A second line written to name is refused EINVAL, in one write or on the same open

bash writes printf 'a\nb\n' a line at a time, so each line arrived as a whole name on the held open and renamed the pane twice. An open that has named its pane now refuses a further line, as a two-line write already was.

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

1 files changed, 10 insertions, 0 deletions

diff --git a/src/ninep/tree.zig b/src/ninep/tree.zig
index 60778b9c..8c0e74a6 100644
--- a/src/ninep/tree.zig
+++ b/src/ninep/tree.zig
@@ -162,6 +162,9 @@ pub const Open = struct {
     /// answered from it again: bash's `read` takes a chunk, keeps a line and
     /// lseeks back to just past it, and a stream has already moved on.
     replay: ?Replay = null,
+    /// A `name` open has named its pane: one name an open, so a second line
+    /// on it (bash writes `printf 'a\nb\n'` a line at a time) is refused.
+    named: bool = false,
 
     pub const Replay = struct { off: u64, bytes: []u8 };
 
@@ -1071,6 +1074,13 @@ fn write(p: *Pardes, req: Req, target: Target) Reply {
         o.pending.clearRetainingCapacity();
         return failText(req.tag, E.INVAL, "a line or Edit block over 1 MiB");
     }
+    if (target == .pane and target.pane.file == .name) {
+        if (o.named or std.mem.count(u8, o.pending.items[0..end], "\n") > 1) {
+            o.pending.clearRetainingCapacity();
+            return failText(req.tag, E.INVAL, "invalid file name: one name a write, on one line");
+        }
+        o.named = true;
+    }
     const whole = p.scratch.allocator().dupe(u8, o.pending.items[0..end]) catch return Reply.fail(req.tag, E.NOMEM);
     const rest = o.pending.items.len - end;
     std.mem.copyForwards(u8, o.pending.items[0..rest], o.pending.items[end..]);