Adding upstream version 0.9.0.upstream/0.9.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 1336 insertions, 0 deletions

diff --git a/src/build/__init__.py b/src/build/__init__.py
new file mode 100644
index 0000000..0425a85
--- /dev/null
+++ b/src/build/__init__.py
@@ -0,0 +1,539 @@
+# SPDX-License-Identifier: MIT
+
+"""
+build - A simple, correct PEP 517 build frontend
+"""
+
+__version__ = '0.9.0'
+
+import contextlib
+import difflib
+import logging
+import os
+import re
+import subprocess
+import sys
+import textwrap
+import types
+import warnings
+import zipfile
+
+from collections import OrderedDict
+from typing import (
+    AbstractSet,
+    Any,
+    Callable,
+    Dict,
+    Iterator,
+    List,
+    Mapping,
+    MutableMapping,
+    Optional,
+    Sequence,
+    Set,
+    Tuple,
+    Type,
+    Union,
+)
+
+import pep517.wrappers
+
+
+TOMLDecodeError: Type[Exception]
+toml_loads: Callable[[str], MutableMapping[str, Any]]
+
+if sys.version_info >= (3, 11):
+    from tomllib import TOMLDecodeError
+    from tomllib import loads as toml_loads
+else:
+    try:
+        from tomli import TOMLDecodeError
+        from tomli import loads as toml_loads
+    except ModuleNotFoundError:  # pragma: no cover
+        from toml import TomlDecodeError as TOMLDecodeError  # type: ignore[import,no-redef]
+        from toml import loads as toml_loads  # type: ignore[no-redef]
+
+
+RunnerType = Callable[[Sequence[str], Optional[str], Optional[Mapping[str, str]]], None]
+ConfigSettingsType = Mapping[str, Union[str, Sequence[str]]]
+PathType = Union[str, 'os.PathLike[str]']
+_ExcInfoType = Union[Tuple[Type[BaseException], BaseException, types.TracebackType], Tuple[None, None, None]]
+
+
+_WHEEL_NAME_REGEX = re.compile(
+    r'(?P<distribution>.+)-(?P<version>.+)'
+    r'(-(?P<build_tag>.+))?-(?P<python_tag>.+)'
+    r'-(?P<abi_tag>.+)-(?P<platform_tag>.+)\.whl'
+)
+
+
+_DEFAULT_BACKEND = {
+    'build-backend': 'setuptools.build_meta:__legacy__',
+    'requires': ['setuptools >= 40.8.0', 'wheel'],
+}
+
+
+_logger = logging.getLogger(__name__)
+
+
+class BuildException(Exception):
+    """
+    Exception raised by :class:`ProjectBuilder`
+    """
+
+
+class BuildBackendException(Exception):
+    """
+    Exception raised when a backend operation fails
+    """
+
+    def __init__(
+        self, exception: Exception, description: Optional[str] = None, exc_info: _ExcInfoType = (None, None, None)
+    ) -> None:
+        super().__init__()
+        self.exception = exception
+        self.exc_info = exc_info
+        self._description = description
+
+    def __str__(self) -> str:
+        if self._description:
+            return self._description
+        return f'Backend operation failed: {self.exception!r}'
+
+
+class BuildSystemTableValidationError(BuildException):
+    """
+    Exception raised when the ``[build-system]`` table in pyproject.toml is invalid.
+    """
+
+    def __str__(self) -> str:
+        return f'Failed to validate `build-system` in pyproject.toml: {self.args[0]}'
+
+
+class FailedProcessError(Exception):
+    """
+    Exception raised when an setup or prepration operation fails.
+    """
+
+    def __init__(self, exception: subprocess.CalledProcessError, description: str) -> None:
+        super().__init__()
+        self.exception = exception
+        self._description = description
+
+    def __str__(self) -> str:
+        cmd = ' '.join(self.exception.cmd)
+        description = f"{self._description}\n  Command '{cmd}' failed with return code {self.exception.returncode}"
+        for stream_name in ('stdout', 'stderr'):
+            stream = getattr(self.exception, stream_name)
+            if stream:
+                description += f'\n  {stream_name}:\n'
+                description += textwrap.indent(stream.decode(), '    ')
+        return description
+
+
+class TypoWarning(Warning):
+    """
+    Warning raised when a possible typo is found
+    """
+
+
+@contextlib.contextmanager
+def _working_directory(path: str) -> Iterator[None]:
+    current = os.getcwd()
+
+    os.chdir(path)
+
+    try:
+        yield
+    finally:
+        os.chdir(current)
+
+
+def _validate_source_directory(srcdir: PathType) -> None:
+    if not os.path.isdir(srcdir):
+        raise BuildException(f'Source {srcdir} is not a directory')
+    pyproject_toml = os.path.join(srcdir, 'pyproject.toml')
+    setup_py = os.path.join(srcdir, 'setup.py')
+    if not os.path.exists(pyproject_toml) and not os.path.exists(setup_py):
+        raise BuildException(f'Source {srcdir} does not appear to be a Python project: no pyproject.toml or setup.py')
+
+
+def check_dependency(
+    req_string: str, ancestral_req_strings: Tuple[str, ...] = (), parent_extras: AbstractSet[str] = frozenset()
+) -> Iterator[Tuple[str, ...]]:
+    """
+    Verify that a dependency and all of its dependencies are met.
+
+    :param req_string: Requirement string
+    :param parent_extras: Extras (eg. "test" in myproject[test])
+    :yields: Unmet dependencies
+    """
+    import packaging.requirements
+
+    if sys.version_info >= (3, 8):
+        import importlib.metadata as importlib_metadata
+    else:
+        import importlib_metadata
+
+    req = packaging.requirements.Requirement(req_string)
+    normalised_req_string = str(req)
+
+    # ``Requirement`` doesn't implement ``__eq__`` so we cannot compare reqs for
+    # equality directly but the string representation is stable.
