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bcad7419bf
Summary: Initial commit to include the fbcode_builder sources in the eden github repository. fbshipit-source-id: 49098cecda04a7e9dd9dcc0b569fffc96f0f719b
100 lines
3.2 KiB
Python
100 lines
3.2 KiB
Python
#!/usr/bin/env python
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# Copyright (c) Facebook, Inc. and its affiliates.
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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from __future__ import unicode_literals
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'''
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Almost every FBCodeBuilder string is ultimately passed to a shell. Escaping
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too little or too much tends to be the most common error. The utilities in
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this file give a systematic way of avoiding such bugs:
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- When you write literal strings destined for the shell, use `ShellQuoted`.
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- When these literal strings are parameterized, use `ShellQuoted.format`.
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- Any parameters that are raw strings get `shell_quote`d automatically,
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while any ShellQuoted parameters will be left intact.
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- Use `path_join` to join path components.
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- Use `shell_join` to join already-quoted command arguments or shell lines.
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'''
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import os
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from collections import namedtuple
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class ShellQuoted(namedtuple('ShellQuoted', ('do_not_use_raw_str',))):
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'''
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Wrap a string with this to make it transparent to shell_quote(). It
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will almost always suffice to use ShellQuoted.format(), path_join(),
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or shell_join().
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If you really must, use raw_shell() to access the raw string.
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'''
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def __new__(cls, s):
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'No need to nest ShellQuoted.'
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return super(ShellQuoted, cls).__new__(
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cls, s.do_not_use_raw_str if isinstance(s, ShellQuoted) else s
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)
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def __str__(self):
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raise RuntimeError(
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'One does not simply convert {0} to a string -- use path_join() '
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'or ShellQuoted.format() instead'.format(repr(self))
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)
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def __repr__(self):
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return '{0}({1})'.format(
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self.__class__.__name__, repr(self.do_not_use_raw_str)
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)
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def format(self, **kwargs):
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'''
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Use instead of str.format() when the arguments are either
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`ShellQuoted()` or raw strings needing to be `shell_quote()`d.
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Positional args are deliberately not supported since they are more
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error-prone.
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'''
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return ShellQuoted(self.do_not_use_raw_str.format(**dict(
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(k, shell_quote(v).do_not_use_raw_str) for k, v in kwargs.items()
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)))
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def shell_quote(s):
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'Quotes a string if it is not already quoted'
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return s if isinstance(s, ShellQuoted) \
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else ShellQuoted("'" + str(s).replace("'", "'\\''") + "'")
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def raw_shell(s):
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'Not a member of ShellQuoted so we get a useful error for raw strings'
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if isinstance(s, ShellQuoted):
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return s.do_not_use_raw_str
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raise RuntimeError('{0} should have been ShellQuoted'.format(s))
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def shell_join(delim, it):
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'Joins an iterable of ShellQuoted with a delimiter between each two'
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return ShellQuoted(delim.join(raw_shell(s) for s in it))
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def path_join(*args):
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'Joins ShellQuoted and raw pieces of paths to make a shell-quoted path'
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return ShellQuoted(os.path.join(*[
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raw_shell(shell_quote(s)) for s in args
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]))
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def shell_comment(c):
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'Do not shell-escape raw strings in comments, but do handle line breaks.'
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return ShellQuoted('# {c}').format(c=ShellQuoted(
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(raw_shell(c) if isinstance(c, ShellQuoted) else c)
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.replace('\n', '\n# ')
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))
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