core/namespace: rework the return semantics of clone_device_node yet again

Returning 0 on not-found/wrong-type is confusing. Let's return -ENXIO in that
case instead, and explicitly ignore it in the call site where we want to do that.
I think this is clearer and less likely to be used errenously in case another
call site is added.

C.f. 152c475f95c7b9b20d293 and 98b1d2b8d9ea27087a598.

diff --git a/src/core/namespace.c b/src/core/namespace.c
index 9195037..9ed6339 100644 (file)
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -585,7 +585,7 @@ static int clone_device_node(const char *d, const char *temporary_mount, bool *m
 
         if (stat(d, &st) < 0) {
                 if (errno == ENOENT)
-                        return 0;
+                        return -ENXIO;
                 return -errno;
         }
 
@@ -594,7 +594,7 @@ static int clone_device_node(const char *d, const char *temporary_mount, bool *m
                 return -EINVAL;
 
         if (st.st_rdev == 0)
-                return 0;
+                return -ENXIO;
 
         dn = strjoina(temporary_mount, d);
 
@@ -604,7 +604,7 @@ static int clone_device_node(const char *d, const char *temporary_mount, bool *m
                 mac_selinux_create_file_clear();
 
                 if (r == 0)
-                        return 1;
+                        return 0;
                 if (errno != EPERM)
                         return log_debug_errno(errno, "mknod failed for %s: %m", d);
 
@@ -628,7 +628,7 @@ static int clone_device_node(const char *d, const char *temporary_mount, bool *m
         if (mount(d, dn, NULL, MS_BIND, NULL) < 0)
                 return log_debug_errno(errno, "mount failed for %s: %m", d);
 
-        return 1;
+        return 0;
 }
 
 static int mount_private_dev(MountEntry *m) {
@@ -686,10 +686,6 @@ static int mount_private_dev(MountEntry *m) {
                 r = clone_device_node("/dev/ptmx", temporary_mount, &can_mknod);
                 if (r < 0)
                         goto fail;
-                if (r == 0) {
-                        r = -ENXIO;
-                        goto fail;
-                }
         }
 
         devshm = strjoina(temporary_mount, "/dev/shm");
@@ -713,7 +709,8 @@ static int mount_private_dev(MountEntry *m) {
 
         NULSTR_FOREACH(d, devnodes) {
                 r = clone_device_node(d, temporary_mount, &can_mknod);
-                if (r < 0)
+                /* ENXIO means the the *source* is not a device file, skip creation in that case */
+                if (r < 0 && r != -ENXIO)
                         goto fail;
         }