A command line runs when its newline comes, or at its open's close, never because a write was short: a long line cut by a mount is one line

A write shorter than its message, and not a multiple of 4096, was taken
as whole, its tail a line. 9ns cuts a FUSE write of up to 512 KiB into
65512-byte Twrites, the last one short, so a 600 KiB `Edit ,c/.../`
arrived cut and its tail ran as an unknown control message; the 1 MiB
refusal failed the same way. Each open now holds a partial line until
its newline, or its release, which ends the last line; an Edit block is
whole when it closes, as before. A name write with a NUL still fails
its write at once. selfmount writes a 600 KiB Edit line and a 1.1 MiB
line through a real 9ns mount; building.typ says how lines are cut.

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

1 files changed, 3 insertions, 3 deletions

diff --git a/src/ninep/pane.zig b/src/ninep/pane.zig
index 48c2888e..e2ec31d1 100644
--- a/src/ninep/pane.zig
+++ b/src/ninep/pane.zig
@@ -914,7 +914,7 @@ fn writeFlag(p: *Pardes, req: Req, pane: *Pane, file: PaneFile) Reply {
 /// (editors/acme/xfid.c:650-652). A blank inside a name is taken here, as
 /// pardes names files with spaces; one at either end is refused, not
 /// quietly cut off, so the name a script wrote is the name it gets.
-const e_name_char = "bad character in file name";
+pub const e_name_char = "bad character in file name";
 
 /// Why `name` is not one file name, with the reason, or null: a newline, a
 /// control byte, DEL or a C1 control (U+0080-U+009F), a blank at either
@@ -1566,10 +1566,10 @@ test "a name cut across writes is one name, applied once at its newline or its c
     _ = call(p, .{ .tag = 2, .op = .write, .node = node, .handle = h, .data = "me.txt\n" });
     try testing.expectEqualStrings("/tmp/pardes-name.txt", nameOf(p, p.panes[p.paneBySerial(serial).?].?));
     _ = call(p, .{ .tag = 3, .op = .release, .node = node, .handle = h, .opened = true });
-    // No newline, the whole write: applied at once, on its own open.
+    // No newline: held, whatever the write's size, and applied at the close.
     const h3 = call(p, .{ .tag = 1, .op = .open, .node = node, .omode = 1 }).reply.handle;
     _ = call(p, .{ .tag = 2, .op = .write, .node = node, .handle = h3, .data = "/tmp/pardes-closed.txt" });
-    try testing.expectEqualStrings("/tmp/pardes-closed.txt", nameOf(p, p.panes[p.paneBySerial(serial).?].?));
+    try testing.expectEqualStrings("/tmp/pardes-name.txt", nameOf(p, p.panes[p.paneBySerial(serial).?].?));
     _ = call(p, .{ .tag = 3, .op = .release, .node = node, .handle = h3, .opened = true });
     try testing.expectEqualStrings("/tmp/pardes-closed.txt", nameOf(p, p.panes[p.paneBySerial(serial).?].?));
 }