Commit d48b642

Eric Bower  ·  2026-04-03 11:26:35 -0400 EDT
parent 77d03a5 
feat: new client leader policy

The last client to send user input bytes (non-ansi escape codes) becomes the leader. The client
leader controls resizing and any other terminal state changes. Non-leader clients are read-only
until they send user input bytes and takeover leadership.

Closes: https://github.com/neurosnap/zmx/issues/73
2 files changed,  +81, -7
M CHANGELOG.md
M src/main.zig
M CHANGELOG.md
+6, -0
......@@ -4,6 +4,12 @@ Use spec: https://common-changelog.org/
44
55 ## Staged
66
7+### Added
8+
9+- New client leader policy: last client to send user input bytes (non-ansi escape codes) becomes the leader
10+ - The client leader controls resizing and any other terminal state changes
11+ - Non-leader clients are read-only until they send user input bytes and takeover leadership
12+
713 ### Changed
814
915 - `zmx kill` now supports multiple args and it will kill sessions that match a prefix
M src/main.zig
+75, -7
......@@ -122,6 +122,7 @@ pub fn main() !void {
122122 .command = command,
123123 .cwd = cwd,
124124 .created_at = @intCast(std.time.timestamp()),
125+ .leader_client_fd = null,
125126 };
126127 daemon.socket_path = socket.getSocketPath(alloc, cfg.socket_dir, sesh) catch |err| switch (err) {
127128 error.NameTooLong => return socket.printSessionNameTooLong(sesh, cfg.socket_dir),
......@@ -157,6 +158,7 @@ pub fn main() !void {
157158 .created_at = @intCast(std.time.timestamp()),
158159 .is_task_mode = true,
159160 .task_command = cmd_args_raw.items,
161+ .leader_client_fd = undefined,
160162 };
161163 daemon.socket_path = socket.getSocketPath(alloc, cfg.socket_dir, sesh) catch |err| switch (err) {
162164 error.NameTooLong => return socket.printSessionNameTooLong(sesh, cfg.socket_dir),
......@@ -334,6 +336,7 @@ const Daemon = struct {
334336 cfg: *Cfg,
335337 alloc: std.mem.Allocator,
336338 clients: std.ArrayList(*Client),
339+ leader_client_fd: ?i32,
337340 session_name: []const u8,
338341 socket_path: []const u8,
339342 running: bool,
......@@ -356,7 +359,7 @@ const Daemon = struct {
356359 }
357360
358361 pub fn shutdown(self: *Daemon) void {
359- std.log.info("shutting down daemon session_name={s}", .{self.session_name});
362+ std.log.info("shutting down daemon session={s}", .{self.session_name});
360363 self.running = false;
361364
362365 for (self.clients.items) |client| {
......@@ -538,7 +541,7 @@ const Daemon = struct {
538541 posix.close(pty_fd);
539542 _ = posix.waitpid(self.pid, 0);
540543 posix.close(server_sock_fd);
541- std.log.info("deleting socket file session_name={s}", .{self.session_name});
544+ std.log.info("deleting socket file session={s}", .{self.session_name});
542545 dir.deleteFile(self.session_name) catch |err| {
543546 std.log.warn("failed to delete socket file err={s}", .{@errorName(err)});
544547 };
......@@ -571,6 +574,7 @@ const Daemon = struct {
571574 );
572575 return;
573576 }
577+ std.log.debug("buffering pty input data={x}", .{data});
574578 self.pty_write_buf.appendSlice(self.alloc, data) catch |err| {
575579 std.log.warn(
576580 "pty input dropped {d} bytes: {s}",
......@@ -579,8 +583,50 @@ const Daemon = struct {
579583 };
580584 }
581585
582- pub fn handleInput(self: *Daemon, payload: []const u8) void {
583- self.queuePtyInput(payload);
586+ pub fn handleInput(self: *Daemon, client: *Client, payload: []const u8) !void {
587+ // client is leader, send entire payload (ansi escape codes + text)
588+ if (self.leader_client_fd == client.socket_fd) {
589+ self.queuePtyInput(payload);
590+ return;
591+ }
592+
593+ // quick check to see if a newline happened so we can set that client to leader
594+ // without creating a ghostty vt
