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.
---
Updated to not touch dst on failure.
Still not using buffer_replace(), since it does not seem to make the
code simpler.
---
doc/APIchanges | 3 +++
libavutil/buffer.c | 26 ++++++++++++++++++++++++++
libavutil/buffer.h | 16 ++++++++++++++++
libavutil/version.h | 2 +-
4 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/doc/APIchanges b/doc/APIchanges
index 72a4833fbc..5a3f0165a8 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -15,6 +15,9 @@ libavutil: 2017-10-21
API changes, most recent first:
+2020-xx-xx - xxxxxxxxxx - lavu 56.51.100 - buffer.h
+ Add a av_buffer_replace() convenience function.
+
2020-07-xx - xxxxxxxxxx - lavu 56.57.100 - cpu.h
Add AV_CPU_FLAG_MMI and AV_CPU_FLAG_MSA.
diff --git a/libavutil/buffer.c b/libavutil/buffer.c
index 38a554208a..39539f99e9 100644
--- a/libavutil/buffer.c
+++ b/libavutil/buffer.c
@@ -215,6 +215,32 @@ int av_buffer_realloc(AVBufferRef **pbuf, int size)
return 0;
}
+int av_buffer_replace(AVBufferRef **pdst, AVBufferRef *src)
+{
+ AVBufferRef *dst = *pdst;
+ AVBufferRef *tmp;
+
+ if (!src) {
+ av_buffer_unref(pdst);
+ return 0;
+ }
+
+ if (dst && dst->buffer == src->buffer) {
+ /* make sure the data pointers match */
+ dst->data = src->data;
+ dst->size = src->size;
+ return 0;
+ }
+
+ tmp = av_buffer_ref(src);
+ if (!tmp)
+ return AVERROR(ENOMEM);
+
+ av_buffer_unref(pdst);
+ *pdst = tmp;
+ return 0;
+}
+
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 c0f3f6cc9a..fd4e381efa 100644
--- a/libavutil/buffer.h
+++ b/libavutil/buffer.h
@@ -197,6 +197,22 @@ 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 left untouched.
+ * @param src A buffer reference to replace dst with. May be NULL, then this
+ * function is equivalent to av_buffer_unref(dst).
+ * @return 0 on success
+ * AVERROR(ENOMEM) on memory allocation failure.
+ */
+int av_buffer_replace(AVBufferRef **dst, AVBufferRef *src);
+
/**
* @}
*/
diff --git a/libavutil/version.h b/libavutil/version.h
index 975fb87f31..3e7e1f410b 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
*/
#define LIBAVUTIL_VERSION_MAJOR 56
-#define LIBAVUTIL_VERSION_MINOR 57
+#define LIBAVUTIL_VERSION_MINOR 58
#define LIBAVUTIL_VERSION_MICRO 100
#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
--
2.27.0
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