[FFmpeg-devel] [PATCH 1/5] avformat/rtsp: make use of avio_get_str() to load the sdp

[Martin Storsjö]

On Wed, 1 Dec 2021, lance.lmwang at gmail.com wrote:

> On Wed, Dec 01, 2021 at 03:55:37PM +0200, Martin Storsjö wrote:
>> On Wed, 1 Dec 2021, lance.lmwang at gmail.com wrote:
>> 
>> > From: Limin Wang <lance.lmwang at gmail.com>
>> > 
>> > Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
>> > ---
>> > libavformat/rtsp.c | 30 ++++++++++++++++++++----------
>> > 1 file changed, 20 insertions(+), 10 deletions(-)
>> > 
>> > diff --git a/libavformat/rtsp.c b/libavformat/rtsp.c
>> > index e6a4993..ec8be8b 100644
>> > --- a/libavformat/rtsp.c
>> > +++ b/libavformat/rtsp.c
>> > @@ -2369,11 +2369,29 @@ static void append_source_addrs(char *buf, int size, const char *name,
>> >         av_strlcatf(buf, size, ",%s", addrs[i]->addr);
>> > }
>> > 
>> > +static char *read_sdp_str(AVIOContext *pb, int size)
>> > +{
>> > +    int n;
>> > +    char *str;
>> > +
>> > +    if (size < 0 || size == INT_MAX)
>> > +        return NULL;
>> > +
>> > +    str = av_malloc(size + 1);
>> > +    if (!str)
>> > +        return NULL;
>> > +    n = avio_get_str(pb, size, str, size + 1);
>> > +    if (n < size)
>> > +        avio_skip(pb, size - n);
>> 
>> What? Why do you want to skip past data in the input? Size here is just a
>> random static upper limit of how large an SDP file would be.
> yes, my fault, don't need to run avio_skip(). For avio_get_str() will return error only
> buflen <=0, so str is valid anyway.
>
>> 
>> This patch totally lacks a motivation of why you want to do this.
>
> considering the SDP is strings in file, so I think it's better to use avio_get_str().

Maybe, but warranting a patch changing things on its own, IMO.

> Also, I'm considering to remove limit of SDP_MAX_SIZE after that.

If you'd defer this patch to a patchset that does that, it might make more 
sense. But I don't see much value in applying it on its own.

// Martin