7 files changed, 558 insertions, 0 deletions
diff --git a/src/os/signal/example_test.go b/src/os/signal/example_test.go
new file mode 100644
index 000000000..079ee5070
--- /dev/null
+++ b/src/os/signal/example_test.go
@@ -0,0 +1,23 @@
+// Copyright 2013 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 signal_test
+
+import (
+	"fmt"
+	"os"
+	"os/signal"
+)
+
+func ExampleNotify() {
+	// Set up channel on which to send signal notifications.
+	// We must use a buffered channel or risk missing the signal
+	// if we're not ready to receive when the signal is sent.
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, os.Interrupt, os.Kill)
+
+	// Block until a signal is received.
+	s := <-c
+	fmt.Println("Got signal:", s)
+}
diff --git a/src/os/signal/sig.s b/src/os/signal/sig.s
new file mode 100644
index 000000000..d54c284b5
--- /dev/null
+++ b/src/os/signal/sig.s
@@ -0,0 +1,23 @@
+// Copyright 2012 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.
+
+// Assembly to get into package runtime without using exported symbols.
+
+// +build amd64 amd64p32 arm 386
+
+#include "textflag.h"
+
+#ifdef GOARCH_arm
+#define JMP B
+#endif
+
+TEXT ·signal_disable(SB),NOSPLIT,$0
+	JMP runtime·signal_disable(SB)
+
+TEXT ·signal_enable(SB),NOSPLIT,$0
+	JMP runtime·signal_enable(SB)
+
+TEXT ·signal_recv(SB),NOSPLIT,$0
+	JMP runtime·signal_recv(SB)
+
diff --git a/src/os/signal/signal.go b/src/os/signal/signal.go
new file mode 100644
index 000000000..300427549
--- /dev/null
+++ b/src/os/signal/signal.go
@@ -0,0 +1,131 @@
+// Copyright 2012 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 signal implements access to incoming signals.
+package signal
+
+// BUG(rsc): This package is not yet implemented on Plan 9.
+
+import (
+	"os"
+	"sync"
+)
+
+var handlers struct {
+	sync.Mutex
+	m   map[chan<- os.Signal]*handler
+	ref [numSig]int64
+}
+
+type handler struct {
+	mask [(numSig + 31) / 32]uint32
+}
+
+func (h *handler) want(sig int) bool {
+	return (h.mask[sig/32]>>uint(sig&31))&1 != 0
+}
+
+func (h *handler) set(sig int) {
+	h.mask[sig/32] |= 1 << uint(sig&31)
+}
+
+// Notify causes package signal to relay incoming signals to c.
+// If no signals are listed, all incoming signals will be relayed to c.
+// Otherwise, just the listed signals will.
+//
+// Package signal will not block sending to c: the caller must ensure
+// that c has sufficient buffer space to keep up with the expected
+// signal rate.  For a channel used for notification of just one signal value,
+// a buffer of size 1 is sufficient.
+//
+// It is allowed to call Notify multiple times with the same channel:
+// each call expands the set of signals sent to that channel.
+// The only way to remove signals from the set is to call Stop.
+//
+// It is allowed to call Notify multiple times with different channels
+// and the same signals: each channel receives copies of incoming
+// signals independently.
+func Notify(c chan<- os.Signal, sig ...os.Signal) {
+	if c == nil {
+		panic("os/signal: Notify using nil channel")
+	}
+
+	handlers.Lock()
+	defer handlers.Unlock()
+
+	h := handlers.m[c]
+	if h == nil {
+		if handlers.m == nil {
+			handlers.m = make(map[chan<- os.Signal]*handler)
+		}
+		h = new(handler)
+		handlers.m[c] = h
+	}
+
+	add := func(n int) {
+		if n < 0 {
+			return
+		}
+		if !h.want(n) {
+			h.set(n)
+			if handlers.ref[n] == 0 {
+				enableSignal(n)
+			}
+			handlers.ref[n]++
+		}
+	}
+
+	if len(sig) == 0 {
+		for n := 0; n < numSig; n++ {
+			add(n)
+		}
+	} else {
+		for _, s := range sig {
+			add(signum(s))
+		}
+	}
+}
+
+// Stop causes package signal to stop relaying incoming signals to c.
+// It undoes the effect of all prior calls to Notify using c.
+// When Stop returns, it is guaranteed that c will receive no more signals.
