internal/poll, os/exec, runtime: replace PollDescriptor by IsPollDescriptor

This commit changes poll.PollDescriptor by poll.IsPollDescriptor. This
is needed for OS like AIX which have more than one FD using inside their
netpoll implementation.

Change-Id: I49e12a8d74045c501e19fdd8527cf166a3c64850
Reviewed-on: https://go-review.googlesource.com/c/146938
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/internal/poll/fd_plan9.go

@@ -193,10 +193,10 @@ func isInterrupted(err error) bool {
 	return err != nil && stringsHasSuffix(err.Error(), "interrupted")
 }
 
-// PollDescriptor returns the descriptor being used by the poller,
-// or ^uintptr(0) if there isn't one. This is only used for testing.
-func PollDescriptor() uintptr {
-	return ^uintptr(0)
+// IsPollDescriptor returns true if fd is the descriptor being used by the poller.
+// This is only used for testing.
+func IsPollDescriptor(fd uintptr) bool {
+	return false
 }
 
 // RawControl invokes the user-defined function f for a non-IO

src/internal/poll/fd_poll_nacljs.go

@@ -92,8 +92,8 @@ func setDeadlineImpl(fd *FD, t time.Time, mode int) error {
 	return nil
 }
 
-// PollDescriptor returns the descriptor being used by the poller,
-// or ^uintptr(0) if there isn't one. This is only used for testing.
-func PollDescriptor() uintptr {
-	return ^uintptr(0)
+// IsPollDescriptor returns true if fd is the descriptor being used by the poller.
+// This is only used for testing.
+func IsPollDescriptor(fd uintptr) bool {
+	return false
 }

src/internal/poll/fd_poll_runtime.go

@@ -19,7 +19,6 @@ import (
 func runtimeNano() int64
 
 func runtime_pollServerInit()
-func runtime_pollServerDescriptor() uintptr
 func runtime_pollOpen(fd uintptr) (uintptr, int)
 func runtime_pollClose(ctx uintptr)
 func runtime_pollWait(ctx uintptr, mode int) int
@@ -27,6 +26,7 @@ func runtime_pollWaitCanceled(ctx uintptr, mode int) int
 func runtime_pollReset(ctx uintptr, mode int) int
 func runtime_pollSetDeadline(ctx uintptr, d int64, mode int)
 func runtime_pollUnblock(ctx uintptr)
+func runtime_isPollServerDescriptor(fd uintptr) bool
 
 type pollDesc struct {
 	runtimeCtx uintptr
@@ -154,8 +154,8 @@ func setDeadlineImpl(fd *FD, t time.Time, mode int) error {
 	return nil
 }
 
-// PollDescriptor returns the descriptor being used by the poller,
-// or ^uintptr(0) if there isn't one. This is only used for testing.
-func PollDescriptor() uintptr {
-	return runtime_pollServerDescriptor()
+// IsPollDescriptor returns true if fd is the descriptor being used by the poller.
+// This is only used for testing.
+func IsPollDescriptor(fd uintptr) bool {
+	return runtime_isPollServerDescriptor(fd)
 }

src/os/exec/exec_test.go

@@ -459,7 +459,7 @@ func basefds() uintptr {
 	// The poll (epoll/kqueue) descriptor can be numerically
 	// either between stderr and the testlog-fd, or after
 	// testlog-fd.
-	if poll.PollDescriptor() == n {
+	if poll.IsPollDescriptor(n) {
 		n++
 	}
 	for _, arg := range os.Args {
@@ -472,7 +472,7 @@ func basefds() uintptr {
 
 func closeUnexpectedFds(t *testing.T, m string) {
 	for fd := basefds(); fd <= 101; fd++ {
-		if fd == poll.PollDescriptor() {
+		if poll.IsPollDescriptor(fd) {
 			continue
 		}
 		err := os.NewFile(fd, "").Close()
@@ -734,6 +734,8 @@ func TestHelperProcess(*testing.T) {
 		ofcmd = "fstat"
 	case "plan9":
 		ofcmd = "/bin/cat"
+	case "aix":
+		ofcmd = "procfiles"
 	}
 
 	args := os.Args
@@ -837,7 +839,7 @@ func TestHelperProcess(*testing.T) {
 			// Now verify that there are no other open fds.
 			var files []*os.File
 			for wantfd := basefds() + 1; wantfd <= 100; wantfd++ {
-				if wantfd == poll.PollDescriptor() {
+				if poll.IsPollDescriptor(wantfd) {
 					continue
 				}
 				f, err := os.Open(os.Args[0])
@@ -851,6 +853,8 @@ func TestHelperProcess(*testing.T) {
 					switch runtime.GOOS {
 					case "plan9":
 						args = []string{fmt.Sprintf("/proc/%d/fd", os.Getpid())}
+					case "aix":
+						args = []string{fmt.Sprint(os.Getpid())}
 					default:
 						args = []string{"-p", fmt.Sprint(os.Getpid())}
 					}

src/runtime/netpoll.go

@@ -93,12 +93,19 @@ func netpollinited() bool {
 	return atomic.Load(&netpollInited) != 0
 }
 
-//go:linkname poll_runtime_pollServerDescriptor internal/poll.runtime_pollServerDescriptor
-
-// poll_runtime_pollServerDescriptor returns the descriptor being used,
-// or ^uintptr(0) if the system does not use a poll descriptor.
-func poll_runtime_pollServerDescriptor() uintptr {
-	return netpolldescriptor()
+//go:linkname poll_runtime_isPollServerDescriptor internal/poll.runtime_isPollServerDescriptor
+
+// poll_runtime_isPollServerDescriptor returns true if fd is a
+// descriptor being used by netpoll.
+func poll_runtime_isPollServerDescriptor(fd uintptr) bool {
+	fds := netpolldescriptor()
+	if GOOS != "aix" {
+		return fd == fds
+	} else {
+		// AIX have a pipe in its netpoll implementation.
+		// Therefore, two fd are returned by netpolldescriptor using a mask.
+		return fd == fds&0xFFFF || fd == (fds>>16)&0xFFFF
+	}
 }
 
 //go:linkname poll_runtime_pollOpen internal/poll.runtime_pollOpen