Perform proper cleanup for signals with 'Term' action (#3057)

[i3/i3] / src / main.c

diff --git a/src/main.c b/src/main.c
index d87b9a29b0bcb75febe7e60b91b52bb220b50e97..b634b139f90276db0e4273d28a70922f732a63f5 100644 (file)
--- a/src/main.c
+++ b/src/main.c
@@ -174,21 +174,64 @@ static void i3_exit(void) {
         fflush(stderr);
         shm_unlink(shmlogname);
     }
+    ipc_shutdown(SHUTDOWN_REASON_EXIT);
+    unlink(config.ipc_socket_path);
 }
 
 /*
- * (One-shot) Handler for all signals with default action "Term", see signal(7)
+ * (One-shot) Handler for all signals with default action "Core", see signal(7)
  *
  * Unlinks the SHM log and re-raises the signal.
  *
  */
-static void handle_signal(int sig, siginfo_t *info, void *data) {
+static void handle_core_signal(int sig, siginfo_t *info, void *data) {
     if (*shmlogname != '\0') {
         shm_unlink(shmlogname);
     }
     raise(sig);
 }
 
+/*
+ * (One-shot) Handler for all signals with default action "Term", see signal(7)
+ *
+ * Exits the program gracefully.
+ *
+ */
+static void handle_term_signal(struct ev_loop *loop, ev_signal *signal, int revents) {
+    /* We exit gracefully here in the sense that cleanup handlers
+     * installed via atexit are invoked. */
+    exit(128 + signal->signum);
+}
+
+/*
+ * Set up handlers for all signals with default action "Term", see signal(7)
+ *
+ */
+static void setup_term_handlers(void) {
+    static struct ev_signal signal_watchers[6];
+    size_t num_watchers = sizeof(signal_watchers) / sizeof(signal_watchers[0]);
+
+    /* We have to rely on libev functionality here and should not use
+     * sigaction handlers because we need to invoke the exit handlers
+     * and cannot do so from an asynchronous signal handling context as
+     * not all code triggered during exit is signal safe (and exiting
+     * the main loop from said handler is not easily possible). libev's
+     * signal handlers does not impose such a constraint on us. */
+    ev_signal_init(&signal_watchers[0], handle_term_signal, SIGHUP);
+    ev_signal_init(&signal_watchers[1], handle_term_signal, SIGINT);
+    ev_signal_init(&signal_watchers[2], handle_term_signal, SIGALRM);
+    ev_signal_init(&signal_watchers[3], handle_term_signal, SIGTERM);
+    ev_signal_init(&signal_watchers[4], handle_term_signal, SIGUSR1);
+    ev_signal_init(&signal_watchers[5], handle_term_signal, SIGUSR1);
+    for (size_t i = 0; i < num_watchers; i++) {
+        ev_signal_start(main_loop, &signal_watchers[i]);
+        /* The signal handlers should not block ev_run from returning
+         * and so none of the signal handlers should hold a reference to
+         * the main loop. */
+        ev_unref(main_loop);
+    }
+}
+
 int main(int argc, char *argv[]) {
     /* Keep a symbol pointing to the I3_VERSION string constant so that we have
      * it in gdb backtraces. */
@@ -853,15 +896,15 @@ int main(int argc, char *argv[]) {
         err(EXIT_FAILURE, "pledge");
 #endif
 
-    struct sigaction action;
-
-    action.sa_sigaction = handle_signal;
-    action.sa_flags = SA_NODEFER | SA_RESETHAND | SA_SIGINFO;
-    sigemptyset(&action.sa_mask);
-
     if (!disable_signalhandler)
         setup_signal_handler();
     else {
+        struct sigaction action;
+
+        action.sa_sigaction = handle_core_signal;
+        action.sa_flags = SA_NODEFER | SA_RESETHAND | SA_SIGINFO;
+        sigemptyset(&action.sa_mask);
+
         /* Catch all signals with default action "Core", see signal(7) */
         if (sigaction(SIGQUIT, &action, NULL) == -1 ||
             sigaction(SIGILL, &action, NULL) == -1 ||
@@ -871,14 +914,7 @@ int main(int argc, char *argv[]) {
             ELOG("Could not setup signal handler.\n");
     }
 
-    /* Catch all signals with default action "Term", see signal(7) */
-    if (sigaction(SIGHUP, &action, NULL) == -1 ||
-        sigaction(SIGINT, &action, NULL) == -1 ||
-        sigaction(SIGALRM, &action, NULL) == -1 ||
-        sigaction(SIGUSR1, &action, NULL) == -1 ||
-        sigaction(SIGUSR2, &action, NULL) == -1)
-        ELOG("Could not setup signal handler.\n");
-
+    setup_term_handlers();
     /* Ignore SIGPIPE to survive errors when an IPC client disconnects
      * while we are sending them a message */
     signal(SIGPIPE, SIG_IGN);
@@ -921,7 +957,7 @@ int main(int argc, char *argv[]) {
         free(command);
     }
 
-    /* Make sure to destroy the event loop to invoke the cleeanup callbacks
+    /* Make sure to destroy the event loop to invoke the cleanup callbacks
      * when calling exit() */
     atexit(i3_exit);