# ******************************************************************************

# getpath.py

# ******************************************************************************

# This script is designed to be precompiled to bytecode, frozen into the

# main binary, and then directly evaluated. It is not an importable module,

# and does not import any other modules (besides winreg on Windows).

# Rather, the values listed below must be specified in the globals dict

# used when evaluating the bytecode.

# See _PyConfig_InitPathConfig in Modules/getpath.c for the execution.

# ******************************************************************************

# REQUIRED GLOBALS

# ******************************************************************************

# ** Helper functions **

# abspath(path) -- make relative paths absolute against CWD

# basename(path) -- the filename of path

# dirname(path) -- the directory name of path

# hassuffix(path, suffix) -- returns True if path has suffix

# isabs(path) -- path is absolute or not

# isdir(path) -- path exists and is a directory

# isfile(path) -- path exists and is a file

# isxfile(path) -- path exists and is an executable file

# joinpath(*paths) -- combine the paths

# readlines(path) -- a list of each line of text in the UTF-8 encoded file

# realpath(path) -- resolves symlinks in path

# warn(message) -- print a warning (if enabled)

# ** Values known at compile time **

# os_name -- [in] one of 'nt', 'posix', 'darwin'

# PREFIX -- [in] sysconfig.get_config_var(...)

# EXEC_PREFIX -- [in] sysconfig.get_config_var(...)

# PYTHONPATH -- [in] sysconfig.get_config_var(...)

# WITH_NEXT_FRAMEWORK -- [in] sysconfig.get_config_var(...)

# VPATH -- [in] sysconfig.get_config_var(...)

# PLATLIBDIR -- [in] sysconfig.get_config_var(...)

# PYDEBUGEXT -- [in, opt] '_d' on Windows for debug builds

# EXE_SUFFIX -- [in, opt] '.exe' on Windows/Cygwin/similar

# VERSION_MAJOR -- [in] sys.version_info.major

# VERSION_MINOR -- [in] sys.version_info.minor

# PYWINVER -- [in] the Windows platform-specific version (e.g. 3.8-32)

# ** Values read from the environment **

# There is no need to check the use_environment flag before reading

# these, as the flag will be tested in this script.

# Also note that ENV_PYTHONPATH is read from config['pythonpath_env']

# to allow for embedders who choose to specify it via that struct.

# ENV_PATH -- [in] getenv(...)

# ENV_PYTHONHOME -- [in] getenv(...)

# ENV_PYTHONEXECUTABLE -- [in] getenv(...)

# ENV___PYVENV_LAUNCHER__ -- [in] getenv(...)

# ** Values calculated at runtime **

# config -- [in/out] dict of the PyConfig structure

# real_executable -- [in, optional] resolved path to main process

# On Windows and macOS, read directly from the running process

# Otherwise, leave None and it will be calculated from executable

# executable_dir -- [in, optional] real directory containing binary

# If None, will be calculated from real_executable or executable

# py_setpath -- [in] argument provided to Py_SetPath

# If None, 'prefix' and 'exec_prefix' may be updated in config

# library -- [in, optional] path of dylib/DLL/so

# Only used for locating ._pth files

# winreg -- [in, optional] the winreg module (only on Windows)

# ******************************************************************************

# HIGH-LEVEL ALGORITHM

# ******************************************************************************

# IMPORTANT: The code is the actual specification at time of writing.

# This prose description is based on the original comment from the old

# getpath.c to help capture the intent, but should not be considered

# a specification.

# Search in some common locations for the associated Python libraries.

# Two directories must be found, the platform independent directory

# (prefix), containing the common .py and .pyc files, and the platform

# dependent directory (exec_prefix), containing the shared library

# modules. Note that prefix and exec_prefix can be the same directory,

# but for some installations, they are different.

# This script carries out separate searches for prefix and exec_prefix.

# Each search tries a number of different locations until a ``landmark''

# file or directory is found. If no prefix or exec_prefix is found, a

# warning message is issued and the preprocessor defined PREFIX and

# EXEC_PREFIX are used (even though they will not work); python carries on

# as best as is possible, but most imports will fail.

# Before any searches are done, the location of the executable is

# determined. If Py_SetPath() was called, or if we are running on

# Windows, the 'real_executable' path is used (if known). Otherwise,

# we use the config-specified program name or default to argv[0].

