Move signal processing to the main loop using signalfd

src/main.c

@@ -1,6 +1,7 @@
 /*
- * Driver for multi-threaded daap server
+ * Copyright (C) 2009 Julien BLACHE <jb@jblache.org>
  *
+ * Pieces from mt-daapd:
  * Copyright (C) 2003 Ron Pedde (ron@pedde.com)
  *
  * This program is free software; you can redistribute it and/or modify
@@ -74,6 +75,7 @@
 #ifdef HAVE_SYS_WAIT_H
 #include <sys/wait.h>
 #endif
+#include <sys/signalfd.h>
 
 #include "daapd.h"
 
@@ -275,15 +277,6 @@ mainloop_cb(int fd, short event, void *arg)
 
   rescan_counter += MAIN_SLEEP_INTERVAL;
 
-  /* Handle signals */ /* JB: FIXME */
-  os_wait(0);
-
-  if (config.stop)
-    {
-      event_loopbreak();
-      return;
-    }
-
   main_timer = (struct event *)arg;
   evutil_timerclear(&tv);
   tv.tv_sec = MAIN_SLEEP_INTERVAL;
@@ -331,6 +324,58 @@ mainloop_cb(int fd, short event, void *arg)
     }
 }
 
+static void
+signal_cb(int fd, short event, void *arg)
+{
+  struct sigaction sa_ign;
+  struct sigaction sa_dfl;
+  struct signalfd_siginfo info;
+  int status;
+
+  sa_ign.sa_handler=SIG_IGN;
+  sa_ign.sa_flags=0;
+  sigemptyset(&sa_ign.sa_mask);
+
+  sa_dfl.sa_handler=SIG_DFL;
+  sa_dfl.sa_flags=0;
+  sigemptyset(&sa_dfl.sa_mask);
+
+  while (read(fd, &info, sizeof(struct signalfd_siginfo)) > 0)
+    {
+      switch (info.ssi_signo)
+	{
+	  case SIGCHLD:
+	    DPRINTF(E_LOG, L_MAIN, "Got SIGCHLD, reaping children\n");
+
+	    while (wait3(&status, WNOHANG, NULL) > 0)
+	      /* Nothing. */ ;
+	    break;
+
+	  case SIGINT:
+	  case SIGTERM:
+	    DPRINTF(E_LOG, L_MAIN, "Got SIGTERM or SIGINT\n");
+
+	    config.stop = 1;
+	    break;
+
+	  case SIGHUP:
+	    DPRINTF(E_LOG, L_MAIN, "Got SIGHUP\n");
+
+	    if (!config.stop)
+	      {
+		conf_reload();
+		err_reopen();
+
+		config.reload = 1;
+	      }
+	    break;
+	}
+    }
+
+  if (config.stop)
+    event_base_loopbreak(evbase_main);
+}
+
 /**
  * Kick off the daap server and wait for events.
  *
@@ -372,6 +417,9 @@ int main(int argc, char *argv[]) {
     char *plugindir;
     struct event *main_timer;
     struct timeval tv;
+    sigset_t sigs;
+    int sigfd;
+    struct event sig_event;
     int ret;
 
     int err;
@@ -539,6 +587,20 @@ int main(int argc, char *argv[]) {
         DPRINTF(E_LOG,L_MAIN,"Plugin loaded: %s\n",plugin_get_description(phandle));
     }
 
+    /* Block signals for all threads except the main one */
+    sigemptyset(&sigs);
+    sigaddset(&sigs, SIGINT);
+    sigaddset(&sigs, SIGHUP);
+    sigaddset(&sigs, SIGCHLD);
+    sigaddset(&sigs, SIGTERM);
+    sigaddset(&sigs, SIGPIPE);
+    ret = pthread_sigmask(SIG_BLOCK, &sigs, NULL);
+    if (ret != 0)
+      {
+        DPRINTF(E_LOG, L_MAIN, "Error setting signal set\n");
+	exit(EXIT_FAILURE);
+      }
+
     runas = conf_alloc_string("general","runas","nobody");
 
     if(!os_init(config.foreground,runas)) {
@@ -691,6 +753,20 @@ int main(int argc, char *argv[]) {
        (!conf_get_int("scanning","skip_first",0)))
         config.reload = 1; /* force a reload on start */
 
+    /* Set up signal fd */
+    sigfd = signalfd(-1, &sigs, SFD_NONBLOCK | SFD_CLOEXEC);
+    if (sigfd < 0)
+      {
+	DPRINTF(E_FATAL, L_MAIN, "Could not setup signalfd: %s\n", strerror(errno));
+
+	mdns_deinit();
+	exit(EXIT_FAILURE);
+      }
+
+    event_set(&sig_event, sigfd, EV_READ, signal_cb, NULL);
+    event_base_set(evbase_main, &sig_event);
+    event_add(&sig_event, NULL);
+
     /* Set up main timer */
     evtimer_set(main_timer, mainloop_cb, main_timer);
     event_base_set(evbase_main, main_timer);

src/os-unix.c

@@ -64,7 +64,6 @@
 
 /* Forwards */
 static int _os_daemon_start(void);
-static int _os_start_signal_handler(void);
 
