"""distutils.msvc9compiler
Contains MSVCCompiler, an implementation of the abstract CCompiler class
for the Microsoft Visual Studio 2008.
The module is compatible with VS 2005 and VS 2008. You can find legacy support
for older versions of VS in distutils.msvccompiler.
"""
# Written by Perry Stoll
# hacked by Robin Becker and Thomas Heller to do a better job of
# finding DevStudio (through the registry)
# ported to VS2005 and VS 2008 by Christian Heimes
__revision__ = "$Id$"
import os
import subprocess
import sys
import re
from distutils.errors import (DistutilsExecError, DistutilsPlatformError,
CompileError, LibError, LinkError)
from distutils.ccompiler import CCompiler, gen_lib_options
from distutils import log
from distutils.util import get_platform
import _winreg
RegOpenKeyEx = _winreg.OpenKeyEx
RegEnumKey = _winreg.EnumKey
RegEnumValue = _winreg.EnumValue
RegError = _winreg.error
HKEYS = (_winreg.HKEY_USERS,
_winreg.HKEY_CURRENT_USER,
_winreg.HKEY_LOCAL_MACHINE,
_winreg.HKEY_CLASSES_ROOT)
NATIVE_WIN64 = (sys.platform == 'win32' and sys.maxsize > 2**32)
if NATIVE_WIN64:
# Visual C++ is a 32-bit application, so we need to look in
# the corresponding registry branch, if we're running a
# 64-bit Python on Win64
VS_BASE = r"Software\Wow6432Node\Microsoft\VisualStudio\%0.1f"
VSEXPRESS_BASE = r"Software\Wow6432Node\Microsoft\VCExpress\%0.1f"
WINSDK_BASE = r"Software\Wow6432Node\Microsoft\Microsoft SDKs\Windows"
NET_BASE = r"Software\Wow6432Node\Microsoft\.NETFramework"
else:
VS_BASE = r"Software\Microsoft\VisualStudio\%0.1f"
VSEXPRESS_BASE = r"Software\Microsoft\VCExpress\%0.1f"
WINSDK_BASE = r"Software\Microsoft\Microsoft SDKs\Windows"
NET_BASE = r"Software\Microsoft\.NETFramework"
# A map keyed by get_platform() return values to values accepted by
# 'vcvarsall.bat'. Note a cross-compile may combine these (eg, 'x86_amd64' is
# the param to cross-compile on x86 targetting amd64.)
PLAT_TO_VCVARS = {
'win32' : 'x86',
'win-amd64' : 'amd64',
'win-ia64' : 'ia64',
}
class Reg:
"""Helper class to read values from the registry
"""
def get_value(cls, path, key):
for base in HKEYS:
d = cls.read_values(base, path)
if d and key in d:
return d[key]
raise KeyError(key)
get_value = classmethod(get_value)
def read_keys(cls, base, key):
"""Return list of registry keys."""
try:
handle = RegOpenKeyEx(base, key)
except RegError:
return None
L = []
i = 0
while True:
try:
k = RegEnumKey(handle, i)
except RegError:
break
L.append(k)
i += 1
return L
read_keys = classmethod(read_keys)
def read_values(cls, base, key):
"""Return dict of registry keys and values.
All names are converted to lowercase.
"""
try:
handle = RegOpenKeyEx(base, key)
except RegError:
return None
d = {}
i = 0
while True:
try:
name, value, type = RegEnumValue(handle, i)
except RegError:
break
name = name.lower()
d[cls.convert_mbcs(name)] = cls.convert_mbcs(value)
i += 1
return d
read_values = classmethod(read_values)
def convert_mbcs(s):
dec = getattr(s, "decode", None)
if dec is not None:
try:
s = dec("mbcs")
except UnicodeError:
pass
return s
convert_mbcs = staticmethod(convert_mbcs)
class MacroExpander:
def __init__(self, version):
self.macros = {}
self.vsbase = VS_BASE % version
self.load_macros(version)
def set_macro(self, macro, path, key):
self.macros["$(%s)" % macro] = Reg.get_value(path, key)
def load_macros(self, version):
self.set_macro("VCInstallDir", self.vsbase + r"\Setup\VC", "productdir")
self.set_macro("VSInstallDir", self.vsbase + r"\Setup\VS", "productdir")
self.set_macro("FrameworkDir", NET_BASE, "installroot")
try:
if version >= 8.0:
self.set_macro("FrameworkSDKDir", NET_BASE,
"sdkinstallrootv2.0")
else:
raise KeyError("sdkinstallrootv2.0")
except KeyError:
raise DistutilsPlatformError(
"""Python was built with Visual Studio 2008;
extensions must be built with a compiler than can generate compatible binaries.
