fixes for BSDI. see ChangeLog.

[citadel.git] / citadel / sysdep.c

diff --git a/citadel/sysdep.c b/citadel/sysdep.c
index 69bc573a8929eeceec14c11e141993a129a88899..ad4c59037f2a45f3ec679a4147a45af99ecea958 100644 (file)
--- a/citadel/sysdep.c
+++ b/citadel/sysdep.c
@@ -154,6 +154,33 @@ void dump_tracked() {
        }
 #endif
 
+#ifndef HAVE_PTHREAD_CANCEL
+/*
+ * signal handler to fake thread cancellation; only required on BSDI as far
+ * as I know.
+ */
+
+static pthread_t main_thread_id;
+
+static RETSIGTYPE cancel_thread(int signum) {
+       pthread_exit(NULL);
+       }
+#endif
+
+/*
+ * we used to use master_cleanup() as a signal handler to shut down the server.
+ * however, master_cleanup() and the functions it calls do some things that
+ * aren't such a good idea to do from a signal handler: acquiring mutexes,
+ * playing with signal masks on BSDI systems, etc. so instead we install the
+ * following signal handler to set a global variable to inform the main loop
+ * that it's time to call master_cleanup() and exit.
+ */
+
+static volatile int time_to_die = 0;
+
+static RETSIGTYPE signal_cleanup(int signum) {
+       time_to_die = 1;
+       }
 
 
 /*
@@ -178,13 +205,17 @@ void init_sysdep(void) {
 
        /*
         * The action for unexpected signals and exceptions should be to
-        * call master_cleanup() to gracefully shut down the server.
+        * call signal_cleanup() to gracefully shut down the server.
         */
-       signal(SIGINT, (void(*)(int))master_cleanup);
-       signal(SIGQUIT, (void(*)(int))master_cleanup);
-       signal(SIGHUP, (void(*)(int))master_cleanup);
-       signal(SIGTERM, (void(*)(int))master_cleanup);
+       signal(SIGINT, signal_cleanup);
+       signal(SIGQUIT, signal_cleanup);
+       signal(SIGHUP, signal_cleanup);
+       signal(SIGTERM, signal_cleanup);
        signal(SIGPIPE, SIG_IGN);
+#ifndef HAVE_PTHREAD_CANCEL /* fake it - only BSDI afaik */
+       main_thread_id = pthread_self();
+       signal(SIGUSR1, cancel_thread);
+#endif
        }
 
 
@@ -193,12 +224,26 @@ void init_sysdep(void) {
  */
 void begin_critical_section(int which_one)
 {
+#ifdef HAVE_PTHREAD_CANCEL
        int oldval;
+#else
+       sigset_t set;
+#endif
 
        /* lprintf(8, "begin_critical_section(%d)\n", which_one); */
 
+#ifdef HAVE_PTHREAD_CANCEL
        /* Don't get interrupted during the critical section */
        pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, &oldval);
+#else
+       /* We're faking cancellation with signals. Block SIGUSR1 while we're in
+        * the critical section. */
+       if (!pthread_equal(pthread_self(), main_thread_id)) {
+               sigemptyset(&set);
+               sigaddset(&set, SIGUSR1);
+               pthread_sigmask(SIG_BLOCK, &set, NULL);
+               }
+#endif
 
        /* Obtain a semaphore */
        pthread_mutex_lock(&Critters[which_one]);
@@ -210,19 +255,33 @@ void begin_critical_section(int which_one)
  */
 void end_critical_section(int which_one)
 {
+#ifdef HAVE_PTHREAD_CANCEL
        int oldval;
+#else
+       sigset_t set;
+#endif
 
        /* lprintf(8, "  end_critical_section(%d)\n", which_one); */
 
        /* Let go of the semaphore */
        pthread_mutex_unlock(&Critters[which_one]);
 
+#ifdef HAVE_PTHREAD_CANCEL
        /* If a cancel was sent during the critical section, do it now.
         * Then re-enable thread cancellation.
         */
        pthread_testcancel();
        pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldval);
        pthread_testcancel();
+#else
+       /* We're faking it. Unblock SIGUSR1; signals sent during the critical
+        * section should now be able to kill us. */
+       if (!pthread_equal(pthread_self(), main_thread_id)) {
+               sigemptyset(&set);
+               sigaddset(&set, SIGUSR1);
+               pthread_sigmask(SIG_UNBLOCK, &set, NULL);
+               }
+#endif
 
        }
 
@@ -332,11 +391,15 @@ struct CitContext *CreateNewContext(void) {
  */
 void InitMyContext(struct CitContext *con)
 {
+#ifdef HAVE_PTHREAD_CANCEL
        int oldval;
+#endif
 
        con->mythread = pthread_self();
+#ifdef HAVE_PTHREAD_CANCEL
        pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &oldval);
        pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, &oldval);
+#endif
        if (pthread_setspecific(MyConKey, (void *)con) != 0) {
                lprintf(1, "ERROR!  pthread_setspecific() failed: %s\n",
                        strerror(errno));
@@ -568,8 +631,12 @@ void kill_session(int session_to_kill) {
        lprintf(9, "kill_session() finished scanning.\n");
 
        if (killme != 0) {
+#ifdef HAVE_PTHREAD_CANCEL
                lprintf(9, "calling pthread_cancel()\n");
                pthread_cancel(killme);
+#else
+               pthread_kill(killme, SIGUSR1);
+#endif
                }
        }
 
@@ -709,6 +776,8 @@ int main(int argc, char **argv)
        char tracefile[128];            /* Name of file to log traces to */
        int a, i;                       /* General-purpose variables */
        char convbuf[128];
+       fd_set readfds;
+       struct timeval tv;
         
        /* specify default port name and trace file */
        strcpy(tracefile, "");
@@ -792,7 +861,17 @@ int main(int argc, char **argv)
         * Endless loop.  Listen on the master socket.  When a connection
         * comes in, create a socket, a context, and a thread.
         */     
-       while (1) {
+       while (!time_to_die) {
+               /* we need to check if a signal has been delivered. because
+                * syscalls may be restartable across signals, we call
+                * select with a timeout of 1 second and repeatedly check for
+                * time_to_die... */
+               FD_ZERO(&readfds);
+               FD_SET(msock, &readfds);
+               tv.tv_sec = 1;
+               tv.tv_usec = 0;
+               if (select(msock + 1, &readfds, NULL, NULL, &tv) <= 0)
+                       continue;
                alen = sizeof fsin;
                ssock = accept(msock, (struct sockaddr *)&fsin, &alen);
                if (ssock < 0) {
@@ -839,5 +918,7 @@ int main(int argc, char **argv)
                        lprintf(9, "done!\n");
                        }
                }
+       master_cleanup();
+       return 0;
        }