From 9997a812e76955b16f3a65bfe6bb6cab87e0ee56 Mon Sep 17 00:00:00 2001 From: Diego Biurrun Date: Fri, 13 Sep 2013 20:01:30 +0200 Subject: [PATCH] mem: Document the non-compatibility of av_realloc() and av_malloc() --- libavutil/mem.h | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/libavutil/mem.h b/libavutil/mem.h index 5eae3cf50e..b473dd7460 100644 --- a/libavutil/mem.h +++ b/libavutil/mem.h @@ -106,8 +106,12 @@ av_alloc_size(1, 2) static inline void *av_malloc_array(size_t nmemb, size_t siz * reallocated. * @return Pointer to a newly-reallocated block or NULL if the block * cannot be reallocated or the function is used to free the memory block. - * @note av_realloc() is not guaranteed to maintain the alignment of - * pointers originating from the av_malloc() family of functions. + * @warning Pointers originating from the av_malloc() family of functions must + * not be passed to av_realloc(). The former can be implemented using + * memalign() (or other functions), and there is no guarantee that + * pointers from such functions can be passed to realloc() at all. + * The situation is undefined according to POSIX and may crash with + * some libc implementations. * @see av_fast_realloc() */ void *av_realloc(void *ptr, size_t size) av_alloc_size(2); @@ -122,8 +126,12 @@ void *av_realloc(void *ptr, size_t size) av_alloc_size(2); * @param size Size of the single element * @return Pointer to a newly-reallocated block or NULL if the block * cannot be reallocated or the function is used to free the memory block. - * @note av_realloc_array() is not guaranteed to maintain the alignment of - * pointers originating from the av_malloc() family of functions. + * @warning Pointers originating from the av_malloc() family of functions must + * not be passed to av_realloc(). The former can be implemented using + * memalign() (or other functions), and there is no guarantee that + * pointers from such functions can be passed to realloc() at all. + * The situation is undefined according to POSIX and may crash with + * some libc implementations. */ av_alloc_size(2, 3) void *av_realloc_array(void *ptr, size_t nmemb, size_t size); @@ -137,8 +145,12 @@ av_alloc_size(2, 3) void *av_realloc_array(void *ptr, size_t nmemb, size_t size) * @param nmemb Number of elements * @param size Size of the single element * @return Zero on success, an AVERROR error code on failure. - * @note av_reallocp_array() is not guaranteed to maintain the alignment of - * pointers originating from the av_malloc() family of functions. + * @warning Pointers originating from the av_malloc() family of functions must + * not be passed to av_realloc(). The former can be implemented using + * memalign() (or other functions), and there is no guarantee that + * pointers from such functions can be passed to realloc() at all. + * The situation is undefined according to POSIX and may crash with + * some libc implementations. */ av_alloc_size(2, 3) int av_reallocp_array(void *ptr, size_t nmemb, size_t size);