# If this has one or more slashes in it, it is made absolute against

# the current working directory. If it only contains a name, it must

# have been invoked from the shell's path, so we search $PATH for the

# named executable and use that. If the executable was not found on

# $PATH (or there was no $PATH environment variable), the original

# argv[0] string is used.

# At this point, provided Py_SetPath was not used, the

# __PYVENV_LAUNCHER__ variable may override the executable (on macOS,

# the PYTHON_EXECUTABLE variable may also override). This allows

# certain launchers that run Python as a subprocess to properly

# specify the executable path. They are not intended for users.

# Next, the executable location is examined to see if it is a symbolic

# link. If so, the link is realpath-ed and the directory of the link

# target is used for the remaining searches. The same steps are

# performed for prefix and for exec_prefix, but with different landmarks.

# Step 1. Are we running in a virtual environment? Unless 'home' has

# been specified another way, check for a pyvenv.cfg and use its 'home'

# property to override the executable dir used later for prefix searches.

# We do not activate the venv here - that is performed later by site.py.

# Step 2. Is there a ._pth file? A ._pth file lives adjacent to the

# runtime library (if any) or the actual executable (not the symlink),

# and contains precisely the intended contents of sys.path as relative

# paths (to its own location). Its presence also enables isolated mode

# and suppresses other environment variable usage. Unless already

# specified by Py_SetHome(), the directory containing the ._pth file is

# set as 'home'.

# Step 3. Are we running python out of the build directory? This is

# checked by looking for the BUILDDIR_TXT file, which contains the

# relative path to the platlib dir. The executable_dir value is

# derived from joining the VPATH preprocessor variable to the

# directory containing pybuilddir.txt. If it is not found, the

# BUILD_LANDMARK file is found, which is part of the source tree.

# prefix is then found by searching up for a file that should only

# exist in the source tree, and the stdlib dir is set to prefix/Lib.

# Step 4. If 'home' is set, either by Py_SetHome(), ENV_PYTHONHOME,

# a pyvenv.cfg file, ._pth file, or by detecting a build directory, it

# is assumed to point to prefix and exec_prefix. $PYTHONHOME can be a

# single directory, which is used for both, or the prefix and exec_prefix

# directories separated by DELIM (colon on POSIX; semicolon on Windows).

# Step 5. Try to find prefix and exec_prefix relative to executable_dir,

# backtracking up the path until it is exhausted. This is the most common

# step to succeed. Note that if prefix and exec_prefix are different,

# exec_prefix is more likely to be found; however if exec_prefix is a

# subdirectory of prefix, both will be found.

# Step 6. Search the directories pointed to by the preprocessor variables

# PREFIX and EXEC_PREFIX. These are supplied by the Makefile but can be

# passed in as options to the configure script.

# That's it!

# Well, almost. Once we have determined prefix and exec_prefix, the

# preprocessor variable PYTHONPATH is used to construct a path. Each

# relative path on PYTHONPATH is prefixed with prefix. Then the directory

# containing the shared library modules is appended. The environment

# variable $PYTHONPATH is inserted in front of it all. On POSIX, if we are

# in a build directory, both prefix and exec_prefix are reset to the

# corresponding preprocessor variables (so sys.prefix will reflect the

# installation location, even though sys.path points into the build

# directory). This seems to make more sense given that currently the only

# known use of sys.prefix and sys.exec_prefix is for the ILU installation

# process to find the installed Python tree.

# An embedding application can use Py_SetPath() to override all of

# these automatic path computations.

# ******************************************************************************

# PLATFORM CONSTANTS

# ******************************************************************************

platlibdir = config.get('platlibdir') or PLATLIBDIR

if os_name == 'posix' or os_name == 'darwin':

BUILDDIR_TXT = 'pybuilddir.txt'

BUILD_LANDMARK = 'Modules/Setup.local'

DEFAULT_PROGRAM_NAME = f'python{VERSION_MAJOR}'

STDLIB_SUBDIR = f'{platlibdir}/python{VERSION_MAJOR}.{VERSION_MINOR}'

STDLIB_LANDMARKS = [f'{STDLIB_SUBDIR}/os.py', f'{STDLIB_SUBDIR}/os.pyc']

