else if (ost->filters)
>         return av_strdup(ost->filters);
> 
>@@ -585,7 +585,7 @@ static OutputStream *new_video_stream(Muxer *mux, OptionsContext *o, int source_
>                 av_dict_set(&ost->encoder_opts, "stats", logfilename, AV_DICT_DONT_OVERWRITE);
>             } else {
>                 if (video_enc->flags & AV_CODEC_FLAG_PASS2) {
>-                    char  *logbuffer = read_file(logfilename);
>+                    char  *logbuffer = file_read(logfilename);
> 
>                     if (!logbuffer) {
>                         av_log(NULL, AV_LOG_FATAL, "Error reading log file '%s' for pass-2 encoding\n",
>diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
>index ead4ee1b38..9245e02813 100644
>--- a/fftools/ffmpeg_opt.c
>+++ b/fftools/ffmpeg_opt.c
>@@ -1300,7 +1300,7 @@ static int open_input_file(OptionsContext *o, const char *filename)
> }
> 
> /* read file contents into a string */
>-char *read_file(const char *filename)
>+char *file_read(const char *filename)
> {
>     AVIOContext *pb      = NULL;
>     int ret = avio_open(&pb, filename, AVIO_FLAG_READ);
>@@ -1725,7 +1725,7 @@ static int opt_filter_complex(void *optctx, const char *opt, const char *arg)
> static int opt_filter_complex_script(void *optctx, const char *opt, const char *arg)
> {
>     FilterGraph *fg;
>-    char *graph_desc = read_file(arg);
>+    char *graph_desc = file_read(arg);
>     if (!graph_desc)
>         return AVERROR(EINVAL);
> 

Hi,

`file_read` is just as likely to cause naming conflicts. And I have seen really insane libraries with no namespacing getting preloaded, so it is unfortunately not even only a problem with libraries that FFmpeg links with.

If you're going to treat this as an FFmpeg bug... I fear that the only solution consists of prefixing all extern symbols for namespacing.