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, 9 insertions, 0 deletions

diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index c88eb328..d6d7a6ee 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -4056,3 +4056,12 @@ test "a command pane an exec open was answered is leased to it while it stays op
     try testing.expectEqual(Status.ok, wr(p, exec, "echo c\n").reply.status);
     try testing.expectEqual(a_pane, p.paneBySerial(p.fs.results[0]).?);
 }
+
+test "a Save whose directory is missing because one above refuses says permission denied, not no such directory" {
+    const p = try withFile(testing.allocator, "x\n");
+    defer p.deinit();
+    p.saveFailed(0, "/proc/1/root/x/f.txt", error.FileNotFound);
+    try testing.expect(th.logHas(p, "Save /proc/1/root/x/f.txt: permission denied"));
+    p.saveFailed(0, "/tmp/pardes-surely-missing-dir/f.txt", error.FileNotFound);
+    try testing.expect(th.logHas(p, "no such directory"));
+}