sapling/build/fbcode_builder/shell_quoting.py
Zsolt Dollenstein dbfe4a85f3 Opt in opensource/fbcode_builder to pyfmt
Reviewed By: zertosh

Differential Revision: D29612107

fbshipit-source-id: ac450058134e23a3831db35d2e49c80eb8cde36a
2021-07-09 06:24:16 -07:00

104 lines
3.2 KiB
Python

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