Visual Studio 2008 was not found on this system. If you have Cygwin installed,
you can try compiling with MingW32, by passing "-c mingw32" to setup.py.""")
if version >= 9.0:
self.set_macro("FrameworkVersion", self.vsbase, "clr version")
self.set_macro("WindowsSdkDir", WINSDK_BASE, "currentinstallfolder")
else:
p = r"Software\Microsoft\NET Framework Setup\Product"
for base in HKEYS:
try:
h = RegOpenKeyEx(base, p)
except RegError:
continue
key = RegEnumKey(h, 0)
d = Reg.get_value(base, r"%s\%s" % (p, key))
self.macros["$(FrameworkVersion)"] = d["version"]
def sub(self, s):
for k, v in self.macros.items():
s = s.replace(k, v)
return s
def get_build_version():
"""Return the version of MSVC that was used to build Python.
For Python 2.3 and up, the version number is included in
sys.version. For earlier versions, assume the compiler is MSVC 6.
"""
prefix = "MSC v."
i = sys.version.find(prefix)
if i == -1:
return 6
i = i + len(prefix)
s, rest = sys.version[i:].split(" ", 1)
majorVersion = int(s[:-2]) - 6
minorVersion = int(s[2:3]) / 10.0
# I don't think paths are affected by minor version in version 6
if majorVersion == 6:
minorVersion = 0
if majorVersion >= 6:
return majorVersion + minorVersion
# else we don't know what version of the compiler this is
return None
def normalize_and_reduce_paths(paths):
"""Return a list of normalized paths with duplicates removed.
The current order of paths is maintained.
"""
# Paths are normalized so things like: /a and /a/ aren't both preserved.
reduced_paths = []
for p in paths:
np = os.path.normpath(p)
# XXX(nnorwitz): O(n**2), if reduced_paths gets long perhaps use a set.
if np not in reduced_paths:
reduced_paths.append(np)
return reduced_paths
def removeDuplicates(variable):
"""Remove duplicate values of an environment variable.
"""
oldList = variable.split(os.pathsep)
newList = []
for i in oldList:
if i not in newList:
newList.append(i)
newVariable = os.pathsep.join(newList)
return newVariable
def find_vcvarsall(version):
"""Find the vcvarsall.bat file
At first it tries to find the productdir of VS 2008 in the registry. If
that fails it falls back to the VS90COMNTOOLS env var.
"""
vsbase = VS_BASE % version
try:
productdir = Reg.get_value(r"%s\Setup\VC" % vsbase,
"productdir")
except KeyError:
productdir = None
# trying Express edition
if productdir is None:
vsbase = VSEXPRESS_BASE % version
try:
productdir = Reg.get_value(r"%s\Setup\VC" % vsbase,
"productdir")
except KeyError:
productdir = None
log.debug("Unable to find productdir in registry")
if not productdir or not os.path.isdir(productdir):
toolskey = "VS%0.f0COMNTOOLS" % version
toolsdir = os.environ.get(toolskey, None)
if toolsdir and os.path.isdir(toolsdir):
productdir = os.path.join(toolsdir, os.pardir, os.pardir, "VC")
productdir = os.path.abspath(productdir)
if not os.path.isdir(productdir):
log.debug("%s is not a valid directory" % productdir)
return None
else:
log.debug("Env var %s is not set or invalid" % toolskey)
if not productdir:
log.debug("No productdir found")
return None
vcvarsall = os.path.join(productdir, "vcvarsall.bat")
if os.path.isfile(vcvarsall):
return vcvarsall
log.debug("Unable to find vcvarsall.bat")
return None
def query_vcvarsall(version, arch="x86"):
"""Launch vcvarsall.bat and read the settings from its environment
"""
vcvarsall = find_vcvarsall(version)
interesting = set(("include", "lib", "libpath", "path"))
result = {}
if vcvarsall is None:
raise DistutilsPlatformError("Unable to find vcvarsall.bat")
log.debug("Calling 'vcvarsall.bat %s' (version=%s)", arch, version)
popen = subprocess.Popen('"%s" %s & set' % (vcvarsall, arch),
stdout=subprocess.PIPE,
stderr=subprocess.PIPE)
try:
stdout, stderr = popen.communicate()
if popen.wait() != 0:
raise DistutilsPlatformError(stderr.decode("mbcs"))
stdout = stdout.decode("mbcs")
for line in stdout.split("\n"):
line = Reg.convert_mbcs(line)
if '=' not in line:
continue
line = line.strip()
key, value = line.split('=', 1)
key = key.lower()
if key in interesting:
if value.endswith(os.pathsep):
value = value[:-1]
result[key] = removeDuplicates(value)
finally:
popen.stdout.close()
popen.stderr.close()
if len(result) != len(interesting):
raise ValueError(str(list(result.keys())))
return result
# More globals
VERSION = get_build_version()
if VERSION < 8.0:
raise DistutilsPlatformError("VC %0.1f is not supported by this module" % VERSION)
# MACROS = MacroExpander(VERSION)
class MSVCCompiler(CCompiler) :
"""Concrete class that implements an interface to Microsoft Visual C++,
as defined by the CCompiler abstract class."""
