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

[lance.lmwang at gmail.com]

On Wed, Dec 01, 2021 at 06:55:19PM +0100, Marton Balint wrote:
> 
> 
> On Wed, 1 Dec 2021, lance.lmwang at gmail.com wrote:
> 
> > On Wed, Dec 01, 2021 at 05:17:08PM +0200, Martin Storsjö wrote:
> > > 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.
> > 
> > Yes, I consider to add new api which is avio_get_str_len() to get the
> > string len from pb, before that, I want to hear no objection to use
> > avio_get_str(). then I'll submit a patchset for the complete change for
> > review.
> 
> I thought you simply want to read the file to memory. You don't need new API
> function to do that, simply use avio_read_to_bprint() with INT_MAX upper
> limit. It will allocate the necessary buffer for you, and you can check if
> ENOMEM happened with av_bprint_is_complete(), and free the buffer after
> parsing with av_bprint_finalize().

that's cool, I haven't notice avio_read_to_bprint() existing, will try 
it.


> 
> Regards,
> Marton
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-- 
Thanks,
Limin Wang