Merge commit 'db4fa08d4da3cc840e6f97e6869a877f2b4c9474' as 'waflib'

1 files changed, 1021 insertions, 0 deletions

diff --git a/waflib/Utils.py b/waflib/Utils.py
new file mode 100644
index 0000000..b4665c4
--- /dev/null
+++ b/waflib/Utils.py
@@ -0,0 +1,1021 @@
+#!/usr/bin/env python
+# encoding: utf-8
+# Thomas Nagy, 2005-2018 (ita)
+
+"""
+Utilities and platform-specific fixes
+
+The portability fixes try to provide a consistent behavior of the Waf API
+through Python versions 2.5 to 3.X and across different platforms (win32, linux, etc)
+"""
+
+from __future__ import with_statement
+
+import atexit, os, sys, errno, inspect, re, datetime, platform, base64, signal, functools, time
+
+try:
+	import cPickle
+except ImportError:
+	import pickle as cPickle
+
+# leave this
+if os.name == 'posix' and sys.version_info[0] < 3:
+	try:
+		import subprocess32 as subprocess
+	except ImportError:
+		import subprocess
+else:
+	import subprocess
+
+try:
+	TimeoutExpired = subprocess.TimeoutExpired
+except AttributeError:
+	class TimeoutExpired(Exception):
+		pass
+
+from collections import deque, defaultdict
+
+try:
+	import _winreg as winreg
+except ImportError:
+	try:
+		import winreg
+	except ImportError:
+		winreg = None
+
+from waflib import Errors
+
+try:
+	from hashlib import md5
+except ImportError:
+	try:
+		from md5 import md5
+	except ImportError:
+		# never fail to enable fixes from another module
+		pass
+
+try:
+	import threading
+except ImportError:
+	if not 'JOBS' in os.environ:
+		# no threading :-(
+		os.environ['JOBS'] = '1'
+
+	class threading(object):
+		"""
+		A fake threading class for platforms lacking the threading module.
+		Use ``waf -j1`` on those platforms
+		"""
+		pass
+	class Lock(object):
+		"""Fake Lock class"""
+		def acquire(self):
+			pass
+		def release(self):
+			pass
+	threading.Lock = threading.Thread = Lock
+
+SIG_NIL = 'SIG_NIL_SIG_NIL_'.encode()
+"""Arbitrary null value for hashes. Modify this value according to the hash function in use"""
+
+O644 = 420
+"""Constant representing the permissions for regular files (0644 raises a syntax error on python 3)"""
+
+O755 = 493
+"""Constant representing the permissions for executable files (0755 raises a syntax error on python 3)"""
+
+rot_chr = ['\\', '|', '/', '-']
+"List of characters to use when displaying the throbber (progress bar)"
+
+rot_idx = 0
+"Index of the current throbber character (progress bar)"
+
+class ordered_iter_dict(dict):
+	"""Ordered dictionary that provides iteration from the most recently inserted keys first"""
+	def __init__(self, *k, **kw):
+		self.lst = deque()
+		dict.__init__(self, *k, **kw)
+	def clear(self):
+		dict.clear(self)
+		self.lst = deque()
+	def __setitem__(self, key, value):
+		if key in dict.keys(self):
+			self.lst.remove(key)
+		dict.__setitem__(self, key, value)
+		self.lst.append(key)
+	def __delitem__(self, key):
+		dict.__delitem__(self, key)
+		try:
+			self.lst.remove(key)
+		except ValueError:
+			pass
+	def __iter__(self):
+		return reversed(self.lst)
+	def keys(self):
+		return reversed(self.lst)
+
+class lru_node(object):
+	"""
+	Used by :py:class:`waflib.Utils.lru_cache`
+	"""
+	__slots__ = ('next', 'prev', 'key', 'val')
+	def __init__(self):
+		self.next = self
+		self.prev = self
+		self.key = None
+		self.val = None
+
+class lru_cache(object):
+	"""
+	A simple least-recently used cache with lazy allocation
+	"""