compiler_type = 'msvc'
# Just set this so CCompiler's constructor doesn't barf. We currently
# don't use the 'set_executables()' bureaucracy provided by CCompiler,
# as it really isn't necessary for this sort of single-compiler class.
# Would be nice to have a consistent interface with UnixCCompiler,
# though, so it's worth thinking about.
executables = {}
# Private class data (need to distinguish C from C++ source for compiler)
_c_extensions = ['.c']
_cpp_extensions = ['.cc', '.cpp', '.cxx']
_rc_extensions = ['.rc']
_mc_extensions = ['.mc']
# Needed for the filename generation methods provided by the
# base class, CCompiler.
src_extensions = (_c_extensions + _cpp_extensions +
_rc_extensions + _mc_extensions)
res_extension = '.res'
obj_extension = '.obj'
static_lib_extension = '.lib'
shared_lib_extension = '.dll'
static_lib_format = shared_lib_format = '%s%s'
exe_extension = '.exe'
def __init__(self, verbose=0, dry_run=0, force=0):
CCompiler.__init__ (self, verbose, dry_run, force)
self.__version = VERSION
self.__root = r"Software\Microsoft\VisualStudio"
# self.__macros = MACROS
self.__paths = []
# target platform (.plat_name is consistent with 'bdist')
self.plat_name = None
self.__arch = None # deprecated name
self.initialized = False
def initialize(self, plat_name=None):
# multi-init means we would need to check platform same each time...
assert not self.initialized, "don't init multiple times"
if plat_name is None:
plat_name = get_platform()
# sanity check for platforms to prevent obscure errors later.
ok_plats = 'win32', 'win-amd64', 'win-ia64'
if plat_name not in ok_plats:
raise DistutilsPlatformError("--plat-name must be one of %s" %
(ok_plats,))
if "DISTUTILS_USE_SDK" in os.environ and "MSSdk" in os.environ and self.find_exe("cl.exe"):
# Assume that the SDK set up everything alright; don't try to be
# smarter
self.cc = "cl.exe"
self.linker = "link.exe"
self.lib = "lib.exe"
self.rc = "rc.exe"
self.mc = "mc.exe"
else:
# On x86, 'vcvars32.bat amd64' creates an env that doesn't work;
# to cross compile, you use 'x86_amd64'.
# On AMD64, 'vcvars32.bat amd64' is a native build env; to cross
# compile use 'x86' (ie, it runs the x86 compiler directly)
# No idea how itanium handles this, if at all.
if plat_name == get_platform() or plat_name == 'win32':
# native build or cross-compile to win32
plat_spec = PLAT_TO_VCVARS[plat_name]
else:
# cross compile from win32 -> some 64bit
plat_spec = PLAT_TO_VCVARS[get_platform()] + '_' + \
PLAT_TO_VCVARS[plat_name]
vc_env = query_vcvarsall(VERSION, plat_spec)
# take care to only use strings in the environment.
self.__paths = vc_env['path'].encode('mbcs').split(os.pathsep)
os.environ['lib'] = vc_env['lib'].encode('mbcs')
os.environ['include'] = vc_env['include'].encode('mbcs')
if len(self.__paths) == 0:
raise DistutilsPlatformError("Python was built with %s, "
"and extensions need to be built with the same "
"version of the compiler, but it isn't installed."
