[FFmpeg-devel] [PATCH] http: Check for AVERROR_EOF in the check for premature end

[Jan Ekström]

On Fri, Nov 13, 2020 at 12:17 AM Martin Storsjö <martin at martin.st> wrote:
>
> When the check was added (in 3668701f9600, in 2015), some IO
> functions returned 0 on EOF (in particular, the TCP protocol
> did, but the TLS protocol returned AVERROR_EOF). Since
> 0e1f771d2200d in 2017, the TCP protocol also returns AVERROR_EOF
> instead of 0, making the check for premature end never have the
> intended effect.
> ---
>  libavformat/http.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/http.c b/libavformat/http.c
> index 3d25d652d3..2d24c00e18 100644
> --- a/libavformat/http.c
> +++ b/libavformat/http.c
> @@ -1436,7 +1436,8 @@ static int http_buf_read(URLContext *h, uint8_t *buf, int size)
>          if ((!s->willclose || s->chunksize == UINT64_MAX) && s->off >= target_end)
>              return AVERROR_EOF;
>          len = ffurl_read(s->hd, buf, size);
> -        if (!len && (!s->willclose || s->chunksize == UINT64_MAX) && s->off < target_end) {
> +        if ((!len || len == AVERROR_EOF) &&
> +            (!s->willclose || s->chunksize == UINT64_MAX) && s->off < target_end) {
>              av_log(h, AV_LOG_ERROR,
>                     "Stream ends prematurely at %"PRIu64", should be %"PRIu64"\n",
>                     s->off, target_end
> --
> 2.24.3 (Apple Git-128)

Change-wise should be OK. Empty or EOF with not enough read leading to
AVERROR(EIO), former being already current behavior.

That said, if this error case always was only regarding EOF use cases
we might want to check the case in ticket 4039 - if simplifying the
check to EOF only still has it work as expected. But that I think is a
separate check/change.

Jan