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EDIT :: identify.py

from __future__ import annotations import errno import math import os.path import re import shlex import stat import string import sys from typing import IO from identify import extensions from identify import interpreters from identify.vendor import licenses printable = frozenset(string.printable) DIRECTORY = 'directory' SYMLINK = 'symlink' SOCKET = 'socket' FILE = 'file' EXECUTABLE = 'executable' NON_EXECUTABLE = 'non-executable' TEXT = 'text' BINARY = 'binary' TYPE_TAGS = frozenset((DIRECTORY, FILE, SYMLINK, SOCKET)) MODE_TAGS = frozenset((EXECUTABLE, NON_EXECUTABLE)) ENCODING_TAGS = frozenset((BINARY, TEXT)) _ALL_TAGS = {*TYPE_TAGS, *MODE_TAGS, *ENCODING_TAGS} _ALL_TAGS.update(*extensions.EXTENSIONS.values()) _ALL_TAGS.update(*extensions.EXTENSIONS_NEED_BINARY_CHECK.values()) _ALL_TAGS.update(*extensions.NAMES.values()) _ALL_TAGS.update(*interpreters.INTERPRETERS.values()) ALL_TAGS = frozenset(_ALL_TAGS) def tags_from_path(path: str) -> set[str]: try: sr = os.lstat(path) except (OSError, ValueError): # same error-handling as `os.lexists()` raise ValueError(f'{path} does not exist.') mode = sr.st_mode if stat.S_ISDIR(mode): return {DIRECTORY} if stat.S_ISLNK(mode): return {SYMLINK} if stat.S_ISSOCK(mode): return {SOCKET} tags = {FILE} executable = os.access(path, os.X_OK) if executable: tags.add(EXECUTABLE) else: tags.add(NON_EXECUTABLE) # As an optimization, if we're able to read tags from the filename, then we # don't peek at the file contents. t = tags_from_filename(os.path.basename(path)) if len(t) > 0: tags.update(t) else: if executable: shebang = parse_shebang_from_file(path) if len(shebang) > 0: tags.update(tags_from_interpreter(shebang[0])) # some extensions can be both binary and text # see EXTENSIONS_NEED_BINARY_CHECK if not ENCODING_TAGS & tags: if file_is_text(path): tags.add(TEXT) else: tags.add(BINARY) assert ENCODING_TAGS & tags, tags assert MODE_TAGS & tags, tags return tags def tags_from_filename(path: str) -> set[str]: _, filename = os.path.split(path) _, ext = os.path.splitext(filename) ret = set() # Allow e.g. "Dockerfile.xenial" to match "Dockerfile" for part in [filename] + filename.split('.'): if part in extensions.NAMES: ret.update(extensions.NAMES[part]) break if len(ext) > 0: ext = ext[1:].lower() if ext in extensions.EXTENSIONS: ret.update(extensions.EXTENSIONS[ext]) elif ext in extensions.EXTENSIONS_NEED_BINARY_CHECK: ret.update(extensions.EXTENSIONS_NEED_BINARY_CHECK[ext]) return ret def tags_from_interpreter(interpreter: str) -> set[str]: _, _, interpreter = interpreter.rpartition('/') # Try "python3.5.2" => "python3.5" => "python3" until one matches. while interpreter: if interpreter in interpreters.INTERPRETERS: return interpreters.INTERPRETERS[interpreter] else: interpreter, _, _ = interpreter.rpartition('.') return set() def is_text(bytesio: IO[bytes]) -> bool: """Return whether the first KB of contents seems to be binary. This is roughly based on libmagic's binary/text detection: https://github.com/file/file/blob/df74b09b9027676088c797528edcaae5a9ce9ad0/src/encoding.c#L203-L228 """ text_chars = ( bytearray([7, 8, 9, 10, 11, 12, 13, 27]) + bytearray(range(0x20, 0x7F)) + bytearray(range(0x80, 0X100)) ) return not bool(bytesio.read(1024).translate(None, text_chars)) def file_is_text(path: str) -> bool: if not os.path.lexists(path): raise ValueError(f'{path} does not exist.') with open(path, 'rb') as f: return is_text(f) def _shebang_split(line: str) -> list[str]: try: # shebangs aren't supposed to be quoted, though some tools such as # setuptools will write them with quotes so we'll best-guess parse # with shlex first return shlex.split(line) except ValueError: # failing that, we'll do a more "traditional" shebang parsing which # just involves splitting by whitespace return line.split() def _parse_nix_shebang( bytesio: IO[bytes], cmd: tuple[str, ...], ) -> tuple[str, ...]: while bytesio.read(2) == b'#!': next_line_b = bytesio.readline() try: next_line = next_line_b.decode('UTF-8') except UnicodeDecodeError: return cmd for c in next_line: if c not in printable: return cmd line_tokens = tuple(_shebang_split(next_line.strip())) for i, token in enumerate(line_tokens[:-1]): if token != '-i': continue # the argument to -i flag cmd = (line_tokens[i + 1],) return cmd def parse_shebang(bytesio: IO[bytes]) -> tuple[str, ...]: """Parse the shebang from a file opened for reading binary.""" if bytesio.read(2) != b'#!': return () first_line_b = bytesio.readline() try: first_line = first_line_b.decode('UTF-8') except UnicodeDecodeError: return () # Require only printable ascii for c in first_line: if c not in printable: return () cmd = tuple(_shebang_split(first_line.strip())) if cmd[:2] == ('/usr/bin/env', '-S'): cmd = cmd[2:] elif cmd[:1] == ('/usr/bin/env',): cmd = cmd[1:] if cmd == ('nix-shell',): return _parse_nix_shebang(bytesio, cmd) return cmd def parse_shebang_from_file(path: str) -> tuple[str, ...]: """Parse the shebang given a file path.""" if not os.path.lexists(path): raise ValueError(f'{path} does not exist.') if not os.access(path, os.X_OK): return () try: with open(path, 'rb') as f: return parse_shebang(f) except OSError as e: if e.errno == errno.EINVAL: return () else: raise COPYRIGHT_RE = re.compile(r'^\s*(Copyright|\(C\)) .*$', re.I | re.MULTILINE) WS_RE = re.compile(r'\s+') def _norm_license(s: str) -> str: s = COPYRIGHT_RE.sub('', s) s = WS_RE.sub(' ', s) return s.strip() def license_id(filename: str) -> str | None: """Return the spdx id for the license contained in `filename`. If no license is detected, returns `None`. spdx: https://spdx.org/licenses/ licenses from choosealicense.com: https://github.com/choosealicense.com Approximate algorithm: 1. strip copyright line 2. normalize whitespace (replace all whitespace with a single space) 3. check exact text match with existing licenses 4. failing that use edit distance """ import ukkonen # `pip install identify[license]` with open(filename, encoding='UTF-8') as f: contents = f.read() norm = _norm_license(contents) min_edit_dist = sys.maxsize min_edit_dist_spdx = '' cutoff = math.ceil(.05 * len(norm)) # try exact matches for spdx, text in licenses.LICENSES: norm_license = _norm_license(text) if norm == norm_license: return spdx # skip the slow calculation if the lengths are very different if norm and abs(len(norm) - len(norm_license)) / len(norm) > .05: continue edit_dist = ukkonen.distance(norm, norm_license, cutoff) if edit_dist < cutoff and edit_dist < min_edit_dist: min_edit_dist = edit_dist min_edit_dist_spdx = spdx # if there's less than 5% edited from the license, we found our match if norm and min_edit_dist < cutoff: return min_edit_dist_spdx else: # no matches :'( return None

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