monitor: log which pipe fd is currently used

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/monitor.c b/src/lxc/monitor.c
index fab6f55681a680b3ae207177de7784b27e054abb..1afaa5ae2364daa251343d1220a4fdb2c3936045 100644 (file)
--- a/src/lxc/monitor.c
+++ b/src/lxc/monitor.c
@@ -284,11 +284,13 @@ int lxc_monitor_read(int fd, struct lxc_msg *msg)
 /* Used to spawn a monitord either on startup of a daemon container, or when
  * lxc-monitor starts.
  */
+#define __INT_LEN 21
 int lxc_monitord_spawn(const char *lxcpath)
 {
-       pid_t pid1, pid2;
+       int ret;
        int pipefd[2];
-       char pipefd_str[11];
+       char pipefd_str[__INT_LEN];
+       pid_t pid1, pid2;
 
        char *const args[] = {
            LXC_MONITORD_PATH,
@@ -308,6 +310,7 @@ int lxc_monitord_spawn(const char *lxcpath)
                DEBUG("Going to wait for pid %d.", pid1);
                if (waitpid(pid1, NULL, 0) != pid1)
                        return -1;
+               DEBUG("Finished waiting on pid %d.", pid1);
                return 0;
        }
 
@@ -351,7 +354,11 @@ int lxc_monitord_spawn(const char *lxcpath)
 
        close(pipefd[0]);
 
-       sprintf(pipefd_str, "%d", pipefd[1]);
+       ret = snprintf(pipefd_str, __INT_LEN, "%d", pipefd[1]);
+       if (ret < 0 || ret >= __INT_LEN)
+               exit(EXIT_FAILURE);
+
+       DEBUG("Using pipe file descriptor %d for monitord.", pipefd[1]);
 
        execvp(args[0], args);