337 lines
12 KiB
Python
337 lines
12 KiB
Python
"""
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Creates and manages isolated build environments.
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"""
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import abc
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import functools
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import logging
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import os
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import platform
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import shutil
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import subprocess
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import sys
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import sysconfig
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import tempfile
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from types import TracebackType
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from typing import Callable, Collection, List, Optional, Tuple, Type
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import build
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if sys.version_info < (3, 8):
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import importlib_metadata as metadata
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else:
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from importlib import metadata
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try:
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import virtualenv
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except ModuleNotFoundError:
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virtualenv = None
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_logger = logging.getLogger('build.env')
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class IsolatedEnv(metaclass=abc.ABCMeta):
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"""Abstract base of isolated build environments, as required by the build project."""
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@property
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@abc.abstractmethod
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def executable(self) -> str:
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"""The executable of the isolated build environment."""
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raise NotImplementedError
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@property
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@abc.abstractmethod
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def scripts_dir(self) -> str:
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"""The scripts directory of the isolated build environment."""
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raise NotImplementedError
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@abc.abstractmethod
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def install(self, requirements: Collection[str]) -> None:
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"""
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Install packages from PEP 508 requirements in the isolated build environment.
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:param requirements: PEP 508 requirements
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"""
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raise NotImplementedError
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@functools.lru_cache(maxsize=None)
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def _should_use_virtualenv() -> bool:
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import packaging.requirements
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# virtualenv might be incompatible if it was installed separately
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# from build. This verifies that virtualenv and all of its
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# dependencies are installed as specified by build.
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return virtualenv is not None and not any(
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packaging.requirements.Requirement(d[1]).name == 'virtualenv'
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for d in build.check_dependency('build[virtualenv]')
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if len(d) > 1
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)
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def _subprocess(cmd: List[str]) -> None:
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"""Invoke subprocess and output stdout and stderr if it fails."""
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try:
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subprocess.run(cmd, check=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
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except subprocess.CalledProcessError as e:
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print(e.output.decode(), end='', file=sys.stderr)
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raise e
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class IsolatedEnvBuilder:
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"""Builder object for isolated environments."""
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def __init__(self) -> None:
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self._path: Optional[str] = None
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def __enter__(self) -> IsolatedEnv:
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"""
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Create an isolated build environment.
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:return: The isolated build environment
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"""
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# Call ``realpath`` to prevent spurious warning from being emitted
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# that the venv location has changed on Windows. The username is
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# DOS-encoded in the output of tempfile - the location is the same
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# but the representation of it is different, which confuses venv.
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# Ref: https://bugs.python.org/issue46171
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self._path = os.path.realpath(tempfile.mkdtemp(prefix='build-env-'))
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try:
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# use virtualenv when available (as it's faster than venv)
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if _should_use_virtualenv():
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self.log('Creating virtualenv isolated environment...')
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executable, scripts_dir = _create_isolated_env_virtualenv(self._path)
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else:
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self.log('Creating venv isolated environment...')
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executable, scripts_dir = _create_isolated_env_venv(self._path)
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return _IsolatedEnvVenvPip(
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path=self._path,
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python_executable=executable,
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scripts_dir=scripts_dir,
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log=self.log,
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)
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except Exception: # cleanup folder if creation fails
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self.__exit__(*sys.exc_info())
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raise
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def __exit__(
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self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]
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) -> None:
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"""
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Delete the created isolated build environment.
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:param exc_type: The type of exception raised (if any)
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:param exc_val: The value of exception raised (if any)
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:param exc_tb: The traceback of exception raised (if any)
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"""
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if self._path is not None and os.path.exists(self._path): # in case the user already deleted skip remove
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shutil.rmtree(self._path)
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@staticmethod
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def log(message: str) -> None:
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"""
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Prints message
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The default implementation uses the logging module but this function can be
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overwritten by users to have a different implementation.
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:param msg: Message to output
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"""
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if sys.version_info >= (3, 8):
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_logger.log(logging.INFO, message, stacklevel=2)
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else:
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_logger.log(logging.INFO, message)
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class _IsolatedEnvVenvPip(IsolatedEnv):
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"""
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Isolated build environment context manager
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Non-standard paths injected directly to sys.path will still be passed to the environment.
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"""
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def __init__(
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self,
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path: str,
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python_executable: str,
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scripts_dir: str,
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log: Callable[[str], None],
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) -> None:
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"""
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:param path: The path where the environment exists
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:param python_executable: The python executable within the environment
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:param log: Log function
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"""
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self._path = path
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self._python_executable = python_executable
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self._scripts_dir = scripts_dir
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self._log = log
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@property
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def path(self) -> str:
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"""The location of the isolated build environment."""
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return self._path
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@property
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def executable(self) -> str:
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"""The python executable of the isolated build environment."""
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return self._python_executable
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@property
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def scripts_dir(self) -> str:
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return self._scripts_dir
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def install(self, requirements: Collection[str]) -> None:
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"""
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Install packages from PEP 508 requirements in the isolated build environment.
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:param requirements: PEP 508 requirement specification to install
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:note: Passing non-PEP 508 strings will result in undefined behavior, you *should not* rely on it. It is
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merely an implementation detail, it may change any time without warning.
