302 lines
10 KiB
Python
302 lines
10 KiB
Python
"""
|
||
weasyprint.utils
|
||
----------------
|
||
|
||
Various utility functions and classes.
|
||
|
||
:copyright: Copyright 2011-2019 Simon Sapin and contributors, see AUTHORS.
|
||
:license: BSD, see LICENSE for details.
|
||
|
||
"""
|
||
|
||
import codecs
|
||
import contextlib
|
||
import email
|
||
import gzip
|
||
import io
|
||
import os.path
|
||
import re
|
||
import sys
|
||
import traceback
|
||
import zlib
|
||
from base64 import decodebytes
|
||
from gzip import GzipFile
|
||
from urllib.parse import quote, unquote, urljoin, urlsplit
|
||
from urllib.request import Request, pathname2url, urlopen
|
||
|
||
from . import VERSION_STRING
|
||
from .logger import LOGGER
|
||
|
||
# See http://stackoverflow.com/a/11687993/1162888
|
||
# Both are needed in Python 3 as the re module does not like to mix
|
||
# http://tools.ietf.org/html/rfc3986#section-3.1
|
||
UNICODE_SCHEME_RE = re.compile('^([a-zA-Z][a-zA-Z0-9.+-]+):')
|
||
BYTES_SCHEME_RE = re.compile(b'^([a-zA-Z][a-zA-Z0-9.+-]+):')
|
||
|
||
# getfilesystemencoding() on Linux is sometimes stupid...
|
||
FILESYSTEM_ENCODING = sys.getfilesystemencoding()
|
||
try:
|
||
if codecs.lookup(FILESYSTEM_ENCODING).name == 'ascii':
|
||
FILESYSTEM_ENCODING = 'utf-8'
|
||
except LookupError:
|
||
FILESYSTEM_ENCODING = 'utf-8'
|
||
|
||
|
||
class StreamingGzipFile(GzipFile):
|
||
def __init__(self, fileobj):
|
||
GzipFile.__init__(self, fileobj=fileobj)
|
||
self.fileobj_to_close = fileobj
|
||
|
||
def close(self):
|
||
GzipFile.close(self)
|
||
self.fileobj_to_close.close()
|
||
|
||
# Inform html5lib to not rely on these:
|
||
seek = tell = None
|
||
|
||
|
||
def parse_email(data):
|
||
if isinstance(data, bytes):
|
||
data = data.decode('utf8')
|
||
return email.message_from_string(data)
|
||
|
||
|
||
def iri_to_uri(url):
|
||
"""Turn an IRI that can contain any Unicode character into an ASCII-only
|
||
URI that conforms to RFC 3986.
|
||
"""
|
||
if url.startswith('data:'):
|
||
# Data URIs can be huge, but don’t need this anyway.
|
||
return url
|
||
# Use UTF-8 as per RFC 3987 (IRI), except for file://
|
||
url = url.encode(FILESYSTEM_ENCODING
|
||
if url.startswith('file:') else 'utf-8')
|
||
# This is a full URI, not just a component. Only %-encode characters
|
||
# that are not allowed at all in URIs. Everthing else is "safe":
|
||
# * Reserved characters: /:?#[]@!$&'()*+,;=
|
||
# * Unreserved characters: ASCII letters, digits and -._~
|
||
# Of these, only '~' is not in urllib’s "always safe" list.
|
||
# * '%' to avoid double-encoding
|
||
return quote(url, safe=b"/:?#[]@!$&'()*+,;=~%")
|
||
|
||
|
||
def path2url(path):
|
||
"""Return file URL of `path`.
|
||
Accepts 'str' or 'bytes', returns 'str'
|
||
"""
|
||
# Ensure 'str'
|
||
if isinstance(path, bytes):
|
||
path = path.decode(sys.getfilesystemencoding())
|
||
# if a trailing path.sep is given -- keep it
|
||
wants_trailing_slash = path.endswith(os.path.sep) or path.endswith('/')
|
||
path = os.path.abspath(path)
|
||
if wants_trailing_slash or os.path.isdir(path):
