[alsa-devel] ["PATCH alsa-lib"] Change snd_dlopen() function to return the error string

[Takashi Iwai]

On Mon, 27 Nov 2017 19:19:51 +0100,
Takashi Sakamoto wrote:
> 
> Hi Jaroslav,
> 
> On Nov 27 2017 17:50, Jaroslav Kysela wrote:
> > The dlopen() function might fail also for another reason than
> > a missing file, thus return the error string from dlerror().
> >
> > Signed-off-by: Jaroslav Kysela <perex at perex.cz>
> > ---
> >   include/global.h        |  2 +-
> >   src/Versions.in         |  5 +++++
> >   src/conf.c              | 13 ++++++-----
> >   src/dlmisc.c            | 60 +++++++++++++++++++++++++++++++++++++++----------
> >   src/hwdep/hwdep.c       |  6 ++---
> >   src/mixer/simple_abst.c | 10 ++++-----
> >   src/pcm/pcm_hooks.c     |  8 +++----
> >   src/pcm/pcm_meter.c     |  6 ++---
> >   src/rawmidi/rawmidi.c   |  6 ++---
> >   src/seq/seq.c           |  6 ++---
> >   src/timer/timer.c       |  6 ++---
> >   src/timer/timer_query.c |  6 ++---
> >   12 files changed, 88 insertions(+), 46 deletions(-)
> 
> Unfortunately, this patch brings build error in my environment (Ubuntu
> 17.10 amd64, gcc7.2.0 from gcc-7 7.2.0-8ubuntu3).
> 
> $ ./gitcompile
> $ make
> make[2]: Entering directory '/tmp/alsa-lib/src'
>   CCLD     libasound.la
> /usr/bin/ld: unable to find version dependency `ALSA_1.1.6'
> pcm/.libs/libpcm.a(pcm_generic.o): In function `snd1_pcm_generic_hwsync':
> /tmp/alsa-lib/src/pcm/pcm_generic.c:142: warning:
> collect2: error: ld returned 1 exit status
> Makefile:491: recipe for target 'libasound.la' failed
> make[2]: *** [libasound.la] Error 1
> 
> At present, I don't know exactly the reason, but I'll start
> investigating it in next morning (I'd like to have sleep...).

It's likely a bogus definition in version symbols.
It has to be a form like:

  ALSA_1.1.6 {
    global:
      @SYMBOL_PREFIX at snd_dlopen;
  } ALSA_1.1.5;

while the patch put "ALSA_1.1.6" to both places.

Besides that, I'm scared by the versioned symbols, of which I have
only a bad memory.

Can we simply introduce another function (e.g. snd_dlopen_new() or
whatever) and make the existing snd_dlopen() a wrapper for that?


thanks,

Takashi