+	__slots__ = ('maxlen', 'table', 'head')
+	def __init__(self, maxlen=100):
+		self.maxlen = maxlen
+		"""
+		Maximum amount of elements in the cache
+		"""
+		self.table = {}
+		"""
+		Mapping key-value
+		"""
+		self.head = lru_node()
+		self.head.next = self.head
+		self.head.prev = self.head
+
+	def __getitem__(self, key):
+		node = self.table[key]
+		# assert(key==node.key)
+		if node is self.head:
+			return node.val
+
+		# detach the node found
+		node.prev.next = node.next
+		node.next.prev = node.prev
+
+		# replace the head
+		node.next = self.head.next
+		node.prev = self.head
+		self.head = node.next.prev = node.prev.next = node
+
+		return node.val
+
+	def __setitem__(self, key, val):
+		if key in self.table:
+			# update the value for an existing key
+			node = self.table[key]
+			node.val = val
+			self.__getitem__(key)
+		else:
+			if len(self.table) < self.maxlen:
+				# the very first item is unused until the maximum is reached
+				node = lru_node()
+				node.prev = self.head
+				node.next = self.head.next
+				node.prev.next = node.next.prev = node
+			else:
+				node = self.head = self.head.next
+				try:
+					# that's another key
+					del self.table[node.key]
+				except KeyError:
+					pass
+
+			node.key = key
+			node.val = val
+			self.table[key] = node
+
+class lazy_generator(object):
+	def __init__(self, fun, params):
+		self.fun = fun
+		self.params = params
+
+	def __iter__(self):
+		return self
+
+	def __next__(self):
+		try:
+			it = self.it
+		except AttributeError:
+			it = self.it = self.fun(*self.params)
+		return next(it)
+
+	next = __next__
+
+is_win32 = os.sep == '\\' or sys.platform == 'win32' # msys2
+"""
+Whether this system is a Windows series
+"""
+
+def readf(fname, m='r', encoding='latin-1'):
+	"""
+	Reads an entire file into a string. See also :py:meth:`waflib.Node.Node.readf`::
+
+		def build(ctx):
+			from waflib import Utils
+			txt = Utils.readf(self.path.find_node('wscript').abspath())
+			txt = ctx.path.find_node('wscript').read()
+
+	:type  fname: string
+	:param fname: Path to file
+	:type  m: string
+	:param m: Open mode
+	:type encoding: string
+	:param encoding: encoding value, only used for python 3
+	:rtype: string
+	:return: Content of the file
+	"""
+
+	if sys.hexversion > 0x3000000 and not 'b' in m:
+		m += 'b'
+		with open(fname, m) as f:
+			txt = f.read()
+		if encoding:
+			txt = txt.decode(encoding)
+		else:
+			txt = txt.decode()
+	else:
+		with open(fname, m) as f:
+			txt = f.read()
+	return txt
+
+def writef(fname, data, m='w', encoding='latin-1'):
+	"""
+	Writes an entire file from a string.
+	See also :py:meth:`waflib.Node.Node.writef`::
+
+		def build(ctx):
+			from waflib import Utils
+			txt = Utils.writef(self.path.make_node('i_like_kittens').abspath(), 'some data')
+			self.path.make_node('i_like_kittens').write('some data')
+
+	:type  fname: string
+	:param fname: Path to file
+	:type   data: string
+	:param  data: The contents to write to the file
+	:type  m: string
+	:param m: Open mode
+	:type encoding: string
+	:param encoding: encoding value, only used for python 3
+	"""
+	if sys.hexversion > 0x3000000 and not 'b' in m:
+		data = data.encode(encoding)
+		m += 'b'
+	with open(fname, m) as f:
+		f.write(data)
+
+def h_file(fname):
+	"""
+	Computes a hash value for a file by using md5. Use the md5_tstamp
+	extension to get faster build hashes if necessary.
