[FFmpeg-devel] [PATCH] Revert redefinition of AVERROR_NUMEXPECTED and AVERROR_INVALIDDATA at the next major bump.

[Michael Niedermayer]

On Sat, Jul 17, 2010 at 03:37:51PM +0200, Stefano Sabatini wrote:
> On date Sunday 2010-04-04 04:05:23 +0200, Michael Niedermayer encoded:
> > On Sun, Apr 04, 2010 at 12:20:43AM +0200, Stefano Sabatini wrote:
> > > On date Saturday 2010-04-03 22:03:23 +0200, Michael Niedermayer encoded:
> > > > On Sat, Apr 03, 2010 at 05:08:48PM +0200, Stefano Sabatini wrote:
> > > [...]
> > > > > Regression test passed (both with LIBAVUTIL_MAJOR_VERSION == 50 and ==
> > > > > 51).
> > > > 
> > > > bumping it to 51 will changes the codes returned by all libs using libavutil
> > > > all of them would need to bump major.
> > > > i dont think this is reasonable, thus we should undo all error redefinitions
> > > > before they become real and debian burns you at the stake
> > > 
> > > /* the jackasses changed the error codes, so I need to build a
> > >  * backward compatibility layer */
> > > #if LIBFOO_VERSION < NEXT && LIBAVUTIL_VERSION_MAJOR > 50
> > > #define FOO_GET_AV_ERROR_CODE(err) (err == AVERROR_EOF         ? AVERROR(EPIPE ) : \
> > >                                     err == AVERROR_NUMEXPECTED ? AVERROR(EDOM)   : \
> > >                                     err == AVERROR_INVALIDDATA ? AVERROR(EINVAL) : err)
> > > #else
> > > #define FOO_GET_AV_ERROR_CODE(err) (err)
> > > #endif
> > > 
> > > 
> > > I'm not saying that's nice, but at least it is possible.
> > 
> > given the interresting cases ive seen with several shared libs and
> > dependancies amongth them i doubt anyone will come up with a variant
> > that works
> 
> I see the problem and I agree that the current solution is not
> acceptable, check attached.
> 
> Anyway the current solution is definitively not fine as well, we have
> two different error codes (AVERROR(EINVAL) and AVERROR_INVALIDDATA)
> which cannot be distinguished.
> 
> So I propose to defer that, while this shouldn't be done immediately,
> we should try to coordinate a major bump for all the libav* libraries,
> let's call it The Big Bump.

its scary what an error code bikeshed can lead to. 
and i must say with all the flaming i do against gnu libc & co, one thing
they do manage quite well and that is keeping ABI compatible and not bumping
every libs major version when someone determines that their error
codes fail to distinhuish invalid values from invalid data. 

AVERROR_INVALIDDATA == AVERROR(EINVAL)
you can though add a new define with a new value

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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