Seccomp-BPF uses SIGSYS signal to trigger
the trap handler attached to sys_open.
If the signal is blocked then the kernel kills
the process whenever pulse audio calls 'open'.
The result backtrace is terminating in sys_open.
That's why it is required to keep SIGSYS unblocked
if it is currently unblocked and trapped.
This patch allows to have pulse audio working
in the Chromium sandbox.
Signed-off-by: Julien Isorce <j.isorce at samsung.com>
---
src/pulse/thread-mainloop.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/src/pulse/thread-mainloop.c b/src/pulse/thread-mainloop.c
index afd0581..232b5d0 100644
--- a/src/pulse/thread-mainloop.c
+++ b/src/pulse/thread-mainloop.c
@@ -77,10 +77,23 @@ static void thread(void *userdata) {
#ifndef OS_IS_WIN32
sigset_t mask;
+ sigset_t prev_mask;
+ struct sigaction sa;
- /* Make sure that signals are delivered to the main thread */
sigfillset(&mask);
- pthread_sigmask(SIG_BLOCK, &mask, NULL);
+
+ /* If SIGSYS is currently unblocked and trapped
+ * then keep it unblocked. */
+ if (!pthread_sigmask(SIG_SETMASK, NULL, &prev_mask) &&
+ !sigismember(&prev_mask, SIGSYS) &&
+ !sigaction(SIGSYS, NULL, &sa)
+ && sa.sa_handler != SIG_DFL) {
+ sigdelset(&mask, SIGSYS);
+ }
+
+ /* Make sure that signals are delivered to the main thread.
+ * Use SIG_SETMASK because SIG_BLOCK does an union with current set.*/
+ pthread_sigmask(SIG_SETMASK, &mask, NULL);
#endif
pa_mutex_lock(m->mutex);
--
1.9.1
