try to detect when stupid clients forks and refuse all service from then on

src/pulse/fork-detect.c

@@ -0,0 +1,59 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2009 Lennart Poettering
+
+  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 <unistd.h>
+
+#include <pulsecore/atomic.h>
+#include <pulsecore/macro.h>
+
+#include "fork-detect.h"
+
+int pa_detect_fork(void) {
+    static pa_atomic_t pid = PA_ATOMIC_INIT((int) -1);
+
+    /* Some really stupid applications (Hey, vim, that means you!)
+     * love to fork after initializing
+     * gtk/libcanberra/pulseaudio. This is really bad style. We
+     * however have to deal with this cleanly, so we try to detect the
+     * forks making sure all our calls fail cleanly after the fork. */
+
+    pa_assert(sizeof(pa_atomic_t) >= sizeof(pid_t));
+
+    for (;;) {
+        pid_t stored_pid = (pid_t) pa_atomic_load(&pid);
+
+        /* First let's check whether the current pid matches the stored one */
+        if (stored_pid == getpid())
+            return FALSE;
+
+        /* Does it contain a different PID than ours? Then the process got forked. */
+        if ((int) stored_pid != (int) -1)
+            return TRUE;
+
+        /* Ok, it still contains no PID, then store it */
+        if (pa_atomic_cmpxchg(&pid, (int) -1, (int) getpid()))
+            return FALSE;
+    }
+}