An exec line over 1024 bytes fails the write, naming the limit

A command line longer than the 1024 bytes a command pane takes was said on
the message row after the write had already succeeded. An exec write (the
root's, a pane's, tagexec, a column's) now refuses it before anything runs,
EINVAL with "a command line is at most 1024 bytes" and an err record; a
builtin's line, a long Msg or an Edit block, is not limited.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/src/ninep/cols.zig b/src/ninep/cols.zig
index 8a3474b3..ad7d30f8 100644
--- a/src/ninep/cols.zig
+++ b/src/ninep/cols.zig
@@ -158,6 +158,7 @@ pub fn writeExec(p: *Pardes, req: Req, serial: ?u32) Reply {
         const line = std.mem.trim(u8, raw, " \t\r");
         if (line.len == 0) continue;
         for (line) |c| if (c < ' ' and c != '\t') return Reply.fail(req.tag, E.INVAL);
+        if (pardes.ctlfs.ctl.tooLong(req, line)) |refusal| return refusal;
         const col = if (serial) |s| layout.columnBySerial(p, s) orelse return Reply.fail(req.tag, E.NOENT) else null;
         if (p.panes[p.active] == null) return Reply.fail(req.tag, E.NOENT);
         p.exec_column = col;