log the container console when it is daemonized and the log is enabled

src/lxc/lxc_start.c

@@ -135,9 +135,30 @@ int main(int argc, char *argv[])
 			 my_args.progname, my_args.quiet))
 		return err;
 
-	if (my_args.daemonize && daemon(0 ,0)) {
-		SYSERROR("failed to daemonize '%s'", my_args.name);
-		return err;
+	if (my_args.daemonize) {
+
+                /* do not chdir as we want to open the log file,
+		 * change the directory right after.
+		 * do not close 0, 1, 2, we want to do that
+		 * ourself because we don't want /dev/null
+		 * being reopened.
+		 */
+		if (daemon(1 ,1)) {
+			SYSERROR("failed to daemonize '%s'", my_args.name);
+			return err;
+		}
+
+		close(0);
+		close(1);
+		close(2);
+
+		if (my_args.log_file) {
+			open(my_args.log_file, O_WRONLY | O_CLOEXEC);
+			open(my_args.log_file, O_RDONLY | O_CLOEXEC);
+			open(my_args.log_file, O_RDONLY | O_CLOEXEC);
+		}
+
+		chdir("/");
 	}
 
 	save_tty(&tios);

src/lxc/start.c

@@ -332,6 +332,41 @@ static void remove_init_pid(const char *name, pid_t pid)
 	unlink(init);
 }
 
+static int fdname(int fd, char *name, size_t size)
+{
+	char path[MAXPATHLEN];
+
+	snprintf(path, MAXPATHLEN, "/proc/self/fd/%d", fd);
+
+	return readlink(path, name, size) < 0 ? -1 : 0;
+}
+
+static int console_init(char *console, size_t size)
+{
+	struct stat stat;
+	int i;
+
+	for (i = 0; i < 3; i++) {
+		if (!isatty(i))
+			continue;
+
+		if (ttyname_r(i, console, size)) {
+			SYSERROR("failed to retrieve tty name");
+			return -1;
+		}
+		return 0;
+	}
+
+	if (!fstat(0, &stat)) {
+		if (S_ISREG(stat.st_mode) || S_ISCHR(stat.st_mode) ||
+		    S_ISFIFO(stat.st_mode) || S_ISLNK(stat.st_mode))
+			return fdname(0, console, size);
+	}
+
+	console[0] = '\0';
+	return 0;
+}
+
 int lxc_init(const char *name, struct lxc_handler *handler)
 {
 	int err = -1;
@@ -348,9 +383,10 @@ int lxc_init(const char *name, struct lxc_handler *handler)
 		goto out_put_lock;
 	}
 
-	/* If we are not attached to a tty, disable it */
-	if (ttyname_r(0, handler->tty, sizeof(handler->tty)))
-		handler->tty[0] = '\0';
+	if (console_init(handler->tty, sizeof(handler->tty))) {
+		ERROR("failed to initialize the console");
+		goto out_aborting;
+	}
 
 	if (lxc_create_tty(name, &handler->tty_info)) {
 		ERROR("failed to create the ttys");