--- /dev/null
+// 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 linux darwin
+
+package syscall_test
+
+import (
+ "flag"
+ "fmt"
+ "io/ioutil"
+ "net"
+ "os"
+ "os/exec"
+ "syscall"
+ "testing"
+ "time"
+)
+
+// TestPassFD tests passing a file descriptor over a Unix socket.
+//
+// This test involved both a parent and child process. The parent
+// process is invoked as a normal test, with "go test", which then
+// runs the child process by running the current test binary with args
+// "-test.run=^TestPassFD$" and an environment variable used to signal
+// that the test should become the child process instead.
+func TestPassFD(t *testing.T) {
+ if os.Getenv("GO_WANT_HELPER_PROCESS") == "1" {
+ passFDChild()
+ return
+ }
+
+ tempDir, err := ioutil.TempDir("", "TestPassFD")
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer os.RemoveAll(tempDir)
+
+ fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM, 0)
+ if err != nil {
+ t.Fatalf("Socketpair: %v", err)
+ }
+ defer syscall.Close(fds[0])
+ defer syscall.Close(fds[1])
+ writeFile := os.NewFile(uintptr(fds[0]), "child-writes")
+ readFile := os.NewFile(uintptr(fds[1]), "parent-reads")
+ defer writeFile.Close()
+ defer readFile.Close()
+
+ cmd := exec.Command(os.Args[0], "-test.run=^TestPassFD$", "--", tempDir)
+ cmd.Env = append([]string{"GO_WANT_HELPER_PROCESS=1"}, os.Environ()...)
+ cmd.ExtraFiles = []*os.File{writeFile}
+
+ out, err := cmd.CombinedOutput()
+ if len(out) > 0 || err != nil {
+ t.Fatalf("child process: %q, %v", out, err)
+ }
+
+ c, err := net.FileConn(readFile)
+ if err != nil {
+ t.Fatalf("FileConn: %v", err)
+ }
+ defer c.Close()
+
+ uc, ok := c.(*net.UnixConn)
+ if !ok {
+ t.Fatalf("unexpected FileConn type; expected UnixConn, got %T", c)
+ }
+
+ buf := make([]byte, 32) // expect 1 byte
+ oob := make([]byte, 32) // expect 24 bytes
+ closeUnix := time.AfterFunc(5*time.Second, func() {
+ t.Logf("timeout reading from unix socket")
+ uc.Close()
+ })
+ _, oobn, _, _, err := uc.ReadMsgUnix(buf, oob)
+ closeUnix.Stop()
+
+ scms, err := syscall.ParseSocketControlMessage(oob[:oobn])
+ if err != nil {
+ t.Fatalf("ParseSocketControlMessage: %v", err)
+ }
+ if len(scms) != 1 {
+ t.Fatalf("expected 1 SocketControlMessage; got scms = %#v", scms)
+ }
+ scm := scms[0]
+ gotFds, err := syscall.ParseUnixRights(&scm)
+ if err != nil {
+ t.Fatalf("syscall.ParseUnixRights: %v", err)
+ }
+ if len(gotFds) != 1 {
+ t.Fatalf("wanted 1 fd; got %#v", gotFds)
+ }
+
+ f := os.NewFile(uintptr(gotFds[0]), "fd-from-child")
+ defer f.Close()
+
+ got, err := ioutil.ReadAll(f)
+ want := "Hello from child process!\n"
+ if string(got) != want {
+ t.Errorf("child process ReadAll: %q, %v; want %q", got, err, want)
+ }
+}
+
+// passFDChild is the child process used by TestPassFD.
+func passFDChild() {
+ defer os.Exit(0)
+
+ // Look for our fd. It should be fd 3, but we work around an fd leak
+ // bug here (http://golang.org/issue/2603) to let it be elsewhere.
+ var uc *net.UnixConn
+ for fd := uintptr(3); fd <= 10; fd++ {
+ f := os.NewFile(fd, "unix-conn")
+ var ok bool
+ netc, _ := net.FileConn(f)
+ uc, ok = netc.(*net.UnixConn)
+ if ok {
+ break
+ }
+ }
+ if uc == nil {
+ fmt.Println("failed to find unix fd")
+ return
+ }
+
+ // Make a file f to send to our parent process on uc.
+ // We make it in tempDir, which our parent will clean up.
+ flag.Parse()
+ tempDir := flag.Arg(0)
+ f, err := ioutil.TempFile(tempDir, "")
+ if err != nil {
+ fmt.Printf("TempFile: %v", err)
+ return
+ }
+
+ f.Write([]byte("Hello from child process!\n"))
+ f.Seek(0, 0)
+
+ rights := syscall.UnixRights(int(f.Fd()))
+ dummyByte := []byte("x")
+ n, oobn, err := uc.WriteMsgUnix(dummyByte, rights, nil)
+ if err != nil {
+ fmt.Printf("WriteMsgUnix: %v", err)
+ return
+ }
+ if n != 1 || oobn != len(rights) {
+ fmt.Printf("WriteMsgUnix = %d, %d; want 1, %d", n, oobn, len(rights))
+ return
+ }
+}