diff options
Diffstat (limited to 'Lib/importlib/_bootstrap.py')
| -rw-r--r-- | Lib/importlib/_bootstrap.py | 1138 |
1 files changed, 792 insertions, 346 deletions
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py index 90eb1a7..3069bd8 100644 --- a/Lib/importlib/_bootstrap.py +++ b/Lib/importlib/_bootstrap.py @@ -6,33 +6,93 @@ such it requires the injection of specific modules and attributes in order to work. One should use importlib as the public-facing version of this module. """ - -# Injected modules are '_warnings', 'imp', 'sys', 'marshal', 'errno', '_io', -# and '_os' (a.k.a. 'posix', 'nt' or 'os2'). -# Injected attribute is path_sep. # +# IMPORTANT: Whenever making changes to this module, be sure to run +# a top-level make in order to get the frozen version of the module +# update. Not doing so, will result in the Makefile to fail for +# all others who don't have a ./python around to freeze the module +# in the early stages of compilation. +# + +# See importlib._setup() for what is injected into the global namespace. + # When editing this code be aware that code executed at import time CANNOT # reference any injected objects! This includes not only global code but also # anything specified at the class level. +# XXX Make sure all public names have no single leading underscore and all +# others do. + # Bootstrap-related code ###################################################### -# XXX Could also expose Modules/getpath.c:joinpath() -def _path_join(*args): - """Replacement for os.path.join.""" - return path_sep.join(x[:-len(path_sep)] if x.endswith(path_sep) else x - for x in args if x) +_CASE_INSENSITIVE_PLATFORMS = 'win', 'cygwin', 'darwin' -def _path_exists(path): - """Replacement for os.path.exists.""" - try: - _os.stat(path) - except OSError: - return False +def _make_relax_case(): + if sys.platform.startswith(_CASE_INSENSITIVE_PLATFORMS): + def _relax_case(): + """True if filenames must be checked case-insensitively.""" + return b'PYTHONCASEOK' in _os.environ else: - return True + def _relax_case(): + """True if filenames must be checked case-insensitively.""" + return False + return _relax_case + + +# TODO: Expose from marshal +def _w_long(x): + """Convert a 32-bit integer to little-endian. + + XXX Temporary until marshal's long functions are exposed. + + """ + x = int(x) + int_bytes = [] + int_bytes.append(x & 0xFF) + int_bytes.append((x >> 8) & 0xFF) + int_bytes.append((x >> 16) & 0xFF) + int_bytes.append((x >> 24) & 0xFF) + return bytearray(int_bytes) + + +# TODO: Expose from marshal +def _r_long(int_bytes): + """Convert 4 bytes in little-endian to an integer. + + XXX Temporary until marshal's long function are exposed. + + """ + x = int_bytes[0] + x |= int_bytes[1] << 8 + x |= int_bytes[2] << 16 + x |= int_bytes[3] << 24 + return x + + +def _path_join(*path_parts): + """Replacement for os.path.join().""" + new_parts = [] + for part in path_parts: + if not part: + continue + new_parts.append(part) + if part[-1] not in path_separators: + new_parts.append(path_sep) + return ''.join(new_parts[:-1]) # Drop superfluous path separator. + + +def _path_split(path): + """Replacement for os.path.split().""" + for x in reversed(path): + if x in path_separators: + sep = x + break + else: + sep = path_sep + front, _, tail = path.rpartition(sep) + return front, tail def _path_is_mode_type(path, mode): @@ -58,61 +118,251 @@ def _path_isdir(path): return _path_is_mode_type(path, 0o040000) -def _path_without_ext(path, ext_type): - """Replacement for os.path.splitext()[0].""" - for suffix in _suffix_list(ext_type): - if path.endswith(suffix): - return path[:-len(suffix)] - else: - raise ValueError("path is not of the specified type") - - -def _path_absolute(path): - """Replacement for os.path.abspath.""" - if not path: - path = _os.getcwd() +def _write_atomic(path, data): + """Best-effort function to write data to a path atomically. + Be prepared to handle a FileExistsError if concurrent writing of the + temporary file is attempted.""" + # id() is used to generate a pseudo-random filename. + path_tmp = '{}.{}'.format(path, id(path)) + fd = _os.open(path_tmp, _os.O_EXCL | _os.O_CREAT | _os.O_WRONLY, 0o666) try: - return _os._getfullpathname(path) - except AttributeError: - if path.startswith('/'): - return path - else: - return _path_join(_os.getcwd(), path) + # We first write data to a temporary file, and then use os.replace() to + # perform an atomic rename. + with _io.FileIO(fd, 'wb') as file: + file.write(data) + _os.replace(path_tmp, path) + except OSError: + try: + _os.unlink(path_tmp) + except OSError: + pass + raise def _wrap(new, old): """Simple substitute for functools.wraps.""" - for replace in ['__module__', '__name__', '__doc__']: - setattr(new, replace, getattr(old, replace)) + for replace in ['__module__', '__name__', '__qualname__', '__doc__']: + if hasattr(old, replace): + setattr(new, replace, getattr(old, replace)) new.__dict__.update(old.__dict__) -code_type = type(_wrap.__code__) +_code_type = type(_wrap.__code__) + + +def new_module(name): + """Create a new module. + + The module is not entered into sys.modules. + + """ + return type(_io)(name) + + +# Module-level locking ######################################################## + +# A dict mapping module names to weakrefs of _ModuleLock instances +_module_locks = {} +# A dict mapping thread ids to _ModuleLock instances +_blocking_on = {} + + +class _DeadlockError(RuntimeError): + pass + + +class _ModuleLock: + """A recursive lock implementation which is able to detect deadlocks + (e.g. thread 1 trying to take locks A then B, and thread 2 trying to + take locks B then A). + """ + + def __init__(self, name): + self.lock = _thread.allocate_lock() + self.wakeup = _thread.allocate_lock() + self.name = name + self.owner = None + self.count = 0 + self.waiters = 0 + + def has_deadlock(self): + # Deadlock avoidance for concurrent circular imports. + me = _thread.get_ident() + tid = self.owner + while True: + lock = _blocking_on.get(tid) + if lock