+
+	:type fname: string
+	:param fname: path to the file to hash
+	:return: hash of the file contents
+	:rtype: string or bytes
+	"""
+	m = md5()
+	with open(fname, 'rb') as f:
+		while fname:
+			fname = f.read(200000)
+			m.update(fname)
+	return m.digest()
+
+def readf_win32(f, m='r', encoding='latin-1'):
+	flags = os.O_NOINHERIT | os.O_RDONLY
+	if 'b' in m:
+		flags |= os.O_BINARY
+	if '+' in m:
+		flags |= os.O_RDWR
+	try:
+		fd = os.open(f, flags)
+	except OSError:
+		raise IOError('Cannot read from %r' % f)
+
+	if sys.hexversion > 0x3000000 and not 'b' in m:
+		m += 'b'
+		with os.fdopen(fd, m) as f:
+			txt = f.read()
+		if encoding:
+			txt = txt.decode(encoding)
+		else:
+			txt = txt.decode()
+	else:
+		with os.fdopen(fd, m) as f:
+			txt = f.read()
+	return txt
+
+def writef_win32(f, data, m='w', encoding='latin-1'):
+	if sys.hexversion > 0x3000000 and not 'b' in m:
+		data = data.encode(encoding)
+		m += 'b'
+	flags = os.O_CREAT | os.O_TRUNC | os.O_WRONLY | os.O_NOINHERIT
+	if 'b' in m:
+		flags |= os.O_BINARY
+	if '+' in m:
+		flags |= os.O_RDWR
+	try:
+		fd = os.open(f, flags)
+	except OSError:
+		raise OSError('Cannot write to %r' % f)
+	with os.fdopen(fd, m) as f:
+		f.write(data)
+
+def h_file_win32(fname):
+	try:
+		fd = os.open(fname, os.O_BINARY | os.O_RDONLY | os.O_NOINHERIT)
+	except OSError:
+		raise OSError('Cannot read from %r' % fname)
+	m = md5()
+	with os.fdopen(fd, 'rb') as f:
+		while fname:
+			fname = f.read(200000)
+			m.update(fname)
+	return m.digest()
+
+# always save these
+readf_unix = readf
+writef_unix = writef
+h_file_unix = h_file
+if hasattr(os, 'O_NOINHERIT') and sys.hexversion < 0x3040000:
+	# replace the default functions
+	readf = readf_win32
+	writef = writef_win32
+	h_file = h_file_win32
+
+try:
+	x = ''.encode('hex')
+except LookupError:
+	import binascii
+	def to_hex(s):
+		ret = binascii.hexlify(s)
+		if not isinstance(ret, str):
+			ret = ret.decode('utf-8')
+		return ret
+else:
+	def to_hex(s):
+		return s.encode('hex')
+
+to_hex.__doc__ = """
+Return the hexadecimal representation of a string
+
+:param s: string to convert
+:type s: string
+"""
+
+def listdir_win32(s):
+	"""
+	Lists the contents of a folder in a portable manner.
+	On Win32, returns the list of drive letters: ['C:', 'X:', 'Z:'] when an empty string is given.
+
+	:type s: string
+	:param s: a string, which can be empty on Windows
+	"""
+	if not s:
+		try:
+			import ctypes
+		except ImportError:
+			# there is nothing much we can do
+			return [x + ':\\' for x in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ']
+		else:
+			dlen = 4 # length of "?:\\x00"
+			maxdrives = 26
+			buf = ctypes.create_string_buffer(maxdrives * dlen)
+			ndrives = ctypes.windll.kernel32.GetLogicalDriveStringsA(maxdrives*dlen, ctypes.byref(buf))
+			return [ str(buf.raw[4*i:4*i+2].decode('ascii')) for i in range(int(ndrives/dlen)) ]
+
+	if len(s) == 2 and s[1] == ":":
+		s += os.sep
+
+	if not os.path.isdir(s):
+		e = OSError('%s is not a directory' % s)
+		e.errno = errno.ENOENT
+		raise e
+	return os.listdir(s)
+
+listdir = os.listdir
+if is_win32:
+	listdir = listdir_win32
+
+def num2ver(ver):
+	"""
+	Converts a string, tuple or version number into an integer. The number is supposed to have at most 4 digits::
+
+		from waflib.Utils import num2ver
+		num2ver('1.3.2') == num2ver((1,3,2)) == num2ver((1,3,2,0))
+
+	:type ver: string or tuple of numbers
+	:param ver: a version number
+	"""
+	if isinstance(ver, str):
+		ver = tuple(ver.split('.'))