+    if normalised_req_string in ancestral_req_strings:
+        # cyclical dependency, already checked.
+        return
+
+    if req.marker:
+        extras = frozenset(('',)).union(parent_extras)
+        # a requirement can have multiple extras but ``evaluate`` can
+        # only check one at a time.
+        if all(not req.marker.evaluate(environment={'extra': e}) for e in extras):
+            # if the marker conditions are not met, we pretend that the
+            # dependency is satisfied.
+            return
+
+    try:
+        dist = importlib_metadata.distribution(req.name)  # type: ignore[no-untyped-call]
+    except importlib_metadata.PackageNotFoundError:
+        # dependency is not installed in the environment.
+        yield ancestral_req_strings + (normalised_req_string,)
+    else:
+        if req.specifier and not req.specifier.contains(dist.version, prereleases=True):
+            # the installed version is incompatible.
+            yield ancestral_req_strings + (normalised_req_string,)
+        elif dist.requires:
+            for other_req_string in dist.requires:
+                # yields transitive dependencies that are not satisfied.
+                yield from check_dependency(other_req_string, ancestral_req_strings + (normalised_req_string,), req.extras)
+
+
+def _find_typo(dictionary: Mapping[str, str], expected: str) -> None:
+    for obj in dictionary:
+        if difflib.SequenceMatcher(None, expected, obj).ratio() >= 0.8:
+            warnings.warn(
+                f"Found '{obj}' in pyproject.toml, did you mean '{expected}'?",
+                TypoWarning,
+            )
+
+
+def _parse_build_system_table(pyproject_toml: Mapping[str, Any]) -> Dict[str, Any]:
+    # If pyproject.toml is missing (per PEP 517) or [build-system] is missing
+    # (per PEP 518), use default values
+    if 'build-system' not in pyproject_toml:
+        _find_typo(pyproject_toml, 'build-system')
+        return _DEFAULT_BACKEND
+
+    build_system_table = dict(pyproject_toml['build-system'])
+
+    # If [build-system] is present, it must have a ``requires`` field (per PEP 518)
+    if 'requires' not in build_system_table:
+        _find_typo(build_system_table, 'requires')
+        raise BuildSystemTableValidationError('`requires` is a required property')
+    elif not isinstance(build_system_table['requires'], list) or not all(
+        isinstance(i, str) for i in build_system_table['requires']
+    ):
+        raise BuildSystemTableValidationError('`requires` must be an array of strings')
+
+    if 'build-backend' not in build_system_table:
+        _find_typo(build_system_table, 'build-backend')
+        # If ``build-backend`` is missing, inject the legacy setuptools backend
+        # but leave ``requires`` intact to emulate pip
+        build_system_table['build-backend'] = _DEFAULT_BACKEND['build-backend']
+    elif not isinstance(build_system_table['build-backend'], str):
+        raise BuildSystemTableValidationError('`build-backend` must be a string')
+
+    if 'backend-path' in build_system_table and (
+        not isinstance(build_system_table['backend-path'], list)
+        or not all(isinstance(i, str) for i in build_system_table['backend-path'])
+    ):
+        raise BuildSystemTableValidationError('`backend-path` must be an array of strings')
+
+    unknown_props = build_system_table.keys() - {'requires', 'build-backend', 'backend-path'}
+    if unknown_props:
+        raise BuildSystemTableValidationError(f'Unknown properties: {", ".join(unknown_props)}')
+
+    return build_system_table
+
+
+class ProjectBuilder:
+    """
+    The PEP 517 consumer API.
+    """
+
+    def __init__(
+        self,
+        srcdir: PathType,
+        python_executable: str = sys.executable,
+        scripts_dir: Optional[str] = None,
+        runner: RunnerType = pep517.wrappers.default_subprocess_runner,
+    ) -> None:
+        """
+        :param srcdir: The source directory
+        :param scripts_dir: The location of the scripts dir (defaults to the folder where the python executable lives)
+        :param python_executable: The python executable where the backend lives
+        :param runner: An alternative runner for backend subprocesses
+
+        The 'runner', if provided, must accept the following arguments:
+
+        - cmd: a list of strings representing the command and arguments to
+          execute, as would be passed to e.g. 'subprocess.check_call'.
+        - cwd: a string representing the working directory that must be
+          used for the subprocess. Corresponds to the provided srcdir.
+        - extra_environ: a dict mapping environment variable names to values
+          which must be set for the subprocess execution.
+
+        The default runner simply calls the backend hooks in a subprocess, writing backend output
+        to stdout/stderr.
+        """
+        self._srcdir: str = os.path.abspath(srcdir)
+        _validate_source_directory(srcdir)
+
+        spec_file = os.path.join(srcdir, 'pyproject.toml')
+
+        try:
+            with open(spec_file, 'rb') as f:
+                spec = toml_loads(f.read().decode())
+        except FileNotFoundError:
+            spec = {}
+        except PermissionError as e:
+            raise BuildException(f"{e.strerror}: '{e.filename}' ")  # noqa: B904 # use raise from
+        except TOMLDecodeError as e:
+            raise BuildException(f'Failed to parse {spec_file}: {e} ')  # noqa: B904 # use raise from
+
+        self._build_system = _parse_build_system_table(spec)
+        self._backend = self._build_system['build-backend']
+        self._scripts_dir = scripts_dir
+        self._hook_runner = runner
+        self._hook = pep517.wrappers.Pep517HookCaller(
+            self.srcdir,
+            self._backend,
+            backend_path=self._build_system.get('backend-path'),
+            python_executable=python_executable,
+            runner=self._runner,
+        )
+
+    def _runner(
+        self, cmd: Sequence[str], cwd: Optional[str] = None, extra_environ: Optional[Mapping[str, str]] = None
+    ) -> None:
+        # if script dir is specified must be inserted at the start of PATH (avoid duplicate path while doing so)
+        if self.scripts_dir is not None:
+            paths: Dict[str, None] = OrderedDict()
+            paths[str(self.scripts_dir)] = None
+            if 'PATH' in os.environ:
+                paths.update((i, None) for i in os.environ['PATH'].split(os.pathsep))
+            extra_environ = {} if extra_environ is None else dict(extra_environ)
+            extra_environ['PATH'] = os.pathsep.join(paths)
+        self._hook_runner(cmd, cwd, extra_environ)
+
+    @property
+    def srcdir(self) -> str:
+        """Project source directory."""
