[FFmpeg-devel] [PATCH] UDP fixes join multicast group on Darwin arch

Diego Biurrun diego
Wed Apr 22 16:47:52 CEST 2009

On Tue, Apr 21, 2009 at 12:55:37PM +0200, S?bastien Zwickert wrote:
> On Apr 20, 2009, at 6:11 PM, Diego Biurrun wrote:
> >On Fri, Apr 17, 2009 at 04:25:42PM +0200, S?bastien Zwickert wrote:
> >>
> >>I found that udp_join_multicast_group() in libavformat/udp.c is  
> >>broken because IP_ADD_MEMBERSHIP and ip_mreq struct aren't defined
> >>on Darwin Kernel Version 9.6.0 architecture.
> >>I've read this archive
> >>http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2008-August/051136.html
> >>and i've added the _DARWIN_C_SOURCE definition at the top of the   
> >>udp.c file.
> >
> >The problem is that this struct and definition are only defined when
> >_POSIX_C_SOURCE is not defined.  But we compile with _POSIX_C_SOURCE
> >set, so it fails.
> Almost right, this struct is only defined when _POSIX_C_SOURCE is not  
> defined OR when _DARWIN_C_SOURCE is defined.
> This struct is defined on Apple system in <netinet/in.h> under this  
> condition :
> #if !defined(_POSIX_C_SOURCE) || defined(_DARWIN_C_SOURCE)

On my Mac OS X 10.4 it is under


> >I'm not sure if this is a bug in the Apple system headers or if we
> >should disable _POSIX_C_SOURCE on Darwin (probably not) or if we  
> >should avoid that struct and that definition...
> Maybe, disable _POSIX_C_SOURCE is an appropriate solution on Darwin  
> because in this case the system headers will act as if we had have  
> defined _DARWIN_C_SOURCE, which causes the library and kernel calls to  
> conform to _POSIX_C_SOURCE with non-POSIX extensions. Defining  
> _POSIX_C_SOURCE excludes all non-POSIX extentions on Darwin.
> The link below is the Apple's document (man compat) about the  
> compatibility settings:
> http://developer.apple.com/documentation/Darwin/Reference/Manpages/man5/compat.5.html
> Another document explaining Apple's unix conoformance:
> http://developer.apple.com/ReleaseNotes/Darwin/RN-Unix03Conformance/index.html

man compat only speaks of _APPLE_C_SOURCE on my system.


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