fix(daemon): redirect stdio to /dev/null after fork

Commit `e70e8b2`

x1f9 · 2026-04-02 17:32:40 -0400 EDT

parent efd35ac

fix(daemon): redirect stdio to /dev/null after fork

The existing FD close loop (3-63) handles bats' internal file
descriptors, but bats' `run` keyword captures output via pipes
on FDs 0-2. The daemon inherits these pipe write ends and holds
them open, so bats never gets EOF and hangs.

Redirect stdin/stdout/stderr to /dev/null right after setsid().
The daemon communicates exclusively via its unix socket — it never
reads stdin or writes stdout/stderr. This is standard daemon
hygiene and completes the inherited-FD fix.

1 files changed, +23, -0

M src/main.zig

+23, -0

......@@ -695,6 +695,29 @@ const Daemon = struct {

                log_system.deinit();

                // Redirect stdin/stdout/stderr to /dev/null. The daemon
                // communicates via its unix socket, not stdio. Without
                // this, any pipe on FDs 0-2 (e.g. from bats' `run`
                // keyword) stays open for the daemon's lifetime, causing
                // the caller to hang waiting for EOF.
                {
                    const devnull = std.posix.open(
                        "/dev/null",
                        .{ .ACCMODE = .RDWR },
                        0,
                    ) catch |err| {
                        std.log.warn("failed to open /dev/null: {s}", .{@errorName(err)});
                        return err;
                    };
                    inline for (.{ posix.STDIN_FILENO, posix.STDOUT_FILENO, posix.STDERR_FILENO }) |fd| {
                        _ = posix.dup2(devnull, fd) catch |err| {
                            std.log.warn("dup2 /dev/null -> {d}: {s}", .{ fd, @errorName(err) });
                            return err;
                        };
                    }
                    if (devnull > 2) posix.close(devnull);
                }

                // Close file descriptors inherited from the parent that the
                // daemon doesn't need. This prevents test harnesses (like
                // bats) from hanging — they wait for their internal FDs (3+)

...	...		@@ -695,6 +695,29 @@ const Daemon = struct {
695	695
696	696		log_system.deinit();
697	697
	698	+	// Redirect stdin/stdout/stderr to /dev/null. The daemon
	699	+	// communicates via its unix socket, not stdio. Without
	700	+	// this, any pipe on FDs 0-2 (e.g. from bats' `run`
	701	+	// keyword) stays open for the daemon's lifetime, causing
	702	+	// the caller to hang waiting for EOF.
	703	+	{
	704	+	const devnull = std.posix.open(
	705	+	"/dev/null",
	706	+	.{ .ACCMODE = .RDWR },
	707	+	0,
	708	+	) catch \|err\| {
	709	+	std.log.warn("failed to open /dev/null: {s}", .{@errorName(err)});
	710	+	return err;
	711	+	};
	712	+	inline for (.{ posix.STDIN_FILENO, posix.STDOUT_FILENO, posix.STDERR_FILENO }) \|fd\| {
	713	+	_ = posix.dup2(devnull, fd) catch \|err\| {
	714	+	std.log.warn("dup2 /dev/null -> {d}: {s}", .{ fd, @errorName(err) });
	715	+	return err;
	716	+	};
	717	+	}
	718	+	if (devnull > 2) posix.close(devnull);
	719	+	}
	720	+
698	721		// Close file descriptors inherited from the parent that the
699	722		// daemon doesn't need. This prevents test harnesses (like
700	723		// bats) from hanging — they wait for their internal FDs (3+)

Commit e70e8b2

Commit `e70e8b2`