+        return self._srcdir
+
+    @property
+    def python_executable(self) -> str:
+        """
+        The Python executable used to invoke the backend.
+        """
+        # make mypy happy
+        exe: str = self._hook.python_executable
+        return exe
+
+    @python_executable.setter
+    def python_executable(self, value: str) -> None:
+        self._hook.python_executable = value
+
+    @property
+    def scripts_dir(self) -> Optional[str]:
+        """
+        The folder where the scripts are stored for the python executable.
+        """
+        return self._scripts_dir
+
+    @scripts_dir.setter
+    def scripts_dir(self, value: Optional[str]) -> None:
+        self._scripts_dir = value
+
+    @property
+    def build_system_requires(self) -> Set[str]:
+        """
+        The dependencies defined in the ``pyproject.toml``'s
+        ``build-system.requires`` field or the default build dependencies
+        if ``pyproject.toml`` is missing or ``build-system`` is undefined.
+        """
+        return set(self._build_system['requires'])
+
+    def get_requires_for_build(self, distribution: str, config_settings: Optional[ConfigSettingsType] = None) -> Set[str]:
+        """
+        Return the dependencies defined by the backend in addition to
+        :attr:`build_system_requires` for a given distribution.
+
+        :param distribution: Distribution to get the dependencies of
+            (``sdist`` or ``wheel``)
+        :param config_settings: Config settings for the build backend
+        """
+        self.log(f'Getting build dependencies for {distribution}...')
+        hook_name = f'get_requires_for_build_{distribution}'
+        get_requires = getattr(self._hook, hook_name)
+
+        with self._handle_backend(hook_name):
+            return set(get_requires(config_settings))
+
+    def check_dependencies(
+        self, distribution: str, config_settings: Optional[ConfigSettingsType] = None
+    ) -> Set[Tuple[str, ...]]:
+        """
+        Return the dependencies which are not satisfied from the combined set of
+        :attr:`build_system_requires` and :meth:`get_requires_for_build` for a given
+        distribution.
+
+        :param distribution: Distribution to check (``sdist`` or ``wheel``)
+        :param config_settings: Config settings for the build backend
+        :returns: Set of variable-length unmet dependency tuples
+        """
+        dependencies = self.get_requires_for_build(distribution, config_settings).union(self.build_system_requires)
+        return {u for d in dependencies for u in check_dependency(d)}
+
+    def prepare(
+        self, distribution: str, output_directory: PathType, config_settings: Optional[ConfigSettingsType] = None
+    ) -> Optional[str]:
+        """
+        Prepare metadata for a distribution.
+
+        :param distribution: Distribution to build (must be ``wheel``)
+        :param output_directory: Directory to put the prepared metadata in
+        :param config_settings: Config settings for the build backend
+        :returns: The full path to the prepared metadata directory
+        """
+        self.log(f'Getting metadata for {distribution}...')
+        try:
+            return self._call_backend(
+                f'prepare_metadata_for_build_{distribution}',
+                output_directory,
+                config_settings,
+                _allow_fallback=False,
+            )
+        except BuildBackendException as exception:
+            if isinstance(exception.exception, pep517.wrappers.HookMissing):
+                return None
+            raise
+
+    def build(
+        self,
+        distribution: str,
+        output_directory: PathType,
+        config_settings: Optional[ConfigSettingsType] = None,
+        metadata_directory: Optional[str] = None,
+    ) -> str:
+        """
+        Build a distribution.
+
+        :param distribution: Distribution to build (``sdist`` or ``wheel``)
+        :param output_directory: Directory to put the built distribution in
+        :param config_settings: Config settings for the build backend
+        :param metadata_directory: If provided, should be the return value of a
+            previous ``prepare`` call on the same ``distribution`` kind
+        :returns: The full path to the built distribution
+        """
+        self.log(f'Building {distribution}...')
+        kwargs = {} if metadata_directory is None else {'metadata_directory': metadata_directory}
+        return self._call_backend(f'build_{distribution}', output_directory, config_settings, **kwargs)
+
+    def metadata_path(self, output_directory: PathType) -> str:
+        """
+        Generate the metadata directory of a distribution and return its path.
+
+        If the backend does not support the ``prepare_metadata_for_build_wheel``
+        hook, a wheel will be built and the metadata will be extracted from it.
