[FFmpeg-devel] [PATCH 1/2] libavformat/avio: Add avio_get_dyn_buf function

[Soft Works]

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.
---
 libavformat/avio.h    | 12 ++++++++++++
 libavformat/aviobuf.c | 17 +++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/libavformat/avio.h b/libavformat/avio.h
index b1ce1d1..f2b9a6f 100644
--- a/libavformat/avio.h
+++ b/libavformat/avio.h
@@ -704,6 +704,18 @@ int avio_closep(AVIOContext **s);
 int avio_open_dyn_buf(AVIOContext **s);
 
 /**
+ * Return the written size and a pointer to the buffer. 
+ * The AVIOContext stream is left intact.
+ * The buffer must NOT be freed. 
+ * No padding is added to the buffer.
+ *
+ * @param s IO context
+ * @param pbuffer pointer to a byte buffer
+ * @return the length of the byte buffer
+ */
+int avio_get_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
+
+/**
  * Return the written size and a pointer to the buffer. The buffer
  * must be freed with av_free().
  * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 134d627..bf7e5f8 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;
-- 
2.10.2.windows.1