[PATCH v2] teamd: Don't ever kill PID 0

[Lubomir Rintel]

It's a suicide. daemon_pid_file_is_running() may return 0 in case a PID file
exists but is empty. It's safe to assume the daemon is not running -- it either
lost race while dying between opening and writing a PID file, or the system
crashed.

Signed-off-by: Lubomir Rintel <lkundrak(a)v3.sk&gt;
---
Changes since v1:
    - Remove the pid file upon startup if we're not running.
      Otherwise we'd fail to override it.

 teamd/teamd.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/teamd/teamd.c b/teamd/teamd.c
index ed5ff1a..4885b14 100644
--- a/teamd/teamd.c
+++ b/teamd/teamd.c
@@ -1458,7 +1458,9 @@ static int teamd_start(struct teamd_context *ctx, enum
teamd_exit_code *p_ret)
 	}
 
 	pid = daemon_pid_file_is_running();
-	if (pid >= 0) {
+	if (pid == 0)
+		daemon_pid_file_remove();
+	if (pid > 0) {
 		teamd_log_err("Daemon already running on PID %u.", pid);
 		return -EEXIST;
 	}
@@ -1729,14 +1731,18 @@ int main(int argc, char **argv)
 	case DAEMON_CMD_VERSION:
 		break;
 	case DAEMON_CMD_KILL:
-		err = daemon_pid_file_kill_wait(SIGTERM, 5);
-		if (err)
-			teamd_log_warn("Failed to kill daemon: %s", strerror(errno));
-		else
-			ret = TEAMD_EXIT_SUCCESS;
+		if (daemon_pid_file_is_running() > 0) {
+			err = daemon_pid_file_kill_wait(SIGTERM, 5);
+			if (err)
+				teamd_log_warn("Failed to kill daemon: %s", strerror(errno));
+			else
+				ret = TEAMD_EXIT_SUCCESS;
+		} else {
+			teamd_log_warn("Daemon not running");
+		}
 		break;
 	case DAEMON_CMD_CHECK:
-		ret = (daemon_pid_file_is_running() >= 0) ? TEAMD_EXIT_SUCCESS :
+		ret = (daemon_pid_file_is_running() > 0) ? TEAMD_EXIT_SUCCESS :
 							    TEAMD_EXIT_FAILURE;
 		break;
 	case DAEMON_CMD_RUN:
-- 
1.9.3