download.pyā¢11.1 kB
"""Download files with progress indicators."""
import email.message
import logging
import mimetypes
import os
from http import HTTPStatus
from typing import BinaryIO, Iterable, Optional, Tuple
from pip._vendor.requests.models import Response
from pip._vendor.urllib3.exceptions import ReadTimeoutError
from pip._internal.cli.progress_bars import get_download_progress_renderer
from pip._internal.exceptions import IncompleteDownloadError, NetworkConnectionError
from pip._internal.models.index import PyPI
from pip._internal.models.link import Link
from pip._internal.network.cache import is_from_cache
from pip._internal.network.session import PipSession
from pip._internal.network.utils import HEADERS, raise_for_status, response_chunks
from pip._internal.utils.misc import format_size, redact_auth_from_url, splitext
logger = logging.getLogger(__name__)
def _get_http_response_size(resp: Response) -> Optional[int]:
try:
return int(resp.headers["content-length"])
except (ValueError, KeyError, TypeError):
return None
def _get_http_response_etag_or_last_modified(resp: Response) -> Optional[str]:
"""
Return either the ETag or Last-Modified header (or None if neither exists).
The return value can be used in an If-Range header.
"""
return resp.headers.get("etag", resp.headers.get("last-modified"))
def _prepare_download(
resp: Response,
link: Link,
progress_bar: str,
total_length: Optional[int],
range_start: Optional[int] = 0,
) -> Iterable[bytes]:
if link.netloc == PyPI.file_storage_domain:
url = link.show_url
else:
url = link.url_without_fragment
logged_url = redact_auth_from_url(url)
if total_length:
if range_start:
logged_url = (
f"{logged_url} ({format_size(range_start)}/{format_size(total_length)})"
)
else:
logged_url = f"{logged_url} ({format_size(total_length)})"
if is_from_cache(resp):
logger.info("Using cached %s", logged_url)
elif range_start:
logger.info("Resuming download %s", logged_url)
else:
logger.info("Downloading %s", logged_url)
if logger.getEffectiveLevel() > logging.INFO:
show_progress = False
elif is_from_cache(resp):
show_progress = False
elif not total_length:
show_progress = True
elif total_length > (512 * 1024):
show_progress = True
else:
show_progress = False
chunks = response_chunks(resp)
if not show_progress:
return chunks
renderer = get_download_progress_renderer(
bar_type=progress_bar, size=total_length, initial_progress=range_start
)
return renderer(chunks)
def sanitize_content_filename(filename: str) -> str:
"""
Sanitize the "filename" value from a Content-Disposition header.
"""
return os.path.basename(filename)
def parse_content_disposition(content_disposition: str, default_filename: str) -> str:
"""
Parse the "filename" value from a Content-Disposition header, and
return the default filename if the result is empty.
"""
m = email.message.Message()
m["content-type"] = content_disposition
filename = m.get_param("filename")
if filename:
# We need to sanitize the filename to prevent directory traversal
# in case the filename contains ".." path parts.
filename = sanitize_content_filename(str(filename))
return filename or default_filename
def _get_http_response_filename(resp: Response, link: Link) -> str:
"""Get an ideal filename from the given HTTP response, falling back to
the link filename if not provided.
"""
filename = link.filename # fallback
# Have a look at the Content-Disposition header for a better guess
content_disposition = resp.headers.get("content-disposition")
if content_disposition:
filename = parse_content_disposition(content_disposition, filename)
ext: Optional[str] = splitext(filename)[1]
if not ext:
ext = mimetypes.guess_extension(resp.headers.get("content-type", ""))
if ext:
filename += ext
if not ext and link.url != resp.url:
ext = os.path.splitext(resp.url)[1]
if ext:
filename += ext
return filename
def _http_get_download(
session: PipSession,
link: Link,
range_start: Optional[int] = 0,
if_range: Optional[str] = None,
) -> Response:
target_url = link.url.split("#", 1)[0]
headers = HEADERS.copy()
# request a partial download
if range_start:
headers["Range"] = f"bytes={range_start}-"
# make sure the file hasn't changed
if if_range:
headers["If-Range"] = if_range
try:
resp = session.get(target_url, headers=headers, stream=True)
raise_for_status(resp)
except NetworkConnectionError as e:
assert e.response is not None
logger.critical("HTTP error %s while getting %s", e.response.status_code, link)
raise
return resp
class Downloader:
def __init__(
self,
session: PipSession,
progress_bar: str,
resume_retries: int,
) -> None:
assert (
resume_retries >= 0
), "Number of max resume retries must be bigger or equal to zero"
self._session = session
self._progress_bar = progress_bar
self._resume_retries = resume_retries
def __call__(self, link: Link, location: str) -> Tuple[str, str]:
"""Download the file given by link into location."""
