A common pattern e.g. in libavcodec is replacing/updating buffer
references: unref old one, ref new one. This function allows simplifying
such code an avoiding unnecessary refs+unrefs if the references are
already equivalent.
---
doc/APIchanges | 3 +++
libavutil/buffer.c | 22 ++++++++++++++++++++++
libavutil/buffer.h | 17 +++++++++++++++++
3 files changed, 42 insertions(+)
diff --git a/doc/APIchanges b/doc/APIchanges
index fb5534b5f5..757d814eee 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -15,6 +15,9 @@ libavutil: 2017-10-21
API changes, most recent first:
+2020-xx-xx - xxxxxxxxxx - lavc 56.50.100 - buffer.h
+ Add a av_buffer_replace() convenience function.
+
2020-xx-xx - xxxxxxxxxx - lavc 58.88.100 - avcodec.h codec.h
Move AVCodec-related public API to new header codec.h.
diff --git a/libavutil/buffer.c b/libavutil/buffer.c
index 6d9cb7428e..ecd83da9c3 100644
--- a/libavutil/buffer.c
+++ b/libavutil/buffer.c
@@ -216,6 +216,28 @@ int av_buffer_realloc(AVBufferRef **pbuf, int size)
return 0;
}
+int av_buffer_replace(AVBufferRef **pdst, AVBufferRef *src)
+{
+ AVBufferRef *dst = *pdst;
+
+ if (!src) {
+ av_buffer_unref(pdst);
+ return !!dst;
+ }
+
+ if (dst && dst->buffer == src->buffer) {
+ /* make sure the data pointers match */
+ dst->data = src->data;
+ dst->size = src->size;
+ return 0;
+ }
+
+ av_buffer_unref(pdst);
+ *pdst = av_buffer_ref(src);
+
+ return *pdst ? 1 : AVERROR(ENOMEM);
+}
+
AVBufferPool *av_buffer_pool_init2(int size, void *opaque,
AVBufferRef* (*alloc)(void *opaque, int
size),
void (*pool_free)(void *opaque))
diff --git a/libavutil/buffer.h b/libavutil/buffer.h
index e0f94314f4..497dc98c20 100644
--- a/libavutil/buffer.h
+++ b/libavutil/buffer.h
@@ -197,6 +197,23 @@ int av_buffer_make_writable(AVBufferRef **buf);
*/
int av_buffer_realloc(AVBufferRef **buf, int size);
+/**
+ * Ensure dst refers to the same data as src.
+ *
+ * When *dst is already equivalent to src, do nothing. Otherwise unreference
dst
+ * and replace it with a new reference to src.
+ *
+ * @param dst Pointer to either a valid buffer reference or NULL. On success,
+ * this will point to a buffer reference equivalent to src. On
+ * failure, dst will be unreferenced.
+ * @param src A buffer reference to replace dst with. May be NULL, then this
+ * function is equivalent to av_buffer_unref(dst).
+ * @return 0 if dst was equivalent to src on input and nothing was done
+ * 1 if dst was replaced with a new reference to src
+ * A negative error code on failure.
+ */
+int av_buffer_replace(AVBufferRef **dst, AVBufferRef *src);
+
/**
* @}
*/
--
2.26.2
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