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Add SECURITY.md (#3612)
[etc/vim.git] / src / blackd / __init__.py
1 import asyncio
2 import logging
3 from concurrent.futures import Executor, ProcessPoolExecutor
4 from datetime import datetime
5 from functools import partial
6 from multiprocessing import freeze_support
7 from typing import Set, Tuple
8
9 try:
10     from aiohttp import web
11
12     from .middlewares import cors
13 except ImportError as ie:
14     raise ImportError(
15         f"aiohttp dependency is not installed: {ie}. "
16         + "Please re-install black with the '[d]' extra install "
17         + "to obtain aiohttp_cors: `pip install black[d]`"
18     ) from None
19
20 import click
21
22 import black
23 from _black_version import version as __version__
24 from black.concurrency import maybe_install_uvloop
25
26 # This is used internally by tests to shut down the server prematurely
27 _stop_signal = asyncio.Event()
28
29 # Request headers
30 PROTOCOL_VERSION_HEADER = "X-Protocol-Version"
31 LINE_LENGTH_HEADER = "X-Line-Length"
32 PYTHON_VARIANT_HEADER = "X-Python-Variant"
33 SKIP_SOURCE_FIRST_LINE = "X-Skip-Source-First-Line"
34 SKIP_STRING_NORMALIZATION_HEADER = "X-Skip-String-Normalization"
35 SKIP_MAGIC_TRAILING_COMMA = "X-Skip-Magic-Trailing-Comma"
36 PREVIEW = "X-Preview"
37 FAST_OR_SAFE_HEADER = "X-Fast-Or-Safe"
38 DIFF_HEADER = "X-Diff"
39
40 BLACK_HEADERS = [
41     PROTOCOL_VERSION_HEADER,
42     LINE_LENGTH_HEADER,
43     PYTHON_VARIANT_HEADER,
44     SKIP_SOURCE_FIRST_LINE,
45     SKIP_STRING_NORMALIZATION_HEADER,
46     SKIP_MAGIC_TRAILING_COMMA,
47     PREVIEW,
48     FAST_OR_SAFE_HEADER,
49     DIFF_HEADER,
50 ]
51
52 # Response headers
53 BLACK_VERSION_HEADER = "X-Black-Version"
54
55
56 class InvalidVariantHeader(Exception):
57     pass
58
59
60 @click.command(context_settings={"help_option_names": ["-h", "--help"]})
61 @click.option(
62     "--bind-host", type=str, help="Address to bind the server to.", default="localhost"
63 )
64 @click.option("--bind-port", type=int, help="Port to listen on", default=45484)
65 @click.version_option(version=black.__version__)
66 def main(bind_host: str, bind_port: int) -> None:
67     logging.basicConfig(level=logging.INFO)
68     app = make_app()
69     ver = black.__version__
70     black.out(f"blackd version {ver} listening on {bind_host} port {bind_port}")
71     web.run_app(app, host=bind_host, port=bind_port, handle_signals=True, print=None)
72
73
74 def make_app() -> web.Application:
75     app = web.Application(
76         middlewares=[cors(allow_headers=(*BLACK_HEADERS, "Content-Type"))]
77     )
78     executor = ProcessPoolExecutor()
79     app.add_routes([web.post("/", partial(handle, executor=executor))])
80     return app
81
82
83 async def handle(request: web.Request, executor: Executor) -> web.Response:
84     headers = {BLACK_VERSION_HEADER: __version__}
85     try:
86         if request.headers.get(PROTOCOL_VERSION_HEADER, "1") != "1":
87             return web.Response(
88                 status=501, text="This server only supports protocol version 1"
89             )
90         try:
91             line_length = int(
92                 request.headers.get(LINE_LENGTH_HEADER, black.DEFAULT_LINE_LENGTH)
93             )
94         except ValueError:
95             return web.Response(status=400, text="Invalid line length header value")
96
97         if PYTHON_VARIANT_HEADER in request.headers:
98             value = request.headers[PYTHON_VARIANT_HEADER]
99             try:
100                 pyi, versions = parse_python_variant_header(value)
101             except InvalidVariantHeader as e:
102                 return web.Response(
103                     status=400,
104                     text=f"Invalid value for {PYTHON_VARIANT_HEADER}: {e.args[0]}",
105                 )
106         else:
107             pyi = False
108             versions = set()
109
110         skip_string_normalization = bool(
111             request.headers.get(SKIP_STRING_NORMALIZATION_HEADER, False)
112         )
113         skip_magic_trailing_comma = bool(
114             request.headers.get(SKIP_MAGIC_TRAILING_COMMA, False)
115         )
116         skip_source_first_line = bool(
117             request.headers.get(SKIP_SOURCE_FIRST_LINE, False)
118         )
119         preview = bool(request.headers.get(PREVIEW, False))
120         fast = False
121         if request.headers.get(FAST_OR_SAFE_HEADER, "safe") == "fast":
