[pulseaudio-discuss] [PATCH 21/56] bluetooth: Create pa_bluetooth_discovery for BlueZ 5

[João Paulo Rechi Vita]

On Jul 18, 2013 10:32 AM, "Tanu Kaskinen" <tanu.kaskinen at linux.intel.com>
wrote:
>
> On Fri, 2013-07-12 at 15:06 -0300, jprvita at gmail.com wrote:
> > From: João Paulo Rechi Vita <jprvita at openbossa.org>
> >
> > pa_bluetooth_discovery is the struct that holds information about known
> > Bluetooth audio devices and other information about the Bluetooth stack.
> >
> > This commit also creates bluez5-util.[ch], which will hold a lot of
> > utility functions to help with the BlueZ 5 support.
>
> So there will be bluez4-util.so and bluez5-util.so, and those will
> contain identical symbols. It's possible to load both bluez 4 and 5
> modules at the same time, so the bluez*-util libraries will conflict in
> a way that will cause crashing or weird behavior. Since we lost the
> opportunity to have a shared Bluetooth core for all backends, I think it
> would be OK to change the generic "pa_bluetooth" prefix (and "pa_bt", if
> it's still used somewhere) to "pa_bluez5". That would resolve the symbol
> conflict between the two libraries.
>

Good catch, I haven't thought about this problem before.

> Another, perhaps easier solution would be to use symbol versioning in
> the libraries. I'm not 100% sure that this works, but I think it should
> work.
>

How does it works? I have never done or seen it anywhere.

> To be clear, I don't think it's a valid use case to load both versions
> at the same time, but we must not crash due to configuration errors.
>

Yes, I agree.

> > ---
> >  src/Makefile.am                                | 10 +++-
> >  src/modules/bluetooth/bluez5-util.c            | 74
++++++++++++++++++++++++++
> >  src/modules/bluetooth/bluez5-util.h            | 32 +++++++++++
> >  src/modules/bluetooth/module-bluez5-discover.c | 33 ++++++++++++
> >  4 files changed, 148 insertions(+), 1 deletion(-)
> >  create mode 100644 src/modules/bluetooth/bluez5-util.c
> >  create mode 100644 src/modules/bluetooth/bluez5-util.h
> >
> > diff --git a/src/Makefile.am b/src/Makefile.am
> > index 733c338..52cd63f 100644
> > --- a/src/Makefile.am
> > +++ b/src/Makefile.am
> > @@ -1333,6 +1333,7 @@ endif
> >  if HAVE_BLUEZ_5
> >  modlibexec_LTLIBRARIES += \
> >               module-bluetooth-policy.la \
> > +             libbluez5-util.la \
> >               module-bluez5-discover.la
> >  endif
> >
> > @@ -2049,9 +2050,16 @@ module_bluez4_device_la_LIBADD =
$(MODULE_LIBADD) $(DBUS_LIBS) $(SBC_LIBS) libbl
> >  module_bluez4_device_la_CFLAGS = $(AM_CFLAGS) $(DBUS_CFLAGS)
$(SBC_CFLAGS)
> >
> >  # Bluetooth BlueZ 5 sink / source
> > +libbluez5_util_la_SOURCES = \
> > +             modules/bluetooth/bluez5-util.c \
> > +             modules/bluetooth/bluez5-util.h
> > +libbluez5_util_la_LDFLAGS = -avoid-version
> > +libbluez5_util_la_LIBADD = $(MODULE_LIBADD) $(DBUS_LIBS)
> > +libbluez5_util_la_CFLAGS = $(AM_CFLAGS) $(DBUS_CFLAGS)
> > +
> >  module_bluez5_discover_la_SOURCES =
modules/bluetooth/module-bluez5-discover.c
> >  module_bluez5_discover_la_LDFLAGS = $(MODULE_LDFLAGS)
> > -module_bluez5_discover_la_LIBADD = $(MODULE_LIBADD) $(DBUS_LIBS)
> > +module_bluez5_discover_la_LIBADD = $(MODULE_LIBADD) $(DBUS_LIBS)
libbluez5-util.la
> >  module_bluez5_discover_la_CFLAGS = $(AM_CFLAGS) $(DBUS_CFLAGS)
> >
> >  # Apple Airtunes/RAOP
> > diff --git a/src/modules/bluetooth/bluez5-util.c
b/src/modules/bluetooth/bluez5-util.c
> > new file mode 100644
> > index 0000000..0f23bff
> > --- /dev/null
> > +++ b/src/modules/bluetooth/bluez5-util.c
> > @@ -0,0 +1,74 @@
> > +/***
> > +  This file is part of PulseAudio.
> > +
> > +  Copyright 2008-2013 João Paulo Rechi Vita
> > +
> > +  PulseAudio is free software; you can redistribute it and/or modify
> > +  it under the terms of the GNU Lesser General Public License as
> > +  published by the Free Software Foundation; either version 2.1 of the
> > +  License, or (at your option) any later version.
> > +
> > +  PulseAudio is distributed in the hope that it will be useful, but
> > +  WITHOUT ANY WARRANTY; without even the implied warranty of
> > +  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> > +  General Public License for more details.
> > +
> > +  You should have received a copy of the GNU Lesser General Public
> > +  License along with PulseAudio; if not, write to the Free Software
> > +  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
> > +  USA.
> > +***/
> > +
> > +#ifdef HAVE_CONFIG_H
> > +#include <config.h>
> > +#endif
> > +
> > +#include <pulse/xmalloc.h>
> > +
> > +#include <pulsecore/core.h>
> > +#include <pulsecore/macro.h>
> > +#include <pulsecore/refcnt.h>
> > +#include <pulsecore/shared.h>
> > +
> > +#include "bluez5-util.h"
> > +
> > +struct pa_bluetooth_discovery {
> > +    PA_REFCNT_DECLARE;
> > +
> > +    pa_core *core;
> > +};
> > +
> > +pa_bluetooth_discovery* pa_bluetooth_discovery_get(pa_core *c) {
> > +    pa_bluetooth_discovery *y;
> > +
> > +    if ((y = pa_shared_get(c, "bluetooth-discovery")))
> > +        return pa_bluetooth_discovery_ref(y);
>
> This is another source of crashy conflicts: bluez4-util uses the same
> shared name, so you may end up returning bluez4 version of
> pa_bluetooth_discovery to bluez5 code, or vice versa.
>

For this one we can simply use different names for BlueZ 4 and BlueZ 5.

> --
> Tanu
>
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