lsns: tolerate lsns_ioctl(fd, NS_GET_{PARENT,USERNS}) failing with ENOSYS

With the original code, "lsns/filedesc" test case failed on
"build (qemu-user, s390x)" and "build (qemu-user, riscv64)".

On the platforms, lsns_ioctl(fd, NS_GET_{PARENT,USERNS}) failed
with ENOSYS. The error stoped the iteration for gathering
information from /proc/[0-9]+. As a result, lsns printed
nothing. We don't expect this behavior.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
(cherry picked from commit f2a8b20d9c63f771d1fddd639ea1ec3fe034dc6d)

diff --git a/sys-utils/lsns.c b/sys-utils/lsns.c
index 1f3574f99c9a737c1fcebc051064a8e157d80f56..4ea01d2376c41477b7d2da5b16af0569af2de4b4 100644 (file)
--- a/sys-utils/lsns.c
+++ b/sys-utils/lsns.c
@@ -308,7 +308,11 @@ static int get_ns_ino(int dir, const char *nsname, ino_t *ino, ino_t *pino, ino_
                return -errno;
        if (strcmp(nsname, "pid") == 0 || strcmp(nsname, "user") == 0) {
                if ((pfd = lsns_ioctl(fd, NS_GET_PARENT)) < 0) {
-                       if (errno == EPERM)
+                       if (errno == EPERM
+                           /* On the test platforms, "build (qemu-user, s390x)" and
+                            * "build (qemu-user, riscv64)", the ioctl reported ENOSYS.
+                            */
+                           || errno == ENOSYS)
                                goto user;
                        close(fd);
                        return -errno;
@@ -323,7 +327,11 @@ static int get_ns_ino(int dir, const char *nsname, ino_t *ino, ino_t *pino, ino_
        }
  user:
        if ((ofd = lsns_ioctl(fd, NS_GET_USERNS)) < 0) {
-               if (errno == EPERM)
+               if (errno == EPERM
+                   /* On the test platforms, "build (qemu-user, s390x)" and
+                    * "build (qemu-user, riscv64)", the ioctl reported ENOSYS.
+                    */
+                   || errno == ENOSYS)
                        goto out;
                close(fd);
                return -errno;