+
+        :param output_directory: Directory to put the metadata distribution in
+        :returns: The path of the metadata directory
+        """
+        # prepare_metadata hook
+        metadata = self.prepare('wheel', output_directory)
+        if metadata is not None:
+            return metadata
+
+        # fallback to build_wheel hook
+        wheel = self.build('wheel', output_directory)
+        match = _WHEEL_NAME_REGEX.match(os.path.basename(wheel))
+        if not match:
+            raise ValueError('Invalid wheel')
+        distinfo = f"{match['distribution']}-{match['version']}.dist-info"
+        member_prefix = f'{distinfo}/'
+        with zipfile.ZipFile(wheel) as w:
+            w.extractall(
+                output_directory,
+                (member for member in w.namelist() if member.startswith(member_prefix)),
+            )
+        return os.path.join(output_directory, distinfo)
+
+    def _call_backend(
+        self, hook_name: str, outdir: PathType, config_settings: Optional[ConfigSettingsType] = None, **kwargs: Any
+    ) -> str:
+        outdir = os.path.abspath(outdir)
+
+        callback = getattr(self._hook, hook_name)
+
+        if os.path.exists(outdir):
+            if not os.path.isdir(outdir):
+                raise BuildException(f"Build path '{outdir}' exists and is not a directory")
+        else:
+            os.makedirs(outdir)
+
+        with self._handle_backend(hook_name):
+            basename: str = callback(outdir, config_settings, **kwargs)
+
+        return os.path.join(outdir, basename)
+
+    @contextlib.contextmanager
+    def _handle_backend(self, hook: str) -> Iterator[None]:
+        with _working_directory(self.srcdir):
+            try:
+                yield
+            except pep517.wrappers.BackendUnavailable as exception:
+                raise BuildBackendException(  # noqa: B904 # use raise from
+                    exception,
+                    f"Backend '{self._backend}' is not available.",
+                    sys.exc_info(),
+                )
+            except subprocess.CalledProcessError as exception:
+                raise BuildBackendException(  # noqa: B904 # use raise from
+                    exception, f'Backend subprocess exited when trying to invoke {hook}'
+                )
+            except Exception as exception:
+                raise BuildBackendException(exception, exc_info=sys.exc_info())  # noqa: B904 # use raise from
+
+    @staticmethod
+    def log(message: str) -> None:
+        """
+        Log a message.
+
+        The default implementation uses the logging module but this function can be
+        overridden by users to have a different implementation.
+
+        :param message: Message to output
+        """
+        if sys.version_info >= (3, 8):
+            _logger.log(logging.INFO, message, stacklevel=2)
+        else:
+            _logger.log(logging.INFO, message)
+
+
+__all__ = [
+    '__version__',
+    'BuildSystemTableValidationError',
+    'BuildBackendException',
+    'BuildException',
+    'ConfigSettingsType',
+    'FailedProcessError',
+    'ProjectBuilder',
+    'RunnerType',
+    'TypoWarning',
+    'check_dependency',
+]
+
+
+def __dir__() -> List[str]:
+    return __all__
diff --git a/src/build/__main__.py b/src/build/__main__.py
new file mode 100644
index 0000000..67b21d1
--- /dev/null
+++ b/src/build/__main__.py
@@ -0,0 +1,397 @@
+# SPDX-License-Identifier: MIT
+
+
+import argparse
+import contextlib
+import os
+import platform
+import shutil
+import subprocess
+import sys
+import tarfile
+import tempfile
+import textwrap
+import traceback
+import warnings
+
+from typing import Dict, Iterator, List, NoReturn, Optional, Sequence, TextIO, Type, Union
+
+import build
+
+from build import BuildBackendException, BuildException, ConfigSettingsType, FailedProcessError, PathType, ProjectBuilder
+from build.env import IsolatedEnvBuilder
+
+
+_COLORS = {
+    'red': '\33[91m',
+    'green': '\33[92m',
+    'yellow': '\33[93m',
+    'bold': '\33[1m',
+    'dim': '\33[2m',
+    'underline': '\33[4m',
+    'reset': '\33[0m',
+}
+_NO_COLORS = {color: '' for color in _COLORS}
+
+
+def _init_colors() -> Dict[str, str]:
+    if 'NO_COLOR' in os.environ:
+        if 'FORCE_COLOR' in os.environ:
+            warnings.warn('Both NO_COLOR and FORCE_COLOR environment variables are set, disabling color')
+        return _NO_COLORS
+    elif 'FORCE_COLOR' in os.environ or sys.stdout.isatty():
+        return _COLORS
+    return _NO_COLORS
+
+
+_STYLES = _init_colors()
+
+
+def _cprint(fmt: str = '', msg: str = '') -> None:
+    print(fmt.format(msg, **_STYLES), flush=True)
+
+
+def _showwarning(
+    message: Union[Warning, str],
+    category: Type[Warning],
+    filename: str,
+    lineno: int,
+    file: Optional[TextIO] = None,
+    line: Optional[str] = None,
+) -> None:  # pragma: no cover
+    _cprint('{yellow}WARNING{reset} {}', str(message))
+
+
+def _setup_cli() -> None:
+    warnings.showwarning = _showwarning
+
+    if platform.system() == 'Windows':
+        try:
+            import colorama
+
+            colorama.init()
+        except ModuleNotFoundError:
+            pass
+
+
+def _error(msg: str, code: int = 1) -> NoReturn:  # pragma: no cover
+    """
+    Print an error message and exit. Will color the output when writing to a TTY.
