mirror of
https://github.com/python/cpython.git
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427 lines
16 KiB
Python
Executable file
427 lines
16 KiB
Python
Executable file
"""runpy.py - locating and running Python code using the module namespace
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Provides support for locating and running Python scripts using the Python
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module namespace instead of the native filesystem.
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This allows Python code to play nicely with non-filesystem based PEP 302
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importers when locating support scripts as well as when importing modules.
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"""
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# Written by Nick Coghlan <ncoghlan at gmail.com>
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# to implement PEP 338 (Executing Modules as Scripts)
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import sys
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import imp
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__all__ = [
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"run_module",
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]
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try:
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_get_loader = imp.get_loader
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except AttributeError:
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# get_loader() is not provided by the imp module, so emulate it
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# as best we can using the PEP 302 import machinery exposed since
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# Python 2.3. The emulation isn't perfect, but the differences
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# in the way names are shadowed shouldn't matter in practice.
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import os.path
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import marshal # Handle compiled Python files
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# This helper is needed in order for the PEP 302 emulation to
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# correctly handle compiled files
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def _read_compiled_file(compiled_file):
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magic = compiled_file.read(4)
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if magic != imp.get_magic():
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return None
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try:
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compiled_file.read(4) # Skip timestamp
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return marshal.load(compiled_file)
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except Exception:
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return None
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class _AbsoluteImporter(object):
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"""PEP 302 importer wrapper for top level import machinery"""
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def find_module(self, mod_name, path=None):
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if path is not None:
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return None
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try:
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file, filename, mod_info = imp.find_module(mod_name)
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except ImportError:
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return None
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suffix, mode, mod_type = mod_info
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if mod_type == imp.PY_SOURCE:
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loader = _SourceFileLoader(mod_name, file,
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filename, mod_info)
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elif mod_type == imp.PY_COMPILED:
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loader = _CompiledFileLoader(mod_name, file,
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filename, mod_info)
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elif mod_type == imp.PKG_DIRECTORY:
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loader = _PackageDirLoader(mod_name, file,
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filename, mod_info)
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elif mod_type == imp.C_EXTENSION:
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loader = _FileSystemLoader(mod_name, file,
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filename, mod_info)
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else:
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loader = _BasicLoader(mod_name, file,
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filename, mod_info)
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return loader
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class _FileSystemImporter(object):
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"""PEP 302 importer wrapper for filesystem based imports"""
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def __init__(self, path_item=None):
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if path_item is not None:
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if path_item != '' and not os.path.isdir(path_item):
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raise ImportError("%s is not a directory" % path_item)
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self.path_dir = path_item
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else:
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raise ImportError("Filesystem importer requires "
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"a directory name")
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def find_module(self, mod_name, path=None):
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if path is not None:
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return None
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path_dir = self.path_dir
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if path_dir == '':
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path_dir = os.getcwd()
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sub_name = mod_name.rsplit(".", 1)[-1]
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try:
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file, filename, mod_info = imp.find_module(sub_name,
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[path_dir])
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except ImportError:
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return None
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if not filename.startswith(path_dir):
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return None
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suffix, mode, mod_type = mod_info
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if mod_type == imp.PY_SOURCE:
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loader = _SourceFileLoader(mod_name, file,
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filename, mod_info)
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elif mod_type == imp.PY_COMPILED:
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loader = _CompiledFileLoader(mod_name, file,
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filename, mod_info)
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elif mod_type == imp.PKG_DIRECTORY:
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loader = _PackageDirLoader(mod_name, file,
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filename, mod_info)
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elif mod_type == imp.C_EXTENSION:
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loader = _FileSystemLoader(mod_name, file,
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filename, mod_info)
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else:
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loader = _BasicLoader(mod_name, file,
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filename, mod_info)
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return loader
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class _BasicLoader(object):
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"""PEP 302 loader wrapper for top level import machinery"""
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def __init__(self, mod_name, file, filename, mod_info):
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self.mod_name = mod_name
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self.file = file
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self.filename = filename
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self.mod_info = mod_info
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def _fix_name(self, mod_name):
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if mod_name is None:
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mod_name = self.mod_name
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elif mod_name != self.mod_name:
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raise ImportError("Loader for module %s cannot handle "
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"module %s" % (self.mod_name, mod_name))
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return mod_name
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def load_module(self, mod_name=None):
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mod_name = self._fix_name(mod_name)
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mod = imp.load_module(mod_name, self.file,
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self.filename, self.mod_info)
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mod.__loader__ = self # for introspection
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return mod
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def get_code(self, mod_name=None):
