init: Retain traditional restart behavior for critical and oneshot services.

Adds an SVC_RESTART state that's used for an explicit "restart" of a
running service.  This retains the traditional restart behavior for
critical and oneshot services (previously altered by 7e36edd8), whereby
these services are "simply restarted" instead of counting as a crash (for a
critical serivce) or going into the disabled state (for a oneshot service).

init/builtins.c

@@ -523,8 +523,7 @@ int do_restart(int nargs, char **args)
     struct service *svc;
     svc = service_find_by_name(args[1]);
     if (svc) {
-        service_stop(svc);
-        service_start(svc, NULL);
+        service_restart(svc);
     }
     return 0;
 }

init/init.c

@@ -169,7 +169,7 @@ void service_start(struct service *svc, const char *dynamic_args)
          * state and immediately takes it out of the restarting
          * state if it was in there
          */
-    svc->flags &= (~(SVC_DISABLED|SVC_RESTARTING|SVC_RESET));
+    svc->flags &= (~(SVC_DISABLED|SVC_RESTARTING|SVC_RESET|SVC_RESTART));
     svc->time_started = 0;
 
         /* running processes require no additional work -- if
@@ -366,14 +366,14 @@ void service_start(struct service *svc, const char *dynamic_args)
         notify_service_state(svc->name, "running");
 }
 
-/* The how field should be either SVC_DISABLED or SVC_RESET */
+/* The how field should be either SVC_DISABLED, SVC_RESET, or SVC_RESTART */
 static void service_stop_or_reset(struct service *svc, int how)
 {
     /* The service is still SVC_RUNNING until its process exits, but if it has
      * already exited it shoudn't attempt a restart yet. */
     svc->flags &= (~SVC_RESTARTING);
 
-    if ((how != SVC_DISABLED) && (how != SVC_RESET)) {
+    if ((how != SVC_DISABLED) && (how != SVC_RESET) && (how != SVC_RESTART)) {
         /* Hrm, an illegal flag.  Default to SVC_DISABLED */
         how = SVC_DISABLED;
     }
@@ -405,6 +405,17 @@ void service_stop(struct service *svc)
     service_stop_or_reset(svc, SVC_DISABLED);
 }
 
+void service_restart(struct service *svc)
+{
+    if (svc->flags & SVC_RUNNING) {
+        /* Stop, wait, then start the service. */
+        service_stop_or_reset(svc, SVC_RESTART);
+    } else if (!(svc->flags & SVC_RESTARTING)) {
+        /* Just start the service since it's not running. */
+        service_start(svc, NULL);
+    } /* else: Service is restarting anyways. */
+}
+
 void property_changed(const char *name, const char *value)
 {
     if (property_triggers_enabled)
@@ -471,6 +482,17 @@ static void msg_stop(const char *name)
     }
 }
 
+static void msg_restart(const char *name)
+{
+    struct service *svc = service_find_by_name(name);
+
+    if (svc) {
+        service_restart(svc);
+    } else {
+        ERROR("no such service '%s'\n", name);
+    }
+}
+
 void handle_control_message(const char *msg, const char *arg)
 {
     if (!strcmp(msg,"start")) {
@@ -478,8 +500,7 @@ void handle_control_message(const char *msg, const char *arg)
     } else if (!strcmp(msg,"stop")) {
         msg_stop(arg);
     } else if (!strcmp(msg,"restart")) {
-        msg_stop(arg);
-        msg_start(arg);
+        msg_restart(arg);
     } else {
         ERROR("unknown control msg '%s'\n", msg);
     }

init/init.h

@@ -72,6 +72,7 @@ struct svcenvinfo {
 #define SVC_RESET       0x40  /* Use when stopping a process, but not disabling
                                  so it can be restarted with its class */
 #define SVC_RC_DISABLED 0x80  /* Remember if the disabled flag was set in the rc script */
+#define SVC_RESTART     0x100 /* Use to safely restart (stop, wait, start) a service */
 
 #define NR_SVC_SUPP_GIDS 12    /* twelve supplementary groups */
 
@@ -129,6 +130,7 @@ void service_for_each_flags(unsigned matchflags,
                             void (*func)(struct service *svc));
 void service_stop(struct service *svc);
 void service_reset(struct service *svc);
+void service_restart(struct service *svc);
 void service_start(struct service *svc, const char *dynamic_args);
 void property_changed(const char *name, const char *value);
 

init/signal_handler.c

@@ -63,7 +63,7 @@ static int wait_for_one_process(int block)
 
     NOTICE("process '%s', pid %d exited\n", svc->name, pid);
 
-    if (!(svc->flags & SVC_ONESHOT)) {
+    if (!(svc->flags & SVC_ONESHOT) || (svc->flags & SVC_RESTART)) {
         kill(-pid, SIGKILL);
         NOTICE("process '%s' killing any children in process group\n", svc->name);
     }
@@ -78,8 +78,9 @@ static int wait_for_one_process(int block)
     svc->pid = 0;
     svc->flags &= (~SVC_RUNNING);
 
-        /* oneshot processes go into the disabled state on exit */
-    if (svc->flags & SVC_ONESHOT) {
+        /* oneshot processes go into the disabled state on exit,
+         * except when manually restarted. */
+    if ((svc->flags & SVC_ONESHOT) && !(svc->flags & SVC_RESTART)) {
         svc->flags |= SVC_DISABLED;
     }
 
@@ -90,7 +91,7 @@ static int wait_for_one_process(int block)
     }
 
     now = gettime();
-    if (svc->flags & SVC_CRITICAL) {
+    if ((svc->flags & SVC_CRITICAL) && !(svc->flags & SVC_RESTART)) {
         if (svc->time_crashed + CRITICAL_CRASH_WINDOW >= now) {
             if (++svc->nr_crashed > CRITICAL_CRASH_THRESHOLD) {
                 ERROR("critical process '%s' exited %d times in %d minutes; "
@@ -105,6 +106,7 @@ static int wait_for_one_process(int block)
         }
     }
 
+    svc->flags &= (~SVC_RESTART);
     svc->flags |= SVC_RESTARTING;
 
     /* Execute all onrestart commands for this service. */