is None: + return False + tid = lock.owner + if tid == me: + return True + + def acquire(self): + """ + Acquire the module lock. If a potential deadlock is detected, + a _DeadlockError is raised. + Otherwise, the lock is always acquired and True is returned. + """ + tid = _thread.get_ident() + _blocking_on[tid] = self + try: + while True: + with self.lock: + if self.count == 0 or self.owner == tid: + self.owner = tid + self.count += 1 + return True + if self.has_deadlock(): + raise _DeadlockError("deadlock detected by %r" % self) + if self.wakeup.acquire(False): + self.waiters += 1 + # Wait for a release() call + self.wakeup.acquire() + self.wakeup.release() + finally: + del _blocking_on[tid] + + def release(self): + tid = _thread.get_ident() + with self.lock: + if self.owner != tid: + raise RuntimeError("cannot release un-acquired lock") + assert self.count > 0 + self.count -= 1 + if self.count == 0: + self.owner = None + if self.waiters: + self.waiters -= 1 + self.wakeup.release() + + def __repr__(self): + return "_ModuleLock(%r) at %d" % (self.name, id(self)) + + +class _DummyModuleLock: + """A simple _ModuleLock equivalent for Python builds without + multi-threading support.""" + + def __init__(self, name): + self.name = name + self.count = 0 + + def acquire(self): + self.count += 1 + return True + + def release(self): + if self.count == 0: + raise RuntimeError("cannot release un-acquired lock") + self.count -= 1 + + def __repr__(self): + return "_DummyModuleLock(%r) at %d" % (self.name, id(self)) + + +# The following two functions are for consumption by Python/import.c. + +def _get_module_lock(name): + """Get or create the module lock for a given module name. + + Should only be called with the import lock taken.""" + lock = None + if name in _module_locks: + lock = _module_locks[name]() + if lock is None: + if _thread is None: + lock = _DummyModuleLock(name) + else: + lock = _ModuleLock(name) + def cb(_): + del _module_locks[name] + _module_locks[name] = _weakref.ref(lock, cb) + return lock + +def _lock_unlock_module(name): + """Release the global import lock, and acquires then release the + module lock for a given module name. + This is used to ensure a module is completely initialized, in the + event it is being imported by another thread. + + Should only be called with the import lock taken.""" + lock = _get_module_lock(name) + _imp.release_lock() + try: + lock.acquire() + except _DeadlockError: + # Concurrent circular import, we'll accept a partially initialized + # module object. + pass + else: + lock.release() + # Finder/loader utility code ################################################## +_PYCACHE = '__pycache__' + +SOURCE_SUFFIXES = ['.py'] # _setup() adds .pyw as needed. + +DEBUG_BYTECODE_SUFFIXES = ['.pyc'] +OPTIMIZED_BYTECODE_SUFFIXES = ['.pyo'] +if __debug__: + BYTECODE_SUFFIXES = DEBUG_BYTECODE_SUFFIXES +else: + BYTECODE_SUFFIXES = OPTIMIZED_BYTECODE_SUFFIXES + +def cache_from_source(path, debug_override=None): + """Given the path to a .py file, return the path to its .pyc/.pyo file. + + The .py file does not need to exist; this simply returns the path to the + .pyc/.pyo file calculated as if the .py file were imported. The extension + will be .pyc unless __debug__ is not defined, then it will be .pyo. + + If debug_override is not None, then it must be a boolean and is taken as + the value of __debug__ instead. + + """ + debug = __debug__ if debug_override is None else debug_override + if debug: + suffixes = DEBUG_BYTECODE_SUFFIXES + else: + suffixes = OPTIMIZED_BYTECODE_SUFFIXES + head, tail = _path_split(path) + base_filename, sep, _ = tail.partition('.') + filename = ''.join([base_filename, sep, _TAG, suffixes[0]]) + return _path_join(head, _PYCACHE, filename) + + +def _verbose_message(message, *args): + """Print the message to stderr if -v/PYTHONVERBOSE is turned on.""" + if sys.flags.verbose: + if not message.startswith(('#', 'import ')): + message = '# ' + message + print(message.format(*args), file=sys.stderr) + + def set_package(fxn): """Set __package__ on the returned module.""" - def wrapper(*args, **kwargs): + def set_package_wrapper(*args, **kwargs): module = fxn(*args, **kwargs) if not hasattr(module, '__package__') or module.__package__ is None: module.__package__ = module.__name__ if not hasattr(module, '__path__'): module.__package__ = module.__package__.rpartition('.')[0] return module - _wrap(wrapper, fxn) - return wrapper + _wrap(set_package_wrapper, fxn) + return set_package_wrapper def set_loader(fxn): """Set __loader__ on the returned module.""" - def wrapper(self, *args, **kwargs): + def set_loader_wrapper(self, *args, **kwargs): module = fxn(self, *args, **kwargs) if not hasattr(module, '__loader__'): module.__loader__ = self return module - _wrap(wrapper, fxn) - return wrapper + _wrap(set_loader_wrapper, fxn) + return set_loader_wrapper def module_for_loader(fxn): @@ -120,31 +370,50 @@ def module_for_loader(fxn): The decorated function is passed the module to use instead of the module name. The module passed in to the function is either from sys.modules if - it already exists or is a new module which has __name__ set and is inserted - into sys.modules. If an exception is raised and the decorator created the - module it is subsequently removed from sys.modules. + it already exists or is a new module. If the module is new, then __name__ + is set the first argument to the method, __loader__ is set to self, and + __package__ is set accordingly (if self.is_package() is defined) will be set + before it is passed to the decorated function (if self.is_package() does + not work for the module it will be set post-load). + + If an exception is raised and the decorator created the module it is + subsequently removed from sys.modules. The decorator assumes that the decorated function takes the module name as the second argument. """ - def decorated(self, fullname, *args, **kwargs): + def module_for_loader_wrapper(self, fullname, *args, **kwargs): module = sys.modules.get(fullname) - is_reload = bool(module) + is_reload = module is not None if not is_reload: # This must be done before open() is called as the 'io' module # implicitly imports 'locale' and would otherwise trigger an # infinite loop. - module = imp.new_module(fullname) + module = new_module(fullname) sys.modules[fullname] = module + module.