[FFmpeg-devel] [PATCH v2 1/4] avutil/internal: add FF_ALLOC_TYPED_ARRAY_OR_GOTO & FF_ALLOCZ_TYPED_ARRAY_OR_GOTO
Nicolas George
george at nsup.org
Tue May 12 12:49:01 EEST 2020
lance.lmwang at gmail.com (12020-05-11):
> From: Limin Wang <lance.lmwang at gmail.com>
>
> These are similar to the existing FF_ALLOC_ARRAY_OR_GOTO & FF_ALLOCZ_ARRAY_OR_GOTO,
> but the elsize is calcuated by sizeof(*p)
>
> Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> ---
> libavutil/internal.h | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/libavutil/internal.h b/libavutil/internal.h
> index 4acbcf5..1be9001 100644
> --- a/libavutil/internal.h
> +++ b/libavutil/internal.h
> @@ -173,6 +173,24 @@
> }\
> }
>
> +#define FF_ALLOC_TYPED_ARRAY_OR_GOTO(ctx, p, nelem, label)\
> +{\
> + p = av_malloc_array(nelem, sizeof(*p));\
> + if (!p) {\
> + av_log(ctx, AV_LOG_ERROR, "Cannot allocate memory.\n");\
> + goto label;\
> + }\
> +}
> +
> +#define FF_ALLOCZ_TYPED_ARRAY_OR_GOTO(ctx, p, nelem, label)\
> +{\
> + p = av_mallocz_array(nelem, sizeof(*p));\
> + if (!p) {\
> + av_log(ctx, AV_LOG_ERROR, "Cannot allocate memory.\n");\
> + goto label;\
> + }\
> +}
> +
> #include "libm.h"
>
> /**
Please NO!
These functions have a terrible design, let us fix them before extending
them.
First design mistake: no error code. A helper function for testing
memory allocation failure where AVERROR(ENOMEM) does not appear is
absurd.
Second design mistake: printing a message. Return the error code, let
the caller print the error message.
Third design mistake: hard-coded use of goto.
Best design:
#define FF_ALLOC_ARRAY_OR_GOTO(p, nelem, elsize, ret, error)\
{\
p = av_malloc_array(nelem, elsize);\
if (!p) {\
ret = AVERROR(ENOMEM); \
error;
}\
}
Regards,
--
Nicolas George
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