A detached session stopped by SIGTERM, SIGINT or SIGHUP unlinks its sockets

The signals' default action ended the process where it stood, leaving
pardes-9p-*.sock and pardes-detached-*.sock for the next session to trip on.
The detached session now takes them to mean quit: the handler sets a flag and
wakes the loop, which leaves as Exit does, through the teardown that unlinks
both. fs.py sends each of the three and checks the sockets are gone.

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

1 files changed, 16 insertions, 1 deletions

diff --git a/src/detached/server.zig b/src/detached/server.zig
index 5bf2384b..b47bda1b 100644
--- a/src/detached/server.zig
+++ b/src/detached/server.zig
@@ -1181,6 +1181,17 @@ pub const Session = struct {
     }
 };
 
+/// SIGTERM, SIGINT or SIGHUP: quit as Exit does, through the loop, so its
+/// sockets are unlinked on the way out rather than left for the next
+/// session to trip on. The handler only sets the flag and wakes the loop.
+var quit_signalled = std.atomic.Value(bool).init(false);
+var quit_wake: c_int = -1;
+
+fn onQuitSignal(_: std.posix.SIG) callconv(.c) void {
+    quit_signalled.store(true, .release);
+    if (quit_wake >= 0) _ = libc.send(quit_wake, "q", 1, nosignal);
+}
+
 pub fn run(init: std.process.Init, opts: pardes.Options, name: []const u8) !void {
     const gpa = init.gpa;
     const allocs = pardes.memory.init(gpa);
@@ -1231,7 +1242,11 @@ pub fn run(init: std.process.Init, opts: pardes.Options, name: []const u8) !void
     core.host = h;
     while (core.nextEffect()) |effect| core.perform(effect);
     session.in_loop = true;
-    while (!session.core.quit) {
+    quit_wake = session.mailbox.wake[1];
+    const on_quit: std.posix.Sigaction = .{ .handler = .{ .handler = onQuitSignal }, .mask = std.posix.sigemptyset(), .flags = 0 };
+    for ([_]std.posix.SIG{ .HUP, .INT, .TERM }) |sig| std.posix.sigaction(sig, &on_quit, null);
+    defer quit_wake = -1;
+    while (!session.core.quit and !quit_signalled.load(.acquire)) {
         pardes.turn.restoreSettled();
         try session.core.pump(h);
         if (session.core.quit) break;