monitor: add more logging

Execing lxc-monitord is quite a crucial step so let's be very obsessive about logging possible errors to guide us in debugging. Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

monitor: add more logging
8a76c270 · Christian Brauner · Stéphane Graber · 047fbbf5 · 8a76c270
Commit 8a76c270 authored Nov 26, 2016 by Christian Brauner Committed by Stéphane Graber Nov 30, 2016
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Showing with 7 additions and 2 deletions

monitor.c src/lxc/monitor.c +7 -2

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--- a/src/lxc/monitor.c
+++ b/src/lxc/monitor.c
@@ -349,18 +349,23 @@ int lxc_monitord_spawn(const char *lxcpath)
 	}

 	lxc_check_inherited(NULL, true, pipefd[1]);
-	if (null_stdfds() < 0)
+	if (null_stdfds() < 0) {
+		SYSERROR("Failed to dup2() standard file descriptors to /dev/null.");
 		exit(EXIT_FAILURE);
+	}

 	close(pipefd[0]);

 	ret = snprintf(pipefd_str, __INT_LEN, "%d", pipefd[1]);
-	if (ret < 0 || ret >= __INT_LEN)
+	if (ret < 0 || ret >= __INT_LEN) {
+		ERROR("Failed to create pid argument to pass to monitord.");
 		exit(EXIT_FAILURE);
+	}

 	DEBUG("Using pipe file descriptor %d for monitord.", pipefd[1]);

 	execvp(args[0], args);
+	ERROR("Failed to exec lxc-monitord.");

 	exit(EXIT_FAILURE);
 }