gistfile1.txt

// +build windows

package util

// Copyright (c) Yasuhiro MATSUMOTO <mattn.jp@gmail.com>
//
// MIT License (Expat)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

import (
	"strings"
	"syscall"
	"unicode/utf16"
	"unsafe"
)

const (
	fileNameInfo uintptr = 2
	fileTypePipe         = 3
)

var (
	kernel32                         = syscall.NewLazyDLL("kernel32.dll")
	procGetConsoleMode               = kernel32.NewProc("GetConsoleMode")
	procGetFileInformationByHandleEx = kernel32.NewProc("GetFileInformationByHandleEx")
	procGetFileType                  = kernel32.NewProc("GetFileType")
)

func init() {
	// Check if GetFileInformationByHandleEx is available.
	if procGetFileInformationByHandleEx.Find() != nil {
		procGetFileInformationByHandleEx = nil
	}
}

func isTTY(fd int) bool {
	ptrFD := (uintptr)(unsafe.Pointer(&fd))
	return isTerminal(ptrFD) || isCygwinTerminal(ptrFD)
}

// isTerminal return true if the file descriptor is terminal.
func isTerminal(fd uintptr) bool {
	var st uint32
	r, _, e := syscall.Syscall(procGetConsoleMode.Addr(), 2, fd, uintptr(unsafe.Pointer(&st)), 0)
	return r != 0 && e == 0
}

// Check pipe name is used for cygwin/msys2 pty.
// Cygwin/MSYS2 PTY has a name like:
//   \{cygwin,msys}-XXXXXXXXXXXXXXXX-ptyN-{from,to}-master
func isCygwinPipeName(name string) bool {
	token := strings.Split(name, "-")
	if len(token) < 5 {
		return false
	}

	if token[0] != `\msys` && token[0] != `\cygwin` {
		return false
	}

	if token[1] == "" {
		return false
	}

	if !strings.HasPrefix(token[2], "pty") {
		return false
	}

	if token[3] != `from` && token[3] != `to` {
		return false
	}

	if token[4] != "master" {
		return false
	}

	return true
}

// IsCygwinTerminal() return true if the file descriptor is a cygwin or msys2
// terminal.
func isCygwinTerminal(fd uintptr) bool {
	if procGetFileInformationByHandleEx == nil {
		return false
	}

	// Cygwin/msys's pty is a pipe.
	ft, _, e := syscall.Syscall(procGetFileType.Addr(), 1, fd, 0, 0)
	if ft != fileTypePipe || e != 0 {
		return false
	}

	var buf [2 + syscall.MAX_PATH]uint16
	r, _, e := syscall.Syscall6(procGetFileInformationByHandleEx.Addr(),
		4, fd, fileNameInfo, uintptr(unsafe.Pointer(&buf)),
		uintptr(len(buf)*2), 0, 0)
	if r == 0 || e != 0 {
		return false
	}

	l := *(*uint32)(unsafe.Pointer(&buf))
	return isCygwinPipeName(string(utf16.Decode(buf[2 : 2+l/2])))
}