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From:   Fabrice Fontaine <fontaine.fabrice@gmail.com>
To:     linux-bluetooth@vger.kernel.org
Cc:     Fabrice Fontaine <fontaine.fabrice@gmail.com>,
        "Yann E . MORIN" <yann.morin.1998@free.fr>
Subject: [PATCH] profiles/audio/media.c: fix build with glibc >= 2.34
Date:   Sun, 12 Sep 2021 22:48:39 +0200
Message-Id: <20210912204839.3018089-1-fontaine.fabrice@gmail.com>
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pause() is defined in glibc since the very early times; it appears in
upstream commit 28f540f45bba (initial import) in 1995 [0].

Bluez has been defining a function named pause() for ages too, since
commit caab74c97542 (media: Implement new callbacks for pass-through
operations) in 2013 [1]

With the recent bump to glibc 2.34.xxx, the build now fails because the
two pause() clash:

profiles/audio/media.c:1284:13: error: conflicting types for 'pause'
 1284 | static bool pause(void *user_data)
      |             ^~~~~
In file included from /tmp/instance-0/output-1/per-package/bluez5_utils/host/s390x-buildroot-linux-gnu/sysroot/usr/include/bits/sigstksz.h:24,
                 from /tmp/instance-0/output-1/per-package/bluez5_utils/host/s390x-buildroot-linux-gnu/sysroot/usr/include/signal.h:328,
                 from /tmp/instance-0/output-1/per-package/bluez5_utils/host/bin/../s390x-buildroot-linux-gnu/sysroot/usr/include/glib-2.0/glib/gbacktrace.h:36,
                 from /tmp/instance-0/output-1/per-package/bluez5_utils/host/bin/../s390x-buildroot-linux-gnu/sysroot/usr/include/glib-2.0/glib.h:34,
                 from profiles/audio/media.c:21:
/tmp/instance-0/output-1/per-package/bluez5_utils/host/s390x-buildroot-linux-gnu/sysroot/usr/include/unistd.h:489:12: note: previous declaration of 'pause' was here
  489 | extern int pause (void);
      |            ^~~~~

The culprit is indeed glibc 2.34, as can be seen in this result matrix:

         \   bluez5_utils
    glibc \  5.60  |  5.61
    -------\-------+--------
    2.33   |  OK   |   OK
    -------+-------+--------
    2.34   |  KO   |   KO

The underlying reason that pause() is now causing issues with glibc 2.34
is not obvious: glibc is a big beast, and finding such issues is not
easy. However, we can see that the pause() provided by NPTL has been
dropped in favour of the generic one, so maybe this is causing symbol
visibility or weakness to change or something...

We fix that by renaming the local pause() in bluez5_utils with a
namespace-prefix, like some other functions there already have.

Fixes:
  - http://autobuild.buildroot.org/results/c4fbface34be8815838fd7201621d7a8fddd32c5
  - http://autobuild.buildroot.org/results/62b88740f19fbe4a1ad7959dc141d539eb88c1f8

[0] https://sourceware.org/git/?p=glibc.git;a=commit;h=28f540f45bbacd939bfd07f213bcad2bf730b1bf
[1] https://github.com/bluez/bluez/commit/caab74c97542a56b591f0b16b44ab6ba4b40f0f5

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
---
 profiles/audio/media.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/profiles/audio/media.c b/profiles/audio/media.c
index 267722542..f93b74e67 100644
--- a/profiles/audio/media.c
+++ b/profiles/audio/media.c
@@ -1281,7 +1281,7 @@ static bool stop(void *user_data)
 	return media_player_send(mp, "Stop");
 }
 
-static bool pause(void *user_data)
+static bool media_player_pause(void *user_data)
 {
 	struct media_player *mp = user_data;
 
@@ -1331,7 +1331,7 @@ static struct avrcp_player_cb player_cb = {
 	.set_volume = set_volume,
 	.play = play,
 	.stop = stop,
-	.pause = pause,
+	.pause = media_player_pause,
 	.next = next,
 	.previous = previous,
 };
-- 
2.33.0