__loader__ = self + try: + is_package = self.is_package(fullname) + except (ImportError, AttributeError): + pass + else: + if is_package: + module.__package__ = fullname + else: + module.__package__ = fullname.rpartition('.')[0] try: + module.__initializing__ = True + # If __package__ was not set above, __import__() will do it later. return fxn(self, module, *args, **kwargs) except: if not is_reload: del sys.modules[fullname] raise - _wrap(decorated, fxn) - return decorated + finally: + module.__initializing__ = False + _wrap(module_for_loader_wrapper, fxn) + return module_for_loader_wrapper def _check_name(method): @@ -155,38 +424,36 @@ def _check_name(method): compared against. If the comparison fails then ImportError is raised. """ - def inner(self, name, *args, **kwargs): - if self._name != name: - raise ImportError("loader cannot handle %s" % name) + def _check_name_wrapper(self, name=None, *args, **kwargs): + if name is None: + name = self.name + elif self.name != name: + raise ImportError("loader cannot handle %s" % name, name=name) return method(self, name, *args, **kwargs) - _wrap(inner, method) - return inner + _wrap(_check_name_wrapper, method) + return _check_name_wrapper def _requires_builtin(fxn): """Decorator to verify the named module is built-in.""" - def wrapper(self, fullname): + def _requires_builtin_wrapper(self, fullname): if fullname not in sys.builtin_module_names: - raise ImportError("{0} is not a built-in module".format(fullname)) + raise ImportError("{0} is not a built-in module".format(fullname), + name=fullname) return fxn(self, fullname) - _wrap(wrapper, fxn) - return wrapper + _wrap(_requires_builtin_wrapper, fxn) + return _requires_builtin_wrapper def _requires_frozen(fxn): """Decorator to verify the named module is frozen.""" - def wrapper(self, fullname): - if not imp.is_frozen(fullname): - raise ImportError("{0} is not a frozen module".format(fullname)) + def _requires_frozen_wrapper(self, fullname): + if not _imp.is_frozen(fullname): + raise ImportError("{0} is not a frozen module".format(fullname), + name=fullname) return fxn(self, fullname) - _wrap(wrapper, fxn) - return wrapper - - -def _suffix_list(suffix_type): - """Return a list of file suffixes based on the imp file type.""" - return [suffix[0] for suffix in imp.get_suffixes() - if suffix[2] == suffix_type] + _wrap(_requires_frozen_wrapper, fxn) + return _requires_frozen_wrapper # Loaders ##################################################################### @@ -209,7 +476,7 @@ class BuiltinImporter: """ if path is not None: return None - return cls if imp.is_builtin(fullname) else None + return cls if _imp.is_builtin(fullname) else None @classmethod @set_package @@ -219,7 +486,7 @@ class BuiltinImporter: """Load a built-in module.""" is_reload = fullname in sys.modules try: - return imp.init_builtin(fullname) + return _imp.init_builtin(fullname) except: if not is_reload and fullname in sys.modules: del sys.modules[fullname] @@ -240,7 +507,7 @@ class BuiltinImporter: @classmethod @_requires_builtin def is_package(cls, fullname): - """Return None as built-in module are never packages.""" + """Return None as built-in modules are never packages.""" return False @@ -256,7 +523,7 @@ class FrozenImporter: @classmethod def find_module(cls, fullname, path=None): """Find a frozen module.""" - return cls if imp.is_frozen(fullname) else None + return cls if _imp.is_frozen(fullname) else None @classmethod @set_package @@ -266,7 +533,7 @@ class FrozenImporter: """Load a frozen module.""" is_reload = fullname in sys.modules try: - return imp.init_frozen(fullname) + return _imp.init_frozen(fullname) except: if not is_reload and fullname in sys.modules: del sys.modules[fullname] @@ -276,7 +543,7 @@ class FrozenImporter: @_requires_frozen def get_code(cls, fullname): """Return the code object for the frozen module.""" - return imp.get_frozen_object(fullname) + return _imp.get_frozen_object(fullname) @classmethod @_requires_frozen @@ -288,39 +555,64 @@ class FrozenImporter: @_requires_frozen def is_package(cls, fullname): """Return if the frozen module is a package.""" - return imp.is_frozen_package(fullname) + return _imp.is_frozen_package(fullname) class _LoaderBasics: """Base class of common code needed by both SourceLoader and - _SourcelessFileLoader.""" + SourcelessFileLoader.""" def is_package(self, fullname): """Concrete implementation of InspectLoader.is_package by checking if the path returned by get_filename has a filename of '__init__.py'.""" - filename = self.get_filename(fullname).rpartition(path_sep)[2] + filename = _path_split(self.get_filename(fullname))[1] return filename.rsplit('.', 1)[0] == '__init__' - def _bytes_from_bytecode(self, fullname, data, source_mtime): + def _bytes_from_bytecode(self, fullname, data, bytecode_path, source_stats): """Return the marshalled bytes from bytecode, verifying the magic - number and timestamp along the way. + number, timestamp and source size along the way. - If source_mtime is None then skip the timestamp check. + If source_stats is None then skip the timestamp check. """ magic = data[:4] raw_timestamp = data[4:8] - if len(magic) != 4 or magic != imp.get_magic(): - raise ImportError("bad magic number in {}".format(fullname)) + raw_size = data[8:12] + if magic != _MAGIC_NUMBER: + msg = 'bad magic number in {!r}: {!r}'.format(fullname, magic) + raise ImportError(msg, name=fullname, path=bytecode_path) elif len(raw_timestamp) != 4: - raise EOFError("bad timestamp in {}".format(fullname)) - elif source_mtime is not None: - if marshal._r_long(raw_timestamp) != source_mtime: - raise ImportError("bytecode is stale for {}".format(fullname)) + message = 'bad timestamp in {}'.format(fullname) + _verbose_message(message) + raise EOFError(message) + elif len(raw_size) != 4: + message = 'bad size in {}'.format(fullname) + _verbose_message(message) + raise EOFError(message) + if source_stats is not None: + try: + source_mtime = int(source_stats['mtime']) + except KeyError: + pass + else: + if _r_long(raw_timestamp) != source_mtime: + message = 'bytecode is stale for {}'.format(fullname) + _verbose_message(message) + raise ImportError(message, name=fullname, + path=bytecode_path) + try: + source_size = source_stats['size'] & 0xFFFFFFFF + except KeyError: + pass + else: + if _r_long(raw_size) != source_size: + raise ImportError( + "bytecode is stale for {}".format(fullname), + name=fullname, path=bytecode_path) # Can't return the code object as errors from marshal loading need to # propagate even when source is available. - return data[8:] + return data[12:] @module_for_loader def _load_module(self, module, *, sourceless=False): @@ -330,12 +622,12 @@ class _LoaderBasics: code_object = self.get_code(name) module.__file__ = self.get_filename(name) if not sourceless: - module.__cached__ = imp.cache_from_source(module.__file__) + module.__cached__ = cache_from_source(module.__file__) else: module.__cached__ = module.__file__ module.__package__ = name if self.is_package(name): - module.__path__ = [module.__file__.rsplit(path_sep, 1)[0]] + module.__path__ = [_path_split(module.__file__)[0]] else: module.__package__ = module.__package__.rpartition('.')[0] module.__loader__ = self @@ -348,11 +640,20 @@ class SourceLoader(_LoaderBasics): def path_mtime(self, path): """Optional method that returns the modification time (an int) for the specified path, where path is a str. + """ + raise NotImplementedError - Implementing this method allows the loader to read bytecode files. + def path_stats(self, path): + """Optional method returning a metadata dict for the specified path + to by the path (str). + Possible keys: + - 'mtime' (mandatory) is the numeric timestamp of last source + code modification; + - 'size' (optional) is the size in bytes of the source code. + Implementing this method allows the loader to read bytecode files. """ - raise NotImplementedError + return {'mtime': self.path_mtime(path)} def set_data(self, path, data): """Optional method which writes data (bytes) to a file path (a str). @@ -370,7 +671,8 @@ class SourceLoader(_LoaderBasics): try: source_bytes = self.get_data(path) except IOError: - raise ImportError("source not available through get_data()") + raise ImportError("source not available through get_data()", + name=fullname) encoding = tokenize.detect_encoding(_io.BytesIO(source_bytes).readline) newline_decoder = _io.IncrementalNewlineDecoder(None, True) return newline_decoder.decode(source_bytes.decode(encoding[0])) @@ -378,19 +680,20 @@ class SourceLoader(_LoaderBasics): def get_code(self, fullname): """Concrete implementation of InspectLoader.get_code. - Reading of bytecode requires path_mtime to be implemented. To write + Reading of bytecode requires path_stats to be implemented. To write bytecode, set_data must also be implemented. """ source_path = self.get_filename(fullname) - bytecode_path = imp.cache_from_source(source_path) + bytecode_path = cache_from_source(source_path) source_mtime = None if bytecode_path is not None: try: - source_mtime = self.path_mtime(source_path) + st = self.path_stats(source_path) except NotImplementedError: pass else: + source_mtime = int(st['mtime']) try: data = self.get_data(bytecode_path) except IOError: @@ -398,29 +701,36 @@ class SourceLoader(_LoaderBasics): else: try: bytes_data = self._bytes_from_bytecode(fullname, data, - source_mtime) + bytecode_path, + st) except (ImportError, EOFError): pass else: + _verbose_message('{} matches {}', bytecode_path, + source_path) found = marshal.loads(bytes_data) - if isinstance(found, code_type): + if isinstance(found, _code_type): + _imp._fix_co_filename(found, source_path) + _verbose_message('code object from {}', + bytecode_path) return found else: msg = "Non-code object in {}" - raise ImportError(msg.format(bytecode_path)) + raise ImportError(msg.format(bytecode_path), + name=fullname, path=bytecode_path) source_bytes = self.get_data(source_path) code_object = compile(source_bytes, source_path, 'exec', dont_inherit=True) + _verbose_message('code object from {}', source_path) if (not sys.dont_write_bytecode and bytecode_path is not None and - source_mtime is not None): - # If e.g. Jython ever implements imp.cache_from_source to have - # their own cached file format, this block of code will most likely - # throw an exception. - data = bytearray(imp.get_magic()) - data.extend(marshal._w_long(source_mtime)) + source_mtime is not None): + data = bytearray(_MAGIC_NUMBER) + data.extend(_w_long(source_mtime)) + data.extend(_w_long(len(source_bytes))) data.extend(marshal.dumps(code_object)) try: self.set_data(bytecode_path, data) + _verbose_message('wrote {!r}', bytecode_path) except NotImplementedError: pass return code_object @@ -436,7 +746,7 @@ class SourceLoader(_LoaderBasics): return self._load_module(fullname) -class _FileLoader: +class FileLoader: """Base file loader class which implements the loader protocol methods that require file system usage.""" @@ -444,13 +754,18 @@ class _FileLoader: def __init__(self, fullname, path): """Cache the module name and the path to the file found by the finder.""" - self._name = fullname - self._path = path + self.name = fullname + self.path = path + + @_check_name + def load_module(self, fullname): + """Load a module from a file.""" + return super().load_module(fullname) @_check_name def get_filename(self, fullname): """Return the path to the source file as found by the finder.""" - return self._path + return self.path def get_data(self, path): """Return the data from path as raw bytes.""" @@ -458,52 +773,45 @@ class _FileLoader: return file.read() -class _SourceFileLoader(_FileLoader, SourceLoader): +class SourceFileLoader(FileLoader, SourceLoader): """Concrete