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return None
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def get_source(self, mod_name=None):
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return None
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def is_package(self, mod_name=None):
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return False
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def close(self):
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if self.file:
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self.file.close()
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def __del__(self):
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self.close()
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class _FileSystemLoader(_BasicLoader):
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"""PEP 302 loader wrapper for filesystem based imports"""
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def get_code(self, mod_name=None):
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mod_name = self._fix_name(mod_name)
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return self._get_code(mod_name)
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def get_data(self, pathname):
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return open(pathname, "rb").read()
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def get_filename(self, mod_name=None):
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mod_name = self._fix_name(mod_name)
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return self._get_filename(mod_name)
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def get_source(self, mod_name=None):
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mod_name = self._fix_name(mod_name)
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return self._get_source(mod_name)
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def is_package(self, mod_name=None):
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mod_name = self._fix_name(mod_name)
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return self._is_package(mod_name)
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def _get_code(self, mod_name):
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return None
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def _get_filename(self, mod_name):
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return self.filename
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def _get_source(self, mod_name):
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return None
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def _is_package(self, mod_name):
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return False
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class _PackageDirLoader(_FileSystemLoader):
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"""PEP 302 loader wrapper for PKG_DIRECTORY directories"""
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def _is_package(self, mod_name):
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return True
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class _SourceFileLoader(_FileSystemLoader):
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"""PEP 302 loader wrapper for PY_SOURCE modules"""
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def _get_code(self, mod_name):
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return compile(self._get_source(mod_name),
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self.filename, 'exec')
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def _get_source(self, mod_name):
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f = self.file
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f.seek(0)
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return f.read()
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class _CompiledFileLoader(_FileSystemLoader):
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"""PEP 302 loader wrapper for PY_COMPILED modules"""
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def _get_code(self, mod_name):
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f = self.file
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f.seek(0)
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return _read_compiled_file(f)
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def _get_importer(path_item):
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"""Retrieve a PEP 302 importer for the given path item
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The returned importer is cached in sys.path_importer_cache
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if it was newly created by a path hook.
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If there is no importer, a wrapper around the basic import
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machinery is returned. This wrapper is never inserted into
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the importer cache (None is inserted instead).
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The cache (or part of it) can be cleared manually if a
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rescan of sys.path_hooks is necessary.
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"""
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try:
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importer = sys.path_importer_cache[path_item]
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except KeyError:
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for path_hook in sys.path_hooks:
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try:
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importer = path_hook(path_item)
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break
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except ImportError:
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pass
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else:
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importer = None
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sys.path_importer_cache[path_item] = importer
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if importer is None:
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try:
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importer = _FileSystemImporter(path_item)
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except ImportError:
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pass
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return importer
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def _get_path_loader(mod_name, path=None):
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"""Retrieve a PEP 302 loader using a path importer"""
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if path is None:
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path = sys.path
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absolute_loader = _AbsoluteImporter().find_module(mod_name)
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if isinstance(absolute_loader, _FileSystemLoader):
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# Found in filesystem, so scan path hooks
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# before accepting this one as the right one
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loader = None
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else:
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# Not found in filesystem, so use top-level loader
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loader = absolute_loader
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else:
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loader = absolute_loader = None
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if loader is None:
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for path_item in path:
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importer = _get_importer(path_item)
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if importer is not None:
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loader = importer.find_module(mod_name)
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if loader is not None:
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# Found a loader for our module
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break
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else:
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# No path hook found, so accept the top level loader
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loader = absolute_loader
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return loader
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def _get_package(pkg_name):
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"""Retrieve a named package"""
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pkg = __import__(pkg_name)
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sub_pkg_names = pkg_name.split(".")
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for sub_pkg in sub_pkg_names[1:]:
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pkg = getattr(pkg, sub_pkg)
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return pkg
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def _get_loader(mod_name, path=None):
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"""Retrieve a PEP 302 loader for the given module or package
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If the module or package is accessible via the normal import
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mechanism, a wrapper around the relevant part of that machinery
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is returned.
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Non PEP 302 mechanisms (e.g. the Windows registry) used by the
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standard import machinery to find files in alternative locations
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are partially supported, but are searched AFTER sys.path. Normally,
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these locations are searched BEFORE sys.path, preventing sys.path
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entries from shadowing them.
