daemon: fix the wrong pid in daemon model

src/lxc/lxc_start.c

@@ -211,7 +211,6 @@ int main(int argc, char *argv[])
 		"/sbin/init",
 		'\0',
 	};
-	FILE *pid_fp = NULL;
 	struct lxc_container *c;
 
 	lxc_list_init(&defines);
@@ -306,13 +305,6 @@ int main(int argc, char *argv[])
 			ERROR("failed to ensure pidfile '%s'", my_args.pidfile);
 			goto out;
 		}
-
-		pid_fp = fopen(my_args.pidfile, "w");
-		if (pid_fp == NULL) {
-			SYSERROR("failed to create pidfile '%s' for '%s'",
-				 my_args.pidfile, my_args.name);
-			goto out;
-		}
 	}
 
 	int i;
@@ -334,23 +326,12 @@ int main(int argc, char *argv[])
 		c->want_daemonize(c, false);
 	}
 
-	if (pid_fp != NULL) {
-		if (fprintf(pid_fp, "%d\n", getpid()) < 0) {
-			SYSERROR("failed to write '%s'", my_args.pidfile);
-			goto out;
-		}
-		fclose(pid_fp);
-		pid_fp = NULL;
-	}
-
 	if (my_args.close_all_fds)
 		c->want_close_all_fds(c, true);
 
 	err = c->start(c, 0, args) ? 0 : -1;
 out:
 	lxc_container_put(c);
-	if (pid_fp)
-		fclose(pid_fp);
 	return err;
 }
 

src/lxc/lxccontainer.c

@@ -545,6 +545,7 @@ static bool lxcapi_start(struct lxc_container *c, int useinit, char * const argv
 	int ret;
 	struct lxc_conf *conf;
 	bool daemonize = false;
+	FILE *pid_fp = NULL;
 	char *default_args[] = {
 		"/sbin/init",
 		'\0',
@@ -600,8 +601,14 @@ static bool lxcapi_start(struct lxc_container *c, int useinit, char * const argv
 		pid_t pid = fork();
 		if (pid < 0)
 			return false;
-		if (pid != 0)
+
+		if (pid != 0) {
+			/* Set to NULL because we don't want father unlink
+			 * the PID file, child will do the free and unlink.
+			 */
+			c->pidfile = NULL;
 			return wait_on_daemonized_start(c, pid);
+		}
 
 		/* second fork to be reparented by init */
 		pid = fork();
@@ -630,6 +637,28 @@ static bool lxcapi_start(struct lxc_container *c, int useinit, char * const argv
 		}
 	}
 
+	/* We need to write PID file after daeminize, so we always
+	 * write the right PID.
+	 */
+	if (c->pidfile) {
+		pid_fp = fopen(c->pidfile, "w");
+		if (pid_fp == NULL) {
+			SYSERROR("Failed to create pidfile '%s' for '%s'",
+				 c->pidfile, c->name);
+			return false;
+		}
+
+		if (fprintf(pid_fp, "%d\n", getpid()) < 0) {
+			SYSERROR("Failed to write '%s'", c->pidfile);
+			fclose(pid_fp);
+			pid_fp = NULL;
+			return false;
+		}
+
+		fclose(pid_fp);
+		pid_fp = NULL;
+	}
+
 reboot:
 	conf->reboot = 0;
 	ret = lxc_start(c->name, argv, conf, c->config_path);