[FFmpeg-devel] [PATCH] avformat/cache: Separate read and seek return-values within cache_read

[Michael Niedermayer]

On Sun, Nov 01, 2015 at 10:56:45PM -0800, Bryan Huh wrote:
> Fixes an issue where an int64_t ffurl_seek return-value was being stored
> in a generic int "r" variable, leading to integer overflow when seeking
> into a large file (>2GB), and ultimately a "Failed to perform internal
> seek" error mesage. The "r" variable was used both for storing the
> result of any seeks and for the result of any reads. Instead, I separate
> the variable into an int64_t seek-variable and int read-variable.
> 
> To test, try running `ffprobe 'cache:http://<something>'` on a file that
> is ~3GB large, whose moov atom is at the end of the file
> ---
>  libavformat/cache.c |   49 +++++++++++++++++++++++++------------------------
>  1 files changed, 25 insertions(+), 24 deletions(-)
> 
> diff --git a/libavformat/cache.c b/libavformat/cache.c
> index a762aa9..b654f45 100644
> --- a/libavformat/cache.c
> +++ b/libavformat/cache.c
> @@ -156,7 +156,8 @@ static int cache_read(URLContext *h, unsigned char *buf, int size)
>  {
>      Context *c= h->priv_data;
>      CacheEntry *entry, *next[2] = {NULL, NULL};

> -    int r;
> +    int64_t off;
> +    int bytes_read = 0;

renaming the variable is unrelated (its not neccessary)
but if you want to rename/split it, i dont mind but it should be in
a seperate patch


>
>      entry = av_tree_find(c->root, &c->logical_pos, cmp, (void**)next);
>  
> @@ -169,21 +170,21 @@ static int cache_read(URLContext *h, unsigned char *buf, int size)
>          if (in_block_pos < entry->size) {
>              int64_t physical_target = entry->physical_pos + in_block_pos;
>  

> -            if (c->cache_pos != physical_target) {
> +            if (c->cache_pos != physical_target)

removing {} is not needed, without it the change is smaller and
simpeler to read (for example when someone reads git log changes)


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Avoid a single point of failure, be that a person or equipment.
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