// Based on ssh/terminal:
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build linux darwin freebsd openbsd netbsd dragonfly
// +build !appengine

package logrus

import (
	"io"
	"os"
	"unsafe"

	"golang.org/x/sys/unix"
)

// IsTerminal returns true if stderr's file descriptor is a terminal.
func IsTerminal(f io.Writer) bool {
	var termios Termios
	switch v := f.(type) {
	case *os.File:
		_, _, err := unix.Syscall6(unix.SYS_IOCTL, uintptr(v.Fd()), ioctlReadTermios, uintptr(unsafe.Pointer(&termios)), 0, 0, 0)
		return err == 0
	default:
		return false
	}
}