avcodec: Add av_fast_padded_malloc().

Wrapper around av_fast_malloc() that keeps FF_INPUT_BUFFER_PADDING_SIZE
zero-padded bytes at the end of the used buffer.

Based on a patch by Reimar Döffinger <Reimar.Doeffinger@gmx.de>.

1 files changed, 13 insertions, 0 deletions

diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index fa609534a5..34eff0031a 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -80,6 +80,19 @@ void av_fast_malloc(void *ptr, unsigned int *size, size_t min_size)
     *size= min_size;
 }
 
+void av_fast_padded_malloc(void *ptr, unsigned int *size, size_t min_size)
+{
+    void **p = ptr;
+    if (min_size > SIZE_MAX - FF_INPUT_BUFFER_PADDING_SIZE) {
+        av_freep(p);
+        *size = 0;
+        return;
+    }
+    av_fast_malloc(p, size, min_size + FF_INPUT_BUFFER_PADDING_SIZE);
+    if (*size)
+        memset((uint8_t *)*p + min_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
+}
+
 /* encoder management */
 static AVCodec *first_avcodec = NULL;