libavformat/avio: Add avio_get_dyn_buf function

This commit adds the avio_get_dyn_buf function which allows accessing
the
content of a DynBuffer without destroying it.

This is required in matroskaenc for preliminary writing (correct) mkv
headers.

Context for this change is fixing regression bug #5977.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

1 files changed, 17 insertions, 0 deletions

diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 134d627a6e..bf7e5f85a0 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -1277,6 +1277,23 @@ int ffio_open_dyn_packet_buf(AVIOContext **s, int max_packet_size)
     return url_open_dyn_buf_internal(s, max_packet_size);
 }
 
+int avio_get_dyn_buf(AVIOContext *s, uint8_t **pbuffer)
+{
+    DynBuffer *d;
+
+    if (!s) {
+        *pbuffer = NULL;
+        return 0;
+    }
+
+    avio_flush(s);
+
+    d = s->opaque;
+    *pbuffer = d->buffer;
+
+    return d->size;
+}
+
 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer)
 {
     DynBuffer *d;