// 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://github.com/timeglass/glass/_vendor/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 := unix.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
}
}
// TestUnixRightsRoundtrip tests that UnixRights, ParseSocketControlMessage,
// and ParseUnixRights are able to successfully round-trip lists of file descriptors.
func TestUnixRightsRoundtrip(t *testing.T) {
testCases := [...][][]int{
{{42}},
{{1, 2}},
{{3, 4, 5}},
{{}},
{{1, 2}, {3, 4, 5}, {}, {7}},
}
for _, testCase := range testCases {
b := []byte{}
var n int
for _, fds := range testCase {
// Last assignment to n wins
n = len(b) + unix.CmsgLen(4*len(fds))
b = append(b, unix.UnixRights(fds...)...)
}
// Truncate b
b = b[:n]
scms, err := unix.ParseSocketControlMessage(b)
if err != nil {
t.Fatalf("ParseSocketControlMessage: %v", err)
}
if len(scms) != len(testCase) {
t.Fatalf("expected %v SocketControlMessage; got scms = %#v", len(testCase), scms)
}
for i, scm := range scms {
gotFds, err := unix.ParseUnixRights(&scm)
if err != nil {
t.Fatalf("ParseUnixRights: %v", err)
}
wantFds := testCase[i]
if len(gotFds) != len(wantFds) {
t.Fatalf("expected %v fds, got %#v", len(wantFds), gotFds)
}
for j, fd := range gotFds {
if fd != wantFds[j] {
t.Fatalf("expected fd %v, got %v", wantFds[j], fd)
}
}
}
}
}