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fix(terminal): setup SIGCHLD handler to catch exits with no writes

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This commit is contained in:
CJ van den Berg 2026-02-27 12:57:43 +01:00
parent 632a7c4453
commit 94f6b342fa
Signed by: neurocyte
GPG key ID: 8EB1E1BB660E3FB9
2 changed files with 44 additions and 3 deletions
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4
build.zig.zon
View file

@ -30,8 +30,8 @@
.hash = "fuzzig-0.1.1-Ji0xivxIAQBD0g8O_NV_0foqoPf3elsg9Sc3pNfdVH4D",
},
.vaxis = .{
.url = "git+https://github.com/neurocyte/libvaxis?ref=main#e83e3f871786fab577bb26e2e4800dd7e9bf4390",
.hash = "vaxis-0.5.1-BWNV_Ke0CQCnpGN5qbzPOFD1V_oBgcIWd1O0PrBYmTMa",
.url = "git+https://github.com/neurocyte/libvaxis?ref=main#5727534c75c7490e3eab1ec65b6998fecf228165",
.hash = "vaxis-0.5.1-BWNV_Aq3CQCFVUB6Ie_kp0ftM2brpixkT_mOERADRiVD",
},
.zeit = .{
.url = "git+https://github.com/rockorager/zeit?ref=zig-0.15#ed2ca60db118414bda2b12df2039e33bad3b0b88",

43
src/tui/terminal_view.zig
View file

@ -390,6 +390,7 @@ const pty = struct {
receiver: Receiver,
parent: tp.pid,
err_code: i64 = 0,
sigchld: ?tp.signal = null,
pub fn spawn(allocator: std.mem.Allocator, vt: *Terminal) !tp.pid {
const self = try allocator.create(@This());
@ -408,6 +409,7 @@ const pty = struct {
fn deinit(self: *@This()) void {
std.log.debug("terminal: pty actor deinit (pid={?})", .{self.vt.cmd.pid});
if (self.sigchld) |s| s.deinit();
self.fd.deinit();
self.parser.buf.deinit();
self.parent.deinit();
@ -424,6 +426,10 @@ const pty = struct {
std.log.debug("terminal: pty initial wait_read failed: {}", .{e});
return tp.exit_error(e, @errorReturnTrace());
};
self.sigchld = tp.signal.init(std.posix.SIG.CHLD, tp.message.fmt(.{"sigchld"})) catch |e| {
std.log.debug("terminal: SIGCHLD signal init failed: {}", .{e});
return tp.exit_error(e, @errorReturnTrace());
};
tp.receive(&self.receiver);
}
@ -450,11 +456,24 @@ const pty = struct {
},
};
} else if (try m.match(.{ "fd", "pty", "read_error", tp.extract(&self.err_code), tp.more })) {
// thespian fires read_error with EPOLLHUP when the child exits cleanly.
// Treat it the same as EIO: reap the child and signal exit.
const code = self.vt.cmd.wait();
std.log.debug("terminal: read_error from fd (err={d}), process exited with code={d}", .{ self.err_code, code });
self.vt.event_queue.push(.{ .exited = code });
self.parent.send(.{ "terminal_view", "output" }) catch {};
return tp.exit_normal();
} else if (try m.match(.{"sigchld"})) {
// SIGCHLD fires when any child exits. Check if it's our child.
if (self.vt.cmd.try_wait()) |code| {
std.log.debug("terminal: child exited (SIGCHLD) with code={d}", .{code});
self.vt.event_queue.push(.{ .exited = code });
self.parent.send(.{ "terminal_view", "output" }) catch {};
return tp.exit_normal();
}
// Not our child (or already reaped) - re-arm the signal and continue.
if (self.sigchld) |s| s.deinit();
self.sigchld = tp.signal.init(std.posix.SIG.CHLD, tp.message.fmt(.{"sigchld"})) catch null;
} else if (try m.match(.{"quit"})) {
std.log.debug("terminal: pty exiting: received quit", .{});
return tp.exit_normal();
@ -469,7 +488,19 @@ const pty = struct {
while (true) {
const n = std.posix.read(self.vt.ptyFd(), &buf) catch |e| switch (e) {
error.WouldBlock => break,
error.WouldBlock => {
// No more data right now. Check if the child already exited -
// on Linux a clean exit may not make the pty fd readable again
// (no EPOLLIN), it just starts returning EIO on the next read.
// Polling here catches that case before we arm wait_read again.
if (self.vt.cmd.try_wait()) |code| {
std.log.debug("terminal: child exited (detected via try_wait) with code={d}", .{code});
self.vt.event_queue.push(.{ .exited = code });
self.parent.send(.{ "terminal_view", "output" }) catch {};
return error.InputOutput;
}
break;
},
error.InputOutput => {
const code = self.vt.cmd.wait();
std.log.debug("terminal: read EIO, process exited with code={d}", .{code});
@ -522,6 +553,16 @@ const pty = struct {
}
}
// Check for child exit once more before sleeping in wait_read.
// A clean exit with no final output will never make the pty fd readable,
// so we must detect it here rather than waiting forever.
if (self.vt.cmd.try_wait()) |code| {
std.log.debug("terminal: child exited (pre-wait_read check) with code={d}", .{code});
self.vt.event_queue.push(.{ .exited = code });
self.parent.send(.{ "terminal_view", "output" }) catch {};
return error.InputOutput;
}
self.fd.wait_read() catch |e| switch (e) {
error.ThespianFileDescriptorWaitReadFailed => {
std.log.debug("terminal: wait_read failed: {} (pid={?})", .{ e, self.vt.cmd.pid });