+	if isinstance(ver, tuple):
+		ret = 0
+		for i in range(4):
+			if i < len(ver):
+				ret += 256**(3 - i) * int(ver[i])
+		return ret
+	return ver
+
+def to_list(val):
+	"""
+	Converts a string argument to a list by splitting it by spaces.
+	Returns the object if not a string::
+
+		from waflib.Utils import to_list
+		lst = to_list('a b c d')
+
+	:param val: list of string or space-separated string
+	:rtype: list
+	:return: Argument converted to list
+	"""
+	if isinstance(val, str):
+		return val.split()
+	else:
+		return val
+
+def console_encoding():
+	try:
+		import ctypes
+	except ImportError:
+		pass
+	else:
+		try:
+			codepage = ctypes.windll.kernel32.GetConsoleCP()
+		except AttributeError:
+			pass
+		else:
+			if codepage:
+				return 'cp%d' % codepage
+	return sys.stdout.encoding or ('cp1252' if is_win32 else 'latin-1')
+
+def split_path_unix(path):
+	return path.split('/')
+
+def split_path_cygwin(path):
+	if path.startswith('//'):
+		ret = path.split('/')[2:]
+		ret[0] = '/' + ret[0]
+		return ret
+	return path.split('/')
+
+re_sp = re.compile('[/\\\\]+')
+def split_path_win32(path):
+	if path.startswith('\\\\'):
+		ret = re_sp.split(path)[1:]
+		ret[0] = '\\\\' + ret[0]
+		if ret[0] == '\\\\?':
+			return ret[1:]
+		return ret
+	return re_sp.split(path)
+
+msysroot = None
+def split_path_msys(path):
+	if path.startswith(('/', '\\')) and not path.startswith(('//', '\\\\')):
+		# msys paths can be in the form /usr/bin
+		global msysroot
+		if not msysroot:
+			# msys has python 2.7 or 3, so we can use this
+			msysroot = subprocess.check_output(['cygpath', '-w', '/']).decode(sys.stdout.encoding or 'latin-1')
+			msysroot = msysroot.strip()
+		path = os.path.normpath(msysroot + os.sep + path)
+	return split_path_win32(path)
+
+if sys.platform == 'cygwin':
+	split_path = split_path_cygwin
+elif is_win32:
+	if os.environ.get('MSYSTEM'):
+		split_path = split_path_msys
+	else:
+		split_path = split_path_win32
+else:
+	split_path = split_path_unix
+
+split_path.__doc__ = """
+Splits a path by / or \\; do not confuse this function with with ``os.path.split``
+
+:type  path: string
+:param path: path to split
+:return:     list of string
+"""
+
+def check_dir(path):
+	"""
+	Ensures that a directory exists (similar to ``mkdir -p``).
+
+	:type  path: string
+	:param path: Path to directory
+	:raises: :py:class:`waflib.Errors.WafError` if the folder cannot be added.
+	"""
+	if not os.path.isdir(path):
+		try:
+			os.makedirs(path)
+		except OSError as e:
+			if not os.path.isdir(path):
+				raise Errors.WafError('Cannot create the folder %r' % path, ex=e)
+
+def check_exe(name, env=None):
+	"""
+	Ensures that a program exists
+
+	:type name: string
+	:param name: path to the program
+	:param env: configuration object
+	:type env: :py:class:`waflib.ConfigSet.ConfigSet`
+	:return: path of the program or None
+	:raises: :py:class:`waflib.Errors.WafError` if the folder cannot be added.
