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 from _version import version as __version__
  14
  15 # This is used internally by tests to shut down the server prematurely
  16 _stop_signal = asyncio.Event()
  17
  18 # Request headers
  19 PROTOCOL_VERSION_HEADER = "X-Protocol-Version"
  20 LINE_LENGTH_HEADER = "X-Line-Length"
  21 PYTHON_VARIANT_HEADER = "X-Python-Variant"
  22 SKIP_STRING_NORMALIZATION_HEADER = "X-Skip-String-Normalization"
  23 FAST_OR_SAFE_HEADER = "X-Fast-Or-Safe"
  24
  25 BLACK_HEADERS = [
  26     PROTOCOL_VERSION_HEADER,
  27     LINE_LENGTH_HEADER,
  28     PYTHON_VARIANT_HEADER,
  29     SKIP_STRING_NORMALIZATION_HEADER,
  30     FAST_OR_SAFE_HEADER,
  31 ]
  32
  33 # Response headers
  34 BLACK_VERSION_HEADER = "X-Black-Version"
  35
  36
  37 class InvalidVariantHeader(Exception):
  38     pass
  39
  40
  41 @click.command(context_settings={"help_option_names": ["-h", "--help"]})
  42 @click.option(
  43     "--bind-host", type=str, help="Address to bind the server to.", default="localhost"
  44 )
  45 @click.option("--bind-port", type=int, help="Port to listen on", default=45484)
  46 @click.version_option(version=black.__version__)
  47 def main(bind_host: str, bind_port: int) -> None:
  48     logging.basicConfig(level=logging.INFO)
  49     app = make_app()
  50     ver = black.__version__
  51     black.out(f"blackd version {ver} listening on {bind_host} port {bind_port}")
  52     web.run_app(app, host=bind_host, port=bind_port, handle_signals=True, print=None)
  53
  54
  55 def make_app() -> web.Application:
  56     app = web.Application()
  57     executor = ProcessPoolExecutor()
  58
  59     cors = aiohttp_cors.setup(app)
  60     resource = cors.add(app.router.add_resource("/"))
  61     cors.add(
  62         resource.add_route("POST", partial(handle, executor=executor)),
  63         {
  64             "*": aiohttp_cors.ResourceOptions(
  65                 allow_headers=(*BLACK_HEADERS, "Content-Type"), expose_headers="*"
  66             )
  67         },
  68     )
  69
  70     return app
  71
  72
  73 async def handle(request: web.Request, executor: Executor) -> web.Response:
  74     headers = {BLACK_VERSION_HEADER: __version__}
  75     try:
  76         if request.headers.get(PROTOCOL_VERSION_HEADER, "1") != "1":
  77             return web.Response(
  78                 status=501, text="This server only supports protocol version 1"
  79             )
  80         try:
  81             line_length = int(
  82                 request.headers.get(LINE_LENGTH_HEADER, black.DEFAULT_LINE_LENGTH)
  83             )
  84         except ValueError:
  85             return web.Response(status=400, text="Invalid line length header value")
  86
  87         if PYTHON_VARIANT_HEADER in request.headers:
  88             value = request.headers[PYTHON_VARIANT_HEADER]
  89             try:
  90                 pyi, versions = parse_python_variant_header(value)
  91             except InvalidVariantHeader as e:
  92                 return web.Response(
  93                     status=400,
  94                     text=f"Invalid value for {PYTHON_VARIANT_HEADER}: {e.args[0]}",
  95                 )
  96         else:
  97             pyi = False
  98             versions = set()
  99
 100         skip_string_normalization = bool(
 101             request.headers.get(SKIP_STRING_NORMALIZATION_HEADER, False)
 102         )
 103         fast = False
 104         if request.headers.get(FAST_OR_SAFE_HEADER, "safe") == "fast":
 105             fast = True
 106         mode = black.FileMode(
 107             target_versions=versions,
 108             is_pyi=pyi,
 109             line_length=line_length,
 110             string_normalization=not skip_string_normalization,
 111         )
 112         req_bytes = await request.content.read()
 113         charset = request.charset if request.charset is not None else "utf8"
 114         req_str = req_bytes.decode(charset)
 115         loop = asyncio.get_event_loop()
 116         formatted_str = await loop.run_in_executor(
 117             executor, partial(black.format_file_contents, req_str, fast=fast, mode=mode)
 118         )
 119         return web.Response(
 120             content_type=request.content_type,
 121             charset=charset,
 122             headers=headers,
 123             text=formatted_str,
 124         )
 125     except black.NothingChanged:
 126         return web.Response(status=204, headers=headers)
 127     except black.InvalidInput as e:
 128         return web.Response(status=400, headers=headers, text=str(e))
 129     except Exception as e:
 130         logging.exception("Exception during handling a request")
 131         return web.Response(status=500, headers=headers, text=str(e))
 132
 133
 134 def parse_python_variant_header(value: str) -> Tuple[bool, Set[black.TargetVersion]]:
 135     if value == "pyi":
 136         return True, set()
 137     else:
 138         versions = set()
 139         for version in value.split(","):
 140             if version.startswith("py"):
 141                 version = version[len("py") :]
 142             if "." in version:
 143                 major_str, *rest = version.split(".")
 144             else:
 145                 major_str = version[0]
 146                 rest = [version[1:]] if len(version) > 1 else []
 147             try:
 148                 major = int(major_str)
 149                 if major not in (2, 3):
 150                     raise InvalidVariantHeader("major version must be 2 or 3")
 151                 if len(rest) > 0:
 152                     minor = int(rest[0])
 153                     if major == 2 and minor != 7:
 154                         raise InvalidVariantHeader(
 155                             "minor version must be 7 for Python 2"
 156                         )
 157                 else:
 158                     # Default to lowest supported minor version.
 159                     minor = 7 if major == 2 else 3
 160                 version_str = f"PY{major}{minor}"
 161                 if major == 3 and not hasattr(black.TargetVersion, version_str):
 162                     raise InvalidVariantHeader(f"3.{minor} is not supported")
 163                 versions.add(black.TargetVersion[version_str])
 164             except (KeyError, ValueError):
 165                 raise InvalidVariantHeader("expected e.g. '3.7', 'py3.5'")
 166         return False, versions
 167
 168
 169 def patched_main() -> None:
 170     freeze_support()
 171     black.patch_click()
 172     main()
 173
 174
 175 if __name__ == "__main__":
 176     patched_main()