// Sigquit is the signal to send to kill a hanging subprocess.
// On Unix we send SIGQUIT, but on non-Unix we only have os.Kill.
var Sigquit = os.Kill

func syscallIsNotSupported(err error) bool {
	return errors.Is(err, fs.ErrPermission) || errors.Is(err, errors.ErrUnsupported)

func findExecutable(file string) error {
	d, err := os.Stat(file)
	if err != nil {
		return err
	}
	if m := d.Mode(); !m.IsDir() && m&0111 != 0 {
		return nil
	}
	return fs.ErrPermission
}

// LookPath searches for an executable named file in the
// directories named by the path environment variable.
// If file begins with "/", "#", "./", or "../", it is tried
// directly and the path is not consulted.

// with whose name starts with a period in its path.
func (fsys dotFileHidingFileSystem) Open(name string) (http.File, error) {
	if containsDotFile(name) { // If dot file, return 403 response
		return nil, fs.ErrPermission
	}

	file, err := fsys.FileSystem.Open(name)
	if err != nil {
		return nil, err
	}
	return dotFileHidingFile{file}, err
}

func ExampleFileServer_dotFileHiding() {

	// In both cases, fall back to checking the permission bits.
	if err == nil || (err != syscall.ENOSYS && err != syscall.EPERM) {
		return err
	}
	if m&0111 != 0 {
		return nil
	}
	return fs.ErrPermission
}

// LookPath searches for an executable named file in the
// directories named by the PATH environment variable.
// If file contains a slash, it is tried directly and the PATH is not consulted.

}

func osIsNotExist(err error) bool {
	return errors.Is(err, os.ErrNotExist)
}

func osIsPermission(err error) bool {
	return errors.Is(err, os.ErrPermission) || errors.Is(err, syscall.EROFS)
}

func osIsExist(err error) bool {
	return errors.Is(err, os.ErrExist)

		return
	}

	hs := make(map[string]byName)
	is := make(map[string][]string)

	file, err := open(hp)
	if err != nil {
		if !errors.Is(err, fs.ErrNotExist) && !errors.Is(err, fs.ErrPermission) {
			return
		}
	}

	if file != nil {
		defer file.close()
		for line, ok := file.readLine(); ok; line, ok = file.readLine() {
			if i := bytealg.IndexByteString(line, '#'); i >= 0 {

var ErrNotFound = errors.New("executable file not found in %PATH%")

func chkStat(file string) error {
	d, err := os.Stat(file)
	if err != nil {
		return err
	}
	if d.IsDir() {
		return fs.ErrPermission
	}
	return nil
}

func hasExt(file string) bool {
	i := strings.LastIndex(file, ".")
	if i < 0 {
		return false
	}
	return strings.LastIndexAny(file, `:\/`) < i
}

		s := errorstr[e]
		if s != "" {
			return s
		}
	}
	return "errno " + itoa.Itoa(int(e))
}

func (e Errno) Is(target error) bool {
	switch target {
	case oserror.ErrPermission:
		return e == EACCES || e == EPERM
	case oserror.ErrExist:
		return e == EEXIST || e == ENOTEMPTY
	case oserror.ErrNotExist:
		return e == ENOENT
	case errorspkg.ErrUnsupported:

	// we can add them here.
	const nonPollable = "/dev/net/tun"

	f, err := os.OpenFile(nonPollable, os.O_RDWR, 0)
	if err != nil {
		if errors.Is(err, fs.ErrNotExist) || errors.Is(err, fs.ErrPermission) || testenv.SyscallIsNotSupported(err) {
			t.Skipf("can't open %q: %v", nonPollable, err)
		}
		t.Fatal(err)
	}
	f.Close()

	// On a Linux laptop, before the problem was fixed,

		s := errorstr[e]
		if s != "" {
			return s
		}
	}
	return "errno " + itoa.Itoa(int(e))
}

func (e Errno) Is(target error) bool {
	switch target {
	case oserror.ErrPermission:
		return e == EACCES || e == EPERM
	case oserror.ErrExist:
		return e == EEXIST || e == ENOTEMPTY
	case oserror.ErrNotExist:
		return e == ENOENT
	case errors.ErrUnsupported:
		return e == ENOSYS
	}