remember the exit code from the init process

error_num seems to be trying to remember the exit code of the init process,
except that nothing actually keeps track of it anywhere. So, let's add a
field to the handler, so that we can keep track of the process' exit
status, and the propagate it to error_num in struct lxc_container so that
people can use it.

Note that this is a slight behavior change, essentially instead of making
error_num always == the return code from start, now it contains slightly
more useful information (the actual exit status). But, there is only one
internal user of error_num which I'll fix in later in the series, so IMO
this is ok.

Signed-off-by: Tycho Andersen <tycho@tycho.ws>

src/lxc/lxccontainer.c

@@ -994,7 +994,7 @@ static bool do_lxcapi_start(struct lxc_container *c, int useinit, char * const a
 		ret = lxc_execute(c->name, argv, 1, handler, c->config_path, daemonize);
 	else
 		ret = lxc_start(c->name, argv, handler, c->config_path, daemonize);
-	c->error_num = ret;
+	c->error_num = handler->exit_status;
 
 	if (conf->reboot == 1) {
 		INFO("Container requested reboot");

src/lxc/start.c

@@ -314,6 +314,27 @@ static int signal_handler(int fd, uint32_t events, void *data,
 	if (ret == 0 && info.si_pid == hdlr->pid)
 		hdlr->init_died = true;
 
+	/* Try to figure out a reasonable exit status to report. */
+	if (hdlr->init_died) {
+		switch (info.si_code) {
+		case CLD_EXITED:
+			hdlr->exit_status = info.si_status << 8;
+			break;
+		case CLD_KILLED:
+		case CLD_DUMPED:
+		case CLD_STOPPED:
+			hdlr->exit_status = info.si_status << 8 | 0x7f;
+			break;
+		case CLD_CONTINUED:
+			/* Huh? The waitid() told us it's dead *and* continued? */
+			WARN("Init %d dead and continued?", hdlr->pid);
+			hdlr->exit_status = 1;
+			break;
+		default:
+			ERROR("Unknown si_code: %d", hdlr->init_died);
+		}
+	}
+
 	/* More robustness, protect ourself from a SIGCHLD sent
 	 * by a process different from the container init.
 	 */

src/lxc/start.h

@@ -109,6 +109,11 @@ struct lxc_handler {
 
 	/* Current state of the container. */
 	lxc_state_t state;
+
+	/* The exit status of the container; not defined unless ->init_died ==
+	 * true.
+	 */
+	int exit_status;
 };
 
 struct lxc_operations {