+
+    :param msg: Error message
+    :param code: Error code
+    """
+    _cprint('{red}ERROR{reset} {}', msg)
+    raise SystemExit(code)
+
+
+class _ProjectBuilder(ProjectBuilder):
+    @staticmethod
+    def log(message: str) -> None:
+        _cprint('{bold}* {}{reset}', message)
+
+
+class _IsolatedEnvBuilder(IsolatedEnvBuilder):
+    @staticmethod
+    def log(message: str) -> None:
+        _cprint('{bold}* {}{reset}', message)
+
+
+def _format_dep_chain(dep_chain: Sequence[str]) -> str:
+    return ' -> '.join(dep.partition(';')[0].strip() for dep in dep_chain)
+
+
+def _build_in_isolated_env(
+    builder: ProjectBuilder, outdir: PathType, distribution: str, config_settings: Optional[ConfigSettingsType]
+) -> str:
+    with _IsolatedEnvBuilder() as env:
+        builder.python_executable = env.executable
+        builder.scripts_dir = env.scripts_dir
+        # first install the build dependencies
+        env.install(builder.build_system_requires)
+        # then get the extra required dependencies from the backend (which was installed in the call above :P)
+        env.install(builder.get_requires_for_build(distribution))
+        return builder.build(distribution, outdir, config_settings or {})
+
+
+def _build_in_current_env(
+    builder: ProjectBuilder,
+    outdir: PathType,
+    distribution: str,
+    config_settings: Optional[ConfigSettingsType],
+    skip_dependency_check: bool = False,
+) -> str:
+    if not skip_dependency_check:
+        missing = builder.check_dependencies(distribution)
+        if missing:
+            dependencies = ''.join('\n\t' + dep for deps in missing for dep in (deps[0], _format_dep_chain(deps[1:])) if dep)
+            _cprint()
+            _error(f'Missing dependencies:{dependencies}')
+
+    return builder.build(distribution, outdir, config_settings or {})
+
+
+def _build(
+    isolation: bool,
+    builder: ProjectBuilder,
+    outdir: PathType,
+    distribution: str,
+    config_settings: Optional[ConfigSettingsType],
+    skip_dependency_check: bool,
+) -> str:
+    if isolation:
+        return _build_in_isolated_env(builder, outdir, distribution, config_settings)
+    else:
+        return _build_in_current_env(builder, outdir, distribution, config_settings, skip_dependency_check)
+
+
+@contextlib.contextmanager
+def _handle_build_error() -> Iterator[None]:
+    try:
+        yield
+    except (BuildException, FailedProcessError) as e:
+        _error(str(e))
+    except BuildBackendException as e:
+        if isinstance(e.exception, subprocess.CalledProcessError):
+            _cprint()
+            _error(str(e))
+
+        if e.exc_info:
+            tb_lines = traceback.format_exception(
+                e.exc_info[0],
+                e.exc_info[1],
+                e.exc_info[2],
+                limit=-1,
+            )
+            tb = ''.join(tb_lines)
+        else:
+            tb = traceback.format_exc(-1)
+        _cprint('\n{dim}{}{reset}\n', tb.strip('\n'))
+        _error(str(e))
+
+
+def _natural_language_list(elements: Sequence[str]) -> str:
+    if len(elements) == 0:
+        raise IndexError('no elements')
+    elif len(elements) == 1:
+        return elements[0]
+    else:
+        return '{} and {}'.format(
+            ', '.join(elements[:-1]),
+            elements[-1],
+        )
+
+
+def build_package(
+    srcdir: PathType,
+    outdir: PathType,
+    distributions: Sequence[str],
+    config_settings: Optional[ConfigSettingsType] = None,
+    isolation: bool = True,
+    skip_dependency_check: bool = False,
+) -> Sequence[str]:
+    """
+    Run the build process.
+
+    :param srcdir: Source directory
+    :param outdir: Output directory
+    :param distribution: Distribution to build (sdist or wheel)
+    :param config_settings: Configuration settings to be passed to the backend
+    :param isolation: Isolate the build in a separate environment
+    :param skip_dependency_check: Do not perform the dependency check
+    """
+    built: List[str] = []
+    builder = _ProjectBuilder(srcdir)
+    for distribution in distributions:
+        out = _build(isolation, builder, outdir, distribution, config_settings, skip_dependency_check)
+        built.append(os.path.basename(out))
+    return built
+
+
+def build_package_via_sdist(
+    srcdir: PathType,
+    outdir: PathType,
+    distributions: Sequence[str],
+    config_settings: Optional[ConfigSettingsType] = None,
+    isolation: bool = True,
+    skip_dependency_check: bool = False,
+) -> Sequence[str]:
+    """
+    Build a sdist and then the specified distributions from it.
+
+    :param srcdir: Source directory
+    :param outdir: Output directory
+    :param distribution: Distribution to build (only wheel)
+    :param config_settings: Configuration settings to be passed to the backend
+    :param isolation: Isolate the build in a separate environment
+    :param skip_dependency_check: Do not perform the dependency check
+    """
+    if 'sdist' in distributions:
+        raise ValueError('Only binary distributions are allowed but sdist was specified')
+
+    builder = _ProjectBuilder(srcdir)
+    sdist = _build(isolation, builder, outdir, 'sdist', config_settings, skip_dependency_check)
+
+    sdist_name = os.path.basename(sdist)
+    sdist_out = tempfile.mkdtemp(prefix='build-via-sdist-')
+    built: List[str] = []
+    # extract sdist
+    with tarfile.open(sdist) as t:
+        t.extractall(sdist_out)
+        try:
+            builder = _ProjectBuilder(os.path.join(sdist_out, sdist_name[: -len('.tar.gz')]))
+            if distributions:
+                builder.log(f'Building {_natural_language_list(distributions)} from sdist')
+            for distribution in distributions:
+                out = _build(isolation, builder, outdir, distribution, config_settings, skip_dependency_check)
+                built.append(os.path.basename(out))
+        finally:
+            shutil.rmtree(sdist_out, ignore_errors=True)
+    return [sdist_name] + built
+
+
+def main_parser() -> argparse.ArgumentParser:
+    """
+    Construct the main parser.
+    """
+    parser = argparse.ArgumentParser(
+        description=textwrap.indent(
+            textwrap.dedent(
+                '''
+                A simple, correct PEP 517 build frontend.
+
+                By default, a source distribution (sdist) is built from {srcdir}
+                and a binary distribution (wheel) is built from the sdist.
+                This is recommended as it will ensure the sdist can be used
+                to build wheels.
+
+                Pass -s/--sdist and/or -w/--wheel to build a specific distribution.
+                If you do this, the default behavior will be disabled, and all
+                artifacts will be built from {srcdir} (even if you combine
+                -w/--wheel with -s/--sdist, the wheel will be built from {srcdir}).