+	"""
+	if not name:
+		raise ValueError('Cannot execute an empty string!')
+	def is_exe(fpath):
+		return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
+
+	fpath, fname = os.path.split(name)
+	if fpath and is_exe(name):
+		return os.path.abspath(name)
+	else:
+		env = env or os.environ
+		for path in env['PATH'].split(os.pathsep):
+			path = path.strip('"')
+			exe_file = os.path.join(path, name)
+			if is_exe(exe_file):
+				return os.path.abspath(exe_file)
+	return None
+
+def def_attrs(cls, **kw):
+	"""
+	Sets default attributes on a class instance
+
+	:type cls: class
+	:param cls: the class to update the given attributes in.
+	:type kw: dict
+	:param kw: dictionary of attributes names and values.
+	"""
+	for k, v in kw.items():
+		if not hasattr(cls, k):
+			setattr(cls, k, v)
+
+def quote_define_name(s):
+	"""
+	Converts a string into an identifier suitable for C defines.
+
+	:type  s: string
+	:param s: String to convert
+	:rtype: string
+	:return: Identifier suitable for C defines
+	"""
+	fu = re.sub('[^a-zA-Z0-9]', '_', s)
+	fu = re.sub('_+', '_', fu)
+	fu = fu.upper()
+	return fu
+
+re_sh = re.compile('\\s|\'|"')
+"""
+Regexp used for shell_escape below
+"""
+
+def shell_escape(cmd):
+	"""
+	Escapes a command:
+	['ls', '-l', 'arg space'] -> ls -l 'arg space'
+	"""
+	if isinstance(cmd, str):
+		return cmd
+	return ' '.join(repr(x) if re_sh.search(x) else x for x in cmd)
+
+def h_list(lst):
+	"""
+	Hashes lists of ordered data.
+
+	Using hash(tup) for tuples would be much more efficient,
+	but Python now enforces hash randomization
+
+	:param lst: list to hash
+	:type lst: list of strings
+	:return: hash of the list
+	"""
+	return md5(repr(lst).encode()).digest()
+
+def h_fun(fun):
+	"""
+	Hash functions
+
+	:param fun: function to hash
+	:type  fun: function
+	:return: hash of the function
+	:rtype: string or bytes
+	"""
+	try:
+		return fun.code
+	except AttributeError:
+		if isinstance(fun, functools.partial):
+			code = list(fun.args)
+			# The method items() provides a sequence of tuples where the first element
+			# represents an optional argument of the partial function application
+			#
+			# The sorting result outcome will be consistent because:
+			# 1. tuples are compared in order of their elements
+			# 2. optional argument namess are unique
+			code.extend(sorted(fun.keywords.items()))
+			code.append(h_fun(fun.func))
+			fun.code = h_list(code)
+			return fun.code
+		try:
+			h = inspect.getsource(fun)
+		except EnvironmentError:
+			h = 'nocode'
+		try:
+			fun.code = h
+		except AttributeError:
+			pass
+		return h
+
+def h_cmd(ins):
+	"""
+	Hashes objects recursively
+
+	:param ins: input object
+	:type ins: string or list or tuple or function
+	:rtype: string or bytes
+	"""
+	# this function is not meant to be particularly fast
+	if isinstance(ins, str):
+		# a command is either a string
+		ret = ins
+	elif isinstance(ins, list) or isinstance(ins, tuple):
+		# or a list of functions/strings
+		ret = str([h_cmd(x) for x in ins])
+	else:
+		# or just a python function
+		ret = str(h_fun(ins))
+	if sys.hexversion > 0x3000000:
+		ret = ret.encode('latin-1', 'xmlcharrefreplace')
+	return ret
+
+reg_subst = re.compile(r"(\\\\)|(\$\$)|\$\{([^}]+)\}")
+def subst_vars(expr, params):
+	"""
+	Replaces ${VAR} with the value of VAR taken from a dict or a config set::
+
+		from waflib import Utils
+		s = Utils.subst_vars('${PREFIX}/bin', env)
+
+	:type  expr: string
+	:param expr: String to perform substitution on
+	:param params: Dictionary or config set to look up variable values.
