[FFmpeg-devel] [PATCH v2] avformat/dashenc: remove the arbitrary restrictions for filename

[Limin Wang]

On Wed, Apr 08, 2020 at 01:54:12AM +0200, Andreas Rheinhardt wrote:
> lance.lmwang at gmail.com:
> > From: Limin Wang <lance.lmwang at gmail.com>
> > 
> > Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
> > ---
> >  libavformat/dashenc.c | 28 ++++++++++++----------------
> >  1 file changed, 12 insertions(+), 16 deletions(-)
> > 
> > diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
> > index 94d4639..f80f6f2 100644
> > --- a/libavformat/dashenc.c
> > +++ b/libavformat/dashenc.c
> > @@ -1832,28 +1832,24 @@ static void dashenc_delete_file(AVFormatContext *s, char *filename) {
> >  static int dashenc_delete_segment_file(AVFormatContext *s, const char* file)
> >  {
> >      DASHContext *c = s->priv_data;
> > -    size_t dirname_len, file_len;
> > -    char filename[1024];
> > -
> > -    dirname_len = strlen(c->dirname);
> > -    if (dirname_len >= sizeof(filename)) {
> > -        av_log(s, AV_LOG_WARNING, "Cannot delete segments as the directory path is too long: %"PRIu64" characters: %s\n",
> > -            (uint64_t)dirname_len, c->dirname);
> > -        return AVERROR(ENAMETOOLONG);
> > -    }
> > +    char *filename;
> > +    AVBPrint buf;
> >  
> > -    memcpy(filename, c->dirname, dirname_len);
> > +    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
> >  
> > -    file_len = strlen(file);
> > -    if ((dirname_len + file_len) >= sizeof(filename)) {
> > -        av_log(s, AV_LOG_WARNING, "Cannot delete segments as the path is too long: %"PRIu64" characters: %s%s\n",
> > -            (uint64_t)(dirname_len + file_len), c->dirname, file);
> > -        return AVERROR(ENAMETOOLONG);
> > +    av_bprintf(&buf, "%s%s", c->dirname, file);
> > +    if (!av_bprint_is_complete(&buf)) {
> > +        av_bprint_finalize(&buf, NULL);
> > +        return AVERROR(ENOMEM);
> > +    }
> > +    if (av_bprint_finalize(&buf, &filename) < 0) {
> 
> No, don't finalize the AVBPrint -- this will make an allocation even if
> the string fits into the internal buffer of the AVBPrint. Instead simply
> use buf.str directly for dashenc_delete_file().

OK, I have update the patch, please help to review whether my understand is correct.
thx.

> 
> - Andreas
> 
> > +        av_log(s, AV_LOG_WARNING, "Out of memory for filename\n");
> > +        return AVERROR(ENOMEM);
> >      }
> >  
> > -    memcpy(filename + dirname_len, file, file_len + 1); // include the terminating zero
> >      dashenc_delete_file(s, filename);
> >  
> > +    av_freep(&filename);
> >      return 0;
> >  }
> >  
> > 
> 
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-- 
Thanks,
Limin Wang