A name under a directory that may not be searched or written is refused, permission denied, and a Save there says so, not no such directory

`pardes noperm/a/b/c` and `pardes /proc/1/root/x` took the missing
directory for one Save would make, opened a pane and exited 0; its Save
then said "no such directory". fs.deniedAbove finds the nearest
directory there and asks whether it may be searched and written:
forwarding refuses such a name, exit 1, "permission denied", and a
failed Save says "permission denied", which the writer's 9P error
carries as EPERM (9ns: EACCES).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 11 insertions, 0 deletions

diff --git a/test/fs.py b/test/fs.py
index 6c6bcbef..2ccd0690 100644
--- a/test/fs.py
+++ b/test/fs.py
@@ -1405,6 +1405,17 @@ def test(binary, quic=False):
             dashed, = serials() - before
             assert client.read(f'/pane/{dashed}/name').rstrip(b'\n') == str(dash).encode()
             client.remove(f'/pane/{dashed}')
+            # A name under a directory that may not be searched is refused,
+            # permission denied, exit 1, no pane: its Save could never be.
+            (root / 'noperm').mkdir()
+            (root / 'noperm').chmod(0)
+            before = serials()
+            try:
+                denied = subprocess.run([binary, 'noperm/a/b/c'], cwd=root, env=env, capture_output=True, timeout=10)
+            finally:
+                (root / 'noperm').chmod(0o755)
+            assert denied.returncode == 1 and b'permission denied' in denied.stderr, denied
+            assert serials() == before
             # --wait waits on the pane its look answered, on the look's own
             # open: a name /index shows escaped (a backslash is `\\` there)
             # is still the pane waited on, not one already gone.