avfilter/buffersrc: switch to activate

Fixes OOM when caller keeps adding frames into filtergraph
that reached EOF by other means, for example EOF is signalled
by other filter in filtergraph or by buffersink.

(cherry picked from commit 84e400ae37)

libavfilter/buffersrc.c

@@ -36,6 +36,7 @@
 #include "audio.h"
 #include "avfilter.h"
 #include "buffersrc.h"
+#include "filters.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
@@ -194,7 +195,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
     if (!frame)
         return av_buffersrc_close(ctx, s->last_pts, flags);
     if (s->eof)
-        return AVERROR(EINVAL);
+        return AVERROR_EOF;
 
     s->last_pts = frame->pts + frame->duration;
 
@@ -484,21 +485,28 @@ static int config_props(AVFilterLink *link)
     return 0;
 }
 
-static int request_frame(AVFilterLink *link)
+static int activate(AVFilterContext *ctx)
 {
-    BufferSourceContext *c = link->src->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+    BufferSourceContext *c = ctx->priv;
 
-    if (c->eof)
-        return AVERROR_EOF;
+    if (!c->eof && ff_outlink_get_status(outlink)) {
+        c->eof = 1;
+        return 0;
+    }
+
+    if (c->eof) {
+        ff_outlink_set_status(outlink, AVERROR_EOF, c->last_pts);
+        return 0;
+    }
     c->nb_failed_requests++;
-    return AVERROR(EAGAIN);
+    return FFERROR_NOT_READY;
 }
 
 static const AVFilterPad avfilter_vsrc_buffer_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_VIDEO,
-        .request_frame = request_frame,
         .config_props  = config_props,
     },
 };
@@ -507,7 +515,7 @@ const AVFilter ff_vsrc_buffer = {
     .name      = "buffer",
     .description = NULL_IF_CONFIG_SMALL("Buffer video frames, and make them accessible to the filterchain."),
     .priv_size = sizeof(BufferSourceContext),
-
+    .activate  = activate,
     .init      = init_video,
     .uninit    = uninit,
 
@@ -521,7 +529,6 @@ static const AVFilterPad avfilter_asrc_abuffer_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_AUDIO,
-        .request_frame = request_frame,
         .config_props  = config_props,
     },
 };
@@ -530,7 +537,7 @@ const AVFilter ff_asrc_abuffer = {
     .name          = "abuffer",
     .description   = NULL_IF_CONFIG_SMALL("Buffer audio frames, and make them accessible to the filterchain."),
     .priv_size     = sizeof(BufferSourceContext),
-
+    .activate  = activate,
     .init      = init_audio,
     .uninit    = uninit,