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// 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
}
}
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