# Copyright 2013 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.


import sys


def IsWindows():
    return sys.platform in ['win32', 'cygwin']


def IsLinux():
    return sys.platform.startswith(('linux', 'freebsd', 'netbsd', 'openbsd'))


def IsMac():
    return sys.platform == 'darwin'


def host_os():
    """
    Returns a string representing the host_os of the current system.
    Possible values: 'win', 'mac', 'linux', 'unknown'.
    """
    if IsWindows():
        return 'win'
    elif IsLinux():
        return 'linux'
    elif IsMac():
        return 'mac'
    else:
        return 'unknown'