595+ if (std.mem.indexOfScalar(u8, payload, '\r')) |_| {
596+ std.log.info(
597+ "setting new leader session={s} client_fd={d}",
598+ .{ self.session_name, client.socket_fd },
599+ );
600+ self.leader_client_fd = client.socket_fd;
601+ self.queuePtyInput(payload);
602+ return;
603+ }
604+
605+ // check if leader needs to be updated
606+ // this is probably really ineffecient but it was the easiest and most robust way
607+ // to strip ansi escape codes and only detect plain text to determine if we need
608+ // to set a new leader
609+ var termx = try ghostty_vt.Terminal.init(client.alloc, .{
610+ .cols = 80,
611+ .rows = 24,
612+ });
613+ defer termx.deinit(client.alloc);
614+ var vt_stream = termx.vtStream();
615+ defer vt_stream.deinit();
616+ try vt_stream.nextSlice(payload);
617+ if (util.serializeTerminal(client.alloc, &termx, .plain)) |output| {
618+ defer client.alloc.free(output);
619+ // if there's no text output then this client is effectively read-only until they type
620+ if (output.len > 0) {
621+ std.log.info(
622+ "setting new leader session={s} client_fd={d}",
623+ .{ self.session_name, client.socket_fd },
624+ );
625+ self.leader_client_fd = client.socket_fd;
626+ // new leader is set to this client so send *entire* payload
627+ self.queuePtyInput(payload);
628+ }
629+ }
584630 }
585631
586632 pub fn handleInit(
......@@ -591,6 +637,10 @@ const Daemon = struct {
591637 payload: []const u8,
592638 ) !void {
593639 if (payload.len != @sizeOf(ipc.Resize)) return;
640+ // no leader is set so set one
641+ if (self.leader_client_fd == null) {
642+ self.leader_client_fd = client.socket_fd;
643+ }
594644
595645 const resize = std.mem.bytesToValue(ipc.Resize, payload);
596646
......@@ -635,11 +685,21 @@ const Daemon = struct {
635685
636686 pub fn handleResize(
637687 self: *Daemon,
688+ client: *Client,
638689 pty_fd: i32,
639690 term: *ghostty_vt.Terminal,
640691 payload: []const u8,
641692 ) !void {
642693 if (payload.len != @sizeOf(ipc.Resize)) return;
694+ if (self.leader_client_fd == null) {
695+ std.log.info(
696+ "setting new leader session={s} client_fd={d}",
697+ .{ self.session_name, client.socket_fd },
698+ );
699+ self.leader_client_fd = client.socket_fd;
700+ }
701+ // only leader can resize
702+ if (self.leader_client_fd != client.socket_fd) return;
643703
644704 const resize = std.mem.bytesToValue(ipc.Resize, payload);
645705 var ws: cross.c.struct_winsize = .{
......@@ -654,7 +714,15 @@ const Daemon = struct {
654714 }
655715
656716 pub fn handleDetach(self: *Daemon, client: *Client, i: usize) void {
657- std.log.info("client detach fd={d}", .{client.socket_fd});
717+ std.log.info("client detach session={s} fd={d}", .{ self.session_name, client.socket_fd });
718+ // leader is trying to disconnect, remove ref and let another client claim leader on input
719+ if (self.leader_client_fd == client.socket_fd) {
720+ std.log.info(
721+ "unsetting leader session={s} fd={d}",
722+ .{ self.session_name, client.socket_fd },
723+ );
724+ self.leader_client_fd = null;
725+ }
658726 _ = self.closeClient(client, i, false);
659727 }
660728
......@@ -1680,9 +1748,9 @@ fn daemonLoop(daemon: *Daemon, server_sock_fd: i32, pty_fd: i32) !void {
16801748
16811749 while (client.read_buf.next()) |msg| {
16821750 switch (msg.header.tag) {
1683- .Input => daemon.handleInput(msg.payload),
1751+ .Input => try daemon.handleInput(client, msg.payload),
16841752 .Init => try daemon.handleInit(client, pty_fd, &term, msg.payload),
1685- .Resize => try daemon.handleResize(pty_fd, &term, msg.payload),
1753+ .Resize => try daemon.handleResize(client, pty_fd, &term, msg.payload),
16861754 .Detach => {
16871755 daemon.handleDetach(client, i);
16881756 break :clients_loop;