On Thu, 11 Mar 2021, James Almer wrote:
This function acts as a replacement for both av_grow_packet() and
av_shrink_packet(), the latter which is now deprecated and will be removed as
it does not correctly handle non-writable packets.
I don't think this is a good idea, av_shrink_packet cannot fail,
av_grow_packet can. By using the same function you are losing the
information if the end result should be checked or not.
Regards,
Marton
Signed-off-by: James Almer <jamr...@gmail.com>
---
libavcodec/avpacket.c | 19 +++++++++++++++----
libavcodec/packet.h | 16 ++++++++++++++++
libavcodec/version.h | 3 +++
3 files changed, 34 insertions(+), 4 deletions(-)
diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
index 32cb71fcf0..7d0dbadbed 100644
--- a/libavcodec/avpacket.c
+++ b/libavcodec/avpacket.c
@@ -100,6 +100,7 @@ int av_new_packet(AVPacket *pkt, int size)
return 0;
}
+#if FF_API_SHRINK_PACKET
void av_shrink_packet(AVPacket *pkt, int size)
{
if (pkt->size <= size)
@@ -107,16 +108,26 @@ void av_shrink_packet(AVPacket *pkt, int size)
pkt->size = size;
memset(pkt->data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
}
+#endif
int av_grow_packet(AVPacket *pkt, int grow_by)
{
- int new_size;
av_assert0((unsigned)pkt->size <= INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE);
if ((unsigned)grow_by >
INT_MAX - (pkt->size + AV_INPUT_BUFFER_PADDING_SIZE))
return AVERROR(ENOMEM);
- new_size = pkt->size + grow_by + AV_INPUT_BUFFER_PADDING_SIZE;
+ return av_packet_resize(pkt, pkt->size + grow_by);
+}
+
+int av_packet_resize(AVPacket *pkt, int size)
+{
+ int new_size;
+
+ if (size < 0 || size > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE)
+ return AVERROR(EINVAL);
+
+ new_size = size + AV_INPUT_BUFFER_PADDING_SIZE;
if (pkt->buf) {
size_t data_offset;
uint8_t *old_data = pkt->data;
@@ -143,10 +154,10 @@ int av_grow_packet(AVPacket *pkt, int grow_by)
if (!pkt->buf)
return AVERROR(ENOMEM);
if (pkt->size > 0)
- memcpy(pkt->buf->data, pkt->data, pkt->size);
+ memcpy(pkt->buf->data, pkt->data, FFMIN(pkt->size, size));
pkt->data = pkt->buf->data;
}
- pkt->size += grow_by;
+ pkt->size = size;
memset(pkt->data + pkt->size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
return 0;
diff --git a/libavcodec/packet.h b/libavcodec/packet.h
index 3d9013d783..1720d973f5 100644
--- a/libavcodec/packet.h
+++ b/libavcodec/packet.h
@@ -484,13 +484,29 @@ void av_init_packet(AVPacket *pkt);
*/
int av_new_packet(AVPacket *pkt, int size);
+#if FF_API_SHRINK_PACKET
/**
* Reduce packet size, correctly zeroing padding
*
* @param pkt packet
* @param size new size
+ *
+ * @deprecated Use av_packet_resize
*/
+attribute_deprecated
void av_shrink_packet(AVPacket *pkt, int size);
+#endif
+
+/**
+ * Resize the payload of a packet, correctly zeroing padding and avoiding data
+ * copy if possible.
+ *
+ * @param pkt packet
+ * @param size new size
+ *
+ * @return 0 on success, a negative AVERROR on error
+ */
+int av_packet_resize(AVPacket *pkt, int size);
/**
* Increase packet size, correctly zeroing padding
diff --git a/libavcodec/version.h b/libavcodec/version.h
index 3124ec8061..6c362b43e2 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -162,5 +162,8 @@
#ifndef FF_API_GET_FRAME_CLASS
#define FF_API_GET_FRAME_CLASS (LIBAVCODEC_VERSION_MAJOR < 60)
#endif
+#ifndef FF_API_SHRINK_PACKET
+#define FF_API_SHRINK_PACKET (LIBAVCODEC_VERSION_MAJOR < 60)
+#endif
#endif /* AVCODEC_VERSION_H */
--
2.30.2
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