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For this to cause a visible difference in behaviour, there must
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be a module or package name that is accessible via both sys.path
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and one of the non PEP 302 file system mechanisms. In this case,
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the emulation will find the former version, while the builtin
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import mechanism will find the latter.
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Items of the following types can be affected by this discrepancy:
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imp.C_EXTENSION
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imp.PY_SOURCE
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imp.PY_COMPILED
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imp.PKG_DIRECTORY
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"""
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try:
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loader = sys.modules[mod_name].__loader__
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except (KeyError, AttributeError):
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loader = None
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if loader is None:
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imp.acquire_lock()
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try:
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# Module not in sys.modules, or uses an unhooked loader
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parts = mod_name.rsplit(".", 1)
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if len(parts) == 2:
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# Sub package, so use parent package's path
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pkg_name, sub_name = parts
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if pkg_name and pkg_name[0] != '.':
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if path is not None:
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raise ImportError("Path argument must be None "
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"for a dotted module name")
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pkg = _get_package(pkg_name)
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try:
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path = pkg.__path__
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except AttributeError:
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raise ImportError(pkg_name +
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" is not a package")
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else:
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raise ImportError("Relative import syntax is not "
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"supported by _get_loader()")
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else:
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# Top level module, so stick with default path
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sub_name = mod_name
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for importer in sys.meta_path:
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loader = importer.find_module(mod_name, path)
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if loader is not None:
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# Found a metahook to handle the module
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break
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else:
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# Handling via the standard path mechanism
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loader = _get_path_loader(mod_name, path)
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finally:
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imp.release_lock()
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return loader
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# This helper is needed due to a missing component in the PEP 302
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# loader protocol (specifically, "get_filename" is non-standard)
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def _get_filename(loader, mod_name):
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try:
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get_filename = loader.get_filename
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except AttributeError:
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return None
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else:
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return get_filename(mod_name)
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# ------------------------------------------------------------
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# Done with the import machinery emulation, on with the code!
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def _run_code(code, run_globals, init_globals,
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mod_name, mod_fname, mod_loader):
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"""Helper for _run_module_code"""
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if init_globals is not None:
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run_globals.update(init_globals)
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run_globals.update(__name__ = mod_name,
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__file__ = mod_fname,
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__loader__ = mod_loader)
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exec code in run_globals
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return run_globals
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def _run_module_code(code, init_globals=None,
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mod_name=None, mod_fname=None,
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mod_loader=None, alter_sys=False):
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"""Helper for run_module"""
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# Set up the top level namespace dictionary
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if alter_sys:
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# Modify sys.argv[0] and sys.module[mod_name]
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temp_module = imp.new_module(mod_name)
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mod_globals = temp_module.__dict__
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saved_argv0 = sys.argv[0]
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restore_module = mod_name in sys.modules
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if restore_module:
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saved_module = sys.modules[mod_name]
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sys.argv[0] = mod_fname
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sys.modules[mod_name] = temp_module
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try:
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_run_code(code, mod_globals, init_globals,
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mod_name, mod_fname, mod_loader)
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finally:
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sys.argv[0] = saved_argv0
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if restore_module:
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sys.modules[mod_name] = saved_module
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else:
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del sys.modules[mod_name]
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# Copy the globals of the temporary module, as they
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# may be cleared when the temporary module goes away
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return mod_globals.copy()
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else:
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# Leave the sys module alone
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return _run_code(code, {}, init_globals,
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mod_name, mod_fname, mod_loader)
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def run_module(mod_name, init_globals=None,
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run_name=None, alter_sys=False):
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"""Execute a module's code without importing it
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Returns the resulting top level namespace dictionary
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"""
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loader = _get_loader(mod_name)
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if loader is None:
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raise ImportError("No module named " + mod_name)
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code = loader.get_code(mod_name)
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if code is None:
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raise ImportError("No code object available for " + mod_name)
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filename = _get_filename(loader, mod_name)
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if run_name is None:
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run_name = mod_name
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return _run_module_code(code, init_globals, run_name,
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filename, loader, alter_sys)
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if __name__ == "__main__":
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# Run the module specified as the next command line argument
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if len(sys.argv) < 2:
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print >> sys.stderr, "No module specified for execution"
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else:
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del sys.argv[0] # Make the requested module sys.argv[0]
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run_module(sys.argv[0], run_name="__main__", alter_sys=True)
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