main: Use signalfd instead of plain signals

It's unsafe to call syslog in the terminat signal handler
because syslog takes an lock. So when the signal handler
kicks in and we were already in syslog, we have a nice
deadlock.

diff --git a/src/main.c b/src/main.c
index bb08e40..a6824c0 100644 (file)
--- a/src/main.c
+++ b/src/main.c
@@ -29,6 +29,7 @@
 #include <unistd.h>
 #include <string.h>
 #include <signal.h>
+#include <sys/signalfd.h>
 #include <getopt.h>
 #include <sys/stat.h>
 #include <net/if.h>
@@ -90,11 +91,31 @@ static void parse_config(GKeyFile *config)
 
 static GMainLoop *main_loop = NULL;
 
-static void sig_term(int sig)
+static gboolean signal_cb(GIOChannel *chan,
+                               GIOCondition cond, gpointer data)
 {
-       connman_info("Terminating");
+       int signal_fd = GPOINTER_TO_INT(data);
+       struct signalfd_siginfo si;
+       ssize_t res;
+
+       if (cond & (G_IO_NVAL | G_IO_ERR))
+               return FALSE;
+
+       res = read(signal_fd, &si, sizeof(si));
+       if (res != sizeof(si))
+               return FALSE;
+
+       switch (si.ssi_signo) {
+       case SIGINT:
+       case SIGTERM:
+               connman_info("Terminating");
+               g_main_loop_quit(main_loop);
+               break;
+       default:
+               break;
+       }
 
-       g_main_loop_quit(main_loop);
+       return TRUE;
 }
 
 static void disconnect_callback(DBusConnection *conn, void *user_data)
@@ -179,7 +200,10 @@ int main(int argc, char *argv[])
        GError *error = NULL;
        DBusConnection *conn;
        DBusError err;
-       struct sigaction sa;
+       int signal_fd;
+       int signal_source;
+       GIOChannel *signal_io;
+       sigset_t mask;
        GKeyFile *config;
 
 #ifdef HAVE_CAPNG
@@ -312,13 +336,32 @@ int main(int argc, char *argv[])
        g_free(option_nodevice);
        g_free(option_noplugin);
 
-       memset(&sa, 0, sizeof(sa));
-       sa.sa_handler = sig_term;
-       sigaction(SIGINT, &sa, NULL);
-       sigaction(SIGTERM, &sa, NULL);
+       sigemptyset(&mask);
+       sigaddset(&mask, SIGTERM);
+       sigaddset(&mask, SIGINT);
+
+       if (sigprocmask(SIG_BLOCK, &mask, NULL) < 0) {
+               fprintf(stderr, "Could not block signals\n");
+               exit(1);
+       }
+
+       signal_fd = signalfd(-1, &mask, 0);
+       if (signal_fd < 0) {
+               fprintf(stderr, "Could not init signalfd\n");
+               exit(1);
+       }
+
+       signal_io = g_io_channel_unix_new(signal_fd);
+       g_io_channel_set_close_on_unref(signal_io, TRUE);
+       signal_source = g_io_add_watch(signal_io,
+                               G_IO_IN | G_IO_HUP | G_IO_ERR | G_IO_NVAL,
+                               signal_cb, GINT_TO_POINTER(signal_fd));
+       g_io_channel_unref(signal_io);
 
        g_main_loop_run(main_loop);
 
+       g_source_remove(signal_source);
+
        __connman_rfkill_cleanup();
        __connman_wispr_cleanup();
        __connman_wpad_cleanup();