resp = _http_get_download(self._session, link)
# NOTE: The original download size needs to be passed down everywhere
# so if the download is resumed (with a HTTP Range request) the progress
# bar will report the right size.
total_length = _get_http_response_size(resp)
content_type = resp.headers.get("Content-Type", "")
filename = _get_http_response_filename(resp, link)
filepath = os.path.join(location, filename)
with open(filepath, "wb") as content_file:
bytes_received = self._process_response(
resp, link, content_file, 0, total_length
)
# If possible, check for an incomplete download and attempt resuming.
if total_length and bytes_received < total_length:
self._attempt_resume(
resp, link, content_file, total_length, bytes_received
)
return filepath, content_type
def _process_response(
self,
resp: Response,
link: Link,
content_file: BinaryIO,
bytes_received: int,
total_length: Optional[int],
) -> int:
"""Process the response and write the chunks to the file."""
chunks = _prepare_download(
resp, link, self._progress_bar, total_length, range_start=bytes_received
)
return self._write_chunks_to_file(
chunks, content_file, allow_partial=bool(total_length)
)
def _write_chunks_to_file(
self, chunks: Iterable[bytes], content_file: BinaryIO, *, allow_partial: bool
) -> int:
"""Write the chunks to the file and return the number of bytes received."""
bytes_received = 0
try:
for chunk in chunks:
bytes_received += len(chunk)
content_file.write(chunk)
except ReadTimeoutError as e:
# If partial downloads are OK (the download will be retried), don't bail.
if not allow_partial:
raise e
# Ensuring bytes_received is returned to attempt resume
logger.warning("Connection timed out while downloading.")
return bytes_received
def _attempt_resume(
self,
resp: Response,
link: Link,
content_file: BinaryIO,
total_length: Optional[int],
bytes_received: int,
) -> None:
"""Attempt to resume the download if connection was dropped."""
etag_or_last_modified = _get_http_response_etag_or_last_modified(resp)
attempts_left = self._resume_retries
while total_length and attempts_left and bytes_received < total_length:
attempts_left -= 1
logger.warning(
"Attempting to resume incomplete download (%s/%s, attempt %d)",
format_size(bytes_received),
format_size(total_length),
(self._resume_retries - attempts_left),
)
try:
# Try to resume the download using a HTTP range request.
resume_resp = _http_get_download(
self._session,
link,
range_start=bytes_received,
if_range=etag_or_last_modified,
)
# Fallback: if the server responded with 200 (i.e., the file has
# since been modified or range requests are unsupported) or any
# other unexpected status, restart the download from the beginning.
must_restart = resume_resp.status_code != HTTPStatus.PARTIAL_CONTENT
if must_restart:
bytes_received, total_length, etag_or_last_modified = (
self._reset_download_state(resume_resp, content_file)
)
bytes_received += self._process_response(
resume_resp, link, content_file, bytes_received, total_length
)
except (ConnectionError, ReadTimeoutError, OSError):
continue
# No more resume attempts. Raise an error if the download is still incomplete.
if total_length and bytes_received < total_length:
os.remove(content_file.name)
raise IncompleteDownloadError(
link, bytes_received, total_length, retries=self._resume_retries
)
def _reset_download_state(
self,
resp: Response,
content_file: BinaryIO,
) -> Tuple[int, Optional[int], Optional[str]]:
"""Reset the download state to restart downloading from the beginning."""
content_file.seek(0)
content_file.truncate()
bytes_received = 0
total_length = _get_http_response_size(resp)
etag_or_last_modified = _get_http_response_etag_or_last_modified(resp)
return bytes_received, total_length, etag_or_last_modified
class BatchDownloader:
def __init__(
self,
session: PipSession,
progress_bar: str,
resume_retries: int,
) -> None:
self._downloader = Downloader(session, progress_bar, resume_retries)
def __call__(
self, links: Iterable[Link], location: str
) -> Iterable[Tuple[Link, Tuple[str, str]]]:
"""Download the files given by links into location."""
for link in links:
filepath, content_type = self._downloader(link, location)
yield link, (filepath, content_type)