1 files changed, 10 insertions, 0 deletions
diff --git a/src/ninep/tree.zig b/src/ninep/tree.zig
index 1990d09e..c78a1aa2 100644
--- a/src/ninep/tree.zig
+++ b/src/ninep/tree.zig
@@ -1270,6 +1270,16 @@ fn writeLines(p: *Pardes, req: Req, target: Target) Reply {
         data = data[nl + 1 ..];
         if (data.len == 0) return .{ .tag = req.tag, .written = @intCast(req.data.len) };
     }
+    // One name an open, on one line: anything after its newline, in this
+    // write or a later one, is refused by the write that brings it, never
+    // left to rename the pane again at the close (`printf 'a\nb' > name`).
+    if (target == .pane and target.pane.file == .name) {
+        const past_newline = if (std.mem.indexOfScalar(u8, data, '\n')) |nl| nl + 1 < data.len else false;
+        if (o.named or past_newline) {
+            o.pending.clearRetainingCapacity();
+            return failText(req.tag, E.INVAL, "invalid file name: one name a write, on one line");
+        }
+    }
     o.pending.appendSlice(p.gpa, data) catch return Reply.fail(req.tag, E.NOMEM);
     // A line runs when its newline comes, or, the last one, when its open
     // is let go (release). Nothing is inferred from a write's size: a mount