Modified startup notification logic to prevent deadlock in issue 471

git-svn-id: http://tint2.googlecode.com/svn/trunk@735 121b4492-b84c-0410-8b4c-0d4edfb3f3cc

CMakeLists.txt

@@ -5,7 +5,7 @@ option( ENABLE_BATTERY "Enable battery status plugin" ON )
 option( ENABLE_TINT2CONF "Enable tint2conf build, a GTK+2 theme configurator for tint2" ON )
 option( ENABLE_EXAMPLES "Install additional tin2rc examples" OFF )
 option( ENABLE_RSVG "Rsvg support (launcher only)" ON )
-option( ENABLE_SN "Startup notification support" OFF )
+option( ENABLE_SN "Startup notification support" ON )
 
 include( FindPkgConfig )
 include( CheckLibraryExists )

src/tint.c

@@ -125,6 +125,9 @@ void init (int argc, char *argv[])
 //	sigprocmask(SIG_BLOCK, &block_mask, 0);
 }
 
+static int sn_pipe_valid = 0;
+static int sn_pipe[2];
+
 #ifdef HAVE_SN
 static int error_trap_depth = 0;
 
@@ -145,6 +148,14 @@ static void error_trap_pop(SnDisplay *display, Display *xdisplay)
 }
 
 static void sigchld_handler(int sig) {
+	if (!sn_pipe_valid)
+		return;
+	ssize_t wur = write(sn_pipe[1], "x", 1);
+	(void) wur;
+	fsync(sn_pipe[1]);
+}
+
+static void sigchld_handler_async() {
 	// Wait for all dead processes
 	pid_t pid;
 	while ((pid = waitpid(-1, NULL, WNOHANG)) > 0) {
@@ -168,7 +179,8 @@ static gint cmp_ptr(gconstpointer a, gconstpointer b) {
 	else
 		return 1;
 }
-
+#else
+static void sigchld_handler_async() {}
 #endif // HAVE_SN
 
 void init_X11_pre_config()
@@ -204,12 +216,17 @@ void init_X11_post_config()
 	server.sn_dsp = sn_display_new (server.dsp, error_trap_push, error_trap_pop);
 	server.pids = g_tree_new (cmp_ptr);
 	// Setup a handler for child termination
+	if (pipe(sn_pipe) != 0) {
+		fprintf(stderr, "Creating pipe failed.\n");
+	} else {
+		sn_pipe_valid = 1;
 		struct sigaction act;
 		memset (&act, 0, sizeof (struct sigaction));
 		act.sa_handler = sigchld_handler;
 		if (sigaction(SIGCHLD, &act, 0)) {
 			perror("sigaction");
 		}
+	}
 #endif // HAVE_SN
 
 	imlib_context_set_display (server.dsp);
@@ -254,6 +271,14 @@ void cleanup()
 	cleanup_server();
 	cleanup_timeout();
 	if (server.dsp) XCloseDisplay(server.dsp);
+
+#ifdef HAVE_SN
+	if (sn_pipe_valid) {
+		sn_pipe_valid = 0;
+		close(sn_pipe[1]);
+		close(sn_pipe[0]);
+	}
+#endif
 }
 
 
@@ -1106,6 +1131,11 @@ start:
 		// Create a File Description Set containing x11_fd
 		FD_ZERO (&fdset);
 		FD_SET (x11_fd, &fdset);
+		int maxfd = x11_fd;
+		if (sn_pipe_valid) {
+			FD_SET (sn_pipe[0], &fdset);
+			maxfd = maxfd < sn_pipe[0] ? sn_pipe[0] : maxfd;
+		}
 		update_next_timeout();
 		if (next_timeout.tv_sec >= 0 && next_timeout.tv_usec >= 0)
 			timeout = &next_timeout;
@@ -1113,7 +1143,14 @@ start:
 			timeout = 0;
 
 		// Wait for X Event or a Timer
-		if (select(x11_fd+1, &fdset, 0, 0, timeout) > 0) {
+		if (select(maxfd+1, &fdset, 0, 0, timeout) > 0) {
+			if (FD_ISSET(sn_pipe[0], &fdset)) {
+				char buffer[1];
+				ssize_t wur = read(sn_pipe[0], buffer, 1);
+				(void) wur;
+				sigchld_handler_async();
+			}
+			if (FD_ISSET(x11_fd, &fdset)) {
 				while (XPending (server.dsp)) {
 					XNextEvent(server.dsp, &e);
 #if HAVE_SN
@@ -1352,6 +1389,7 @@ start:
 					}
 				}
 			}
+		}
 
 		callback_timeout_expired();