implementation of SourceLoader using the file system.""" - def path_mtime(self, path): - """Return the modification time for the path.""" - return int(_os.stat(path).st_mtime) + def path_stats(self, path): + """Return the metadat for the path.""" + st = _os.stat(path) + return {'mtime': st.st_mtime, 'size': st.st_size} def set_data(self, path, data): """Write bytes data to a file.""" - parent, _, filename = path.rpartition(path_sep) + parent, filename = _path_split(path) path_parts = [] # Figure out what directories are missing. while parent and not _path_isdir(parent): - parent, _, part = parent.rpartition(path_sep) + parent, part = _path_split(parent) path_parts.append(part) # Create needed directories. for part in reversed(path_parts): parent = _path_join(parent, part) try: _os.mkdir(parent) - except OSError as exc: + except FileExistsError: # Probably another Python process already created the dir. - if exc.errno == errno.EEXIST: - continue - else: - raise - except IOError as exc: + continue + except PermissionError: # If can't get proper access, then just forget about writing # the data. - if exc.errno == errno.EACCES: - return - else: - raise - try: - with _io.FileIO(path, 'wb') as file: - file.write(data) - except IOError as exc: - # Don't worry if you can't write bytecode. - if exc.errno == errno.EACCES: return - else: - raise + try: + _write_atomic(path, data) + _verbose_message('created {!r}', path) + except (PermissionError, FileExistsError): + # Don't worry if you can't write bytecode or someone is writing + # it at the same time. + pass -class _SourcelessFileLoader(_FileLoader, _LoaderBasics): +class SourcelessFileLoader(FileLoader, _LoaderBasics): """Loader which handles sourceless file imports.""" @@ -513,19 +821,21 @@ class _SourcelessFileLoader(_FileLoader, _LoaderBasics): def get_code(self, fullname): path = self.get_filename(fullname) data = self.get_data(path) - bytes_data = self._bytes_from_bytecode(fullname, data, None) + bytes_data = self._bytes_from_bytecode(fullname, data, path, None) found = marshal.loads(bytes_data) - if isinstance(found, code_type): + if isinstance(found, _code_type): + _verbose_message('code object from {!r}', path) return found else: - raise ImportError("Non-code object in {}".format(path)) + raise ImportError("Non-code object in {}".format(path), + name=fullname, path=path) def get_source(self, fullname): """Return None as there is no source code.""" return None -class _ExtensionFileLoader: +class ExtensionFileLoader: """Loader for extension modules. @@ -534,14 +844,8 @@ class _ExtensionFileLoader: """ def __init__(self, name, path): - """Initialize the loader. - - If is_pkg is True then an exception is raised as extension modules - cannot be the __init__ module for an extension module. - - """ - self._name = name - self._path = path + self.name = name + self.path = path @_check_name @set_package @@ -550,23 +854,22 @@ class _ExtensionFileLoader: """Load an extension module.""" is_reload = fullname in sys.modules try: - return imp.load_dynamic(fullname, self._path) + module = _imp.load_dynamic(fullname, self.path) + _verbose_message('extension module loaded from {!r}', self.path) + return module except: if not is_reload and fullname in sys.modules: del sys.modules[fullname] raise - @_check_name def is_package(self, fullname): """Return False as an extension module can never be a package.""" return False - @_check_name def get_code(self, fullname): """Return None as an extension module cannot create a code object.""" return None - @_check_name def get_source(self, fullname): """Return None as extension modules have no source code.""" return None @@ -579,59 +882,48 @@ class PathFinder: """Meta path finder for sys.(path|path_hooks|path_importer_cache).""" @classmethod - def _path_hooks(cls, path, hooks=None): + def _path_hooks(cls, path): """Search sequence of hooks for a finder for 'path'. If 'hooks' is false then use sys.path_hooks. """ - if not hooks: - hooks = sys.path_hooks - for hook in hooks: + if not sys.path_hooks: + _warnings.warn('sys.path_hooks is empty', ImportWarning) + for hook in sys.path_hooks: try: return hook(path) except ImportError: continue else: - raise ImportError("no path hook found for {0}".format(path)) + return None @classmethod - def _path_importer_cache(cls, path, default=None): + def _path_importer_cache(cls, path): """Get the finder for the path from sys.path_importer_cache. If the path is not in the cache, find the appropriate finder and cache - it. If None is cached, get the default finder and cache that - (if applicable). - - Because of NullImporter, some finder should be returned. The only - explicit fail case is if None is cached but the path cannot be used for - the default hook, for which ImportError is raised. + it. If no finder is available, store None. """ + if path == '': + path = '.' try: finder = sys.path_importer_cache[path] except KeyError: finder = cls._path_hooks(path) sys.path_importer_cache[path] = finder - else: - if finder is None and default: - # Raises ImportError on failure. - finder = default(path) - sys.path_importer_cache[path] = finder return finder @classmethod def find_module(cls, fullname, path=None): """Find the module on sys.path or 'path' based on sys.path_hooks and sys.path_importer_cache.""" - if not path: + if path is None: path = sys.path for entry in path: - try: - finder = cls._path_importer_cache(entry) - except ImportError: - continue - if finder: + finder = cls._path_importer_cache(entry) + if finder is not None: loader = finder.find_module(fullname) if loader: return loader @@ -639,205 +931,300 @@ class PathFinder: return None -class _FileFinder: +class FileFinder: """File-based finder. - Constructor takes a list of objects detailing what file extensions their - loader supports along with whether it can be used for a package. + Interactions with the file system are cached for performance, being + refreshed when the directory the finder is handling has been modified. """ def __init__(self, path, *details): - """Initialize with finder details.""" + """Initialize with the path to search on and a variable number of + 3-tuples containing the loader, file suffixes the loader recognizes, and + a boolean of whether the loader handles packages.""" packages = [] modules = [] - for detail in details: - modules.extend((suffix, detail.loader) for suffix in detail.suffixes) - if detail.supports_packages: - packages.extend((suffix, detail.loader) - for suffix in detail.suffixes) + for loader, suffixes, supports_packages in details: + modules.extend((suffix, loader) for suffix in suffixes) + if supports_packages: + packages.extend((suffix, loader) for suffix in suffixes) self.packages = packages self.modules = modules - self.path = path + # Base (directory) path + self.path = path or '.' + self._path_mtime = -1 + self._path_cache = set() + self._relaxed_path_cache = set() + + def invalidate_caches(self): + """Invalidate the directory mtime.""" + self._path_mtime = -1 def find_module(self, fullname): """Try to find a loader for the specified module.""" tail_module = fullname.rpartition('.')[2] - base_path = _path_join(self.path, tail_module) - if _path_isdir(base_path) and _case_ok(self.path, tail_module): - for suffix, loader in self.packages: - init_filename = '__init__' + suffix - full_path = _path_join(base_path, init_filename) - if (_path_isfile(full_path) and - _case_ok(base_path, init_filename)): - return loader(fullname, full_path) - else: - msg = "Not importing directory {}: missing __init__" - _warnings.warn(msg.format(base_path), ImportWarning) + try: + mtime = _os.stat(self.path).st_mtime + except OSError: + mtime = -1 + if mtime != self._path_mtime: + self._fill_cache() + self._path_mtime = mtime + # tail_module keeps the original casing, for __file__ and friends + if _relax_case(): + cache = self._relaxed_path_cache + cache_module = tail_module.lower() + else: + cache = self._path_cache + cache_module = tail_module + # Check if the module is the name of a directory (and thus a package). + if cache_module in cache: + base_path = _path_join(self.path, tail_module) + if _path_isdir(base_path): + for suffix, loader in self.packages: + init_filename = '__init__' + suffix + full_path = _path_join(base_path, init_filename) + if _path_isfile(full_path): + return loader(fullname, full_path) + else: + msg = "Not importing directory {}: missing __init__" + _warnings.warn(msg.format(base_path), ImportWarning) + # Check for a file w/ a proper suffix exists. for suffix, loader in self.modules: - mod_filename = tail_module + suffix - full_path = _path_join(self.path, mod_filename) - if _path_isfile(full_path) and _case_ok(self.path, mod_filename): - return loader(fullname, full_path) + if cache_module + suffix in cache: + full_path = _path_join(self.path, tail_module + suffix) + if _path_isfile(full_path): + return loader(fullname, full_path) return None -class _SourceFinderDetails: - - loader = _SourceFileLoader - supports_packages = True - - def __init__(self): - self.suffixes = _suffix_list(imp.PY_SOURCE) - -class _SourcelessFinderDetails: - - loader = _SourcelessFileLoader - supports_packages = True + def _fill_cache(self): + """Fill the cache of potential modules and packages for this directory.""" + path = self.path + contents = _os.listdir(path) + # We store two cached versions, to handle runtime changes of the + # PYTHONCASEOK environment variable. + if not sys.platform.startswith('win'): + self._path_cache = set(contents) + else: + # Windows users can import modules with case-insensitive file + # suffixes (for legacy reasons). Make the suffix lowercase here + # so it's done once instead of for every import. This is safe as + # the specified suffixes to check against are always specified in a + # case-sensitive manner. + lower_suffix_contents = set() + for item in contents: + name, dot, suffix = item.partition('.') + if dot: + new_name = '{}.{}'.format(name, suffix.lower()) + else: + new_name = name + lower_suffix_contents.add(new_name) + self._path_cache = lower_suffix_contents + if sys.platform.startswith(_CASE_INSENSITIVE_PLATFORMS): + self._relaxed_path_cache = set(fn.lower() for fn in contents) - def __init__(self): - self.suffixes = _suffix_list(imp.PY_COMPILED) + @classmethod + def path_hook(cls, *loader_details): + """A class method which returns a closure to use on sys.path_hook + which will return an instance using the specified loaders and the path + called on the closure. + If the path called on the closure is not a directory, ImportError is + raised. -class _ExtensionFinderDetails: + """ + def path_hook_for_FileFinder(path): + """Path hook for importlib.machinery.FileFinder.""" + if not _path_isdir(path): + raise ImportError("only directories are supported", path=path) + return cls(path, *loader_details) - loader = _ExtensionFileLoader - supports_packages = False + return path_hook_for_FileFinder - def __init__(self): - self.suffixes = _suffix_list(imp.C_EXTENSION) # Import itself ############################################################### -def _file_path_hook(path): - """If the path is a directory, return a file-based finder.""" - if _path_isdir(path): - return _FileFinder(path, _ExtensionFinderDetails(), - _SourceFinderDetails(), - _SourcelessFinderDetails()) - else: - raise ImportError("only directories are supported") - - -_DEFAULT_PATH_HOOK = _file_path_hook - -class _DefaultPathFinder(PathFinder): - - """Subclass of PathFinder that implements implicit semantics for - __import__.""" - - @classmethod - def _path_hooks(cls, path): - """Search sys.path_hooks as well as implicit path hooks.""" - try: - return super()._path_hooks(path) - except ImportError: - implicit_hooks = [_DEFAULT_PATH_HOOK, imp.NullImporter] - return super()._path_hooks(path, implicit_hooks) - - @classmethod - def _path_importer_cache(cls, path): - """Use the default path hook when None is stored in - sys.path_importer_cache.""" - return super()._path_importer_cache(path, _DEFAULT_PATH_HOOK) - - class _ImportLockContext: """Context manager for the import lock.""" def __enter__(self): """Acquire the import lock.""" - imp.acquire_lock() + _imp.acquire_lock() def __exit__(self, exc_type, exc_value, exc_traceback): """Release the import lock regardless of any raised exceptions.""" - imp.release_lock() + _imp.release_lock() -_IMPLICIT_META_PATH = [BuiltinImporter, FrozenImporter, _DefaultPathFinder] +def _resolve_name(name, package, level): + """Resolve a relative module name to an absolute one.""" + bits = package.rsplit('.', level - 1) + if len(bits) < level: + raise ValueError('attempted relative import beyond top-level package') + base = bits[0] + return '{0}.