+func Stop(c chan<- os.Signal) {
+	handlers.Lock()
+	defer handlers.Unlock()
+
+	h := handlers.m[c]
+	if h == nil {
+		return
+	}
+	delete(handlers.m, c)
+
+	for n := 0; n < numSig; n++ {
+		if h.want(n) {
+			handlers.ref[n]--
+			if handlers.ref[n] == 0 {
+				disableSignal(n)
+			}
+		}
+	}
+}
+
+func process(sig os.Signal) {
+	n := signum(sig)
+	if n < 0 {
+		return
+	}
+
+	handlers.Lock()
+	defer handlers.Unlock()
+
+	for c, h := range handlers.m {
+		if h.want(n) {
+			// send but do not block for it
+			select {
+			case c <- sig:
+			default:
+			}
+		}
+	}
+}
diff --git a/src/os/signal/signal_stub.go b/src/os/signal/signal_stub.go
new file mode 100644
index 000000000..d0a6935ff
--- /dev/null
+++ b/src/os/signal/signal_stub.go
@@ -0,0 +1,17 @@
+// Copyright 2012 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.
+
+// +build plan9
+
+package signal
+
+import "os"
+
+const numSig = 0
+
+func signum(sig os.Signal) int { return -1 }
+
+func disableSignal(int) {}
+
+func enableSignal(int) {}
diff --git a/src/os/signal/signal_test.go b/src/os/signal/signal_test.go
new file mode 100644
index 000000000..22337a72d
--- /dev/null
+++ b/src/os/signal/signal_test.go
@@ -0,0 +1,208 @@
+// Copyright 2009 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.
+
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package signal
+
+import (
+	"flag"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"runtime"
+	"strconv"
+	"syscall"
+	"testing"
+	"time"
+)
+
+func waitSig(t *testing.T, c <-chan os.Signal, sig os.Signal) {
+	select {
+	case s := <-c:
+		if s != sig {
+			t.Fatalf("signal was %v, want %v", s, sig)
+		}
+	case <-time.After(1 * time.Second):
+		t.Fatalf("timeout waiting for %v", sig)
+	}
+}
+
+// Test that basic signal handling works.
+func TestSignal(t *testing.T) {
+	// Ask for SIGHUP
+	c := make(chan os.Signal, 1)
+	Notify(c, syscall.SIGHUP)
+	defer Stop(c)
+
+	// Send this process a SIGHUP
+	t.Logf("sighup...")
+	syscall.Kill(syscall.Getpid(), syscall.SIGHUP)
+	waitSig(t, c, syscall.SIGHUP)
+
+	// Ask for everything we can get.
+	c1 := make(chan os.Signal, 1)
+	Notify(c1)
+
+	// Send this process a SIGWINCH
+	t.Logf("sigwinch...")
+	syscall.Kill(syscall.Getpid(), syscall.SIGWINCH)
+	waitSig(t, c1, syscall.SIGWINCH)
+
+	// Send two more SIGHUPs, to make sure that
+	// they get delivered on c1 and that not reading
+	// from c does not block everything.
+	t.Logf("sighup...")
+	syscall.Kill(syscall.Getpid(), syscall.SIGHUP)
+	waitSig(t, c1, syscall.SIGHUP)
+	t.Logf("sighup...")
+	syscall.Kill(syscall.Getpid(), syscall.SIGHUP)
+	waitSig(t, c1, syscall.SIGHUP)
+
+	// The first SIGHUP should be waiting for us on c.
+	waitSig(t, c, syscall.SIGHUP)
+}
+
+func TestStress(t *testing.T) {
+	dur := 3 * time.Second
+	if testing.Short() {
+		dur = 100 * time.Millisecond
+	}
+	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
+	done := make(chan bool)
+	finished := make(chan bool)
+	go func() {
+		sig := make(chan os.Signal, 1)
+		Notify(sig, syscall.SIGUSR1)
+		defer Stop(sig)
+	Loop:
+		for {
+			select {
+			case <-sig:
+			case <-done:
+				break Loop
+			}
+		}
+		finished <- true
+	}()
+	go func() {
+	Loop:
+		for {
+			select {
+			case <-done:
+				break Loop
+			default:
+				syscall.Kill(syscall.Getpid(), syscall.SIGUSR1)
+				runtime.Gosched()
+			}
+		}
+		finished <- true
+	}()
+	time.Sleep(dur)
+	close(done)
+	<-finished
+	<-finished
+	// When run with 'go test -cpu=1,2,4' SIGUSR1 from this test can slip
+	// into subsequent TestSignal() causing failure.
