avutil/file: allow mapping 0 byte files with av_file_map

Signed-off-by: Marton Balint <cus@passwd.hu>

1 files changed, 2 insertions, 0 deletions

diff --git a/libavutil/file.h b/libavutil/file.h
index 8666c7b1d5..3ef4a6022c 100644
--- a/libavutil/file.h
+++ b/libavutil/file.h
@@ -33,6 +33,8 @@
  * allocated buffer or map it with mmap() when available.
  * In case of success set *bufptr to the read or mmapped buffer, and
  * *size to the size in bytes of the buffer in *bufptr.
+ * Unlike mmap this function succeeds with zero sized files, in this
+ * case *bufptr will be set to NULL and *size will be set to 0.
  * The returned buffer must be released with av_file_unmap().
  *
  * @param log_offset loglevel offset used for logging