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gmain: Reset signal handlers to default when source is destroyed

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If someone creates a unix signal source for e.g. SIGINT, and then
removes it, reset the handler to SIG_DFL.

Not doing this was the source of race conditions in the
glib/tests/unix test, but this will also just make us a "good citizen"
by cleaning up.

For example, if a project temporarily creates a handler for SIGTERM,
and then later removes it, they almost certainly want SIGTERM to
revert to the default of terminating the process, rather than doing
nothing.

https://bugzilla.gnome.org/show_bug.cgi?id=704699
This commit is contained in:
Colin Walters 2013-07-22 19:06:31 +01:00
parent 6fbb146342
commit 2e471acfca
2 changed files with 35 additions and 27 deletions
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51
glib/gmain.c
View File

@ -428,6 +428,7 @@ static volatile sig_atomic_t any_unix_signal_pending;
static volatile int unix_signal_pending[NSIG];
static volatile int any_unix_signal_pending;
#endif
static volatile guint unix_signal_refcount[NSIG];
/* Guards all the data below */
G_LOCK_DEFINE_STATIC (unix_signal_lock);
@ -4952,28 +4953,32 @@ g_unix_signal_watch_dispatch (GSource *source,
}
static void
ensure_unix_signal_handler_installed_unlocked (int signum)
ref_unix_signal_handler_unlocked (int signum)
{
static sigset_t installed_signal_mask;
static gboolean initialized;
struct sigaction action;
if (!initialized)
/* Ensure we have the worker context */
g_get_worker_context ();
unix_signal_refcount[signum]++;
if (unix_signal_refcount[signum] == 1)
{
sigemptyset (&installed_signal_mask);
g_get_worker_context ();
initialized = TRUE;
struct sigaction action;
action.sa_handler = g_unix_signal_handler;
sigemptyset (&action.sa_mask);
action.sa_flags = SA_RESTART | SA_NOCLDSTOP;
sigaction (signum, &action, NULL);
}
}
if (sigismember (&installed_signal_mask, signum))
return;
sigaddset (&installed_signal_mask, signum);
action.sa_handler = g_unix_signal_handler;
sigemptyset (&action.sa_mask);
action.sa_flags = SA_RESTART | SA_NOCLDSTOP;
sigaction (signum, &action, NULL);
static void
unref_unix_signal_handler_unlocked (int signum)
{
unix_signal_refcount[signum]--;
if (unix_signal_refcount[signum] == 0)
{
struct sigaction action;
action.sa_handler = SIG_DFL;
sigemptyset (&action.sa_mask);
sigaction (signum, &action, NULL);
}
}
GSource *
@ -4989,7 +4994,7 @@ _g_main_create_unix_signal_watch (int signum)
unix_signal_source->pending = FALSE;
G_LOCK (unix_signal_lock);
ensure_unix_signal_handler_installed_unlocked (signum);
ref_unix_signal_handler_unlocked (signum);
unix_signal_watches = g_slist_prepend (unix_signal_watches, unix_signal_source);
if (unix_signal_pending[signum])
unix_signal_source->pending = TRUE;
@ -5001,7 +5006,12 @@ _g_main_create_unix_signal_watch (int signum)
static void
g_unix_signal_watch_finalize (GSource *source)
{
GUnixSignalWatchSource *unix_signal_source;
unix_signal_source = (GUnixSignalWatchSource *) source;
G_LOCK (unix_signal_lock);
unref_unix_signal_handler_unlocked (unix_signal_source->signum);
unix_signal_watches = g_slist_remove (unix_signal_watches, source);
G_UNLOCK (unix_signal_lock);
}
@ -5011,6 +5021,7 @@ g_child_watch_finalize (GSource *source)
{
G_LOCK (unix_signal_lock);
unix_child_watches = g_slist_remove (unix_child_watches, source);
unref_unix_signal_handler_unlocked (SIGCHLD);
G_UNLOCK (unix_signal_lock);
}
@ -5096,7 +5107,7 @@ g_child_watch_source_new (GPid pid)
g_source_add_poll (source, &child_watch_source->poll);
#else /* G_OS_WIN32 */
G_LOCK (unix_signal_lock);
ensure_unix_signal_handler_installed_unlocked (SIGCHLD);
ref_unix_signal_handler_unlocked (SIGCHLD);
unix_child_watches = g_slist_prepend (unix_child_watches, child_watch_source);
if (waitpid (pid, &child_watch_source->child_status, WNOHANG) > 0)
child_watch_source->child_exited = TRUE;

11
glib/tests/unix.c
View File

@ -158,18 +158,15 @@ test_sigterm (void)
static void
test_sighup_add_remove (void)
{
GMainLoop *mainloop;
guint id;
mainloop = g_main_loop_new (NULL, FALSE);
struct sigaction action;
sig_received = FALSE;
id = g_unix_signal_add (SIGHUP, on_sig_received, mainloop);
id = g_unix_signal_add (SIGHUP, on_sig_received, NULL);
g_source_remove (id);
kill (getpid (), SIGHUP);
g_assert (!sig_received);
g_main_loop_unref (mainloop);
sigaction (SIGHUP, NULL, &action);
g_assert (action.sa_handler == SIG_DFL);
}
static gboolean