+                '''
+            ).strip(),
+            '    ',
+        ),
+        formatter_class=argparse.RawTextHelpFormatter,
+    )
+    parser.add_argument(
+        'srcdir',
+        type=str,
+        nargs='?',
+        default=os.getcwd(),
+        help='source directory (defaults to current directory)',
+    )
+    parser.add_argument(
+        '--version',
+        '-V',
+        action='version',
+        version=f"build {build.__version__} ({','.join(build.__path__)})",
+    )
+    parser.add_argument(
+        '--sdist',
+        '-s',
+        action='store_true',
+        help='build a source distribution (disables the default behavior)',
+    )
+    parser.add_argument(
+        '--wheel',
+        '-w',
+        action='store_true',
+        help='build a wheel (disables the default behavior)',
+    )
+    parser.add_argument(
+        '--outdir',
+        '-o',
+        type=str,
+        help=f'output directory (defaults to {{srcdir}}{os.sep}dist)',
+    )
+    parser.add_argument(
+        '--skip-dependency-check',
+        '-x',
+        action='store_true',
+        help='do not check that build dependencies are installed',
+    )
+    parser.add_argument(
+        '--no-isolation',
+        '-n',
+        action='store_true',
+        help='do not isolate the build in a virtual environment',
+    )
+    parser.add_argument(
+        '--config-setting',
+        '-C',
+        action='append',
+        help='pass options to the backend.  options which begin with a hyphen must be in the form of '
+        '"--config-setting=--opt(=value)" or "-C--opt(=value)"',
+    )
+    return parser
+
+
+def main(cli_args: Sequence[str], prog: Optional[str] = None) -> None:  # noqa: C901
+    """
+    Parse the CLI arguments and invoke the build process.
+
+    :param cli_args: CLI arguments
+    :param prog: Program name to show in help text
+    """
+    _setup_cli()
+    parser = main_parser()
+    if prog:
+        parser.prog = prog
+    args = parser.parse_args(cli_args)
+
+    distributions = []
+    config_settings = {}
+
+    if args.config_setting:
+        for arg in args.config_setting:
+            setting, _, value = arg.partition('=')
+            if setting not in config_settings:
+                config_settings[setting] = value
+            else:
+                if not isinstance(config_settings[setting], list):
+                    config_settings[setting] = [config_settings[setting]]
+
+                config_settings[setting].append(value)
+
+    if args.sdist:
+        distributions.append('sdist')
+    if args.wheel:
+        distributions.append('wheel')
+
+    # outdir is relative to srcdir only if omitted.
+    outdir = os.path.join(args.srcdir, 'dist') if args.outdir is None else args.outdir
+
+    if distributions:
+        build_call = build_package
+    else:
+        build_call = build_package_via_sdist
+        distributions = ['wheel']
+    try:
+        with _handle_build_error():
+            built = build_call(
+                args.srcdir, outdir, distributions, config_settings, not args.no_isolation, args.skip_dependency_check
+            )
+            artifact_list = _natural_language_list(
+                ['{underline}{}{reset}{bold}{green}'.format(artifact, **_STYLES) for artifact in built]
+            )
+            _cprint('{bold}{green}Successfully built {}{reset}', artifact_list)
+    except Exception as e:  # pragma: no cover
+        tb = traceback.format_exc().strip('\n')
+        _cprint('\n{dim}{}{reset}\n', tb)
+        _error(str(e))
+
+
+def entrypoint() -> None:
+    main(sys.argv[1:])
+
+
+if __name__ == '__main__':  # pragma: no cover
+    main(sys.argv[1:], 'python -m build')
+
+
+__all__ = [
+    'main',
+    'main_parser',
+]
diff --git a/src/build/env.py b/src/build/env.py
new file mode 100644
index 0000000..b4a90a9
--- /dev/null
+++ b/src/build/env.py
@@ -0,0 +1,340 @@
+"""
+Creates and manages isolated build environments.
+"""
+import abc
+import functools
+import logging
+import os
+import platform
+import shutil
+import subprocess
+import sys
+import sysconfig
+import tempfile
+import warnings
+
+from types import TracebackType
+from typing import Callable, Collection, List, Optional, Tuple, Type
+
+import build
+
+
+try:
+    import virtualenv
+except ModuleNotFoundError:
+    virtualenv = None
+
+
+_logger = logging.getLogger(__name__)
+
+
+class IsolatedEnv(metaclass=abc.ABCMeta):
+    """Abstract base of isolated build environments, as required by the build project."""
+
+    @property
+    @abc.abstractmethod
+    def executable(self) -> str:
+        """The executable of the isolated build environment."""
+        raise NotImplementedError
+
+    @property
+    @abc.abstractmethod
+    def scripts_dir(self) -> str:
+        """The scripts directory of the isolated build environment."""
+        raise NotImplementedError
+
+    @abc.abstractmethod
+    def install(self, requirements: Collection[str]) -> None:
+        """
+        Install packages from PEP 508 requirements in the isolated build environment.
+
+        :param requirements: PEP 508 requirements
+        """
+        raise NotImplementedError
+
+
+@functools.lru_cache(maxsize=None)
+def _should_use_virtualenv() -> bool:
+    import packaging.requirements
+
+    # virtualenv might be incompatible if it was installed separately
+    # from build. This verifies that virtualenv and all of its
+    # dependencies are installed as specified by build.
+    return virtualenv is not None and not any(
+        packaging.requirements.Requirement(d[1]).name == 'virtualenv'
+        for d in build.check_dependency('build[virtualenv]')
+        if len(d) > 1
+    )
+
+
+def _subprocess(cmd: List[str]) -> None:
+    """Invoke subprocess and output stdout and stderr if it fails."""
+    try:
+        subprocess.run(cmd, check=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+    except subprocess.CalledProcessError as e:
+        print(e.output.decode(), end='', file=sys.stderr)
+        raise e
+
+
+class IsolatedEnvBuilder:
+    """Builder object for isolated environments."""
+
+    def __init__(self) -> None:
+        self._path: Optional[str] = None
+
+    def __enter__(self) -> IsolatedEnv:
+        """
+        Create an isolated build environment.
