Catch SIGILL, SIGFPE, SIGSEGV in the test runner

core/testing/signal_handler_libc.odin

@@ -4,16 +4,126 @@ package testing
 
 import "base:intrinsics"
 import "core:c/libc"
+import "core:encoding/ansi"
+import "core:sync"
+
+@(private="file") stop_runner_flag: libc.sig_atomic_t
+
+@(private="file") stop_test_gate:   sync.Mutex
+@(private="file") stop_test_index:  libc.sig_atomic_t
+@(private="file") stop_test_reason: libc.sig_atomic_t
+@(private="file") stop_test_alert:  libc.sig_atomic_t
+
+@(private="file", thread_local)
+local_test_index: libc.sig_atomic_t
 
 @(private="file")
-abort_flag: libc.sig_atomic_t
-
-setup_signal_handler :: proc() {
-	libc.signal(libc.SIGINT, proc "c" (sig: libc.int) {
-		intrinsics.atomic_add(&abort_flag, 1)
-	})
+stop_runner_callback :: proc "c" (sig: libc.int) {
+	intrinsics.atomic_store(&stop_runner_flag, 1)
 }
 
-should_abort :: proc() -> bool {
-	return intrinsics.atomic_load(&abort_flag) > 0
+@(private="file")
+stop_test_callback :: proc "c" (sig: libc.int) {
+	if local_test_index == -1 {
+		// We're the test runner, and we ourselves have caught a signal from
+		// which there is no recovery.
+		//
+		// The most we can do now is make sure the user's cursor is visible,
+		// nuke the entire processs, and hope a useful core dump survives.
+
+		// NOTE(Feoramund): Using these write calls in a signal handler is
+		// undefined behavior in C99 but possibly tolerated in POSIX 2008.
+		// Either way, we may as well try to salvage what we can.
+		show_cursor := ansi.CSI + ansi.DECTCEM_SHOW
+		libc.fwrite(raw_data(show_cursor), size_of(byte), len(show_cursor), libc.stdout)
+		libc.fflush(libc.stdout)
+
+		// This is an attempt at being compliant by avoiding printf.
+		sigbuf: [8]byte
+		sigstr: string
+		{
+			signum := cast(int)sig
+			i := len(sigbuf) - 2
+			for signum > 0 {
+				m := signum % 10
+				signum /= 10
+				sigbuf[i] = cast(u8)('0' + m)
+				i -= 1
+			}
+			sigstr = cast(string)sigbuf[i:]
+		}
+
+		advisory_a := `
+The test runner's main thread has caught an unrecoverable error (signal `
+		advisory_b := `) and will now forcibly terminate.
+This is a dire bug and should be reported to the Odin developers.
+`
+		libc.fwrite(raw_data(advisory_a), size_of(byte), len(advisory_a), libc.stderr)
+		libc.fwrite(raw_data(sigstr), size_of(byte), len(sigstr), libc.stderr)
+		libc.fwrite(raw_data(advisory_b), size_of(byte), len(advisory_b), libc.stderr)
+
+		// Try to get a core dump.
+		libc.abort()
+	}
+
+	if sync.mutex_guard(&stop_test_gate) {
+		intrinsics.atomic_store(&stop_test_index, local_test_index)
+		intrinsics.atomic_store(&stop_test_reason, cast(libc.sig_atomic_t)sig)
+		intrinsics.atomic_store(&stop_test_alert, 1)
+
+		for {
+			// Idle until this thread is terminated by the runner,
+			// otherwise we may continue to generate signals.
+			intrinsics.cpu_relax()
+		}
+	}
+}
+
+_setup_signal_handler :: proc() {
+	local_test_index = -1
+
+	// Catch user interrupt / CTRL-C.
+	libc.signal(libc.SIGINT, stop_runner_callback)
+	// Catch polite termination request.
+	libc.signal(libc.SIGTERM, stop_runner_callback)
+
+	// For tests:
+	// Catch asserts and panics.
+	libc.signal(libc.SIGILL, stop_test_callback)
+	// Catch arithmetic errors.
+	libc.signal(libc.SIGFPE, stop_test_callback)
+	// Catch segmentation faults (illegal memory access).
+	libc.signal(libc.SIGSEGV, stop_test_callback)
+}
+
+_setup_task_signal_handler :: proc(test_index: int) {
+	local_test_index = cast(libc.sig_atomic_t)test_index
+}
+
+_should_stop_runner :: proc() -> bool {
+	return intrinsics.atomic_load(&stop_runner_flag) == 1
+}
+
+@(private="file")
+unlock_stop_test_gate :: proc(_: int, _: Stop_Reason, ok: bool) {
+	if ok {
+		sync.mutex_unlock(&stop_test_gate)
+	}
+}
+
+@(deferred_out=unlock_stop_test_gate)
+_should_stop_test :: proc() -> (test_index: int, reason: Stop_Reason, ok: bool) {
+	if intrinsics.atomic_load(&stop_test_alert) == 1 {
+		intrinsics.atomic_store(&stop_test_alert, 0)
+
+		test_index = cast(int)intrinsics.atomic_load(&stop_test_index)
+		switch intrinsics.atomic_load(&stop_test_reason) {
+		case libc.SIGFPE: reason = .Arithmetic_Error
+		case libc.SIGILL: reason = .Illegal_Instruction
+		case libc.SIGSEGV: reason = .Segmentation_Fault
+		}
+		ok = true
+	}
+
+	return
 }