tmpfiles: with "e" don't attempt to set permissions when file doesn't exist (#6682)

tmpfiles.d option "e" when run through systemd-tmpfiles --create should
apply configured permissions (uid,gid) only to already existing
files. When file doesn't exist we bail out with error. Instead we should
silently ignore non-existing files.

$ useradd test
$ cat /etc/tmpfiles.d/foobar.conf
e /tmp/test - test test 1d
$ ls -l /tmp/test
ls: cannot access '/tmp/test': No such file or directory

Before:
$ systemd-tmpfiles --create /etc/tmpfiles.d/foobar.conf
Adjusting owner and mode for /tmp/test failed: No such file or directory
$ echo $?
1

After:
$ systemd-tmpfiles --create /etc/tmpfiles.d/foobar.conf
$ echo $?
0
diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c
index 2ab0cd1..8f960cc0 100644
--- a/src/tmpfiles/tmpfiles.c
+++ b/src/tmpfiles/tmpfiles.c
@@ -617,8 +617,20 @@
          * O_PATH. */
 
         fd = open(path, O_NOFOLLOW|O_CLOEXEC|O_PATH);
-        if (fd < 0)
-                return log_error_errno(errno, "Adjusting owner and mode for %s failed: %m", path);
+        if (fd < 0) {
+                int level = LOG_ERR, r = -errno;
+
+                /* Option "e" operates only on existing objects. Do not
+                 * print errors about non-existent files or directories */
+                if (i->type == EMPTY_DIRECTORY && errno == ENOENT) {
+                        level = LOG_DEBUG;
+                        r = 0;
+                }
+
+                log_full_errno(level, errno, "Adjusting owner and mode for %s failed: %m", path);
+
+                return r;
+        }
 
         if (fstatat(fd, "", &st, AT_EMPTY_PATH) < 0)
                 return log_error_errno(errno, "Failed to fstat() file %s: %m", path);