122             fast = True
123         mode = black.FileMode(
124             target_versions=versions,
125             is_pyi=pyi,
126             line_length=line_length,
127             skip_source_first_line=skip_source_first_line,
128             string_normalization=not skip_string_normalization,
129             magic_trailing_comma=not skip_magic_trailing_comma,
130             preview=preview,
131         )
132         req_bytes = await request.content.read()
133         charset = request.charset if request.charset is not None else "utf8"
134         req_str = req_bytes.decode(charset)
135         then = datetime.utcnow()
136
137         header = ""
138         if skip_source_first_line:
139             first_newline_position: int = req_str.find("\n") + 1
140             header = req_str[:first_newline_position]
141             req_str = req_str[first_newline_position:]
142
143         loop = asyncio.get_event_loop()
144         formatted_str = await loop.run_in_executor(
145             executor, partial(black.format_file_contents, req_str, fast=fast, mode=mode)
146         )
147
148         # Preserve CRLF line endings
149         if req_str[req_str.find("\n") - 1] == "\r":
150             formatted_str = formatted_str.replace("\n", "\r\n")
151             # If, after swapping line endings, nothing changed, then say so
152             if formatted_str == req_str:
153                 raise black.NothingChanged
154
155         # Put the source first line back
156         req_str = header + req_str
157         formatted_str = header + formatted_str
158
159         # Only output the diff in the HTTP response
160         only_diff = bool(request.headers.get(DIFF_HEADER, False))
161         if only_diff:
162             now = datetime.utcnow()
163             src_name = f"In\t{then} +0000"
164             dst_name = f"Out\t{now} +0000"
165             loop = asyncio.get_event_loop()
166             formatted_str = await loop.run_in_executor(
167                 executor,
168                 partial(black.diff, req_str, formatted_str, src_name, dst_name),
169             )
170
171         return web.Response(
172             content_type=request.content_type,
173             charset=charset,
174             headers=headers,
175             text=formatted_str,
176         )
177     except black.NothingChanged:
178         return web.Response(status=204, headers=headers)
179     except black.InvalidInput as e:
180         return web.Response(status=400, headers=headers, text=str(e))
181     except Exception as e:
182         logging.exception("Exception during handling a request")
183         return web.Response(status=500, headers=headers, text=str(e))
184
185
186 def parse_python_variant_header(value: str) -> Tuple[bool, Set[black.TargetVersion]]:
187     if value == "pyi":
188         return True, set()
189     else:
190         versions = set()
191         for version in value.split(","):
192             if version.startswith("py"):
193                 version = version[len("py") :]
194             if "." in version:
195                 major_str, *rest = version.split(".")
196             else:
197                 major_str = version[0]
198                 rest = [version[1:]] if len(version) > 1 else []
199             try:
200                 major = int(major_str)
201                 if major not in (2, 3):
202                     raise InvalidVariantHeader("major version must be 2 or 3")
203                 if len(rest) > 0:
204                     minor = int(rest[0])
205                     if major == 2:
206                         raise InvalidVariantHeader("Python 2 is not supported")
207                 else:
208                     # Default to lowest supported minor version.
209                     minor = 7 if major == 2 else 3
210                 version_str = f"PY{major}{minor}"
211                 if major == 3 and not hasattr(black.TargetVersion, version_str):
212                     raise InvalidVariantHeader(f"3.{minor} is not supported")
213                 versions.add(black.TargetVersion[version_str])
214             except (KeyError, ValueError):
215                 raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'") from None
216         return False, versions
217
218
219 def patched_main() -> None:
220     maybe_install_uvloop()
221     freeze_support()
222     black.patch_click()
223     main()
224
225
226 if __name__ == "__main__":
227     patched_main()