% self.__product)
self.cc = self.find_exe("cl.exe")
self.linker = self.find_exe("link.exe")
self.lib = self.find_exe("lib.exe")
self.rc = self.find_exe("rc.exe") # resource compiler
self.mc = self.find_exe("mc.exe") # message compiler
#self.set_path_env_var('lib')
#self.set_path_env_var('include')
# extend the MSVC path with the current path
try:
for p in os.environ['path'].split(';'):
self.__paths.append(p)
except KeyError:
pass
self.__paths = normalize_and_reduce_paths(self.__paths)
os.environ['path'] = ";".join(self.__paths)
self.preprocess_options = None
if self.__arch == "x86":
self.compile_options = [ '/nologo', '/Ox', '/MD', '/W3',
'/DNDEBUG']
self.compile_options_debug = ['/nologo', '/Od', '/MDd', '/W3',
'/Z7', '/D_DEBUG']
else:
# Win64
self.compile_options = [ '/nologo', '/Ox', '/MD', '/W3', '/GS-' ,
'/DNDEBUG']
self.compile_options_debug = ['/nologo', '/Od', '/MDd', '/W3', '/GS-',
'/Z7', '/D_DEBUG']
self.ldflags_shared = ['/DLL', '/nologo', '/INCREMENTAL:NO']
if self.__version >= 7:
self.ldflags_shared_debug = [
'/DLL', '/nologo', '/INCREMENTAL:no', '/DEBUG', '/pdb:None'
]
self.ldflags_static = [ '/nologo']
self.initialized = True
# -- Worker methods ------------------------------------------------
def object_filenames(self,
source_filenames,
strip_dir=0,
output_dir=''):
# Copied from ccompiler.py, extended to return .res as 'object'-file
# for .rc input file
if output_dir is None: output_dir = ''
obj_names = []
for src_name in source_filenames:
(base, ext) = os.path.splitext (src_name)
base = os.path.splitdrive(base)[1] # Chop off the drive
base = base[os.path.isabs(base):] # If abs, chop off leading /
if ext not in self.src_extensions:
# Better to raise an exception instead of silently continuing
# and later complain about sources and targets having
# different lengths
raise CompileError ("Don't know how to compile %s" % src_name)
if strip_dir:
base = os.path.basename (base)
if ext in self._rc_extensions:
obj_names.append (os.path.join (output_dir,
base + self.res_extension))
elif ext in self._mc_extensions:
obj_names.append (os.path.join (output_dir,
base + self.res_extension))
else:
obj_names.append (os.path.join (output_dir,
base + self.obj_extension))
return obj_names
def compile(self, sources,
output_dir=None, macros=None, include_dirs=None, debug=0,
extra_preargs=None, extra_postargs=None, depends=None):
if not self.initialized:
self.initialize()
compile_info = self._setup_compile(output_dir, macros, include_dirs,
sources, depends, extra_postargs)
macros, objects, extra_postargs, pp_opts, build = compile_info
compile_opts = extra_preargs or []
compile_opts.append ('/c')
if debug:
compile_opts.extend(self.compile_options_debug)
else:
compile_opts.extend(self.compile_options)
for obj in objects:
try:
src, ext = build[obj]
except KeyError:
continue
if debug:
# pass the full pathname to MSVC in debug mode,
# this allows the debugger to find the source file
# without asking the user to browse for it
src = os.path.abspath(src)
if ext in self._c_extensions:
input_opt = "/Tc" + src
elif ext in self._cpp_extensions:
input_opt = "/Tp" + src
elif ext in self._rc_extensions:
# compile .RC to .RES file
input_opt = src
output_opt = "/fo" + obj
try:
self.spawn([self.rc] + pp_opts +
[output_opt] + [input_opt])
except DistutilsExecError, msg:
raise CompileError(msg)
continue
elif ext in self._mc_extensions:
