[FFmpeg-devel] [PATCH] avformat: added named pipe protocol

[Michael Niedermayer]

On Fri, Jun 15, 2012 at 03:05:06PM +0200, Martin Sliwka wrote:
> Dne 15.6.2012 11:32, Martin Sliwka napsal(a):
> >Dne 15.6.2012 2:52, Michael Niedermayer napsal(a):
> >>On Thu, Jun 14, 2012 at 01:10:30PM +0200, Martin Sliwka wrote:
> >>>The new 'npipe' protocol is copy of 'file' protocol with two
> >>>modifications:
> >>>1) URLProtocol::url_seek is not set
> >>>2) URLProtocol::url_open is set to npipe_open(...) which is same as
> >>>file_open(...)
> >>>except for protocol name it stripes from file name.
> >>>
> >>>New protocol is also very similar to already included 'pipe' protocol
> >>>which unfortunately can not be safely modified without
> >>>breaking backward
> >>>compatibility.
> >>>
> >>>Reason for this change is that named pipes are not wokring as
> >>>seekable inputs.
> >>>Problem is that ffio_limit(...) incorrectly limits requested read
> >>>size because
> >>>avio_size(...) (it's fstat(...) in file_seek(...) in fact) can not
> >>>report correct
> >>>file size.
> >>the correct solution is to check if its a fifo and return 0 instead of
> >>the nonsense value from fstat()
> >>a patch doing that is welcome
> >>
> >>also thanks for the testcase
> >>
> >
> >Ok, after some self-education in linux-way of doing things I made
> >this simple and straightforward patch. I tested it on Windows and
> >it works well. Some testing should be made on linux also but I'm
> >unable to get linux version compiled.
> >
> >Martin
> >
> >---
> > libavformat/file.c |    2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> >diff --git a/libavformat/file.c b/libavformat/file.c
> >index db79b5c..59b755d 100644
> >--- a/libavformat/file.c
> >+++ b/libavformat/file.c
> >@@ -99,7 +99,7 @@ static int64_t file_seek(URLContext *h, int64_t
> >pos, int whence)
> >     if (whence == AVSEEK_SIZE) {
> >         struct stat st;
> >         int ret = fstat(fd, &st);
> >-        return ret < 0 ? AVERROR(errno) : st.st_size;
> >+        return ret < 0 ? AVERROR(errno) : (S_ISFIFO(st.st_mode) ?
> >0 : st.st_size);
> >     }
> >     return lseek(fd, pos, whence);
> > }
> >-- 
> >1.7.4.1
> >
> 
> I did tests on Ubuntu 11.04 and fstat(...) is already reporting zero
> size on object created using mkfifo(...) so my patch should be safe.
> 
> Would this be enought or there are some other tests required?

should be enough, if it fails somewhere we can fix it once it happens

patch applied

thanks

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

There seems to be only one solution to NIH syndrom, ... a shooting squad
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