"Ansible compatible" module loader.
Since all Ansible modules ever written are using worst practice Python, the module loader must be rewritten to cope with their horrors. Ansible is woeful software: * AnsibleModule argument declarations appear within the main() function, so they can't be introspected prior to execution. * No if __name__ == '__main__' guard means they can't be introspected without triggering execution. * By default the main() function attempts to read from stdin, hanging our IO thread. * So much unspeakable crap. This rewrites the module loader to avoid actually running a module if it can possibly be avoided. The downside is that the new loader must be aware of far more details of the Python module mechanism. For example with the new importer, namespace packages are broken at the very least. On the plus side, now the module loader will be able to cope with Django.pull/35/head
David Wilson
8 years ago
parent
088d053a4e
commit
3de06ca559
@ -0,0 +1,591 @@
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"""Utilities to support packages."""
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# NOTE: This module must remain compatible with Python 2.3, as it is shared
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# by setuptools for distribution with Python 2.3 and up.
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import os
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import sys
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import imp
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import os.path
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from types import ModuleType
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__all__ = [
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'get_importer', 'iter_importers', 'get_loader', 'find_loader',
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'walk_packages', 'iter_modules', 'get_data',
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'ImpImporter', 'ImpLoader', 'read_code', 'extend_path',
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]
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def read_code(stream):
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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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import marshal
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magic = stream.read(4)
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if magic != imp.get_magic():
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return None
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stream.read(4) # Skip timestamp
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return marshal.load(stream)
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def simplegeneric(func):
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"""Make a trivial single-dispatch generic function"""
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registry = {}
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def wrapper(*args, **kw):
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ob = args[0]
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try:
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cls = ob.__class__
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except AttributeError:
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cls = type(ob)
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try:
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mro = cls.__mro__
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except AttributeError:
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try:
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class cls(cls, object):
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pass
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mro = cls.__mro__[1:]
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except TypeError:
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mro = object, # must be an ExtensionClass or some such :(
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for t in mro:
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if t in registry:
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return registry[t](*args, **kw)
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else:
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return func(*args, **kw)
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try:
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wrapper.__name__ = func.__name__
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except (TypeError, AttributeError):
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pass # Python 2.3 doesn't allow functions to be renamed
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def register(typ, func=None):
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if func is None:
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return lambda f: register(typ, f)
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registry[typ] = func
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return func
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wrapper.__dict__ = func.__dict__
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wrapper.__doc__ = func.__doc__
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wrapper.register = register
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return wrapper
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def walk_packages(path=None, prefix='', onerror=None):
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"""Yields (module_loader, name, ispkg) for all modules recursively
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on path, or, if path is None, all accessible modules.
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'path' should be either None or a list of paths to look for
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modules in.
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'prefix' is a string to output on the front of every module name
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on output.
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Note that this function must import all *packages* (NOT all
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modules!) on the given path, in order to access the __path__
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attribute to find submodules.
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'onerror' is a function which gets called with one argument (the
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name of the package which was being imported) if any exception
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occurs while trying to import a package. If no onerror function is
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supplied, ImportErrors are caught and ignored, while all other
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exceptions are propagated, terminating the search.
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Examples:
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# list all modules python can access
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walk_packages()
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# list all submodules of ctypes
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walk_packages(ctypes.__path__, ctypes.__name__+'.')
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"""
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def seen(p, m={}):
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if p in m:
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return True
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m[p] = True
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for importer, name, ispkg in iter_modules(path, prefix):
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yield importer, name, ispkg
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if ispkg:
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try:
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__import__(name)
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except ImportError:
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if onerror is not None:
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onerror(name)
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except Exception:
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if onerror is not None:
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onerror(name)
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else:
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raise
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else:
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path = getattr(sys.modules[name], '__path__', None) or []
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# don't traverse path items we've seen before
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path = [p for p in path if not seen(p)]
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for item in walk_packages(path, name+'.', onerror):
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yield item
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def iter_modules(path=None, prefix=''):
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"""Yields (module_loader, name, ispkg) for all submodules on path,
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or, if path is None, all top-level modules on sys.path.
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'path' should be either None or a list of paths to look for
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modules in.
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'prefix' is a string to output on the front of every module name
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on output.
