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avformat/avisynth: remove atexit() handler

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The atexit() handler in the avisynth demuxer was added because
there was a conflict in AvxSynth that arose due to their use
of C++ global objects, particularly in relation to having
added a logging function relying on log4cpp.

This conflict was responsible for causing a segfault on exit.
It did not affect Windows with the (at the time) upstream
AviSynth 2.5 and 2.6, nor does it affect AviSynth+.

Unfortunately, none of this was actually shielded by ifdefs
indicating the fact it was only needed for AvxSynth, so four
years ago when AviSynth+ replaced AvxSynth as the handler
for AviSynth scripts on Unix-like OSes, the fact that the
atexit handler was no longer necessary was overlooked.

Signed-off-by: Stephen Hutchinson <qyot27@gmail.com>
This commit is contained in:
Stephen Hutchinson 2024-07-06 22:18:50 -04:00
parent 66592e8b10
commit c0fddbae79
1 changed files with 1 additions and 45 deletions
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46
libavformat/avisynth.c
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@ -115,9 +115,6 @@ typedef struct AviSynthContext {
int error; int error;
uint32_t flags; uint32_t flags;
/* Linked list pointers. */
struct AviSynthContext *next;
} AviSynthContext; } AviSynthContext;
static const int avs_planes_packed[1] = { 0 }; static const int avs_planes_packed[1] = { 0 };
@ -133,15 +130,7 @@ static const int avs_planes_rgba[4] = { AVS_PLANAR_G, AVS_PLANAR_B,
static AVMutex avisynth_mutex = AV_MUTEX_INITIALIZER; static AVMutex avisynth_mutex = AV_MUTEX_INITIALIZER;
/* A conflict between C++ global objects, atexit, and dynamic loading requires
* us to register our own atexit handler to prevent double freeing. */
static AviSynthLibrary avs_library; static AviSynthLibrary avs_library;
static int avs_atexit_called = 0;
/* Linked list of AviSynthContexts. An atexit handler destroys this list. */
static AviSynthContext *avs_ctx_list = NULL;
static av_cold void avisynth_atexit_handler(void);
static av_cold int avisynth_load_library(void) static av_cold int avisynth_load_library(void)
{ {
@ -185,7 +174,6 @@ static av_cold int avisynth_load_library(void)
LOAD_AVS_FUNC(avs_get_env_property, 1); LOAD_AVS_FUNC(avs_get_env_property, 1);
#undef LOAD_AVS_FUNC #undef LOAD_AVS_FUNC
atexit(avisynth_atexit_handler);
return 0; return 0;
fail: fail:
@ -214,30 +202,11 @@ static av_cold int avisynth_context_create(AVFormatContext *s)
} }
} }
if (!avs_ctx_list) {
avs_ctx_list = avs;
} else {
avs->next = avs_ctx_list;
avs_ctx_list = avs;
}
return 0; return 0;
} }
static av_cold void avisynth_context_destroy(AviSynthContext *avs) static av_cold void avisynth_context_destroy(AviSynthContext *avs)
{ {
if (avs_atexit_called)
return;
if (avs == avs_ctx_list) {
avs_ctx_list = avs->next;
} else {
AviSynthContext *prev = avs_ctx_list;
while (prev->next != avs)
prev = prev->next;
prev->next = avs->next;
}
if (avs->clip) { if (avs->clip) {
avs_library.avs_release_clip(avs->clip); avs_library.avs_release_clip(avs->clip);
avs->clip = NULL; avs->clip = NULL;
@ -248,20 +217,6 @@ static av_cold void avisynth_context_destroy(AviSynthContext *avs)
} }
} }
static av_cold void avisynth_atexit_handler(void)
{
AviSynthContext *avs = avs_ctx_list;
while (avs) {
AviSynthContext *next = avs->next;
avisynth_context_destroy(avs);
avs = next;
}
dlclose(avs_library.library);
avs_atexit_called = 1;
}
/* Create AVStream from audio and video data. */ /* Create AVStream from audio and video data. */
static int avisynth_create_stream_video(AVFormatContext *s, AVStream *st) static int avisynth_create_stream_video(AVFormatContext *s, AVStream *st)
{ {
@ -1134,6 +1089,7 @@ static av_cold int avisynth_read_close(AVFormatContext *s)
return AVERROR_UNKNOWN; return AVERROR_UNKNOWN;
avisynth_context_destroy(s->priv_data); avisynth_context_destroy(s->priv_data);
dlclose(avs_library.library);
ff_mutex_unlock(&avisynth_mutex); ff_mutex_unlock(&avisynth_mutex);
return 0; return 0;
} }