+
+        :return: The isolated build environment
+        """
+        # Call ``realpath`` to prevent spurious warning from being emitted
+        # that the venv location has changed on Windows. The username is
+        # DOS-encoded in the output of tempfile - the location is the same
+        # but the representation of it is different, which confuses venv.
+        # Ref: https://bugs.python.org/issue46171
+        self._path = os.path.realpath(tempfile.mkdtemp(prefix='build-env-'))
+        try:
+            # use virtualenv when available (as it's faster than venv)
+            if _should_use_virtualenv():
+                self.log('Creating virtualenv isolated environment...')
+                executable, scripts_dir = _create_isolated_env_virtualenv(self._path)
+            else:
+                self.log('Creating venv isolated environment...')
+                executable, scripts_dir = _create_isolated_env_venv(self._path)
+            return _IsolatedEnvVenvPip(
+                path=self._path,
+                python_executable=executable,
+                scripts_dir=scripts_dir,
+                log=self.log,
+            )
+        except Exception:  # cleanup folder if creation fails
+            self.__exit__(*sys.exc_info())
+            raise
+
+    def __exit__(
+        self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]
+    ) -> None:
+        """
+        Delete the created isolated build environment.
+
+        :param exc_type: The type of exception raised (if any)
+        :param exc_val: The value of exception raised (if any)
+        :param exc_tb: The traceback of exception raised (if any)
+        """
+        if self._path is not None and os.path.exists(self._path):  # in case the user already deleted skip remove
+            shutil.rmtree(self._path)
+
+    @staticmethod
+    def log(message: str) -> None:
+        """
+        Prints message
+
+        The default implementation uses the logging module but this function can be
+        overwritten by users to have a different implementation.
+
+        :param msg: Message to output
+        """
+        if sys.version_info >= (3, 8):
+            _logger.log(logging.INFO, message, stacklevel=2)
+        else:
+            _logger.log(logging.INFO, message)
+
+
+class _IsolatedEnvVenvPip(IsolatedEnv):
+    """
+    Isolated build environment context manager
+
+    Non-standard paths injected directly to sys.path will still be passed to the environment.
+    """
+
+    def __init__(
+        self,
+        path: str,
+        python_executable: str,
+        scripts_dir: str,
+        log: Callable[[str], None],
+    ) -> None:
+        """
+        :param path: The path where the environment exists
+        :param python_executable: The python executable within the environment
+        :param log: Log function
+        """
+        self._path = path
+        self._python_executable = python_executable
+        self._scripts_dir = scripts_dir
+        self._log = log
+
+    @property
+    def path(self) -> str:
+        """The location of the isolated build environment."""
+        return self._path
+
+    @property
+    def executable(self) -> str:
+        """The python executable of the isolated build environment."""
+        return self._python_executable
+
+    @property
+    def scripts_dir(self) -> str:
+        return self._scripts_dir
+
+    def install(self, requirements: Collection[str]) -> None:
+        """
+        Install packages from PEP 508 requirements in the isolated build environment.
+
+        :param requirements: PEP 508 requirement specification to install
+
+        :note: Passing non-PEP 508 strings will result in undefined behavior, you *should not* rely on it. It is
+               merely an implementation detail, it may change any time without warning.
+        """
+        if not requirements:
+            return
+
+        self._log('Installing packages in isolated environment... ({})'.format(', '.join(sorted(requirements))))
+
+        # pip does not honour environment markers in command line arguments
+        # but it does for requirements from a file
+        with tempfile.NamedTemporaryFile('w+', prefix='build-reqs-', suffix='.txt', delete=False) as req_file:
+            req_file.write(os.linesep.join(requirements))
+        try:
+            cmd = [
+                self.executable,
+                '-Im',
+                'pip',
+                'install',
+                '--use-pep517',
+                '--no-warn-script-location',
+                '-r',
+                os.path.abspath(req_file.name),
+            ]
+            _subprocess(cmd)
+        finally:
+            os.unlink(req_file.name)
+
+
+def _create_isolated_env_virtualenv(path: str) -> Tuple[str, str]:
+    """
+    We optionally can use the virtualenv package to provision a virtual environment.
+
+    :param path: The path where to create the isolated build environment
+    :return: The Python executable and script folder
+    """
+    cmd = [str(path), '--no-setuptools', '--no-wheel', '--activators', '']
+    result = virtualenv.cli_run(cmd, setup_logging=False)
+    executable = str(result.creator.exe)
+    script_dir = str(result.creator.script_dir)
+    return executable, script_dir
+
+
+@functools.lru_cache(maxsize=None)
+def _fs_supports_symlink() -> bool:
+    """Return True if symlinks are supported"""
+    # Using definition used by venv.main()
+    if not sys.platform.startswith('win'):
+        return True
+
+    # Windows may support symlinks (setting in Windows 10)
+    with tempfile.NamedTemporaryFile(prefix='build-symlink-') as tmp_file:
+        dest = f'{tmp_file}-b'
+        try:
+            os.symlink(tmp_file.name, dest)
+            os.unlink(dest)
+            return True
+        except (OSError, NotImplementedError, AttributeError):
+            return False
+
+
+def _create_isolated_env_venv(path: str) -> Tuple[str, str]:
+    """
+    On Python 3 we use the venv package from the standard library.
