[FFmpeg-devel] [PATCH]lavf/dashdec: Do not use memcpy() to copy a struct

[James Almer]

On 4/18/2018 2:45 PM, Carl Eugen Hoyos wrote:
> Hi!
> 
> Attached patch is supposed to fix a warning (and a bug), is this the
> right and preferred fix?
> 
> Please comment, Carl Eugen
> 
> 
> 0001-lavf-dashdec-Do-not-use-memcpy-to-copy-a-struct.patch
> 
> 
> From cf7d2aefc1a3b3a2e9f578ede43906ed6ee96bfd Mon Sep 17 00:00:00 2001
> From: Carl Eugen Hoyos <ceffmpeg at gmail.com>
> Date: Wed, 18 Apr 2018 19:42:57 +0200
> Subject: [PATCH] lavf/dashdec: Do not use memcpy() to copy a struct.
> 
> Fixes a warning:
> libavformat/dashdec.c:1900:65: warning: argument to 'sizeof' in 'memcpy' call is the same pointer type 'struct fragment *' as the destination; expected 'struct fragment' or an explicit length
> ---
>  libavformat/dashdec.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavformat/dashdec.c b/libavformat/dashdec.c
> index 6304ad9..917fb54 100644
> --- a/libavformat/dashdec.c
> +++ b/libavformat/dashdec.c
> @@ -1897,7 +1897,7 @@ static int init_section_compare_audio(DASHContext *c)
>  
>  static void copy_init_section(struct representation *rep_dest, struct representation *rep_src)
>  {
> -    memcpy(rep_dest->init_section, rep_src->init_section, sizeof(rep_src->init_section));
> +    rep_dest->init_section = rep_src->init_section;

This would only copy the pointer. The fact memcpy was used here makes me
think the intention was to copy the contents of the struct, so something
like

*rep_dest->init_section = *rep_src->init_section;

or

memcpy(rep_dest->init_section, rep_src->init_section,
sizeof(*rep_src->init_section));

Would be the correct fix.

>      rep_dest->init_sec_buf = av_mallocz(rep_src->init_sec_buf_size);
>      memcpy(rep_dest->init_sec_buf, rep_src->init_sec_buf, rep_src->init_sec_data_len);
>      rep_dest->init_sec_buf_size = rep_src->init_sec_buf_size;
> -- 1.7.10.4
> 
> 
> 
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