| """Lazy ZIP over HTTP""" |
| |
| __all__ = ["HTTPRangeRequestUnsupported", "dist_from_wheel_url"] |
| |
| from bisect import bisect_left, bisect_right |
| from contextlib import contextmanager |
| from tempfile import NamedTemporaryFile |
| from typing import Any, Dict, Generator, List, Optional, Tuple |
| from zipfile import BadZipfile, ZipFile |
| |
| from pip._vendor.packaging.utils import canonicalize_name |
| from pip._vendor.requests.models import CONTENT_CHUNK_SIZE, Response |
| |
| from pip._internal.metadata import BaseDistribution, MemoryWheel, get_wheel_distribution |
| from pip._internal.network.session import PipSession |
| from pip._internal.network.utils import HEADERS, raise_for_status, response_chunks |
| |
| |
| class HTTPRangeRequestUnsupported(Exception): |
| pass |
| |
| |
| def dist_from_wheel_url(name: str, url: str, session: PipSession) -> BaseDistribution: |
| """Return a distribution object from the given wheel URL. |
| |
| This uses HTTP range requests to only fetch the portion of the wheel |
| containing metadata, just enough for the object to be constructed. |
| If such requests are not supported, HTTPRangeRequestUnsupported |
| is raised. |
| """ |
| with LazyZipOverHTTP(url, session) as zf: |
| # For read-only ZIP files, ZipFile only needs methods read, |
| # seek, seekable and tell, not the whole IO protocol. |
| wheel = MemoryWheel(zf.name, zf) # type: ignore |
| # After context manager exit, wheel.name |
| # is an invalid file by intention. |
| return get_wheel_distribution(wheel, canonicalize_name(name)) |
| |
| |
| class LazyZipOverHTTP: |
| """File-like object mapped to a ZIP file over HTTP. |
| |
| This uses HTTP range requests to lazily fetch the file's content, |
| which is supposed to be fed to ZipFile. If such requests are not |
| supported by the server, raise HTTPRangeRequestUnsupported |
| during initialization. |
| """ |
| |
| def __init__( |
| self, url: str, session: PipSession, chunk_size: int = CONTENT_CHUNK_SIZE |
| ) -> None: |
| head = session.head(url, headers=HEADERS) |
| raise_for_status(head) |
| assert head.status_code == 200 |
| self._session, self._url, self._chunk_size = session, url, chunk_size |
| self._length = int(head.headers["Content-Length"]) |
| self._file = NamedTemporaryFile() |
| self.truncate(self._length) |
| self._left: List[int] = [] |
| self._right: List[int] = [] |
| if "bytes" not in head.headers.get("Accept-Ranges", "none"): |
| raise HTTPRangeRequestUnsupported("range request is not supported") |
| self._check_zip() |
| |
| @property |
| def mode(self) -> str: |
| """Opening mode, which is always rb.""" |
| return "rb" |
| |
| @property |
| def name(self) -> str: |
| """Path to the underlying file.""" |
| return self._file.name |
| |
| def seekable(self) -> bool: |
| """Return whether random access is supported, which is True.""" |
| return True |
| |
| def close(self) -> None: |
| """Close the file.""" |
| self._file.close() |
| |
| @property |
| def closed(self) -> bool: |
| """Whether the file is closed.""" |
| return self._file.closed |
| |
| def read(self, size: int = -1) -> bytes: |
| """Read up to size bytes from the object and return them. |
| |
| As a convenience, if size is unspecified or -1, |
| all bytes until EOF are returned. Fewer than |
| size bytes may be returned if EOF is reached. |
| """ |
| download_size = max(size, self._chunk_size) |
| start, length = self.tell(), self._length |
| stop = length if size < 0 else min(start + download_size, length) |
| start = max(0, stop - download_size) |
| self._download(start, stop - 1) |
| return self._file.read(size) |
| |
| def readable(self) -> bool: |
| """Return whether the file is readable, which is True.""" |
| return True |
| |
| def seek(self, offset: int, whence: int = 0) -> int: |
| """Change stream position and return the new absolute position. |
| |
| Seek to offset relative position indicated by whence: |
| * 0: Start of stream (the default). pos should be >= 0; |
| * 1: Current position - pos may be negative; |
| * 2: End of stream - pos usually negative. |
| """ |
| return self._file.seek(offset, whence) |
| |
| def tell(self) -> int: |
| """Return the current position.""" |
| return self._file.tell() |
| |
| def truncate(self, size: Optional[int] = None) -> int: |
| """Resize the stream to the given size in bytes. |
| |
| If size is unspecified resize to the current position. |
| The current stream position isn't changed. |
| |
| Return the new file size. |
| """ |
| return self._file.truncate(size) |
| |
| def writable(self) -> bool: |
| """Return False.""" |
| return False |
| |
| def __enter__(self) -> "LazyZipOverHTTP": |
| self._file.__enter__() |
| return self |
| |
| def __exit__(self, *exc: Any) -> None: |
| self._file.__exit__(*exc) |
| |
| @contextmanager |
| def _stay(self) -> Generator[None, None, None]: |
| """Return a context manager keeping the position. |
| |
| At the end of the block, seek back to original position. |
| """ |
| pos = self.tell() |
| try: |
| yield |
| finally: |
| self.seek(pos) |
| |
| def _check_zip(self) -> None: |
| """Check and download until the file is a valid ZIP.""" |
| end = self._length - 1 |
| for start in reversed(range(0, end, self._chunk_size)): |
| self._download(start, end) |
| with self._stay(): |
| try: |
| # For read-only ZIP files, ZipFile only needs |
| # methods read, seek, seekable and tell. |
| ZipFile(self) # type: ignore |
| except BadZipfile: |
| pass |
| else: |
| break |
| |
| def _stream_response( |
| self, start: int, end: int, base_headers: Dict[str, str] = HEADERS |
| ) -> Response: |
| """Return HTTP response to a range request from start to end.""" |
| headers = base_headers.copy() |
| headers["Range"] = f"bytes={start}-{end}" |
| # TODO: Get range requests to be correctly cached |
| headers["Cache-Control"] = "no-cache" |
| return self._session.get(self._url, headers=headers, stream=True) |
| |
| def _merge( |
| self, start: int, end: int, left: int, right: int |
| ) -> Generator[Tuple[int, int], None, None]: |
| """Return a generator of intervals to be fetched. |
| |
| Args: |
| start (int): Start of needed interval |
| end (int): End of needed interval |
| left (int): Index of first overlapping downloaded data |
| right (int): Index after last overlapping downloaded data |
| """ |
| lslice, rslice = self._left[left:right], self._right[left:right] |
| i = start = min([start] + lslice[:1]) |
| end = max([end] + rslice[-1:]) |
| for j, k in zip(lslice, rslice): |
| if j > i: |
| yield i, j - 1 |
| i = k + 1 |
| if i <= end: |
| yield i, end |
| self._left[left:right], self._right[left:right] = [start], [end] |
| |
| def _download(self, start: int, end: int) -> None: |
| """Download bytes from start to end inclusively.""" |
| with self._stay(): |
| left = bisect_left(self._right, start) |
| right = bisect_right(self._left, end) |
| for start, end in self._merge(start, end, left, right): |
| response = self._stream_response(start, end) |
| response.raise_for_status() |
| self.seek(start) |
| for chunk in response_chunks(response, self._chunk_size): |
| self._file.write(chunk) |