+	// Sleep for a while to reduce the possibility of the failure.
+	time.Sleep(10 * time.Millisecond)
+}
+
+var sendUncaughtSighup = flag.Int("send_uncaught_sighup", 0, "send uncaught SIGHUP during TestStop")
+
+// Test that Stop cancels the channel's registrations.
+func TestStop(t *testing.T) {
+	sigs := []syscall.Signal{
+		syscall.SIGWINCH,
+		syscall.SIGHUP,
+	}
+
+	for _, sig := range sigs {
+		// Send the signal.
+		// If it's SIGWINCH, we should not see it.
+		// If it's SIGHUP, maybe we'll die. Let the flag tell us what to do.
+		if sig != syscall.SIGHUP || *sendUncaughtSighup == 1 {
+			syscall.Kill(syscall.Getpid(), sig)
+		}
+		time.Sleep(100 * time.Millisecond)
+
+		// Ask for signal
+		c := make(chan os.Signal, 1)
+		Notify(c, sig)
+		defer Stop(c)
+
+		// Send this process that signal
+		syscall.Kill(syscall.Getpid(), sig)
+		waitSig(t, c, sig)
+
+		Stop(c)
+		select {
+		case s := <-c:
+			t.Fatalf("unexpected signal %v", s)
+		case <-time.After(100 * time.Millisecond):
+			// nothing to read - good
+		}
+
+		// Send the signal.
+		// If it's SIGWINCH, we should not see it.
+		// If it's SIGHUP, maybe we'll die. Let the flag tell us what to do.
+		if sig != syscall.SIGHUP || *sendUncaughtSighup == 2 {
+			syscall.Kill(syscall.Getpid(), sig)
+		}
+
+		select {
+		case s := <-c:
+			t.Fatalf("unexpected signal %v", s)
+		case <-time.After(100 * time.Millisecond):
+			// nothing to read - good
+		}
+	}
+}
+
+// Test that when run under nohup, an uncaught SIGHUP does not kill the program,
+// but a
+func TestNohup(t *testing.T) {
+	// Ugly: ask for SIGHUP so that child will not have no-hup set
+	// even if test is running under nohup environment.
+	// We have no intention of reading from c.
+	c := make(chan os.Signal, 1)
+	Notify(c, syscall.SIGHUP)
+
+	// When run without nohup, the test should crash on an uncaught SIGHUP.
+	// When run under nohup, the test should ignore uncaught SIGHUPs,
+	// because the runtime is not supposed to be listening for them.
+	// Either way, TestStop should still be able to catch them when it wants them
+	// and then when it stops wanting them, the original behavior should resume.
+	//
+	// send_uncaught_sighup=1 sends the SIGHUP before starting to listen for SIGHUPs.
+	// send_uncaught_sighup=2 sends the SIGHUP after no longer listening for SIGHUPs.
+	//
+	// Both should fail without nohup and succeed with nohup.
+
+	for i := 1; i <= 2; i++ {
+		out, err := exec.Command(os.Args[0], "-test.run=TestStop", "-send_uncaught_sighup="+strconv.Itoa(i)).CombinedOutput()
+		if err == nil {
+			t.Fatalf("ran test with -send_uncaught_sighup=%d and it succeeded: expected failure.\nOutput:\n%s", i, out)
+		}
+	}
+
+	Stop(c)
+
+	// Again, this time with nohup, assuming we can find it.
+	_, err := os.Stat("/usr/bin/nohup")
+	if err != nil {
+		t.Skip("cannot find nohup; skipping second half of test")
+	}
+
+	for i := 1; i <= 2; i++ {
+		os.Remove("nohup.out")
+		out, err := exec.Command("/usr/bin/nohup", os.Args[0], "-test.run=TestStop", "-send_uncaught_sighup="+strconv.Itoa(i)).CombinedOutput()
+
+		data, _ := ioutil.ReadFile("nohup.out")
+		os.Remove("nohup.out")
+		if err != nil {
+			t.Fatalf("ran test with -send_uncaught_sighup=%d under nohup and it failed: expected success.\nError: %v\nOutput:\n%s%s", i, err, out, data)
+		}
+	}
+}
diff --git a/src/os/signal/signal_unix.go b/src/os/signal/signal_unix.go
new file mode 100644
index 000000000..94b8ab3dd
--- /dev/null
+++ b/src/os/signal/signal_unix.go
@@ -0,0 +1,53 @@
+// Copyright 2012 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.