|
||
# Make sure directory names have a trailing slash.
|
||
# Otherwise relative URIs are resolved from the parent directory.
|
||
path += os.path.sep
|
||
wants_trailing_slash = True
|
||
path = pathname2url(path)
|
||
# on Windows pathname2url cuts off trailing slash
|
||
if wants_trailing_slash and not path.endswith('/'):
|
||
path += '/'
|
||
if path.startswith('///'):
|
||
# On Windows pathname2url(r'C:\foo') is apparently '///C:/foo'
|
||
# That enough slashes already.
|
||
return 'file:' + path
|
||
else:
|
||
return 'file://' + path
|
||
|
||
|
||
def url_is_absolute(url):
|
||
return bool(
|
||
(UNICODE_SCHEME_RE if isinstance(url, str) else BYTES_SCHEME_RE)
|
||
.match(url))
|
||
|
||
|
||
def get_url_attribute(element, attr_name, base_url, allow_relative=False):
|
||
"""Get the URI corresponding to the ``attr_name`` attribute.
|
||
|
||
Return ``None`` if:
|
||
|
||
* the attribute is empty or missing or,
|
||
* the value is a relative URI but the document has no base URI and
|
||
``allow_relative`` is ``False``.
|
||
|
||
Otherwise return an URI, absolute if possible.
|
||
|
||
"""
|
||
value = element.get(attr_name, '').strip()
|
||
if value:
|
||
return url_join(
|
||
base_url or '', value, allow_relative, '<%s %s="%s">',
|
||
(element.tag, attr_name, value))
|
||
|
||
|
||
def url_join(base_url, url, allow_relative, context, context_args):
|
||
"""Like urllib.urljoin, but warn if base_url is required but missing."""
|
||
if url_is_absolute(url):
|
||
return iri_to_uri(url)
|
||
elif base_url:
|
||
return iri_to_uri(urljoin(base_url, url))
|
||
elif allow_relative:
|
||
return iri_to_uri(url)
|
||
else:
|
||
LOGGER.error('Relative URI reference without a base URI: ' + context,
|
||
*context_args)
|
||
return None
|
||
|
||
|
||
def get_link_attribute(element, attr_name, base_url):
|
||
"""Return ('external', absolute_uri) or
|
||
('internal', unquoted_fragment_id) or None.
|
||
|
||
"""
|
||
attr_value = element.get(attr_name, '').strip()
|
||
if attr_value.startswith('#') and len(attr_value) > 1:
|
||
# Do not require a base_url when the value is just a fragment.
|
||
return ('url', ('internal', unquote(attr_value[1:])))
|
||
uri = get_url_attribute(element, attr_name, base_url, allow_relative=True)
|
||
if uri:
|
||
if base_url:
|
||
parsed = urlsplit(uri)
|
||
# Compare with fragments removed
|
||
if parsed[:-1] == urlsplit(base_url)[:-1]:
|
||
return ('url', ('internal', unquote(parsed.fragment)))
|
||
return ('url', ('external', uri))
|
||
|
||
|
||
def ensure_url(string):
|
||
"""Get a ``scheme://path`` URL from ``string``.
|
||
|
||
If ``string`` looks like an URL, return it unchanged. Otherwise assume a
|
||
filename and convert it to a ``file://`` URL.
|
||
|
||
"""
|
||
return string if url_is_absolute(string) else path2url(string)
|
||
|
||
|
||
def safe_decodebytes(data):
|
||
"""Decode base64, padding being optional.
|
||
|
||
"From a theoretical point of view, the padding character is not needed,
|
||
since the number of missing bytes can be calculated from the number
|
||
of Base64 digits."
|
||
|
||
https://en.wikipedia.org/wiki/Base64#Padding
|
||
|
||
:param data: Base64 data as an ASCII byte string
|
||
:returns: The decoded byte string.
|
||
|
||
"""
|
||
missing_padding = 4 - len(data) % 4
|
||
if missing_padding:
|
||
data += b'=' * missing_padding
|
||
return decodebytes(data)
|
||
|
||
|
||
HTTP_HEADERS = {
|
||
'User-Agent': VERSION_STRING,
|
||
'Accept': '*/*',
|
||
'Accept-Encoding': 'gzip, deflate',
|
||
}
|
||
|
||
|
||
def default_url_fetcher(url, timeout=10, ssl_context=None):
|
||
"""Fetch an external resource such as an image or stylesheet.
