[lxc-devel] [PATCH 1/1] preserve_ns: ignore open failures due to ENOENT

[Serge Hallyn]

If some /proc/pid/ns/ns file we want is not supported by the kernel,
then just don't do the preserve_ns: don't fail the whole container
start.

Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>
---
 src/lxc/start.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/lxc/start.c b/src/lxc/start.c
index a294d18..6ed4814 100644
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -125,7 +125,7 @@ static void close_ns(int ns_fd[LXC_NS_MAX]) {
 }
 
 static int preserve_ns(int ns_fd[LXC_NS_MAX], int clone_flags, pid_t pid) {
-	int i, saved_errno;
+	int i;
 	char path[MAXPATHLEN];
 
 	for (i = 0; i < LXC_NS_MAX; i++)
@@ -143,18 +143,21 @@ static int preserve_ns(int ns_fd[LXC_NS_MAX], int clone_flags, pid_t pid) {
 		snprintf(path, MAXPATHLEN, "/proc/%d/ns/%s", pid,
 		         ns_info[i].proc_name);
 		ns_fd[i] = open(path, O_RDONLY | O_CLOEXEC);
-		if (ns_fd[i] < 0)
-			goto error;
+		if (ns_fd[i] < 0) {
+			int ret;
+			if (errno == ENOENT) {
+				SYSERROR("failed to open '%s'; continuing", path);
+				ret = 0;
+			} else {
+				SYSERROR("failed to open '%s'; aborting", path);
+				ret = -1;
+			}
+			close_ns(ns_fd);
+			return ret;
+		}
 	}
 
 	return 0;
-
-error:
-	saved_errno = errno;
-	close_ns(ns_fd);
-	errno = saved_errno;
-	SYSERROR("failed to open '%s'", path);
-	return -1;
 }
 
 static int attach_ns(const int ns_fd[LXC_NS_MAX]) {
-- 
2.5.0