runtime: install sigPreempt signal handler for c-archive/c-shared

Fixes #49288

Change-Id: I7bfcbecbefa68871a3e556935a73f241fff44c0e
Reviewed-on: https://go-review.googlesource.com/c/go/+/360861
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>

misc/cgo/testcarchive/carchive_test.go

@@ -931,3 +931,55 @@ func TestManyCalls(t *testing.T) {
 		t.Error(err)
 	}
 }
+
+// Issue 49288.
+func TestPreemption(t *testing.T) {
+	if runtime.Compiler == "gccgo" {
+		t.Skip("skipping asynchronous preemption test with gccgo")
+	}
+
+	t.Parallel()
+
+	if !testWork {
+		defer func() {
+			os.Remove("testp8" + exeSuffix)
+			os.Remove("libgo8.a")
+			os.Remove("libgo8.h")
+		}()
+	}
+
+	cmd := exec.Command("go", "build", "-buildmode=c-archive", "-o", "libgo8.a", "./libgo8")
+	if out, err := cmd.CombinedOutput(); err != nil {
+		t.Logf("%s", out)
+		t.Fatal(err)
+	}
+	checkLineComments(t, "libgo8.h")
+
+	ccArgs := append(cc, "-o", "testp8"+exeSuffix, "main8.c", "libgo8.a")
+	if out, err := exec.Command(ccArgs[0], ccArgs[1:]...).CombinedOutput(); err != nil {
+		t.Logf("%s", out)
+		t.Fatal(err)
+	}
+
+	argv := cmdToRun("./testp8")
+	cmd = exec.Command(argv[0], argv[1:]...)
+	var sb strings.Builder
+	cmd.Stdout = &sb
+	cmd.Stderr = &sb
+	if err := cmd.Start(); err != nil {
+		t.Fatal(err)
+	}
+
+	timer := time.AfterFunc(time.Minute,
+		func() {
+			t.Error("test program timed out")
+			cmd.Process.Kill()
+		},
+	)
+	defer timer.Stop()
+
+	if err := cmd.Wait(); err != nil {
+		t.Log(sb.String())
+		t.Error(err)
+	}
+}

misc/cgo/testcarchive/testdata/libgo8/a.go

@@ -0,0 +1,36 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "C"
+
+import (
+	"os"
+	"runtime"
+	"sync/atomic"
+)
+
+var started int32
+
+// Start a goroutine that loops forever.
+func init() {
+	runtime.GOMAXPROCS(1)
+	go func() {
+		for {
+			atomic.StoreInt32(&started, 1)
+		}
+	}()
+}
+
+//export GoFunction8
+func GoFunction8() {
+	for atomic.LoadInt32(&started) == 0 {
+		runtime.Gosched()
+	}
+	os.Exit(0)
+}
+
+func main() {
+}

misc/cgo/testcarchive/testdata/main8.c

@@ -0,0 +1,16 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test preemption.
+
+#include <stdlib.h>
+
+#include "libgo8.h"
+
+int main() {
+	GoFunction8();
+
+	// That should have exited the program.
+	abort();
+}

src/runtime/signal_unix.go

@@ -167,8 +167,8 @@ func sigInstallGoHandler(sig uint32) bool {
 	}
 
 	// When built using c-archive or c-shared, only install signal
-	// handlers for synchronous signals and SIGPIPE.
+	// handlers for synchronous signals and SIGPIPE and sigPreempt.
-	if (isarchive || islibrary) && t.flags&_SigPanic == 0 && sig != _SIGPIPE {
+	if (isarchive || islibrary) && t.flags&_SigPanic == 0 && sig != _SIGPIPE && sig != sigPreempt {
 		return false
 	}