PLATSTDLIB_LANDMARK = f'{platlibdir}/python{VERSION_MAJOR}.{VERSION_MINOR}/lib-dynload'

BUILDSTDLIB_LANDMARKS = ['Lib/os.py']

VENV_LANDMARK = 'pyvenv.cfg'

ZIP_LANDMARK = f'{platlibdir}/python{VERSION_MAJOR}{VERSION_MINOR}.zip'

DELIM = ':'

SEP = '/'

elif os_name == 'nt':

BUILDDIR_TXT = 'pybuilddir.txt'

BUILD_LANDMARK = f'{VPATH}\\Modules\\Setup.local'

DEFAULT_PROGRAM_NAME = f'python'

STDLIB_SUBDIR = 'Lib'

STDLIB_LANDMARKS = [f'{STDLIB_SUBDIR}\\os.py', f'{STDLIB_SUBDIR}\\os.pyc']

PLATSTDLIB_LANDMARK = f'{platlibdir}'

BUILDSTDLIB_LANDMARKS = ['Lib\\os.py']

VENV_LANDMARK = 'pyvenv.cfg'

ZIP_LANDMARK = f'python{VERSION_MAJOR}{VERSION_MINOR}{PYDEBUGEXT or ""}.zip'

WINREG_KEY = f'SOFTWARE\\Python\\PythonCore\\{PYWINVER}\\PythonPath'

DELIM = ';'

SEP = '\\'

# ******************************************************************************

# HELPER FUNCTIONS (note that we prefer C functions for performance)

# ******************************************************************************

def search_up(prefix, *landmarks, test=isfile):

while prefix:

if any(test(joinpath(prefix, f)) for f in landmarks):

return prefix

prefix = dirname(prefix)

# ******************************************************************************

# READ VARIABLES FROM config

# ******************************************************************************

program_name = config.get('program_name')

home = config.get('home')

executable = config.get('executable')

base_executable = config.get('base_executable')

prefix = config.get('prefix')

exec_prefix = config.get('exec_prefix')

base_prefix = config.get('base_prefix')

base_exec_prefix = config.get('base_exec_prefix')

ENV_PYTHONPATH = config['pythonpath_env']

use_environment = config.get('use_environment', 1)

pythonpath = config.get('module_search_paths')

pythonpath_was_set = config.get('module_search_paths_set')

real_executable_dir = None

stdlib_dir = None

platstdlib_dir = None

# ******************************************************************************

# CALCULATE program_name

# ******************************************************************************

program_name_was_set = bool(program_name)

if not program_name:

try:

program_name = config.get('orig_argv', [])[0]

except IndexError:

pass

if not program_name:

program_name = DEFAULT_PROGRAM_NAME

if EXE_SUFFIX and not hassuffix(program_name, EXE_SUFFIX) and isxfile(program_name + EXE_SUFFIX):

program_name = program_name + EXE_SUFFIX

# ******************************************************************************

# CALCULATE executable

# ******************************************************************************

if py_setpath:

# When Py_SetPath has been called, executable defaults to

# the real executable path.

if not executable:

executable = real_executable

if not executable and SEP in program_name:

# Resolve partial path program_name against current directory

executable = abspath(program_name)

if not executable:

# All platforms default to real_executable if known at this

# stage. POSIX does not set this value.

executable = real_executable

elif os_name == 'darwin':

# QUIRK: On macOS we may know the real executable path, but

# if our caller has lied to us about it (e.g. most of

# test_embed), we need to use their path in order to detect

# whether we are in a build tree. This is true even if the

# executable path was provided in the config.

real_executable = executable

if not executable and program_name and ENV_PATH:

# Resolve names against PATH.

# NOTE: The use_environment value is ignored for this lookup.

# To properly isolate, launch Python with a full path.

for p in ENV_PATH.split(DELIM):

p = joinpath(p, program_name)

if isxfile(p):

executable = p

break

if not executable:

executable = ''

# When we cannot calculate the executable, subsequent searches

# look in the current working directory. Here, we emulate that

# (the former getpath.c would do it apparently by accident).

executable_dir = abspath('.')

