X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fdaemon.c;h=081912b128c230c59550608059ea4cdc9a8b25a0;hb=7103dec49eb569c3196239da6c178a29c3003e2b;hp=9895f7251f057189c25654f405b033d612d2366c;hpb=7943cd51e7eba1442846a853b6ed62e89a05d110;p=openvswitch

diff --git a/lib/daemon.c b/lib/daemon.c
index 9895f725..081912b1 100644
--- a/lib/daemon.c
+++ b/lib/daemon.c
@@ -22,9 +22,11 @@
 #include <string.h>
 #include <sys/wait.h>
 #include <unistd.h>
+#include "command-line.h"
 #include "fatal-signal.h"
 #include "dirs.h"
 #include "lockfile.h"
+#include "process.h"
 #include "socket-util.h"
 #include "timeval.h"
 #include "util.h"
@@ -47,14 +49,18 @@ static bool chdir_ = true;
 /* File descriptor used by daemonize_start() and daemonize_complete(). */
 static int daemonize_fd = -1;
 
+/* --monitor: Should a supervisory process monitor the daemon and restart it if
+ * it dies due to an error signal? */
+static bool monitor;
+
 /* Returns the file name that would be used for a pidfile if 'name' were
  * provided to set_pidfile().  The caller must free the returned string. */
 char *
 make_pidfile_name(const char *name) 
 {
-    return (!name ? xasprintf("%s/%s.pid", ovs_rundir, program_name)
-            : *name == '/' ? xstrdup(name)
-            : xasprintf("%s/%s", ovs_rundir, name));
+    return (!name
+            ? xasprintf("%s/%s.pid", ovs_rundir, program_name)
+            : abs_file_name(ovs_rundir, name));
 }
 
 /* Sets up a following call to daemonize() to create a pidfile named 'name'.
@@ -117,6 +123,14 @@ get_detach(void)
     return detach;
 }
 
+/* Sets up a following call to daemonize() to fork a supervisory process to
+ * monitor the daemon and restart it if it dies due to an error signal.  */
+void
+daemon_set_monitor(void)
+{
+    monitor = true;
+}
+
 /* If a pidfile has been configured and that pidfile already exists and is
  * locked by a running process, returns the pid of the running process.
  * Otherwise, returns 0. */
@@ -286,6 +300,78 @@ fork_notify_startup(int fd)
     }
 }
 
+static bool
+should_restart(int status)
+{
+    if (WIFSIGNALED(status)) {
+        static const int error_signals[] = {
+            SIGABRT, SIGALRM, SIGBUS, SIGFPE, SIGILL, SIGPIPE, SIGSEGV,
+            SIGXCPU, SIGXFSZ
+        };
+
+        size_t i;
+
+        for (i = 0; i < ARRAY_SIZE(error_signals); i++) {
+            if (error_signals[i] == WTERMSIG(status)) {
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+static void
+monitor_daemon(pid_t daemon_pid)
+{
+    /* XXX Should limit the rate at which we restart the daemon. */
+    /* XXX Should log daemon's stderr output at startup time. */
+    const char *saved_program_name;
+    char *status_msg;
+
+    saved_program_name = program_name;
+    program_name = xasprintf("monitor(%s)", program_name);
+    status_msg = xstrdup("healthy");
+    for (;;) {
+        int retval;
+        int status;
+
+        proctitle_set("%s: monitoring pid %lu (%s)",
+                      saved_program_name, (unsigned long int) daemon_pid,
+                      status_msg);
+
+        do {
+            retval = waitpid(daemon_pid, &status, 0);
+        } while (retval == -1 && errno == EINTR);
+
+        if (retval == -1) {
+            ovs_fatal(errno, "waitpid failed");
+        } else if (retval == daemon_pid) {
+            char *s = process_status_msg(status);
+            free(status_msg);
+            status_msg = xasprintf("pid %lu died, %s",
+                                   (unsigned long int) daemon_pid, s);
+            free(s);
+
+            if (should_restart(status)) {
+                VLOG_ERR("%s, restarting", status_msg);
+                daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
+                if (!daemon_pid) {
+                    break;
+                }
+            } else {
+                VLOG_INFO("%s, exiting", status_msg);
+                exit(0);
+            }
+        }
+    }
+    free(status_msg);
+
+    /* Running in new daemon process. */
+    proctitle_restore();
+    free((char *) program_name);
+    program_name = saved_program_name;
+}
+
 /* Close stdin, stdout, stderr.  If we're started from e.g. an SSH session,
  * then this keeps us from holding that session open artificially. */
 static void
@@ -314,6 +400,20 @@ daemonize_start(void)
             /* Running in parent process. */
             exit(0);
         }
+        /* Running in daemon or monitor process. */
+    }
+
+    if (monitor) {
+        int saved_daemonize_fd = daemonize_fd;
+        pid_t daemon_pid;
+
+        daemon_pid = fork_and_wait_for_startup(&daemonize_fd);
+        if (daemon_pid > 0) {
+            /* Running in monitor process. */
+            fork_notify_startup(saved_daemonize_fd);
+            close_standard_fds();
+            monitor_daemon(daemon_pid);
+        }
         /* Running in daemon process. */
     }