# Compile .MC to .RC file to .RES file.
# * '-h dir' specifies the directory for the
# generated include file
# * '-r dir' specifies the target directory of the
# generated RC file and the binary message resource
# it includes
#
# For now (since there are no options to change this),
# we use the source-directory for the include file and
# the build directory for the RC file and message
# resources. This works at least for win32all.
h_dir = os.path.dirname(src)
rc_dir = os.path.dirname(obj)
try:
# first compile .MC to .RC and .H file
self.spawn([self.mc] +
['-h', h_dir, '-r', rc_dir] + [src])
base, _ = os.path.splitext (os.path.basename (src))
rc_file = os.path.join (rc_dir, base + '.rc')
# then compile .RC to .RES file
self.spawn([self.rc] +
["/fo" + obj] + [rc_file])
except DistutilsExecError, msg:
raise CompileError(msg)
continue
else:
# how to handle this file?
raise CompileError("Don't know how to compile %s to %s"
% (src, obj))
output_opt = "/Fo" + obj
try:
self.spawn([self.cc] + compile_opts + pp_opts +
[input_opt, output_opt] +
extra_postargs)
except DistutilsExecError, msg:
raise CompileError(msg)
return objects
def create_static_lib(self,
objects,
output_libname,
output_dir=None,
debug=0,
target_lang=None):
if not self.initialized:
self.initialize()
(objects, output_dir) = self._fix_object_args(objects, output_dir)
output_filename = self.library_filename(output_libname,
output_dir=output_dir)
if self._need_link(objects, output_filename):
lib_args = objects + ['/OUT:' + output_filename]
if debug:
pass # XXX what goes here?
try:
self.spawn([self.lib] + lib_args)
except DistutilsExecError, msg:
raise LibError(msg)
else:
log.debug("skipping %s (up-to-date)", output_filename)
def link(self,
target_desc,
objects,
output_filename,
output_dir=None,
libraries=None,
library_dirs=None,
runtime_library_dirs=None,
export_symbols=None,
debug=0,
extra_preargs=None,
extra_postargs=None,
build_temp=None,
target_lang=None):
if not self.initialized:
self.initialize()
(objects, output_dir) = self._fix_object_args(objects, output_dir)
fixed_args = self._fix_lib_args(libraries, library_dirs,
runtime_library_dirs)
(libraries, library_dirs, runtime_library_dirs) = fixed_args
if runtime_library_dirs:
self.warn ("I don't know what to do with 'runtime_library_dirs': "
+ str (runtime_library_dirs))
lib_opts = gen_lib_options(self,
library_dirs, runtime_library_dirs,
libraries)
if output_dir is not None:
output_filename = os.path.join(output_dir, output_filename)
if self._need_link(objects, output_filename):
if target_desc == CCompiler.EXECUTABLE:
if debug:
ldflags = self.ldflags_shared_debug[1:]
else:
ldflags = self.ldflags_shared[1:]
else:
if debug:
ldflags = self.ldflags_shared_debug
else:
ldflags = self.ldflags_shared
export_opts = []
for sym in (export_symbols or []):
export_opts.append("/EXPORT:" + sym)
ld_args = (ldflags + lib_opts + export_opts +
objects + ['/OUT:' + output_filename])
# The MSVC linker generates .lib and .exp files, which cannot be
# suppressed by any linker switches. The .lib files may even be
# needed! Make sure they are generated in the temporary build
# directory. Since they have different names for debug and release
# builds, they can go into the same directory.
build_temp = os.path.dirname(objects[0])
if export_symbols is not None:
(dll_name, dll_ext) = os.path.splitext(
os.path.basename(output_filename))
implib_file = os.path.join(
build_temp,
self.library_filename(dll_name))
ld_args.append ('/IMPLIB:' + implib_file)
self.manifest_setup_ldargs(output_filename, build_temp, ld_args)
if extra_preargs:
ld_args[:0] = extra_preargs
if extra_postargs:
ld_args.extend(extra_postargs)
self.mkpath(os.path.dirname(output_filename))
try:
self.spawn([self.linker] + ld_args)
except DistutilsExecError, msg:
raise LinkError(msg)
# embed the manifest
# XXX - this is somewhat fragile - if mt.exe fails, distutils
# will still consider the DLL up-to-date, but it will not have a
# manifest. Maybe we should link to a temp file? OTOH, that
# implies a build environment error that shouldn't go undetected.
mfinfo = self.manifest_get_embed_info(target_desc, ld_args)
if mfinfo is not None:
mffilename, mfid = mfinfo
out_arg = '-outputresource:%s;%s' % (output_filename, mfid)
try:
self.spawn(['mt.exe', '-nologo', '-manifest',
mffilename, out_arg])
except DistutilsExecError, msg:
raise LinkError(msg)
else:
log.debug("skipping %s (up-to-date)", output_filename)
def manifest_setup_ldargs(self, output_filename, build_temp, ld_args):