# Also need to set this fallback in case we are running from a

# build directory with an invalid argv0 (i.e. test_sys.test_executable)

real_executable_dir = executable_dir

if ENV_PYTHONEXECUTABLE or ENV___PYVENV_LAUNCHER__:

# If set, these variables imply that we should be using them as

# sys.executable and when searching for venvs. However, we should

# use the argv0 path for prefix calculation

if os_name == 'darwin' and WITH_NEXT_FRAMEWORK:

# In a framework build the binary in {sys.exec_prefix}/bin is

# a stub executable that execs the real interpreter in an

# embedded app bundle. That bundle is an implementation detail

# and should not affect base_executable.

base_executable = f"{dirname(library)}/bin/python{VERSION_MAJOR}.{VERSION_MINOR}"

else:

base_executable = executable

if not real_executable:

real_executable = base_executable

#real_executable_dir = dirname(real_executable)

executable = ENV_PYTHONEXECUTABLE or ENV___PYVENV_LAUNCHER__

executable_dir = dirname(executable)

# ******************************************************************************

# CALCULATE (default) home

# ******************************************************************************

# Used later to distinguish between Py_SetPythonHome and other

# ways that it may have been set

home_was_set = False

if home:

home_was_set = True

elif use_environment and ENV_PYTHONHOME and not py_setpath:

home = ENV_PYTHONHOME

# ******************************************************************************

# READ pyvenv.cfg

# ******************************************************************************

venv_prefix = None

# Calling Py_SetPythonHome(), Py_SetPath() or

# setting $PYTHONHOME will override venv detection.

if not home and not py_setpath:

try:

# prefix2 is just to avoid calculating dirname again later,

# as the path in venv_prefix is the more common case.

venv_prefix2 = executable_dir or dirname(executable)

venv_prefix = dirname(venv_prefix2)

try:

# Read pyvenv.cfg from one level above executable

pyvenvcfg = readlines(joinpath(venv_prefix, VENV_LANDMARK))

except (FileNotFoundError, PermissionError):

# Try the same directory as executable

pyvenvcfg = readlines(joinpath(venv_prefix2, VENV_LANDMARK))

venv_prefix = venv_prefix2

except (FileNotFoundError, PermissionError):

venv_prefix = None

pyvenvcfg = []

for line in pyvenvcfg:

key, had_equ, value = line.partition('=')

if had_equ and key.strip().lower() == 'home':

executable_dir = real_executable_dir = value.strip()

if not base_executable:

# First try to resolve symlinked executables, since that may be

# more accurate than assuming the executable in 'home'.

try:

base_executable = realpath(executable)

if base_executable == executable:

# No change, so probably not a link. Clear it and fall back

base_executable = ''

except OSError:

pass

if not base_executable:

base_executable = joinpath(executable_dir, basename(executable))

# It's possible "python" is executed from within a posix venv but that

# "python" is not available in the "home" directory as the standard

# `make install` does not create it and distros often do not provide it.

#

# In this case, try to fall back to known alternatives

if os_name != 'nt' and not isfile(base_executable):

base_exe = basename(executable)

for candidate in (DEFAULT_PROGRAM_NAME, f'python{VERSION_MAJOR}.{VERSION_MINOR}'):

candidate += EXE_SUFFIX if EXE_SUFFIX else ''

if base_exe == candidate:

continue

candidate = joinpath(executable_dir, candidate)

# Only set base_executable if the candidate exists.

# If no candidate succeeds, subsequent errors related to

# base_executable (like FileNotFoundError) remain in the

# context of the original executable name

if isfile(candidate):

base_executable = candidate

break

break

else:

venv_prefix = None

# ******************************************************************************

# CALCULATE base_executable, real_executable AND executable_dir

# ******************************************************************************

if not base_executable:

base_executable = executable or real_executable or ''

if not real_executable:

real_executable = base_executable

try:

real_executable = realpath(real_executable)

except OSError as ex:

# Only warn if the file actually exists and was unresolvable

# Otherwise users who specify a fake executable may get spurious warnings.

if isfile(real_executable):

warn(f'Failed to find real location of {base_executable}')

if not executable_dir and os_name == 'darwin' and library:

# QUIRK: macOS checks adjacent to its library early

library_dir = dirname(library)

if any(isfile(joinpath(library_dir, p)) for p in STDLIB_LANDMARKS):