+	"""
+	def repl_var(m):
+		if m.group(1):
+			return '\\'
+		if m.group(2):
+			return '$'
+		try:
+			# ConfigSet instances may contain lists
+			return params.get_flat(m.group(3))
+		except AttributeError:
+			return params[m.group(3)]
+		# if you get a TypeError, it means that 'expr' is not a string...
+		# Utils.subst_vars(None, env)  will not work
+	return reg_subst.sub(repl_var, expr)
+
+def destos_to_binfmt(key):
+	"""
+	Returns the binary format based on the unversioned platform name,
+	and defaults to ``elf`` if nothing is found.
+
+	:param key: platform name
+	:type  key: string
+	:return: string representing the binary format
+	"""
+	if key == 'darwin':
+		return 'mac-o'
+	elif key in ('win32', 'cygwin', 'uwin', 'msys'):
+		return 'pe'
+	return 'elf'
+
+def unversioned_sys_platform():
+	"""
+	Returns the unversioned platform name.
+	Some Python platform names contain versions, that depend on
+	the build environment, e.g. linux2, freebsd6, etc.
+	This returns the name without the version number. Exceptions are
+	os2 and win32, which are returned verbatim.
+
+	:rtype: string
+	:return: Unversioned platform name
+	"""
+	s = sys.platform
+	if s.startswith('java'):
+		# The real OS is hidden under the JVM.
+		from java.lang import System
+		s = System.getProperty('os.name')
+		# see http://lopica.sourceforge.net/os.html for a list of possible values
+		if s == 'Mac OS X':
+			return 'darwin'
+		elif s.startswith('Windows '):
+			return 'win32'
+		elif s == 'OS/2':
+			return 'os2'
+		elif s == 'HP-UX':
+			return 'hp-ux'
+		elif s in ('SunOS', 'Solaris'):
+			return 'sunos'
+		else: s = s.lower()
+
+	# powerpc == darwin for our purposes
+	if s == 'powerpc':
+		return 'darwin'
+	if s == 'win32' or s == 'os2':
+		return s
+	if s == 'cli' and os.name == 'nt':
+		# ironpython is only on windows as far as we know
+		return 'win32'
+	return re.split('\d+$', s)[0]
+
+def nada(*k, **kw):
+	"""
+	Does nothing
+
+	:return: None
+	"""
+	pass
+
+class Timer(object):
+	"""
+	Simple object for timing the execution of commands.
