From 5f4719da21f06b58694d52d354f5fda431ff8543 Mon Sep 17 00:00:00 2001 From: Gabriel Schneider Date: Thu, 27 Aug 2026 15:32:02 -0300 Subject: acmefs: a pane's terminal gets pty/data, pty/ctl and pty/status Step 3 of the 9P chain (docs/9p.typ 12.3, docs/registry.typ 9P-8). Nothing here is about 9P: it lands in the FUSE-served tree and any later transport inherits it. A script could write into a terminal that already existed and read its rendered scrollback. It could not START one, RESIZE one or SIGNAL one. Two of those were already effects the core emits, so `exec` and `winsize` are existing capabilities acquiring a name; only `sig` is new, and it brings the one new host method, `push_pty_signal`. pty/ctl winsize | sig INT|TERM|HUP|QUIT|KILL | exec one verb per line, validate-all then apply-all, EINVAL applies nothing -- `writeCtl`'s shape and `writeCtl`'s reason pty/status cols, rows, tty-taken as three %11d fields pty/data write is input to the process; read is the RAW output stream, gated on a reader count so a pane nobody reads costs one branch A pane that is not a terminal has no pty/ at all: the lookup is ENOENT and readdir does not list it. `PaneFile` is an enum(u4) and this takes it from 11 values to 15. ONE REMAINS. That is also why pty/ is a DIRECTORY and not three more flat names -- a subdirectory costs one value and buys its own namespace, so `ctl` and `data` did not have to be renamed. Two things the core does not know, and which are therefore not invented: a child's EXIT STATUS (a shell's death is `Event.eof`, which removes the pane, so there is no directory left to read it in) and RAW/COOKED (the core never sets a termios; the mode belongs to the program on the far side). Verified live against a daemon: pty/ appears only on the terminal pane; a `winsize 0 24` and a `sig SIGINT` are refused; a bad verb beside a good one applies neither; `echo pty-works` written to pty/data runs in the shell and its output reaches the body; and a blocking read of pty/data returns the raw stream, OSC 133 marks and all. fs-bench unchanged and still zero allocations. --- src/tty/tty.zig | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'src/tty/tty.zig') diff --git a/src/tty/tty.zig b/src/tty/tty.zig index 5eb9a277..c85908d6 100644 --- a/src/tty/tty.zig +++ b/src/tty/tty.zig @@ -1034,6 +1034,7 @@ const Shell = struct { .push_spawn = spawn, .push_pty_write = ptyWrite, .push_pty_resize = ptyResize, + .push_pty_signal = ptySignal, .pull_tty_taken = ttyTaken, .push_write_file = writeFile, .push_write_dump = writeDump, @@ -1393,6 +1394,13 @@ const Shell = struct { } } + /// `pty/ctl`'s `sig`. A pane with no pty of ours has nothing to signal, + /// which is the same silence `ptyWrite` above gives it. + fn ptySignal(ctx: ?*anyopaque, pane: u8, sig: pardes.PtySignal) void { + const s = of(ctx); + if (s.ptys[pane]) |pt| look.signalTty(pt.pid, pt.file.handle, sig); + } + /// Is a pane's tty still the prompt we forked? Lazy by construction — it /// runs only where the core is about to type a command line, so the /proc /// walk costs nothing on an ordinary frame. A pane with no pty of ours (a -- cgit v1.3