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"""
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if path is None:
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importers = iter_importers()
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else:
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importers = map(get_importer, path)
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yielded = {}
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for i in importers:
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for name, ispkg in iter_importer_modules(i, prefix):
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if name not in yielded:
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yielded[name] = 1
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yield i, name, ispkg
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#@simplegeneric
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def iter_importer_modules(importer, prefix=''):
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if not hasattr(importer, 'iter_modules'):
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return []
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return importer.iter_modules(prefix)
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iter_importer_modules = simplegeneric(iter_importer_modules)
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class ImpImporter:
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"""PEP 302 Importer that wraps Python's "classic" import algorithm
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ImpImporter(dirname) produces a PEP 302 importer that searches that
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directory. ImpImporter(None) produces a PEP 302 importer that searches
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the current sys.path, plus any modules that are frozen or built-in.
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Note that ImpImporter does not currently support being used by placement
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on sys.meta_path.
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"""
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def __init__(self, path=None):
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self.path = path
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def find_module(self, fullname, path=None):
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# Note: we ignore 'path' argument since it is only used via meta_path
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subname = fullname.split(".")[-1]
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if subname != fullname and self.path is None:
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return None
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if self.path is None:
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path = None
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else:
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path = [os.path.realpath(self.path)]
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try:
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file, filename, etc = imp.find_module(subname, path)
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except ImportError:
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return None
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return ImpLoader(fullname, file, filename, etc)
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def iter_modules(self, prefix=''):
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if self.path is None or not os.path.isdir(self.path):
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return
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yielded = {}
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import inspect
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try:
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filenames = os.listdir(self.path)
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except OSError:
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# ignore unreadable directories like import does
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filenames = []
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filenames.sort() # handle packages before same-named modules
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for fn in filenames:
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modname = inspect.getmodulename(fn)
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if modname=='__init__' or modname in yielded:
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continue
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path = os.path.join(self.path, fn)
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ispkg = False
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if not modname and os.path.isdir(path) and '.' not in fn:
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modname = fn
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try:
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dircontents = os.listdir(path)
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except OSError:
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# ignore unreadable directories like import does
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dircontents = []
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for fn in dircontents:
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subname = inspect.getmodulename(fn)
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if subname=='__init__':
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ispkg = True
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break
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else:
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continue # not a package
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if modname and '.' not in modname:
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yielded[modname] = 1
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yield prefix + modname, ispkg
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class ImpLoader:
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"""PEP 302 Loader that wraps Python's "classic" import algorithm
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"""
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code = source = None
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def __init__(self, fullname, file, filename, etc):
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self.file = file
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self.filename = filename
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self.fullname = fullname
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self.etc = etc
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def load_module(self, fullname):
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self._reopen()
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try:
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mod = imp.load_module(fullname, self.file, self.filename, self.etc)
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finally:
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if self.file:
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self.file.close()
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# Note: we don't set __loader__ because we want the module to look
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# normal; i.e. this is just a wrapper for standard import machinery
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return mod
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def get_data(self, pathname):
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return open(pathname, "rb").read()
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def _reopen(self):
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if self.file and self.file.closed:
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mod_type = self.etc[2]
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if mod_type==imp.PY_SOURCE:
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self.file = open(self.filename, 'rU')
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elif mod_type in (imp.PY_COMPILED, imp.C_EXTENSION):
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self.file = open(self.filename, 'rb')
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def _fix_name(self, fullname):
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if fullname is None:
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fullname = self.fullname
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elif fullname != self.fullname:
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raise ImportError("Loader for module %s cannot handle "
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"module %s" % (self.fullname, fullname))
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return fullname
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def is_package(self, fullname):
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fullname = self._fix_name(fullname)
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return self.etc[2]==imp.PKG_DIRECTORY
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def get_code(self, fullname=None):
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fullname = self._fix_name(fullname)
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if self.code is None:
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mod_type = self.etc[2]
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if mod_type==imp.PY_SOURCE:
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source = self.get_source(fullname)
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self.code = compile(source, self.filename, 'exec')
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elif mod_type==imp.PY_COMPILED:
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self._reopen()
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try:
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self.code = read_code(self.file)
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finally:
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self.file.close()
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elif mod_type==imp.PKG_DIRECTORY:
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self.code = self._get_delegate().get_code()
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return self.code
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def get_source(self, fullname=None):
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fullname = self._fix_name(fullname)
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if self.source is None:
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mod_type = self.etc[2]
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if mod_type==imp.PY_SOURCE:
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self._reopen()
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try:
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self.source = self.file.read()
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finally:
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self.file.close()
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elif mod_type==imp.PY_COMPILED:
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if os.path.exists(self.filename[:-1]):
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f = open(self.filename[:-1], 'rU')
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self.source = f.read()
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f.close()
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elif mod_type==imp.PKG_DIRECTORY:
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self.source = self._get_delegate().get_source()
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return self.source
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def _get_delegate(self):
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return ImpImporter(self.filename).find_module('__init__')
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def get_filename(self, fullname=None):
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fullname = self._fix_name(fullname)
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mod_type = self.etc[2]
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if self.etc[2]==imp.PKG_DIRECTORY:
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return self._get_delegate().get_filename()
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elif self.etc[2] in (imp.PY_SOURCE, imp.PY_COMPILED, imp.C_EXTENSION):
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return self.filename
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return None
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try:
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import zipimport
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from zipimport import zipimporter
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def iter_zipimport_modules(importer, prefix=''):
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dirlist = zipimport._zip_directory_cache[importer.archive].keys()
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dirlist.sort()
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_prefix = importer.prefix
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plen = len(_prefix)
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yielded = {}
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import inspect
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for fn in dirlist:
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if not fn.startswith(_prefix):
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continue
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fn = fn[plen:].split(os.sep)
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if len(fn)==2 and fn[1].startswith('__init__.py'):
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if fn[0] not in yielded:
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yielded[fn[0]] = 1
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yield fn[0], True
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if len(fn)!=1:
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continue
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modname = inspect.getmodulename(fn[0])
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if modname=='__init__':
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continue
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if modname and '.' not in modname and modname not in yielded:
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yielded[modname] = 1
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yield prefix + modname, False
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iter_importer_modules.register(zipimporter, iter_zipimport_modules)
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except ImportError:
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pass
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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.setdefault(path_item, importer)
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if importer is None:
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try:
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importer = ImpImporter(path_item)
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except ImportError:
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importer = None
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return importer
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def iter_importers(fullname=""):
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"""Yield PEP 302 importers for the given module name
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If fullname contains a '.', the importers will be for the package
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containing fullname, otherwise they will be importers for sys.meta_path,
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sys.path, and Python's "classic" import machinery, in that order. If
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the named module is in a package, that package is imported as a side
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effect of invoking this function.
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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, imp.PY_SOURCE, imp.PY_COMPILED, imp.PKG_DIRECTORY
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"""
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if fullname.startswith('.'):
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raise ImportError("Relative module names not supported")
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||||
if '.' in fullname:
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||||
# Get the containing package's __path__
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pkg = '.'.join(fullname.split('.')[:-1])
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if pkg not in sys.modules:
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__import__(pkg)
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path = getattr(sys.modules[pkg], '__path__', None) or []
|
||||
else:
|
||||
for importer in sys.meta_path:
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||||
yield importer
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||||
path = sys.path
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||||
for item in path:
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||||
yield get_importer(item)
|
||||
if '.' not in fullname:
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yield ImpImporter()
|
||||
|
||||
def get_loader(module_or_name):
|
||||
"""Get a PEP 302 "loader" object for module_or_name
|
||||
|
||||
If the module or package is accessible via the normal import
|
||||
mechanism, a wrapper around the relevant part of that machinery
|
||||
is returned. Returns None if the module cannot be found or imported.
|
||||
If the named module is not already imported, its containing package
|
||||
(if any) is imported, in order to establish the package __path__.
|
||||
|
||||
This function uses iter_importers(), and is thus subject to the same
|
||||
limitations regarding platform-specific special import locations such
|
||||
as the Windows registry.
|
||||
"""
|
||||
if module_or_name in sys.modules:
|
||||
module_or_name = sys.modules[module_or_name]
|
||||
if isinstance(module_or_name, ModuleType):
|
||||
module = module_or_name
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||||
loader = getattr(module, '__loader__', None)
|
||||
if loader is not None:
|
||||
return loader
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||||
fullname = module.__name__
|
||||
else:
|
||||
fullname = module_or_name
|
||||
return find_loader(fullname)
|
||||
|
||||
def find_loader(fullname):
|
||||
"""Find a PEP 302 "loader" object for fullname
|
||||
|
||||
If fullname contains dots, path must be the containing package's __path__.
|
||||
Returns None if the module cannot be found or imported. This function uses
|
||||
iter_importers(), and is thus subject to the same limitations regarding
|
||||
platform-specific special import locations such as the Windows registry.
|
||||
"""
|
||||
for importer in iter_importers(fullname):
|
||||
loader = importer.find_module(fullname)
|
||||
if loader is not None:
|
||||
return loader
|
||||
|
||||
return None
|
||||
|
||||
|
||||
def extend_path(path, name):
|
||||
"""Extend a package's path.
|
||||
|
||||
Intended use is to place the following code in a package's __init__.py:
|
||||
|
||||
from pkgutil import extend_path
|
||||
__path__ = extend_path(__path__, __name__)
|
||||
|
||||
This will add to the package's __path__ all subdirectories of
|
||||
directories on sys.path named after the package. This is useful
|
||||
if one wants to distribute different parts of a single logical
|
||||
package as multiple directories.