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"""
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if not requirements:
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return
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self._log('Installing packages in isolated environment... ({})'.format(', '.join(sorted(requirements))))
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# pip does not honour environment markers in command line arguments
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# but it does for requirements from a file
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with tempfile.NamedTemporaryFile('w+', prefix='build-reqs-', suffix='.txt', delete=False) as req_file:
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req_file.write(os.linesep.join(requirements))
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try:
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cmd = [
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self.executable,
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'-Im',
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'pip',
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'install',
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'--use-pep517',
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'--no-warn-script-location',
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'-r',
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os.path.abspath(req_file.name),
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]
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_subprocess(cmd)
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finally:
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os.unlink(req_file.name)
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def _create_isolated_env_virtualenv(path: str) -> Tuple[str, str]:
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"""
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We optionally can use the virtualenv package to provision a virtual environment.
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:param path: The path where to create the isolated build environment
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:return: The Python executable and script folder
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"""
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cmd = [str(path), '--no-setuptools', '--no-wheel', '--activators', '']
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result = virtualenv.cli_run(cmd, setup_logging=False)
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executable = str(result.creator.exe)
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script_dir = str(result.creator.script_dir)
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return executable, script_dir
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@functools.lru_cache(maxsize=None)
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def _fs_supports_symlink() -> bool:
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"""Return True if symlinks are supported"""
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# Using definition used by venv.main()
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if not sys.platform.startswith('win'):
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return True
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# Windows may support symlinks (setting in Windows 10)
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with tempfile.NamedTemporaryFile(prefix='build-symlink-') as tmp_file:
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dest = f'{tmp_file}-b'
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try:
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os.symlink(tmp_file.name, dest)
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os.unlink(dest)
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return True
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except (OSError, NotImplementedError, AttributeError):
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return False
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def _create_isolated_env_venv(path: str) -> Tuple[str, str]:
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"""
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On Python 3 we use the venv package from the standard library.
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:param path: The path where to create the isolated build environment
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:return: The Python executable and script folder
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"""
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import venv
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import packaging.version
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symlinks = _fs_supports_symlink()
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try:
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venv.EnvBuilder(with_pip=True, symlinks=symlinks).create(path)
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except subprocess.CalledProcessError as exc:
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raise build.FailedProcessError(exc, 'Failed to create venv. Maybe try installing virtualenv.') from None
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executable, script_dir, purelib = _find_executable_and_scripts(path)
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# Get the version of pip in the environment
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pip_distribution = next(iter(metadata.distributions(name='pip', path=[purelib]))) # type: ignore[no-untyped-call]
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current_pip_version = packaging.version.Version(pip_distribution.version)
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if platform.system() == 'Darwin' and int(platform.mac_ver()[0].split('.')[0]) >= 11:
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# macOS 11+ name scheme change requires 20.3. Intel macOS 11.0 can be told to report 10.16 for backwards
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# compatibility; but that also fixes earlier versions of pip so this is only needed for 11+.
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is_apple_silicon_python = platform.machine() != 'x86_64'
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minimum_pip_version = '21.0.1' if is_apple_silicon_python else '20.3.0'
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else:
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# PEP-517 and manylinux1 was first implemented in 19.1
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minimum_pip_version = '19.1.0'
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if current_pip_version < packaging.version.Version(minimum_pip_version):
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_subprocess([executable, '-m', 'pip', 'install', f'pip>={minimum_pip_version}'])
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# Avoid the setuptools from ensurepip to break the isolation
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_subprocess([executable, '-m', 'pip', 'uninstall', 'setuptools', '-y'])
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return executable, script_dir
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def _find_executable_and_scripts(path: str) -> Tuple[str, str, str]:
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"""
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Detect the Python executable and script folder of a virtual environment.
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:param path: The location of the virtual environment
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:return: The Python executable, script folder, and purelib folder
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"""
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config_vars = sysconfig.get_config_vars().copy() # globally cached, copy before altering it
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config_vars['base'] = path
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scheme_names = sysconfig.get_scheme_names()
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if 'venv' in scheme_names:
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# Python distributors with custom default installation scheme can set a
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# scheme that can't be used to expand the paths in a venv.
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# This can happen if build itself is not installed in a venv.
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# The distributors are encouraged to set a "venv" scheme to be used for this.
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# See https://bugs.python.org/issue45413
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# and https://github.com/pypa/virtualenv/issues/2208
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paths = sysconfig.get_paths(scheme='venv', vars=config_vars)
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elif 'posix_local' in scheme_names:
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# The Python that ships on Debian/Ubuntu varies the default scheme to
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# install to /usr/local
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# But it does not (yet) set the "venv" scheme.
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# If we're the Debian "posix_local" scheme is available, but "venv"
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# is not, we use "posix_prefix" instead which is venv-compatible there.
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paths = sysconfig.get_paths(scheme='posix_prefix', vars=config_vars)
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elif 'osx_framework_library' in scheme_names:
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# The Python that ships with the macOS developer tools varies the
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# default scheme depending on whether the ``sys.prefix`` is part of a framework.
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# But it does not (yet) set the "venv" scheme.
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# If the Apple-custom "osx_framework_library" scheme is available but "venv"
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# is not, we use "posix_prefix" instead which is venv-compatible there.
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paths = sysconfig.get_paths(scheme='posix_prefix', vars=config_vars)
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else:
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paths = sysconfig.get_paths(vars=config_vars)
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executable = os.path.join(paths['scripts'], 'python.exe' if sys.platform.startswith('win') else 'python')
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if not os.path.exists(executable):
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raise RuntimeError(f'Virtual environment creation failed, executable {executable} missing')
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return executable, paths['scripts'], paths['purelib']
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__all__ = (
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'IsolatedEnvBuilder',
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'IsolatedEnv',
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)
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