+
+// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
+
+package signal
+
+import (
+	"os"
+	"syscall"
+)
+
+// In assembly.
+func signal_disable(uint32)
+func signal_enable(uint32)
+func signal_recv() uint32
+
+func loop() {
+	for {
+		process(syscall.Signal(signal_recv()))
+	}
+}
+
+func init() {
+	signal_enable(0) // first call - initialize
+	go loop()
+}
+
+const (
+	numSig = 65 // max across all systems
+)
+
+func signum(sig os.Signal) int {
+	switch sig := sig.(type) {
+	case syscall.Signal:
+		i := int(sig)
+		if i < 0 || i >= numSig {
+			return -1
+		}
+		return i
+	default:
+		return -1
+	}
+}
+
+func enableSignal(sig int) {
+	signal_enable(uint32(sig))
+}
+
+func disableSignal(sig int) {
+	signal_disable(uint32(sig))
+}
diff --git a/src/os/signal/signal_windows_test.go b/src/os/signal/signal_windows_test.go
new file mode 100644
index 000000000..f3e6706b7
--- /dev/null
+++ b/src/os/signal/signal_windows_test.go
@@ -0,0 +1,103 @@
+// Copyright 2012 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 signal
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"syscall"
+	"testing"
+	"time"
+)
+
+func sendCtrlBreak(t *testing.T, pid int) {
+	d, e := syscall.LoadDLL("kernel32.dll")
+	if e != nil {
+		t.Fatalf("LoadDLL: %v\n", e)
+	}
+	p, e := d.FindProc("GenerateConsoleCtrlEvent")
+	if e != nil {
+		t.Fatalf("FindProc: %v\n", e)
+	}
+	r, _, e := p.Call(syscall.CTRL_BREAK_EVENT, uintptr(pid))
+	if r == 0 {
+		t.Fatalf("GenerateConsoleCtrlEvent: %v\n", e)
+	}
+}
+
+func TestCtrlBreak(t *testing.T) {
+	// create source file
+	const source = `
+package main
+
+import (
+	"log"
+	"os"
+	"os/signal"
+	"time"
+)
+
+
+func main() {
+	c := make(chan os.Signal, 10)
+	signal.Notify(c)
+	select {
+	case s := <-c:
+		if s != os.Interrupt {
+			log.Fatalf("Wrong signal received: got %q, want %q\n", s, os.Interrupt)
+		}
+	case <-time.After(3 * time.Second):
+		log.Fatalf("Timeout waiting for Ctrl+Break\n")
+	}
+}
+`
+	tmp, err := ioutil.TempDir("", "TestCtrlBreak")
+	if err != nil {
+		t.Fatal("TempDir failed: ", err)
+	}
+	defer os.RemoveAll(tmp)
+
+	// write ctrlbreak.go
+	name := filepath.Join(tmp, "ctlbreak")
+	src := name + ".go"
+	f, err := os.Create(src)
+	if err != nil {
+		t.Fatalf("Failed to create %v: %v", src, err)
+	}
+	defer f.Close()
+	f.Write([]byte(source))
+
+	// compile it
+	exe := name + ".exe"
+	defer os.Remove(exe)
+	o, err := exec.Command("go", "build", "-o", exe, src).CombinedOutput()
+	if err != nil {
+		t.Fatalf("Failed to compile: %v\n%v", err, string(o))
+	}
+
+	// run it
+	cmd := exec.Command(exe)
+	var b bytes.Buffer
+	cmd.Stdout = &b
+	cmd.Stderr = &b
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		CreationFlags: syscall.CREATE_NEW_PROCESS_GROUP,
+	}
+	err = cmd.Start()
+	if err != nil {
+		t.Fatalf("Start failed: %v", err)
+	}
+	go func() {
+		time.Sleep(1 * time.Second)
+		sendCtrlBreak(t, cmd.Process.Pid)
+	}()
+	err = cmd.Wait()
+	if err != nil {
+		t.Fatalf("Program exited with error: %v\n%v", err, string(b.Bytes()))
+	}
+}