{1}'.format(base, name) if name else base -_ERR_MSG = 'No module named {}' -def _gcd_import(name, package=None, level=0): - """Import and return the module based on its name, the package the call is - being made from, and the level adjustment. +def _find_module(name, path): + """Find a module's loader.""" + if not sys.meta_path: + _warnings.warn('sys.meta_path is empty', ImportWarning) + for finder in sys.meta_path: + with _ImportLockContext(): + loader = finder.find_module(name, path) + if loader is not None: + # The parent import may have already imported this module. + if name not in sys.modules: + return loader + else: + return sys.modules[name].__loader__ + else: + return None - This function represents the greatest common denominator of functionality - between import_module and __import__. This includes settting __package__ if - the loader did not. - """ +def _sanity_check(name, package, level): + """Verify arguments are "sane".""" + if not isinstance(name, str): + raise TypeError("module name must be str, not {}".format(type(name))) + if level < 0: + raise ValueError('level must be >= 0') if package: - if not hasattr(package, 'rindex'): - raise ValueError("__package__ not set to a string") + if not isinstance(package, str): + raise TypeError("__package__ not set to a string") elif package not in sys.modules: msg = ("Parent module {0!r} not loaded, cannot perform relative " "import") raise SystemError(msg.format(package)) if not name and level == 0: raise ValueError("Empty module name") - if level > 0: - dot = len(package) - for x in range(level, 1, -1): - try: - dot = package.rindex('.', 0, dot) - except ValueError: - raise ValueError("attempted relative import beyond " - "top-level package") - if name: - name = "{0}.{1}".format(package[:dot], name) - else: - name = package[:dot] - with _ImportLockContext(): + + +_ERR_MSG = 'No module named {!r}' + +def _find_and_load_unlocked(name, import_): + path = None + parent = name.rpartition('.')[0] + if parent: + if parent not in sys.modules: + import_(parent) + # Crazy side-effects! + if name in sys.modules: + return sys.modules[name] + # Backwards-compatibility; be nicer to skip the dict lookup. + parent_module = sys.modules[parent] try: - module = sys.modules[name] - if module is None: - message = ("import of {} halted; " - "None in sys.modules".format(name)) - raise ImportError(message) - return module - except KeyError: + path = parent_module.__path__ + except AttributeError: + msg = (_ERR_MSG + '; {} is not a package').format(name, parent) + raise ImportError(msg, name=name) + loader = _find_module(name, path) + if loader is None: + raise ImportError(_ERR_MSG.format(name), name=name) + elif name not in sys.modules: + # The parent import may have already imported this module. + loader.load_module(name) + _verbose_message('import {!r} # {!r}', name, loader) + # Backwards-compatibility; be nicer to skip the dict lookup. + module = sys.modules[name] + if parent: + # Set the module as an attribute on its parent. + parent_module = sys.modules[parent] + setattr(parent_module, name.rpartition('.')[2], module) + # Set __package__ if the loader did not. + if not hasattr(module, '__package__') or module.__package__ is None: + try: + module.__package__ = module.__name__ + if not hasattr(module, '__path__'): + module.__package__ = module.__package__.rpartition('.')[0] + except AttributeError: pass - parent = name.rpartition('.')[0] - path = None - if parent: - if parent not in sys.modules: - _gcd_import(parent) - # Backwards-compatibility; be nicer to skip the dict lookup. - parent_module = sys.modules[parent] - try: - path = parent_module.__path__ - except AttributeError: - msg = (_ERR_MSG + '; {} is not a package').format(name, parent) - raise ImportError(msg) - meta_path = sys.meta_path + _IMPLICIT_META_PATH - for finder in meta_path: - loader = finder.find_module(name, path) - if loader is not None: - # The parent import may have already imported this module. - if name not in sys.modules: - loader.load_module(name) - break - else: - raise ImportError(_ERR_MSG.format(name)) - # Backwards-compatibility; be nicer to skip the dict lookup. - module = sys.modules[name] - if parent: - # Set the module as an attribute on its parent. - setattr(parent_module, name.rpartition('.')[2], module) - # Set __package__ if the loader did not. - if not hasattr(module, '__package__') or module.__package__ is None: - # Watch out for what comes out of sys.modules to not be a module, - # e.g. an int. + # Set loader if need be. + if not hasattr(module, '__loader__'): + try: + module.