|
||||
|
||||
It also looks for *.pkg files beginning where * matches the name
|
||||
argument. This feature is similar to *.pth files (see site.py),
|
||||
except that it doesn't special-case lines starting with 'import'.
|
||||
A *.pkg file is trusted at face value: apart from checking for
|
||||
duplicates, all entries found in a *.pkg file are added to the
|
||||
path, regardless of whether they are exist the filesystem. (This
|
||||
is a feature.)
|
||||
|
||||
If the input path is not a list (as is the case for frozen
|
||||
packages) it is returned unchanged. The input path is not
|
||||
modified; an extended copy is returned. Items are only appended
|
||||
to the copy at the end.
|
||||
|
||||
It is assumed that sys.path is a sequence. Items of sys.path that
|
||||
are not (unicode or 8-bit) strings referring to existing
|
||||
directories are ignored. Unicode items of sys.path that cause
|
||||
errors when used as filenames may cause this function to raise an
|
||||
exception (in line with os.path.isdir() behavior).
|
||||
"""
|
||||
|
||||
if not isinstance(path, list):
|
||||
# This could happen e.g. when this is called from inside a
|
||||
# frozen package. Return the path unchanged in that case.
|
||||
return path
|
||||
|
||||
pname = os.path.join(*name.split('.')) # Reconstitute as relative path
|
||||
# Just in case os.extsep != '.'
|
||||
sname = os.extsep.join(name.split('.'))
|
||||
sname_pkg = sname + os.extsep + "pkg"
|
||||
init_py = "__init__" + os.extsep + "py"
|
||||
|
||||
path = path[:] # Start with a copy of the existing path
|
||||
|
||||
for dir in sys.path:
|
||||
if not isinstance(dir, basestring) or not os.path.isdir(dir):
|
||||
continue
|
||||
subdir = os.path.join(dir, pname)
|
||||
# XXX This may still add duplicate entries to path on
|
||||
# case-insensitive filesystems
|
||||
initfile = os.path.join(subdir, init_py)
|
||||
if subdir not in path and os.path.isfile(initfile):
|
||||
path.append(subdir)
|
||||
# XXX Is this the right thing for subpackages like zope.app?
|
||||
# It looks for a file named "zope.app.pkg"
|
||||
pkgfile = os.path.join(dir, sname_pkg)
|
||||
if os.path.isfile(pkgfile):
|
||||
try:
|
||||
f = open(pkgfile)
|
||||
except IOError, msg:
|
||||
sys.stderr.write("Can't open %s: %s\n" %
|
||||
(pkgfile, msg))
|
||||
else:
|
||||
for line in f:
|
||||
line = line.rstrip('\n')
|
||||
if not line or line.startswith('#'):
|
||||
continue
|
||||
path.append(line) # Don't check for existence!
|
||||
f.close()
|
||||
|
||||
return path
|
||||
|
||||
def get_data(package, resource):
|
||||
"""Get a resource from a package.
|
||||
|
||||
This is a wrapper round the PEP 302 loader get_data API. The package
|
||||
argument should be the name of a package, in standard module format
|
||||
(foo.bar). The resource argument should be in the form of a relative
|
||||
filename, using '/' as the path separator. The parent directory name '..'
|
||||
is not allowed, and nor is a rooted name (starting with a '/').
|
||||
|
||||
The function returns a binary string, which is the contents of the
|
||||
specified resource.
|
||||
|
||||
For packages located in the filesystem, which have already been imported,
|
||||
this is the rough equivalent of
|
||||
|
||||
d = os.path.dirname(sys.modules[package].__file__)
|
||||
data = open(os.path.join(d, resource), 'rb').read()
|
||||
|
||||
If the package cannot be located or loaded, or it uses a PEP 302 loader
|
||||
which does not support get_data(), then None is returned.
|
||||
"""
|
||||
|
||||
loader = get_loader(package)
|
||||
if loader is None or not hasattr(loader, 'get_data'):
|
||||
return None
|
||||
mod = sys.modules.get(package) or loader.load_module(package)
|
||||
if mod is None or not hasattr(mod, '__file__'):
|
||||
return None
|
||||
|
||||
# Modify the resource name to be compatible with the loader.get_data
|
||||
# signature - an os.path format "filename" starting with the dirname of
|
||||
# the package's __file__
|
||||
parts = resource.split('/')
|
||||
parts.insert(0, os.path.dirname(mod.__file__))
|
||||
resource_name = os.path.join(*parts)
|
||||
return loader.get_data(resource_name)
|
||||
Loading…
Reference in New Issue