| Message ID | 20170831180743.10311-1-wachsler@google.com |
|---|---|
| State | New |
| Headers | show |
On Thu, Aug 31, 2017 at 02:07:43PM -0400, Mark Wachsler wrote: > Memory reallocated with av_reallocp_array is supposed to be allocated > with av_realloc, not av_malloc. Our docs did briefly claim this but it was removed years ago in 21f70940ae106bfffa07e73057cdb4b5e81a767a Also FFmpeg has been written with av_realloc*() and av_malloc*() compatibility in mind both before and after 21f70940ae106bfffa07e73057cdb4b5e81a767a So its not 2 but many more that likely would need to be changed If there is a incompatibility then Its easier to fix the incompatibility between av_malloc* and av_realloc* also it is much more maintainable if they are compatibile. Code that works on 99.9 % of the developers systems but breaks on the remaininng 0.1% is really hard to maintain design. That said iam not against this patch and i can apply it (without tabs) if people want but this is far from fixing all these issues DId you try to replace posix_memalign() by aligned_alloc() where its available? ISO C requires aligned_alloc() to be compatibile with realloc() where one can debate the situation of posix_memalign() and realloc() For reference 7.22.3 Memory management functions ... 7.22.3.1 The aligned_alloc function Thus aligned_alloc() is a "Memory management function" in ISO C In the list of undefined behaviors there is: - The pointer argument to the free or realloc function does not match a pointer earlier returned by a memory management function, or the space has been deallocated by a call to free or realloc (7.22.3.3, 7.22.3.5). The undefined behavior is clearly limited to pointers not originating from "Memory management functions", I can see no special case for aligned_alloc() In case your implemnatation of aligned_alloc() and realloc() are incompatibile as well, please fix your implemnatation. Thanks [...]
diff --git a/libavcodec/h2645_parse.c b/libavcodec/h2645_parse.c index b0d9ff66f0..1b2534b2e6 100644 --- a/libavcodec/h2645_parse.c +++ b/libavcodec/h2645_parse.c @@ -318,7 +318,8 @@ int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length, nal = &pkt->nals[pkt->nb_nals]; nal->skipped_bytes_pos_size = 1024; // initial buffer size - nal->skipped_bytes_pos = av_malloc_array(nal->skipped_bytes_pos_size, sizeof(*nal->skipped_bytes_pos)); + nal->skipped_bytes_pos = av_realloc(NULL, nal->skipped_bytes_pos_size * + sizeof(*nal->skipped_bytes_pos)); if (!nal->skipped_bytes_pos) return AVERROR(ENOMEM);