 /* Globals */
 char *_os_pidfile = PIDFILE;
@@ -80,12 +79,6 @@ int os_init(int foreground, char *runas) {
     int pid_fd;
     FILE *pid_fp=NULL;
 
-    /* block signals and set up the signal handling thread */
-    DPRINTF(E_LOG,L_MAIN,"Starting signal handler\n");
-    if(_os_start_signal_handler()) {
-        DPRINTF(E_FATAL,L_MAIN,"Error starting signal handler %s\n",strerror(errno));
-    }
-
     /* open the pidfile, so it can be written once we detach */
     if(!foreground) {
         if(-1 == (pid_fd = open(_os_pidfile,O_CREAT | O_WRONLY | O_TRUNC, 0644))) {
@@ -349,97 +342,6 @@ int os_drop_privs(char *user) {
     return 0;
 }
 
-/**
- * wait for specified time, while setting signal flags
- * (if necessary)
- */
-void os_wait(int seconds) {
-    sigset_t intmask;
-    int status;
-    struct sigaction sa_ign;
-    struct sigaction sa_dfl;
-
-    if (seconds > 0)
-      sleep(seconds);
-
-    sigpending(&intmask);
-
-    sa_ign.sa_handler=SIG_IGN;
-    sa_ign.sa_flags=0;
-    sigemptyset(&sa_ign.sa_mask);
-
-    sa_dfl.sa_handler=SIG_DFL;
-    sa_dfl.sa_flags=0;
-    sigemptyset(&sa_dfl.sa_mask);
-
-
-    if(sigismember(&intmask, SIGCLD)) {
-        DPRINTF(E_LOG,L_MAIN,"Got CLD signal.  Reaping\n");
-        while (wait3(&status, WNOHANG, NULL) > 0) {};
-
-        sigaction(SIGCLD,&sa_ign,NULL);
-        sigaction(SIGCLD,&sa_dfl,NULL);
-    }
-
-    if((sigismember(&intmask, SIGTERM)) ||
-       (sigismember(&intmask, SIGINT))) {
-        DPRINTF(E_LOG,L_MAIN,"Got shutdown signal.\n");
-        config.stop=1;
-
-        sigaction(SIGTERM,&sa_ign,NULL);
-        sigaction(SIGTERM,&sa_dfl,NULL);
-
-        sigaction(SIGINT,&sa_ign,NULL);
-        sigaction(SIGINT,&sa_dfl,NULL);
-    }
-
-    if(sigismember(&intmask, SIGHUP)) {
-        DPRINTF(E_LOG,L_MAIN,"Got HUP signal.\n");
-        /* if we can't reload, it keeps the old config file,
-         * so no real damage */
-        conf_reload();
-        err_reopen();
-
-        config.reload=1;
-
-        sigaction(SIGHUP,&sa_ign,NULL);
-        sigaction(SIGHUP,&sa_dfl,NULL);
-    }
-}
-
-/**
- * Wait for signals and flag the main process.  This is
- * a thread handler for the signal processing thread.  It
- * does absolutely nothing except wait for signals.  The rest
- * of the threads are running with signals blocked, so this thread
- * is guaranteed to catch all the signals.  It sets flags in
- * the config structure that the main thread looks for.  Specifically,
- * the stop flag (from an INT signal), and the reload flag (from HUP).
- * \param arg NULL, but required of a thread procedure
- */
-/**
- * Block signals, then start the signal handler.  The
- * signal handler started by spawning a new thread on
- * signal_handler().
- *
- * \returns 0 on success, -1 on failure with errno set
- */
-int _os_start_signal_handler(void) {
-    sigset_t set;
-
-    if((sigemptyset(&set) == -1) ||
-       (sigaddset(&set,SIGINT) == -1) ||
-       (sigaddset(&set,SIGHUP) == -1) ||
-       (sigaddset(&set,SIGCLD) == -1) ||
-       (sigaddset(&set,SIGTERM) == -1) ||
-       (sigaddset(&set,SIGPIPE) == -1) ||
-       (pthread_sigmask(SIG_BLOCK, &set, NULL) == -1)) {
-        DPRINTF(E_LOG,L_MAIN,"Error setting signal set\n");
-        return -1;
-    }
-
-    return 0;
-}
 
 /**
  * set the pidfile to a non-default value

src/os.h

@@ -28,7 +28,6 @@
 /* backgrounding, signal handling, etc */
 extern int os_init(int foreground, char *runas);
 extern void os_deinit(void);
-extern void os_wait(int seconds);
 
 /* system native logging functions */
 extern int os_opensyslog(void);