# Exceptions here should abort the whole process (to match

# previous behavior)

executable_dir = realpath(library_dir)

real_executable_dir = executable_dir

# If we do not have the executable's directory, we can calculate it.

# This is the directory used to find prefix/exec_prefix if necessary.

if not executable_dir:

executable_dir = real_executable_dir = dirname(real_executable)

# If we do not have the real executable's directory, we calculate it.

# This is the directory used to detect build layouts.

if not real_executable_dir:

real_executable_dir = dirname(real_executable)

# ******************************************************************************

# DETECT _pth FILE

# ******************************************************************************

# The contents of an optional ._pth file are used to totally override

# sys.path calculation. Its presence also implies isolated mode and

# no-site (unless explicitly requested)

pth = None

pth_dir = None

# Calling Py_SetPythonHome() or Py_SetPath() will override ._pth search,

# but environment variables and command-line options cannot.

if not py_setpath and not home_was_set:

# 1. Check adjacent to the main DLL/dylib/so (if set)

# 2. Check adjacent to the original executable

# 3. Check adjacent to our actual executable

# This may allow a venv to override the base_executable's

# ._pth file, but it cannot override the library's one.

for p in [library, executable, real_executable]:

if p:

if os_name == 'nt' and (hassuffix(p, 'exe') or hassuffix(p, 'dll')):

p = p.rpartition('.')[0]

p += '._pth'

try:

pth = readlines(p)

pth_dir = dirname(p)

break

except OSError:

pass

# If we found a ._pth file, disable environment and home

# detection now. Later, we will do the rest.

if pth_dir:

use_environment = 0

home = pth_dir

pythonpath = []

# ******************************************************************************

# CHECK FOR BUILD DIRECTORY

# ******************************************************************************

build_prefix = None

if ((not home_was_set and real_executable_dir and not py_setpath)

or config.get('_is_python_build', 0) > 0):

# Detect a build marker and use it to infer prefix, exec_prefix,

# stdlib_dir and the platstdlib_dir directories.

try:

platstdlib_dir = joinpath(

real_executable_dir,

readlines(joinpath(real_executable_dir, BUILDDIR_TXT))[0],

)

build_prefix = joinpath(real_executable_dir, VPATH)

except IndexError:

# File exists but is empty

platstdlib_dir = real_executable_dir

build_prefix = joinpath(real_executable_dir, VPATH)

except (FileNotFoundError, PermissionError):

if isfile(joinpath(real_executable_dir, BUILD_LANDMARK)):

build_prefix = joinpath(real_executable_dir, VPATH)

if os_name == 'nt':

# QUIRK: Windows builds need platstdlib_dir to be the executable

# dir. Normally the builddir marker handles this, but in this

# case we need to correct manually.

platstdlib_dir = real_executable_dir

if build_prefix:

if os_name == 'nt':

# QUIRK: No searching for more landmarks on Windows

build_stdlib_prefix = build_prefix

else:

build_stdlib_prefix = search_up(build_prefix, *BUILDSTDLIB_LANDMARKS)

# Always use the build prefix for stdlib

if build_stdlib_prefix:

stdlib_dir = joinpath(build_stdlib_prefix, 'Lib')

else:

stdlib_dir = joinpath(build_prefix, 'Lib')

# Only use the build prefix for prefix if it hasn't already been set

if not prefix:

prefix = build_stdlib_prefix

# Do not warn, because 'prefix' never equals 'build_prefix' on POSIX

#elif not venv_prefix and prefix != build_prefix:

# warn('Detected development environment but prefix is already set')

if not exec_prefix:

exec_prefix = build_prefix

# Do not warn, because 'exec_prefix' never equals 'build_prefix' on POSIX

#elif not venv_prefix and exec_prefix != build_prefix:

# warn('Detected development environment but exec_prefix is already set')

config['_is_python_build'] = 1

# ******************************************************************************

# CALCULATE prefix AND exec_prefix

# ******************************************************************************

if py_setpath:

# As documented, calling Py_SetPath will force both prefix

# and exec_prefix to the empty string.

prefix = exec_prefix = ''

else:

# Read prefix and exec_prefix from explicitly set home

if home:

# When multiple paths are listed with ':' or ';' delimiters,

# split into prefix:exec_prefix

prefix, had_delim, exec_prefix = home.partition(DELIM)

if not had_delim:

exec_prefix = prefix

# Reset the standard library directory if it was already set

stdlib_dir = None

# First try to detect prefix by looking alongside our runtime library, if known

if library and not prefix:

library_dir = dirname(library)

if ZIP_LANDMARK:

if os_name == 'nt':

# QUIRK: Windows does not search up for ZIP file

if isfile(joinpath(library_dir, ZIP_LANDMARK)):

prefix = library_dir

else:

prefix = search_up(library_dir, ZIP_LANDMARK)

if STDLIB_SUBDIR and STDLIB_LANDMARKS and not prefix:

if any(isfile(joinpath(library_dir, f)) for f in STDLIB_LANDMARKS):

prefix = library_dir

stdlib_dir = joinpath(prefix, STDLIB_SUBDIR)

# Detect prefix by looking for zip file

if ZIP_LANDMARK and executable_dir and not prefix:

if os_name == 'nt':

# QUIRK: Windows does not search up for ZIP file

if isfile(joinpath(executable_dir, ZIP_LANDMARK)):

prefix = executable_dir

else:

prefix = search_up(executable_dir, ZIP_LANDMARK)

if prefix:

stdlib_dir = joinpath(prefix, STDLIB_SUBDIR)

if not isdir(stdlib_dir):

stdlib_dir = None

# Detect prefix by searching from our executable location for the stdlib_dir

if STDLIB_SUBDIR and STDLIB_LANDMARKS and executable_dir and not prefix:

prefix = search_up(executable_dir, *STDLIB_LANDMARKS)

if prefix:

stdlib_dir = joinpath(prefix, STDLIB_SUBDIR)

if PREFIX and not prefix:

prefix = PREFIX

if not any(isfile(joinpath(prefix, f)) for f in STDLIB_LANDMARKS):

warn('Could not find platform independent libraries <prefix>')

if not prefix:

prefix = abspath('')

warn('Could not find platform independent libraries <prefix>')

# Detect exec_prefix by searching from executable for the platstdlib_dir

if PLATSTDLIB_LANDMARK and not exec_prefix:

if executable_dir:

if os_name == 'nt':

# QUIRK: For compatibility and security, do not search for DLLs

# directory. The fallback below will cover it

exec_prefix = executable_dir

else:

exec_prefix = search_up(executable_dir, PLATSTDLIB_LANDMARK, test=isdir)

if not exec_prefix and EXEC_PREFIX:

exec_prefix = EXEC_PREFIX

if not exec_prefix or not isdir(joinpath(exec_prefix, PLATSTDLIB_LANDMARK)):

if os_name == 'nt':

# QUIRK: If DLLs is missing on Windows, don't warn, just assume

# that it's all the same as prefix.

# gh-98790: We set platstdlib_dir here to avoid adding "DLLs" into

# sys.path when it doesn't exist, which would give site-packages

# precedence over executable_dir, which is *probably* where our PYDs

# live. Ideally, whoever changes our layout will tell us what the

# layout is, but in the past this worked, so it should keep working.

platstdlib_dir = exec_prefix = prefix

else:

warn('Could not find platform dependent libraries <exec_prefix>')

# Fallback: assume exec_prefix == prefix

if not exec_prefix:

exec_prefix = prefix

if not prefix or not exec_prefix:

warn('Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]')

# If we haven't set [plat]stdlib_dir already, set them now

if not stdlib_dir:

if prefix:

stdlib_dir = joinpath(prefix, STDLIB_SUBDIR)

else:

stdlib_dir = ''

if not platstdlib_dir:

if exec_prefix:

platstdlib_dir = joinpath(exec_prefix, PLATSTDLIB_LANDMARK)

else:

platstdlib_dir = ''

# For a venv, update the main prefix/exec_prefix but leave the base ones unchanged

# XXX: We currently do not update prefix here, but it happens in site.py

#if venv_prefix:

# base_prefix = prefix

# base_exec_prefix = exec_prefix

# prefix = exec_prefix = venv_prefix

# ******************************************************************************

# UPDATE pythonpath (sys.path)

# ******************************************************************************

if py_setpath:

# If Py_SetPath was called then it overrides any existing search path

config['module_search_paths'] = py_setpath.split(DELIM)

config['module_search_paths_set'] = 1

elif not pythonpath_was_set:

# If pythonpath was already explicitly set or calculated, we leave it alone.

# This won't matter in normal use, but if an embedded host is trying to

# recalculate paths while running then we do not want to change it.

pythonpath = []

# First add entries from the process environment

if use_environment and ENV_PYTHONPATH:

for p in ENV_PYTHONPATH.split(DELIM):

pythonpath.append(abspath(p))

# Then add the default zip file

if os_name == 'nt':

# QUIRK: Windows uses the library directory rather than the prefix

if library:

library_dir = dirname(library)

else:

library_dir = executable_dir

pythonpath.append(joinpath(library_dir, ZIP_LANDMARK))

elif build_prefix:

# QUIRK: POSIX uses the default prefix when in the build directory

pythonpath.append(joinpath(PREFIX, ZIP_LANDMARK))

else:

pythonpath.append(joinpath(prefix, ZIP_LANDMARK))

if os_name == 'nt' and use_environment and winreg:

# QUIRK: Windows also lists paths in the registry. Paths are stored

# as the default value of each subkey of

# {HKCU,HKLM}\Software\Python\PythonCore\{winver}\PythonPath

# where winver is sys.winver (typically '3.x' or '3.x-32')

for hk in (winreg.HKEY_CURRENT_USER, winreg.HKEY_LOCAL_MACHINE):

try:

key = winreg.OpenKeyEx(hk, WINREG_KEY)

try:

i = 0

while True:

try:

v = winreg.QueryValue(key, winreg.EnumKey(key, i))

except OSError:

break

if isinstance(v, str):

pythonpath.append(v)

i += 1

finally:

winreg.CloseKey(key)

except OSError:

pass

# Then add any entries compiled into the PYTHONPATH macro.

if PYTHONPATH:

for p in PYTHONPATH.split(DELIM):

pythonpath.append(joinpath(prefix, p))

# Then add stdlib_dir and platstdlib_dir

if os_name == 'nt' and venv_prefix:

# QUIRK: Windows generates paths differently in a venv

if platstdlib_dir:

pythonpath.append(platstdlib_dir)

if stdlib_dir:

pythonpath.append(stdlib_dir)

if executable_dir not in pythonpath:

pythonpath.append(executable_dir)

else:

if stdlib_dir:

pythonpath.append(stdlib_dir)

if platstdlib_dir:

pythonpath.append(platstdlib_dir)

config['module_search_paths'] = pythonpath

config['module_search_paths_set'] = 1

# ******************************************************************************

# POSIX prefix/exec_prefix QUIRKS

# ******************************************************************************

# QUIRK: Non-Windows replaces prefix/exec_prefix with defaults when running

# in build directory. This happens after pythonpath calculation.

if os_name != 'nt' and build_prefix:

prefix = config.get('prefix') or PREFIX

exec_prefix = config.get('exec_prefix') or EXEC_PREFIX or prefix

# ******************************************************************************

# SET pythonpath FROM _PTH FILE

# ******************************************************************************

if pth:

config['isolated'] = 1

config['use_environment'] = 0

config['site_import'] = 0

config['safe_path'] = 1

pythonpath = []

for line in pth:

line = line.partition('#')[0].strip()

if not line:

pass

elif line == 'import site':

config['site_import'] = 1

elif line.startswith('import '):

warn("unsupported 'import' line in ._pth file")

else:

pythonpath.append(joinpath(pth_dir, line))

config['module_search_paths'] = pythonpath

config['module_search_paths_set'] = 1

# ******************************************************************************

# UPDATE config FROM CALCULATED VALUES

# ******************************************************************************

config['program_name'] = program_name

config['home'] = home

config['executable'] = executable

config['base_executable'] = base_executable

config['prefix'] = prefix

config['exec_prefix'] = exec_prefix

config['base_prefix'] = base_prefix or prefix

config['base_exec_prefix'] = base_exec_prefix or exec_prefix

config['platlibdir'] = platlibdir

config['stdlib_dir'] = stdlib_dir

config['platstdlib_dir'] = platstdlib_dir