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mitogen/ansible_mitogen/parsing.py

78 lines
3.0 KiB
Python

# Copyright 2019, David Wilson
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
from __future__ import absolute_import, division, print_function
from __future__ import unicode_literals
__metaclass__ = type
import mitogen.core
def parse_script_interpreter(source):
"""
Parse the script interpreter portion of a UNIX hashbang using the rules
Linux uses.
:param str source: String like "/usr/bin/env python".
:returns:
Tuple of `(interpreter, arg)`, where `intepreter` is the script
interpreter and `arg` is its sole argument if present, otherwise
:py:data:`None`.
"""
# Find terminating newline. Assume last byte of binprm_buf if absent.
nl = source.find(b'\n', 0, 128)
if nl == -1:
nl = min(128, len(source))
# Split once on the first run of whitespace. If no whitespace exists,
# bits just contains the interpreter filename.
bits = source[0:nl].strip().split(None, 1)
if len(bits) == 1:
return mitogen.core.to_text(bits[0]), None
return mitogen.core.to_text(bits[0]), mitogen.core.to_text(bits[1])
def parse_hashbang(source):
"""
Parse a UNIX "hashbang line" using the syntax supported by Linux.
:param str source: String like "#!/usr/bin/env python".
:returns:
Tuple of `(interpreter, arg)`, where `intepreter` is the script
interpreter and `arg` is its sole argument if present, otherwise
:py:data:`None`.
"""
# Linux requires first 2 bytes with no whitespace, pretty sure it's the
# same everywhere. See binfmt_script.c.
if not source.startswith(b'#!'):
return None, None
return parse_script_interpreter(source[2:])