+	Its string representation is the duration::
+
+		from waflib.Utils import Timer
+		timer = Timer()
+		a_few_operations()
+		s = str(timer)
+	"""
+	def __init__(self):
+		self.start_time = self.now()
+
+	def __str__(self):
+		delta = self.now() - self.start_time
+		if not isinstance(delta, datetime.timedelta):
+			delta = datetime.timedelta(seconds=delta)
+		days = delta.days
+		hours, rem = divmod(delta.seconds, 3600)
+		minutes, seconds = divmod(rem, 60)
+		seconds += delta.microseconds * 1e-6
+		result = ''
+		if days:
+			result += '%dd' % days
+		if days or hours:
+			result += '%dh' % hours
+		if days or hours or minutes:
+			result += '%dm' % minutes
+		return '%s%.3fs' % (result, seconds)
+
+	def now(self):
+		return datetime.datetime.utcnow()
+
+	if hasattr(time, 'perf_counter'):
+		def now(self):
+			return time.perf_counter()
+
+def read_la_file(path):
+	"""
+	Reads property files, used by msvc.py
+
+	:param path: file to read
+	:type path: string
+	"""
+	sp = re.compile(r'^([^=]+)=\'(.*)\'$')
+	dc = {}
+	for line in readf(path).splitlines():
+		try:
+			_, left, right, _ = sp.split(line.strip())
+			dc[left] = right
+		except ValueError:
+			pass
+	return dc
+
+def run_once(fun):
+	"""
+	Decorator: let a function cache its results, use like this::
+
+		@run_once
+		def foo(k):
+			return 345*2343
+
+	.. note:: in practice this can cause memory leaks, prefer a :py:class:`waflib.Utils.lru_cache`
+
+	:param fun: function to execute
+	:type fun: function
+	:return: the return value of the function executed
+	"""
+	cache = {}
+	def wrap(*k):
+		try:
+			return cache[k]
+		except KeyError:
+			ret = fun(*k)
+			cache[k] = ret
+			return ret
+	wrap.__cache__ = cache
+	wrap.__name__ = fun.__name__
+	return wrap
+
+def get_registry_app_path(key, filename):
+	"""
+	Returns the value of a registry key for an executable
+
+	:type key: string
+	:type filename: list of string
+	"""
+	if not winreg:
+		return None
+	try:
+		result = winreg.QueryValue(key, "Software\\Microsoft\\Windows\\CurrentVersion\\App Paths\\%s.exe" % filename[0])
+	except OSError:
+		pass
+	else:
+		if os.path.isfile(result):
+			return result
+
+def lib64():
+	"""
+	Guess the default ``/usr/lib`` extension for 64-bit applications
+
+	:return: '64' or ''
+	:rtype: string
+	"""
+	# default settings for /usr/lib
+	if os.sep == '/':
+		if platform.architecture()[0] == '64bit':
+			if os.path.exists('/usr/lib64') and not os.path.exists('/usr/lib32'):
+				return '64'
+	return ''
+
+def sane_path(p):
+	# private function for the time being!
+	return os.path.abspath(os.path.expanduser(p))
+
+process_pool = []
+"""
+List of processes started to execute sub-process commands
+"""
+
+def get_process():
+	"""
+	Returns a process object that can execute commands as sub-processes
+
+	:rtype: subprocess.Popen
+	"""
+	try:
+		return process_pool.pop()
+	except IndexError:
+		filepath = os.path.dirname(os.path.abspath(__file__)) + os.sep + 'processor.py'
+		cmd = [sys.executable, '-c', readf(filepath)]
+		return subprocess.Popen(cmd, stdout=subprocess.PIPE, stdin=subprocess.PIPE, bufsize=0)
+
+def run_prefork_process(cmd, kwargs, cargs):
+	"""
+	Delegates process execution to a pre-forked process instance.
+	"""
+	if not 'env' in kwargs:
+		kwargs['env'] = dict(os.environ)
+	try:
+		obj = base64.b64encode(cPickle.dumps([cmd, kwargs, cargs]))
+	except (TypeError, AttributeError):
+		return run_regular_process(cmd, kwargs, cargs)
+
+	proc = get_process()
+	if not proc:
+		return run_regular_process(cmd, kwargs, cargs)
+
+	proc.stdin.write(obj)
+	proc.stdin.write('\n'.encode())
+	proc.stdin.flush()
+	obj = proc.stdout.readline()
+	if not obj:
+		raise OSError('Preforked sub-process %r died' % proc.pid)
+
+	process_pool.append(proc)
+	lst = cPickle.loads(base64.b64decode(obj))
+	# Jython wrapper failures (bash/execvp)
+	assert len(lst) == 5
+	ret, out, err, ex, trace = lst
+	if ex:
+		if ex == 'OSError':
+			raise OSError(trace)
+		elif ex == 'ValueError':
+			raise ValueError(trace)
+		elif ex == 'TimeoutExpired':
+			exc = TimeoutExpired(cmd, timeout=cargs['timeout'], output=out)
+			exc.stderr = err
+			raise exc
+		else:
+			raise Exception(trace)
+	return ret, out, err
+
+def lchown(path, user=-1, group=-1):
+	"""
+	Change the owner/group of a path, raises an OSError if the
+	ownership change fails.
