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EDIT :: _in_process.py

"""This is invoked in a subprocess to call the build backend hooks. It expects: - Command line args: hook_name, control_dir - Environment variables: PEP517_BUILD_BACKEND=entry.point:spec PEP517_BACKEND_PATH=paths (separated with os.pathsep) - control_dir/input.json: - {"kwargs": {...}} Results: - control_dir/output.json - {"return_val": ...} """ from glob import glob from importlib import import_module import os import os.path from os.path import join as pjoin import re import shutil import sys import traceback # This is run as a script, not a module, so it can't do a relative import import compat class BackendUnavailable(Exception): """Raised if we cannot import the backend""" def __init__(self, traceback): self.traceback = traceback class BackendInvalid(Exception): """Raised if the backend is invalid""" def __init__(self, message): self.message = message class HookMissing(Exception): """Raised if a hook is missing and we are not executing the fallback""" def contained_in(filename, directory): """Test if a file is located within the given directory.""" filename = os.path.normcase(os.path.abspath(filename)) directory = os.path.normcase(os.path.abspath(directory)) return os.path.commonprefix([filename, directory]) == directory def _build_backend(): """Find and load the build backend""" # Add in-tree backend directories to the front of sys.path. backend_path = os.environ.get('PEP517_BACKEND_PATH') if backend_path: extra_pathitems = backend_path.split(os.pathsep) sys.path[:0] = extra_pathitems ep = os.environ['PEP517_BUILD_BACKEND'] mod_path, _, obj_path = ep.partition(':') try: obj = import_module(mod_path) except ImportError: raise BackendUnavailable(traceback.format_exc()) if backend_path: if not any( contained_in(obj.__file__, path) for path in extra_pathitems ): raise BackendInvalid("Backend was not loaded from backend-path") if obj_path: for path_part in obj_path.split('.'): obj = getattr(obj, path_part) return obj def get_requires_for_build_wheel(config_settings): """Invoke the optional get_requires_for_build_wheel hook Returns [] if the hook is not defined. """ backend = _build_backend() try: hook = backend.get_requires_for_build_wheel except AttributeError: return [] else: return hook(config_settings) def prepare_metadata_for_build_wheel( metadata_directory, config_settings, _allow_fallback): """Invoke optional prepare_metadata_for_build_wheel Implements a fallback by building a wheel if the hook isn't defined, unless _allow_fallback is False in which case HookMissing is raised. """ backend = _build_backend() try: hook = backend.prepare_metadata_for_build_wheel except AttributeError: if not _allow_fallback: raise HookMissing() return _get_wheel_metadata_from_wheel(backend, metadata_directory, config_settings) else: return hook(metadata_directory, config_settings) WHEEL_BUILT_MARKER = 'PEP517_ALREADY_BUILT_WHEEL' def _dist_info_files(whl_zip): """Identify the .dist-info folder inside a wheel ZipFile.""" res = [] for path in whl_zip.namelist(): m = re.match(r'[^/\\]+-[^/\\]+\.dist-info/', path) if m: res.append(path) if res: return res raise Exception("No .dist-info folder found in wheel") def _get_wheel_metadata_from_wheel( backend, metadata_directory, config_settings): """Build a wheel and extract the metadata from it. Fallback for when the build backend does not define the 'get_wheel_metadata' hook. """ from zipfile import ZipFile whl_basename = backend.build_wheel(metadata_directory, config_settings) with open(os.path.join(metadata_directory, WHEEL_BUILT_MARKER), 'wb'): pass # Touch marker file whl_file = os.path.join(metadata_directory, whl_basename) with ZipFile(whl_file) as zipf: dist_info = _dist_info_files(zipf) zipf.extractall(path=metadata_directory, members=dist_info) return dist_info[0].split('/')[0] def _find_already_built_wheel(metadata_directory): """Check for a wheel already built during the get_wheel_metadata hook. """ if not metadata_directory: return None metadata_parent = os.path.dirname(metadata_directory) if not os.path.isfile(pjoin(metadata_parent, WHEEL_BUILT_MARKER)): return None whl_files = glob(os.path.join(metadata_parent, '*.whl')) if not whl_files: print('Found wheel built marker, but no .whl files') return None if len(whl_files) > 1: print('Found multiple .whl files; unspecified behaviour. ' 'Will call build_wheel.') return None # Exactly one .whl file return whl_files[0] def build_wheel(wheel_directory, config_settings, metadata_directory=None): """Invoke the mandatory build_wheel hook. If a wheel was already built in the prepare_metadata_for_build_wheel fallback, this will copy it rather than rebuilding the wheel. """ prebuilt_whl = _find_already_built_wheel(metadata_directory) if prebuilt_whl: shutil.copy2(prebuilt_whl, wheel_directory) return os.path.basename(prebuilt_whl) return _build_backend().build_wheel(wheel_directory, config_settings, metadata_directory) def get_requires_for_build_sdist(config_settings): """Invoke the optional get_requires_for_build_wheel hook Returns [] if the hook is not defined. """ backend = _build_backend() try: hook = backend.get_requires_for_build_sdist except AttributeError: return [] else: return hook(config_settings) class _DummyException(Exception): """Nothing should ever raise this exception""" class GotUnsupportedOperation(Exception): """For internal use when backend raises UnsupportedOperation""" def __init__(self, traceback): self.traceback = traceback def build_sdist(sdist_directory, config_settings): """Invoke the mandatory build_sdist hook.""" backend = _build_backend() try: return backend.build_sdist(sdist_directory, config_settings) except getattr(backend, 'UnsupportedOperation', _DummyException): raise GotUnsupportedOperation(traceback.format_exc()) HOOK_NAMES = { 'get_requires_for_build_wheel', 'prepare_metadata_for_build_wheel', 'build_wheel', 'get_requires_for_build_sdist', 'build_sdist', } def main(): if len(sys.argv) < 3: sys.exit("Needs args: hook_name, control_dir") hook_name = sys.argv[1] control_dir = sys.argv[2] if hook_name not in HOOK_NAMES: sys.exit("Unknown hook: %s" % hook_name) hook = globals()[hook_name] hook_input = compat.read_json(pjoin(control_dir, 'input.json')) json_out = {'unsupported': False, 'return_val': None} try: json_out['return_val'] = hook(**hook_input['kwargs']) except BackendUnavailable as e: json_out['no_backend'] = True json_out['traceback'] = e.traceback except BackendInvalid as e: json_out['backend_invalid'] = True json_out['backend_error'] = e.message except GotUnsupportedOperation as e: json_out['unsupported'] = True json_out['traceback'] = e.traceback except HookMissing: json_out['hook_missing'] = True compat.write_json(json_out, pjoin(control_dir, 'output.json'), indent=2) if __name__ == '__main__': main()

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