blackd.py

   1 import asyncio
   2 from concurrent.futures import Executor, ProcessPoolExecutor
   3 from functools import partial
   4 import logging
   5 from multiprocessing import freeze_support
   6 from typing import Set, Tuple
   7
   8 from aiohttp import web
   9 import aiohttp_cors
  10 import black
  11 import click
  12
  13 # This is used internally by tests to shut down the server prematurely
  14 _stop_signal = asyncio.Event()
  15
  16 VERSION_HEADER = "X-Protocol-Version"
  17 LINE_LENGTH_HEADER = "X-Line-Length"
  18 PYTHON_VARIANT_HEADER = "X-Python-Variant"
  19 SKIP_STRING_NORMALIZATION_HEADER = "X-Skip-String-Normalization"
  20 FAST_OR_SAFE_HEADER = "X-Fast-Or-Safe"
  21
  22 BLACK_HEADERS = [
  23     VERSION_HEADER,
  24     LINE_LENGTH_HEADER,
  25     PYTHON_VARIANT_HEADER,
  26     SKIP_STRING_NORMALIZATION_HEADER,
  27     FAST_OR_SAFE_HEADER,
  28 ]
  29
  30
  31 class InvalidVariantHeader(Exception):
  32     pass
  33
  34
  35 @click.command(context_settings={"help_option_names": ["-h", "--help"]})
  36 @click.option(
  37     "--bind-host", type=str, help="Address to bind the server to.", default="localhost"
  38 )
  39 @click.option("--bind-port", type=int, help="Port to listen on", default=45484)
  40 @click.version_option(version=black.__version__)
  41 def main(bind_host: str, bind_port: int) -> None:
  42     logging.basicConfig(level=logging.INFO)
  43     app = make_app()
  44     ver = black.__version__
  45     black.out(f"blackd version {ver} listening on {bind_host} port {bind_port}")
  46     web.run_app(app, host=bind_host, port=bind_port, handle_signals=True, print=None)
  47
  48
  49 def make_app() -> web.Application:
  50     app = web.Application()
  51     executor = ProcessPoolExecutor()
  52
  53     cors = aiohttp_cors.setup(app)
  54     resource = cors.add(app.router.add_resource("/"))
  55     cors.add(
  56         resource.add_route("POST", partial(handle, executor=executor)),
  57         {
  58             "*": aiohttp_cors.ResourceOptions(
  59                 allow_headers=(*BLACK_HEADERS, "Content-Type"), expose_headers="*"
  60             )
  61         },
  62     )
  63
  64     return app
  65
  66
  67 async def handle(request: web.Request, executor: Executor) -> web.Response:
  68     try:
  69         if request.headers.get(VERSION_HEADER, "1") != "1":
  70             return web.Response(
  71                 status=501, text="This server only supports protocol version 1"
  72             )
  73         try:
  74             line_length = int(
  75                 request.headers.get(LINE_LENGTH_HEADER, black.DEFAULT_LINE_LENGTH)
  76             )
  77         except ValueError:
  78             return web.Response(status=400, text="Invalid line length header value")
  79
  80         if PYTHON_VARIANT_HEADER in request.headers:
  81             value = request.headers[PYTHON_VARIANT_HEADER]
  82             try:
  83                 pyi, versions = parse_python_variant_header(value)
  84             except InvalidVariantHeader as e:
  85                 return web.Response(
  86                     status=400,
  87                     text=f"Invalid value for {PYTHON_VARIANT_HEADER}: {e.args[0]}",
  88                 )
  89         else:
  90             pyi = False
  91             versions = set()
  92
  93         skip_string_normalization = bool(
  94             request.headers.get(SKIP_STRING_NORMALIZATION_HEADER, False)
  95         )
  96         fast = False
  97         if request.headers.get(FAST_OR_SAFE_HEADER, "safe") == "fast":
  98             fast = True
  99         mode = black.FileMode(
 100             target_versions=versions,
 101             is_pyi=pyi,
 102             line_length=line_length,
 103             string_normalization=not skip_string_normalization,
 104         )
 105         req_bytes = await request.content.read()
 106         charset = request.charset if request.charset is not None else "utf8"
 107         req_str = req_bytes.decode(charset)
 108         loop = asyncio.get_event_loop()
 109         formatted_str = await loop.run_in_executor(
 110             executor, partial(black.format_file_contents, req_str, fast=fast, mode=mode)
 111         )
 112         return web.Response(
 113             content_type=request.content_type, charset=charset, text=formatted_str
 114         )
 115     except black.NothingChanged:
 116         return web.Response(status=204)
 117     except black.InvalidInput as e:
 118         return web.Response(status=400, text=str(e))
 119     except Exception as e:
 120         logging.exception("Exception during handling a request")
 121         return web.Response(status=500, text=str(e))
 122
 123
 124 def parse_python_variant_header(value: str) -> Tuple[bool, Set[black.TargetVersion]]:
 125     if value == "pyi":
 126         return True, set()
 127     else:
 128         versions = set()
 129         for version in value.split(","):
 130             if version.startswith("py"):
 131                 version = version[len("py") :]
 132             if "." in version:
 133                 major_str, *rest = version.split(".")
 134             else:
 135                 major_str = version[0]
 136                 rest = [version[1:]] if len(version) > 1 else []
 137             try:
 138                 major = int(major_str)
 139                 if major not in (2, 3):
 140                     raise InvalidVariantHeader("major version must be 2 or 3")
 141                 if len(rest) > 0:
 142                     minor = int(rest[0])
 143                     if major == 2 and minor != 7:
 144                         raise InvalidVariantHeader(
 145                             "minor version must be 7 for Python 2"
 146                         )
 147                 else:
 148                     # Default to lowest supported minor version.
 149                     minor = 7 if major == 2 else 3
 150                 version_str = f"PY{major}{minor}"
 151                 if major == 3 and not hasattr(black.TargetVersion, version_str):
 152                     raise InvalidVariantHeader(f"3.{minor} is not supported")
 153                 versions.add(black.TargetVersion[version_str])
 154             except (KeyError, ValueError):
 155                 raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'")
 156         return False, versions
 157
 158
 159 def patched_main() -> None:
 160     freeze_support()
 161     black.patch_click()
 162     main()
 163
 164
 165 if __name__ == "__main__":
 166     patched_main()