|
||
|
||
Another callable with the same signature can be given as the
|
||
:obj:`url_fetcher` argument to :class:`HTML` or :class:`CSS`.
|
||
(See :ref:`url-fetchers`.)
|
||
|
||
:type url: str
|
||
:param url: The URL of the resource to fetch.
|
||
:type timeout: int
|
||
:param timeout: The number of seconds before HTTP requests are dropped.
|
||
:type ssl_context: ssl.SSLContext
|
||
:param ssl_context: An SSL context used for HTTP requests.
|
||
:raises: An exception indicating failure, e.g. :obj:`ValueError` on
|
||
syntactically invalid URL.
|
||
:returns: A :obj:`dict` with the following keys:
|
||
|
||
* One of ``string`` (a :obj:`bytestring <bytes>`) or ``file_obj``
|
||
(a :term:`file object`).
|
||
* Optionally: ``mime_type``, a MIME type extracted e.g. from a
|
||
*Content-Type* header. If not provided, the type is guessed from the
|
||
file extension in the URL.
|
||
* Optionally: ``encoding``, a character encoding extracted e.g. from a
|
||
*charset* parameter in a *Content-Type* header
|
||
* Optionally: ``redirected_url``, the actual URL of the resource
|
||
if there were e.g. HTTP redirects.
|
||
* Optionally: ``filename``, the filename of the resource. Usually
|
||
derived from the *filename* parameter in a *Content-Disposition*
|
||
header
|
||
|
||
If a ``file_obj`` key is given, it is the caller’s responsibility
|
||
to call ``file_obj.close()``. The default function used internally to
|
||
fetch data in WeasyPrint tries to close the file object after
|
||
retreiving; but if this URL fetcher is used elsewhere, the file object
|
||
has to be closed manually.
|
||
|
||
"""
|
||
if UNICODE_SCHEME_RE.match(url):
|
||
# See https://bugs.python.org/issue34702
|
||
if url.startswith('file://'):
|
||
url = url.split('?')[0]
|
||
|
||
url = iri_to_uri(url)
|
||
response = urlopen(Request(url, headers=HTTP_HEADERS),
|
||
timeout=timeout, context=ssl_context)
|
||
response_info = response.info()
|
||
result = dict(redirected_url=response.geturl(),
|
||
mime_type=response_info.get_content_type(),
|
||
encoding=response_info.get_param('charset'),
|
||
filename=response_info.get_filename())
|
||
content_encoding = response_info.get('Content-Encoding')
|
||
if content_encoding == 'gzip':
|
||
if StreamingGzipFile is None:
|
||
result['string'] = gzip.GzipFile(
|
||
fileobj=io.BytesIO(response.read())).read()
|
||
response.close()
|
||
else:
|
||
result['file_obj'] = StreamingGzipFile(fileobj=response)
|
||
elif content_encoding == 'deflate':
|
||
data = response.read()
|
||
try:
|
||
result['string'] = zlib.decompress(data)
|
||
except zlib.error:
|
||
# Try without zlib header or checksum
|
||
result['string'] = zlib.decompress(data, -15)
|
||
else:
|
||
result['file_obj'] = response
|
||
return result
|
||
else:
|
||
raise ValueError('Not an absolute URI: %r' % url)
|
||
|
||
|
||
class URLFetchingError(IOError):
|
||
"""Some error happened when fetching an URL."""
|
||
|
||
|
||
@contextlib.contextmanager
|
||
def fetch(url_fetcher, url):
|
||
"""Call an url_fetcher, fill in optional data, and clean up."""
|
||
try:
|
||
result = url_fetcher(url)
|
||
except Exception as exc:
|
||
raise URLFetchingError('%s: %s' % (type(exc).__name__, str(exc)))
|
||
result.setdefault('redirected_url', url)
|
||
result.setdefault('mime_type', None)
|
||
if 'file_obj' in result:
|
||
try:
|
||
yield result
|
||
finally:
|
||
try:
|
||
result['file_obj'].close()
|
||
except Exception:
|
||
# May already be closed or something.
|
||
# This is just cleanup anyway: log but make it non-fatal.
|
||
LOGGER.warning('Error when closing stream for %s:\n%s',
|
||
url, traceback.format_exc())
|
||
else:
|
||
yield result
|