Add -reincarnate flag to FS

When FS is given the -reincarnate flag, FS will be automatically
restarted after any uncontrolled exit.

src/switch.c

@@ -357,6 +357,32 @@ static void daemonize(int *fds)
 	return;
 }
 
+static void reincarnate_protect(char **argv) {
+	int i;
+ refork:
+	if ((i=fork())) { /* parent */
+		int s; pid_t r;
+	rewait:
+		r = waitpid(i, &s, 0);
+		if (r == (pid_t)-1) {
+			if (errno == EINTR) goto rewait;
+			exit(EXIT_FAILURE);
+		}
+		if (r != i) goto rewait;
+		if (WIFEXITED(s)
+			&& (WEXITSTATUS(s) == EXIT_SUCCESS
+				|| WEXITSTATUS(s) == EXIT_FAILURE)) {
+			exit(WEXITSTATUS(s));
+		}
+		if (WIFEXITED(s) || WIFSIGNALED(s)) {
+			if (argv) {
+				execv(argv[0], argv); return;
+			} else goto refork;
+		}
+		goto rewait;
+	}
+}
+
 #endif
 
 static const char usage[] =
@@ -369,6 +395,8 @@ static const char usage[] =
 	"\t-monotonic-clock       -- use monotonic clock as timer source\n"
 #else
 	"\t-nf                    -- no forking\n"
+	"\t-reincarnate           -- restart the switch on an uncontrolled exit\n"
+	"\t-reincarnate-reexec    -- run execv on a restart (helpful for upgrades)\n"
 	"\t-u [user]              -- specify user to switch to\n"
 	"\t-g [group]             -- specify group to switch to\n"
 #endif
@@ -437,6 +465,7 @@ int main(int argc, char *argv[])
 	switch_bool_t do_wait = SWITCH_FALSE;
 	char *runas_user = NULL;
 	char *runas_group = NULL;
+	switch_bool_t reincarnate = SWITCH_FALSE, reincarnate_reexec = SWITCH_FALSE;
 	int fds[2] = { 0, 0 };
 #else
 	switch_bool_t win32_service = SWITCH_FALSE;
@@ -612,6 +641,14 @@ int main(int argc, char *argv[])
 			nf = SWITCH_TRUE;
 		}
 
+		else if (!strcmp(local_argv[x], "-reincarnate")) {
+			reincarnate = SWITCH_TRUE;
+		}
+		else if (!strcmp(local_argv[x], "-reincarnate-reexec")) {
+			reincarnate = SWITCH_TRUE;
+			reincarnate_reexec = SWITCH_TRUE;
+		}
+
 		else if (!strcmp(local_argv[x], "-version")) {
 			fprintf(stdout, "FreeSWITCH version: %s (%s)\n", SWITCH_VERSION_FULL, SWITCH_VERSION_REVISION_HUMAN);
 			exit(EXIT_SUCCESS);
@@ -994,6 +1031,10 @@ int main(int argc, char *argv[])
 		}
 #endif
 	}
+#ifndef WIN32
+	if (reincarnate)
+		reincarnate_protect(reincarnate_reexec ? argv : NULL);
+#endif
 
 	switch (priority) {
 	case 2: