# Copyright 2020 Canonical Ltd. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """Infrastructure for the opslib functionality.""" import logging import os import re import sys from ast import literal_eval from importlib.util import module_from_spec from importlib.machinery import ModuleSpec from pkgutil import get_importer from types import ModuleType from typing import List __all__ = ('use', 'autoimport') logger = logging.getLogger(__name__) _libraries = None _libline_re = re.compile(r'''^LIB([A-Z]+)\s*=\s*([0-9]+|['"][a-zA-Z0-9_.\-@]+['"])''') _libname_re = re.compile(r'''^[a-z][a-z0-9]+$''') # Not perfect, but should do for now. _libauthor_re = re.compile(r'''^[A-Za-z0-9_+.-]+@[a-z0-9_-]+(?:\.[a-z0-9_-]+)*\.[a-z]{2,3}$''') def use(name: str, api: int, author: str) -> ModuleType: """Use a library from the ops libraries. Args: name: the name of the library requested. api: the API version of the library. author: the author of the library. If not given, requests the one in the standard library. Raises: ImportError: if the library cannot be found. TypeError: if the name, api, or author are the wrong type. ValueError: if the name, api, or author are invalid. """ if not isinstance(name, str): raise TypeError("invalid library name: {!r} (must be a str)".format(name)) if not isinstance(author, str): raise TypeError("invalid library author: {!r} (must be a str)".format(author)) if not isinstance(api, int): raise TypeError("invalid library API: {!r} (must be an int)".format(api)) if api < 0: raise ValueError('invalid library api: {} (must be ≥0)'.format(api)) if not _libname_re.match(name): raise ValueError("invalid library name: {!r} (chars and digits only)".format(name)) if not _libauthor_re.match(author): raise ValueError("invalid library author email: {!r}".format(author)) if _libraries is None: autoimport() versions = _libraries.get((name, author), ()) for lib in versions: if lib.api == api: return lib.import_module() others = ', '.join(str(lib.api) for lib in versions) if others: msg = 'cannot find "{}" from "{}" with API version {} (have {})'.format( name, author, api, others) else: msg = 'cannot find library "{}" from "{}"'.format(name, author) raise ImportError(msg, name=name) def autoimport(): """Find all libs in the path and enable use of them. You only need to call this if you've installed a package or otherwise changed sys.path in the current run, and need to see the changes. Otherwise libraries are found on first call of `use`. """ global _libraries _libraries = {} for spec in _find_all_specs(sys.path): lib = _parse_lib(spec) if lib is None: continue versions = _libraries.setdefault((lib.name, lib.author), []) versions.append(lib) versions.sort(reverse=True) def _find_all_specs(path): for sys_dir in path: if sys_dir == "": sys_dir = "." try: top_dirs = os.listdir(sys_dir) except (FileNotFoundError, NotADirectoryError): continue except OSError as e: logger.debug("Tried to look for ops.lib packages under '%s': %s", sys_dir, e) continue logger.debug("Looking for ops.lib packages under '%s'", sys_dir) for top_dir in top_dirs: opslib = os.path.join(sys_dir, top_dir, 'opslib') try: lib_dirs = os.listdir(opslib) except (FileNotFoundError, NotADirectoryError): continue except OSError as e: logger.debug(" Tried '%s': %s", opslib, e) # *lots* of things checked here continue else: logger.debug(" Trying '%s'", opslib) finder = get_importer(opslib) if finder is None: logger.debug(" Finder for '%s' is None", opslib) continue if not hasattr(finder, 'find_spec'): logger.debug(" Finder for '%s' has no find_spec", opslib) continue for lib_dir in lib_dirs: spec_name = "{}.opslib.{}".format(top_dir, lib_dir) spec = finder.find_spec(spec_name) if spec is None: logger.debug(" No spec for %r", spec_name) continue if spec.loader is None: # a namespace package; not supported logger.debug(" No loader for %r (probably a namespace package)", spec_name) continue logger.debug(" Found %r", spec_name) yield spec # only the first this many lines of a file are looked at for the LIB* constants _MAX_LIB_LINES = 99 # these keys, with these types, are needed to have an opslib _NEEDED_KEYS = {'NAME': str, 'AUTHOR': str, 'API': int, 'PATCH': int} def _join_and(keys: List[str]) -> str: if len(keys) == 0: return "" if len(keys) == 1: return keys[0] return ", ".join(keys[:-1]) + ", and " + keys[-1] class _Missing: """Helper to get the difference between what was found and what was needed when logging.""" def __init__(self, found): self._found = found def __str__(self): exp = set(_NEEDED_KEYS) got = set(self._found) if len(got) == 0: return "missing {}".format(_join_and(sorted(exp))) return "got {}, but missing {}".format( _join_and(sorted(got)), _join_and(sorted(exp - got))) def _parse_lib(spec): if spec.origin is None: # "can't happen" logger.warning("No origin for %r (no idea why; please report)", spec.name) return None logger.debug(" Parsing %r", spec.name) try: with open(spec.origin, 'rt', encoding='utf-8') as f: libinfo = {} for n, line in enumerate(f): if len(libinfo) == len(_NEEDED_KEYS): break if n > _MAX_LIB_LINES: logger.debug( " Missing opslib metadata after reading to line %d: %s", _MAX_LIB_LINES, _Missing(libinfo)) return None m = _libline_re.match(line) if m is None: continue key, value = m.groups() if key in _NEEDED_KEYS: value = literal_eval(value) if not isinstance(value, _NEEDED_KEYS[key]): logger.debug( " Bad type for %s: expected %s, got %s", key, _NEEDED_KEYS[key].__name__, type(value).__name__) return None libinfo[key] = value else: if len(libinfo) != len(_NEEDED_KEYS): logger.debug( " Missing opslib metadata after reading to end of file: %s", _Missing(libinfo)) return None except Exception as e: logger.debug(" Failed: %s", e) return None lib = _Lib(spec, libinfo['NAME'], libinfo['AUTHOR'], libinfo['API'], libinfo['PATCH']) logger.debug(" Success: found library %s", lib) return lib class _Lib: def __init__(self, spec: ModuleSpec, name: str, author: str, api: int, patch: int): self.spec = spec self.name = name self.author = author self.api = api self.patch = patch self._module = None def __repr__(self): return "<_Lib {}>".format(self) def __str__(self): return "{0.name} by {0.author}, API {0.api}, patch {0.patch}".format(self) def import_module(self) -> ModuleType: if self._module is None: module = module_from_spec(self.spec) self.spec.loader.exec_module(module) self._module = module return self._module def __eq__(self, other): if not isinstance(other, _Lib): return NotImplemented a = (self.name, self.author, self.api, self.patch) b = (other.name, other.author, other.api, other.patch) return a == b def __lt__(self, other): if not isinstance(other, _Lib): return NotImplemented a = (self.name, self.author, self.api, self.patch) b = (other.name, other.author, other.api, other.patch) return a < b