+
+	:param user: user to change
+	:type user: int or str
+	:param group: group to change
+	:type group: int or str
+	"""
+	if isinstance(user, str):
+		import pwd
+		entry = pwd.getpwnam(user)
+		if not entry:
+			raise OSError('Unknown user %r' % user)
+		user = entry[2]
+	if isinstance(group, str):
+		import grp
+		entry = grp.getgrnam(group)
+		if not entry:
+			raise OSError('Unknown group %r' % group)
+		group = entry[2]
+	return os.lchown(path, user, group)
+
+def run_regular_process(cmd, kwargs, cargs={}):
+	"""
+	Executes a subprocess command by using subprocess.Popen
+	"""
+	proc = subprocess.Popen(cmd, **kwargs)
+	if kwargs.get('stdout') or kwargs.get('stderr'):
+		try:
+			out, err = proc.communicate(**cargs)
+		except TimeoutExpired:
+			if kwargs.get('start_new_session') and hasattr(os, 'killpg'):
+				os.killpg(proc.pid, signal.SIGKILL)
+			else:
+				proc.kill()
+			out, err = proc.communicate()
+			exc = TimeoutExpired(proc.args, timeout=cargs['timeout'], output=out)
+			exc.stderr = err
+			raise exc
+		status = proc.returncode
+	else:
+		out, err = (None, None)
+		try:
+			status = proc.wait(**cargs)
+		except TimeoutExpired as e:
+			if kwargs.get('start_new_session') and hasattr(os, 'killpg'):
+				os.killpg(proc.pid, signal.SIGKILL)
+			else:
+				proc.kill()
+			proc.wait()
+			raise e
+	return status, out, err
+
+def run_process(cmd, kwargs, cargs={}):
+	"""
+	Executes a subprocess by using a pre-forked process when possible
+	or falling back to subprocess.Popen. See :py:func:`waflib.Utils.run_prefork_process`
+	and :py:func:`waflib.Utils.run_regular_process`
+	"""
+	if kwargs.get('stdout') and kwargs.get('stderr'):
+		return run_prefork_process(cmd, kwargs, cargs)
+	else:
+		return run_regular_process(cmd, kwargs, cargs)
+
+def alloc_process_pool(n, force=False):
+	"""
+	Allocates an amount of processes to the default pool so its size is at least *n*.
+	It is useful to call this function early so that the pre-forked
+	processes use as little memory as possible.
+
+	:param n: pool size
+	:type n: integer
+	:param force: if True then *n* more processes are added to the existing pool
+	:type force: bool
+	"""
+	# mandatory on python2, unnecessary on python >= 3.2
+	global run_process, get_process, alloc_process_pool
+	if not force:
+		n = max(n - len(process_pool), 0)
+	try:
+		lst = [get_process() for x in range(n)]
+	except OSError:
+		run_process = run_regular_process
+		get_process = alloc_process_pool = nada
+	else:
+		for x in lst:
+			process_pool.append(x)
+
+def atexit_pool():
+	for k in process_pool:
+		try:
+			os.kill(k.pid, 9)
+		except OSError:
+			pass
+		else:
+			k.wait()
+# see #1889
+if (sys.hexversion<0x207000f and not is_win32) or sys.hexversion>=0x306000f:
+	atexit.register(atexit_pool)
+
+if os.environ.get('WAF_NO_PREFORK') or sys.platform == 'cli' or not sys.executable:
+	run_process = run_regular_process
+	get_process = alloc_process_pool = nada
+