# If we need a manifest at all, an embedded manifest is recommended.
# See MSDN article titled
# "How to: Embed a Manifest Inside a C/C++ Application"
# (currently at http://msdn2.microsoft.com/en-us/library/ms235591(VS.80).aspx)
# Ask the linker to generate the manifest in the temp dir, so
# we can check it, and possibly embed it, later.
temp_manifest = os.path.join(
build_temp,
os.path.basename(output_filename) + ".manifest")
ld_args.append('/MANIFESTFILE:' + temp_manifest)
def manifest_get_embed_info(self, target_desc, ld_args):
# If a manifest should be embedded, return a tuple of
# (manifest_filename, resource_id). Returns None if no manifest
# should be embedded. See http://bugs.python.org/issue7833 for why
# we want to avoid any manifest for extension modules if we can)
for arg in ld_args:
if arg.startswith("/MANIFESTFILE:"):
temp_manifest = arg.split(":", 1)[1]
break
else:
# no /MANIFESTFILE so nothing to do.
return None
if target_desc == CCompiler.EXECUTABLE:
# by default, executables always get the manifest with the
# CRT referenced.
mfid = 1
else:
# Extension modules try and avoid any manifest if possible.
mfid = 2
temp_manifest = self._remove_visual_c_ref(temp_manifest)
if temp_manifest is None:
return None
return temp_manifest, mfid
def _remove_visual_c_ref(self, manifest_file):
try:
# Remove references to the Visual C runtime, so they will
# fall through to the Visual C dependency of Python.exe.
# This way, when installed for a restricted user (e.g.
# runtimes are not in WinSxS folder, but in Python's own
# folder), the runtimes do not need to be in every folder
# with .pyd's.
# Returns either the filename of the modified manifest or
# None if no manifest should be embedded.
manifest_f = open(manifest_file)
try:
manifest_buf = manifest_f.read()
finally:
manifest_f.close()
pattern = re.compile(
r"""<assemblyIdentity.*?name=("|')Microsoft\."""\
r"""VC\d{2}\.CRT("|').*?(/>|</assemblyIdentity>)""",
re.DOTALL)
manifest_buf = re.sub(pattern, "", manifest_buf)
pattern = "<dependentAssembly>\s*</dependentAssembly>"
manifest_buf = re.sub(pattern, "", manifest_buf)
# Now see if any other assemblies are referenced - if not, we
# don't want a manifest embedded.
pattern = re.compile(
r"""<assemblyIdentity.*?name=(?:"|')(.+?)(?:"|')"""
r""".*?(?:/>|</assemblyIdentity>)""", re.DOTALL)
if re.search(pattern, manifest_buf) is None:
return None
manifest_f = open(manifest_file, 'w')
try:
manifest_f.write(manifest_buf)
return manifest_file
finally:
manifest_f.close()
except IOError:
pass
# -- Miscellaneous methods -----------------------------------------
# These are all used by the 'gen_lib_options() function, in
# ccompiler.py.
def library_dir_option(self, dir):
return "/LIBPATH:" + dir
def runtime_library_dir_option(self, dir):
raise DistutilsPlatformError(
"don't know how to set runtime library search path for MSVC++")
def library_option(self, lib):
return self.library_filename(lib)
def find_library_file(self, dirs, lib, debug=0):
# Prefer a debugging library if found (and requested), but deal
# with it if we don't have one.
if debug:
try_names = [lib + "_d", lib]
else:
try_names = [lib]
for dir in dirs:
for name in try_names:
libfile = os.path.join(dir, self.library_filename (name))
if os.path.exists(libfile):
return libfile
else:
# Oops, didn't find it in *any* of 'dirs'
return None
# Helper methods for using the MSVC registry settings
def find_exe(self, exe):
"""Return path to an MSVC executable program.
Tries to find the program in several places: first, one of the
MSVC program search paths from the registry; next, the directories
in the PATH environment variable. If any of those work, return an
absolute path that is known to exist. If none of them work, just
return the original program name, 'exe'.
"""
for p in self.__paths:
fn = os.path.join(os.path.abspath(p), exe)
if os.path.isfile(fn):
return fn
# didn't find it; try existing path
for p in os.environ['Path'].split(';'):
fn = os.path.join(os.path.abspath(p),exe)
if os.path.isfile(fn):
return fn
return exe