[FFmpeg-devel] [PATCH] avutil/internal: Document ugly looking windows specific file related function renaming
michaelni at gmx.at
Fri Feb 3 13:06:55 EET 2017
On Thu, Feb 02, 2017 at 09:07:25AM +0100, wm4 wrote:
> On Wed, 1 Feb 2017 22:24:14 +0100
> Michael Niedermayer <michaelni at gmx.at> wrote:
> > On Wed, Feb 01, 2017 at 03:26:45PM +0100, wm4 wrote:
> > > On Wed, 1 Feb 2017 14:35:50 +0100
> > > Michael Niedermayer <michael at niedermayer.cc> wrote:
> > >
> > > > Found-by: ubitux
> > > > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > > > ---
> > > > libavutil/internal.h | 4 ++++
> > > > 1 file changed, 4 insertions(+)
> > > >
> > > > diff --git a/libavutil/internal.h b/libavutil/internal.h
> > > > index a19975d474..e97034887b 100644
> > > > --- a/libavutil/internal.h
> > > > +++ b/libavutil/internal.h
> > > > @@ -243,8 +243,12 @@ void avpriv_request_sample(void *avc,
> > > > #pragma comment(linker, "/include:" EXTERN_PREFIX "avpriv_snprintf")
> > > > #endif
> > > >
> > > > +// Rename shared function (both use and implementation of them) so they are not shared
> > > > +// and each library carries its own copy of a implementation, this is needed as
> > >
> > > So why are they not appropriately named in the first place?
> > >
> > > > +// the fd numbers are not transportable between libs on windows
> > >
> > > AFAIK they are, as long as they're linked to the same stdlib (which
> > > probably is the case for libav*).
> > here is the commit introducing the first function using this system.
> > I belive its commit message is quite good and explains the reasoning.
> > Beyond that iam the wrong one to discuss this with, iam not a windows
> > developer and i didnt design this, which is not to say i like or
> > dislike it. I just added one function IIRC and i wanted to document it
> > as ubitux seemed to be confused for a moment when seeing it the first
> > time
> > commit e743e7ae6ee7e535c4394bec6fe6650d2b0dbf65
> > Author: Martin Storsjö <martin at martin.st>
> > Date: Fri Aug 9 11:06:46 2013 +0300
> > libavutil: Make avpriv_open a library-internal function on msvcrt
> > Add one copy of the function into each of the libraries, similarly
> > to what we do for log2_tab. When using static libs, only one
> > copy of the file_open.o object file gets included, while when
> > using shared libraries, each of them get a copy of its own.
> > This fixes DLL builds with a statically linked C runtime, where
> > each DLL effectively has got its own instance of the C runtime,
> > where file descriptors can't be shared across runtimes.
> > On systems not using msvcrt, the function is not duplicated.
> > [...]
> Maybe this would be better:
> // If each libav* DLL is statically linked to the C runtime, FDs can
> // not be used across library boundaries. Duplicate these functions in
> // each DLL to avoid this problem.
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
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