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, 4 insertions, 2 deletions

diff --git a/src/ninep/pane.zig b/src/ninep/pane.zig
index b9fa2857..3963c605 100644
--- a/src/ninep/pane.zig
+++ b/src/ninep/pane.zig
@@ -1535,13 +1535,15 @@ test "a name with a component over 255 bytes is refused, and a long path's faile
     try testing.expectEqual(Status.ok, wr(p, Node.of(serial, .name), "/tmp/" ++ "c" ** 255 ++ "\n").reply.status);
     // A Save of a 3000-byte path the host refuses: the waiting write's
     // reason is at the end, the path giving up its middle.
-    const long = "/nonexistent-pardes-root/" ++ ("d" ** 200 ++ "/") ** 15 ++ "f.txt";
+    // (Under /tmp: under / a user's Save is refused permission, not
+    // missing.)
+    const long = "/tmp/nonexistent-pardes-root/" ++ ("d" ** 200 ++ "/") ** 15 ++ "f.txt";
     const id = p.paneBySerial(serial).?;
     try nameBuffer(p, id, long, false);
     p.fs.late_failure_len = 0;
     p.saveFailed(@intCast(id), long, error.AccessDenied);
     const late = p.fs.late_failure[0..p.fs.late_failure_len];
-    try testing.expect(std.mem.startsWith(u8, late, "Save /nonexistent-pardes-root/"));
+    try testing.expect(std.mem.startsWith(u8, late, "Save /tmp/nonexistent-pardes-root/"));
     try testing.expect(std.mem.endsWith(u8, late, "/f.txt: no such directory"));
 }