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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