}

	const (
		// F_GETFD, EBADF, O_RDWR are standard across all unixes we support, so
		// we define them here rather than in each of the OS specific files.
		F_GETFD = 0x01
		EBADF   = 0x09
		O_RDWR  = 0x02
	)

	devNull := []byte("/dev/null\x00")
	for i := 0; i < 3; i++ {
		ret, errno := fcntl(int32(i), F_GETFD, 0)
		if ret >= 0 {
			continue
		}

		if errno != EBADF {

import (
	"internal/runtime/syscall"
	"testing"
)

func TestEpollctlErrorSign(t *testing.T) {
	v := syscall.EpollCtl(-1, 1, -1, &syscall.EpollEvent{})

	const EBADF = 0x09
	if v != EBADF {
		t.Errorf("epollctl = %v, want %v", v, EBADF)
	}

	}
	val, errno := runtime.Fcntl(r, syscall.F_GETFD, 0)
	if val != -1 {
		t.Errorf("Fcntl succeeded unexpectedly")
	} else if syscall.Errno(errno) != syscall.EBADF {
		t.Errorf("Fcntl failed with error %v, expected %v", syscall.Errno(errno), syscall.EBADF)
	}
}

func checkIsPipe(t *testing.T, r, w int32) {
	bw := byte(42)
	if n := runtime.Write(uintptr(w), unsafe.Pointer(&bw), 1); n != 1 {

  // give a chance to get opened.
  for (i = 0; i < 200; i++) {
    n = read(fd, buf, sizeof buf);
    if (n >= 0)
      break;
    if (errno != EBADF && errno != EINVAL) {
      fprintf(stderr, "BUG: read: %s\n", strerror(errno));
      return 2;
    }

    // An EBADF error means that the shared library has not opened the
    // descriptor yet.
    ts.tv_sec = 0;
    ts.tv_nsec = 10000000;
    nanosleep(&ts, NULL);
  }

	// we skip fds that aren't sockets. Once we reach EBADF we know there
	// are no more pre-opens.
	for preopenFd := uintptr(3); ; preopenFd++ {
		f := os.NewFile(preopenFd, "")
		l, err := net.FileListener(f)
		f.Close()

		var se syscall.Errno
		switch errors.As(err, &se); se {
		case syscall.ENOTSOCK:
			continue
		case syscall.EBADF:
			err = nil
		}
		return l, err
	}

package fdtest

import (
	"syscall"
)

// Exists returns true if fd is a valid file descriptor.
func Exists(fd uintptr) bool {
	var s syscall.Stat_t
	err := syscall.Fstat(int(fd), &s)
	return err != syscall.EBADF

#include <sys/fork.h>
#include <sys/port.h>
#include <semaphore.h>
#include <errno.h>
#include <signal.h>
#include <pthread.h>
#include <netdb.h>
*/
import "C"

const (
	EINTR       = C.EINTR
	EBADF       = C.EBADF
	EFAULT      = C.EFAULT
	EAGAIN      = C.EAGAIN
	EBUSY       = C.EBUSY
	ETIME       = C.ETIME
	ETIMEDOUT   = C.ETIMEDOUT
	EWOULDBLOCK = C.EWOULDBLOCK
	EINPROGRESS = C.EINPROGRESS

const (
	E2BIG           Errno = 1
	EACCES          Errno = 2
	EADDRINUSE      Errno = 3
	EADDRNOTAVAIL   Errno = 4
	EAFNOSUPPORT    Errno = 5
	EAGAIN          Errno = 6
	EALREADY        Errno = 7
	EBADF           Errno = 8
	EBADMSG         Errno = 9
	EBUSY           Errno = 10
	ECANCELED       Errno = 11
	ECHILD          Errno = 12
	ECONNABORTED    Errno = 13
	ECONNREFUSED    Errno = 14
	ECONNRESET      Errno = 15

// Invented values to support what package os and others expects.
const (
	E2BIG Errno = APPLICATION_ERROR + iota
	EACCES
	EADDRINUSE
	EADDRNOTAVAIL
	EADV
	EAFNOSUPPORT
	EAGAIN
	EALREADY
	EBADE
	EBADF
	EBADFD
	EBADMSG
	EBADR
	EBADRQC
	EBADSLT
	EBFONT
	EBUSY
	ECANCELED
	ECHILD
	ECHRNG
	ECOMM
	ECONNABORTED
	ECONNREFUSED
	ECONNRESET
	EDEADLK
	EDEADLOCK
	EDESTADDRREQ
	EDOM

	"ENOENT":          ENOENT,
	"ESRCH":           ESRCH,
	"EINTR":           EINTR,
	"EIO":             EIO,
	"ENXIO":           ENXIO,
	"E2BIG":           E2BIG,
	"ENOEXEC":         ENOEXEC,
	"EBADF":           EBADF,
	"ECHILD":          ECHILD,
	"EAGAIN":          EAGAIN,
	"ENOMEM":          ENOMEM,
	"EACCES":          EACCES,
	"EFAULT":          EFAULT,
	"EBUSY":           EBUSY,
	"EEXIST":          EEXIST,