__loader__ = loader + except AttributeError: + pass + return module + + +def _find_and_load(name, import_): + """Find and load the module, and release the import lock.""" + try: + lock = _get_module_lock(name) + finally: + _imp.release_lock() + lock.acquire() + try: + return _find_and_load_unlocked(name, import_) + finally: + lock.release() + + +def _gcd_import(name, package=None, level=0): + """Import and return the module based on its name, the package the call is + being made from, and the level adjustment. + + This function represents the greatest common denominator of functionality + between import_module and __import__. This includes setting __package__ if + the loader did not. + + """ + _sanity_check(name, package, level) + if level > 0: + name = _resolve_name(name, package, level) + _imp.acquire_lock() + if name not in sys.modules: + return _find_and_load(name, _gcd_import) + module = sys.modules[name] + if module is None: + _imp.release_lock() + message = ("import of {} halted; " + "None in sys.modules".format(name)) + raise ImportError(message, name=name) + _lock_unlock_module(name) + return module + + +def _handle_fromlist(module, fromlist, import_): + """Figure out what __import__ should return. + + The import_ parameter is a callable which takes the name of module to + import. It is required to decouple the function from assuming importlib's + import implementation is desired. + + """ + # The hell that is fromlist ... + # If a package was imported, try to import stuff from fromlist. + if hasattr(module, '__path__'): + if '*' in fromlist and hasattr(module, '__all__'): + fromlist = list(fromlist) + fromlist.remove('*') + fromlist.extend(module.__all__) + for x in (y for y in fromlist if not hasattr(module, y)): try: - module.__package__ = module.__name__ - if not hasattr(module, '__path__'): - module.__package__ = module.__package__.rpartition('.')[0] - except AttributeError: + import_('{0}.{1}'.format(module.__name__, x)) + except ImportError: pass - return module + return module + + +def _calc___package__(globals): + """Calculate what __package__ should be. + + __package__ is not guaranteed to be defined or could be set to None + to represent that its proper value is unknown. + + """ + package = globals.get('__package__') + if package is None: + package = globals['__name__'] + if '__path__' not in globals: + package = package.rpartition('.')[0] + return package def __import__(name, globals={}, locals={}, fromlist=[], level=0): @@ -851,40 +1238,99 @@ def __import__(name, globals={}, locals={}, fromlist=[], level=0): import (e.g. ``from ..pkg import mod`` would have a 'level' of 2). """ - if not hasattr(name, 'rpartition'): - raise TypeError("module name must be str, not {}".format(type(name))) if level == 0: module = _gcd_import(name) else: - # __package__ is not guaranteed to be defined or could be set to None - # to represent that it's proper value is unknown - package = globals.get('__package__') - if package is None: - package = globals['__name__'] - if '__path__' not in globals: - package = package.rpartition('.')[0] + package = _calc___package__(globals) module = _gcd_import(name, package, level) - # The hell that is fromlist ... if not fromlist: # Return up to the first dot in 'name'. This is complicated by the fact # that 'name' may be relative. if level == 0: - return sys.modules[name.partition('.')[0]] + return _gcd_import(name.partition('.')[0]) elif not name: return module else: cut_off = len(name) - len(name.partition('.')[0]) - return sys.modules[module.__name__[:-cut_off]] + return sys.modules[module.__name__[:len(module.__name__)-cut_off]] else: - # If a package was imported, try to import stuff from fromlist. - if hasattr(module, '__path__'): - if '*' in fromlist and hasattr(module, '__all__'): - fromlist = list(fromlist) - fromlist.remove('*') - fromlist.extend(module.__all__) - for x in (y for y in fromlist if not hasattr(module,y)): - try: - _gcd_import('{0}.{1}'.format(module.__name__, x)) - except ImportError: - pass - return module + return _handle_fromlist(module, fromlist, _gcd_import) + + +_MAGIC_NUMBER = None # Set in _setup() +_TAG = None # Set in _setup() + + +def _setup(sys_module, _imp_module): + """Setup importlib by importing needed built-in modules and injecting them + into the global namespace. + + As sys is needed for sys.modules access and _imp is needed to load built-in + modules, those two modules must be explicitly passed in. + + """ + global _imp, sys + _imp = _imp_module + sys = sys_module + + for module in (_imp, sys): + if not hasattr(module, '__loader__'): + module.__loader__ = BuiltinImporter + + self_module = sys.modules[__name__] + for builtin_name in ('_io', '_warnings', 'builtins', 'marshal'): + if builtin_name not in sys.modules: + builtin_module = BuiltinImporter.load_module(builtin_name) + else: + builtin_module = sys.modules[builtin_name] + setattr(self_module, builtin_name, builtin_module) + + os_details = ('posix', ['/']), ('nt', ['\\', '/']), ('os2', ['\\', '/']) + for builtin_os, path_separators in os_details: + # Assumption made in _path_join() + assert all(len(sep) == 1 for sep in path_separators) + path_sep = path_separators[0] + if builtin_os in sys.modules: + os_module = sys.modules[builtin_os] + break + else: + try: + os_module = BuiltinImporter.load_module(builtin_os) + # TODO: rip out os2 code after 3.3 is released as per PEP 11 + if builtin_os == 'os2' and 'EMX GCC' in sys.version: + path_sep = path_separators[1] + break + except ImportError: + continue + else: + raise ImportError('importlib requires posix or nt') + + try: + thread_module = BuiltinImporter.load_module('_thread') + except ImportError: + # Python was built without threads + thread_module = None + weakref_module = BuiltinImporter.load_module('_weakref') + + setattr(self_module, '_os', os_module) + setattr(self_module, '_thread', thread_module) + setattr(self_module, '_weakref', weakref_module) + setattr(self_module, 'path_sep', path_sep) + setattr(self_module, 'path_separators', set(path_separators)) + # Constants + setattr(self_module, '_relax_case', _make_relax_case()) + setattr(self_module, '_MAGIC_NUMBER', _imp_module.get_magic()) + setattr(self_module, '_TAG', _imp.get_tag()) + if builtin_os == 'nt': + SOURCE_SUFFIXES.append('.pyw') + + +def _install(sys_module, _imp_module): + """Install importlib as the implementation of import.""" + _setup(sys_module, _imp_module) + extensions = ExtensionFileLoader, _imp_module.extension_suffixes(), False + source = SourceFileLoader, SOURCE_SUFFIXES, True + bytecode = SourcelessFileLoader, BYTECODE_SUFFIXES, True + supported_loaders = [extensions, source, bytecode] + sys.path_hooks.extend([FileFinder.path_hook(*supported_loaders)]) + sys.meta_path.extend([BuiltinImporter, FrozenImporter, PathFinder]) |