+
+    :param path: The path where to create the isolated build environment
+    :return: The Python executable and script folder
+    """
+    import venv
+
+    import packaging.version
+
+    if sys.version_info < (3, 8):
+        import importlib_metadata as metadata
+    else:
+        from importlib import metadata
+
+    symlinks = _fs_supports_symlink()
+    try:
+        with warnings.catch_warnings():
+            if sys.version_info[:3] == (3, 11, 0):
+                warnings.filterwarnings('ignore', 'check_home argument is deprecated and ignored.', DeprecationWarning)
+            venv.EnvBuilder(with_pip=True, symlinks=symlinks).create(path)
+    except subprocess.CalledProcessError as exc:
+        raise build.FailedProcessError(exc, 'Failed to create venv. Maybe try installing virtualenv.') from None
+
+    executable, script_dir, purelib = _find_executable_and_scripts(path)
+
+    # Get the version of pip in the environment
+    pip_distribution = next(iter(metadata.distributions(name='pip', path=[purelib])))  # type: ignore[no-untyped-call]
+    current_pip_version = packaging.version.Version(pip_distribution.version)
+
+    if platform.system() == 'Darwin' and int(platform.mac_ver()[0].split('.')[0]) >= 11:
+        # macOS 11+ name scheme change requires 20.3. Intel macOS 11.0 can be told to report 10.16 for backwards
+        # compatibility; but that also fixes earlier versions of pip so this is only needed for 11+.
+        is_apple_silicon_python = platform.machine() != 'x86_64'
+        minimum_pip_version = '21.0.1' if is_apple_silicon_python else '20.3.0'
+    else:
+        # PEP-517 and manylinux1 was first implemented in 19.1
+        minimum_pip_version = '19.1.0'
+
+    if current_pip_version < packaging.version.Version(minimum_pip_version):
+        _subprocess([executable, '-m', 'pip', 'install', f'pip>={minimum_pip_version}'])
+
+    # Avoid the setuptools from ensurepip to break the isolation
+    _subprocess([executable, '-m', 'pip', 'uninstall', 'setuptools', '-y'])
+    return executable, script_dir
+
+
+def _find_executable_and_scripts(path: str) -> Tuple[str, str, str]:
+    """
+    Detect the Python executable and script folder of a virtual environment.
+
+    :param path: The location of the virtual environment
+    :return: The Python executable, script folder, and purelib folder
+    """
+    config_vars = sysconfig.get_config_vars().copy()  # globally cached, copy before altering it
+    config_vars['base'] = path
+    scheme_names = sysconfig.get_scheme_names()
+    if 'venv' in scheme_names:
+        # Python distributors with custom default installation scheme can set a
+        # scheme that can't be used to expand the paths in a venv.
+        # This can happen if build itself is not installed in a venv.
+        # The distributors are encouraged to set a "venv" scheme to be used for this.
+        # See https://bugs.python.org/issue45413
+        # and https://github.com/pypa/virtualenv/issues/2208
+        paths = sysconfig.get_paths(scheme='venv', vars=config_vars)
+    elif 'posix_local' in scheme_names:
+        # The Python that ships on Debian/Ubuntu varies the default scheme to
+        # install to /usr/local
+        # But it does not (yet) set the "venv" scheme.
+        # If we're the Debian "posix_local" scheme is available, but "venv"
+        # is not, we use "posix_prefix" instead which is venv-compatible there.
+        paths = sysconfig.get_paths(scheme='posix_prefix', vars=config_vars)
+    elif 'osx_framework_library' in scheme_names:
+        # The Python that ships with the macOS developer tools varies the
+        # default scheme depending on whether the ``sys.prefix`` is part of a framework.
+        # But it does not (yet) set the "venv" scheme.
+        # If the Apple-custom "osx_framework_library" scheme is available but "venv"
+        # is not, we use "posix_prefix" instead which is venv-compatible there.
+        paths = sysconfig.get_paths(scheme='posix_prefix', vars=config_vars)
+    else:
+        paths = sysconfig.get_paths(vars=config_vars)
+    executable = os.path.join(paths['scripts'], 'python.exe' if sys.platform.startswith('win') else 'python')
+    if not os.path.exists(executable):
+        raise RuntimeError(f'Virtual environment creation failed, executable {executable} missing')
+
+    return executable, paths['scripts'], paths['purelib']
+
+
+__all__ = [
+    'IsolatedEnvBuilder',
+    'IsolatedEnv',
+]
diff --git a/src/build/py.typed b/src/build/py.typed
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/src/build/py.typed
diff --git a/src/build/util.py b/src/build/util.py
new file mode 100644
index 0000000..6c918ce
--- /dev/null
+++ b/src/build/util.py
@@ -0,0 +1,60 @@
+# SPDX-License-Identifier: MIT
+
+import os
+import pathlib
+import sys
+import tempfile
+
+import pep517
+
+import build
+import build.env
+
+
+if sys.version_info >= (3, 8):
+    import importlib.metadata as importlib_metadata
+else:
+    import importlib_metadata
+
+
+def _project_wheel_metadata(builder: build.ProjectBuilder) -> 'importlib_metadata.PackageMetadata':
+    with tempfile.TemporaryDirectory() as tmpdir:
+        path = pathlib.Path(builder.metadata_path(tmpdir))
+        # https://github.com/python/importlib_metadata/pull/343
+        return importlib_metadata.PathDistribution(path).metadata  # type: ignore[arg-type]
+
+
+def project_wheel_metadata(
+    srcdir: build.PathType,
+    isolated: bool = True,
+) -> 'importlib_metadata.PackageMetadata':
+    """
+    Return the wheel metadata for a project.
+
+    Uses the ``prepare_metadata_for_build_wheel`` hook if available,
+    otherwise ``build_wheel``.
+
+    :param srcdir: Project source directory
+    :param isolated: Whether or not to run invoke the backend in the current
+                     environment or to create an isolated one and invoke it
+                     there.
+    """
+    builder = build.ProjectBuilder(
+        os.fspath(srcdir),
+        runner=pep517.quiet_subprocess_runner,
+    )
+
+    if not isolated:
+        return _project_wheel_metadata(builder)
+
+    with build.env.IsolatedEnvBuilder() as env:
+        builder.python_executable = env.executable
+        builder.scripts_dir = env.scripts_dir
+        env.install(builder.build_system_requires)
+        env.install(builder.get_requires_for_build('wheel'))
+        return _project_wheel_metadata(builder)
+
+
+__all__ = [
+    'project_wheel_metadata',
+]