mirror of
https://github.com/Kozea/WeasyPrint.git
synced 2024-10-04 16:07:57 +03:00
297 lines
9.4 KiB
Python
297 lines
9.4 KiB
Python
# coding: utf8
|
||
"""
|
||
weasyprint.utils
|
||
----------------
|
||
|
||
Various utility functions and classes.
|
||
|
||
:copyright: Copyright 2011-2013 Simon Sapin and contributors, see AUTHORS.
|
||
:license: BSD, see LICENSE for details.
|
||
|
||
"""
|
||
|
||
from __future__ import division, unicode_literals
|
||
|
||
import re
|
||
import sys
|
||
import codecs
|
||
import os.path
|
||
import mimetypes
|
||
import contextlib
|
||
|
||
from . import VERSION_STRING
|
||
from .logger import LOGGER
|
||
from .compat import (
|
||
urljoin, urlsplit, quote, unquote, unquote_to_bytes, urlopen_contenttype,
|
||
Request, parse_email, pathname2url, unicode, base64_decode)
|
||
|
||
|
||
# Unlinke HTML, CSS and PNG, the SVG MIME type is not always builtin
|
||
# in some Python version and therefore not reliable.
|
||
if sys.version_info[0] >= 3:
|
||
mimetypes.add_type('image/svg+xml', '.svg')
|
||
else:
|
||
# Native strings required.
|
||
mimetypes.add_type(b'image/svg+xml', b'.svg')
|
||
|
||
|
||
# getfilesystemencoding() on Linux is sometimes stupid...
|
||
FILESYSTEM_ENCODING = sys.getfilesystemencoding() or 'utf-8'
|
||
try:
|
||
if codecs.lookup(FILESYSTEM_ENCODING).name == 'ascii':
|
||
FILESYSTEM_ENCODING = 'utf-8'
|
||
except LookupError:
|
||
FILESYSTEM_ENCODING = 'utf-8'
|
||
|
||
|
||
# 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.+-]+):')
|
||
|
||
|
||
def iri_to_uri(url):
|
||
"""Turn an IRI that can contain any Unicode character into an ASII-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`"""
|
||
path = os.path.abspath(path)
|
||
if 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
|
||
if isinstance(path, unicode):
|
||
path = path.encode(FILESYSTEM_ENCODING)
|
||
path = pathname2url(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, unicode) else BYTES_SCHEME_RE)
|
||
.match(url))
|
||
|
||
|
||
def element_base_url(element):
|
||
"""Return the URL associated with a lxml document.
|
||
|
||
This is the same as the HtmlElement.base_url property, but dont’t want
|
||
to require HtmlElement.
|
||
|
||
"""
|
||
return element.getroottree().docinfo.URL
|
||
|
||
|
||
def get_url_attribute(element, attr_name):
|
||
"""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.
|
||
|
||
Otherwise, return an absolute URI.
|
||
|
||
"""
|
||
value = element.get(attr_name, '').strip()
|
||
if value:
|
||
return url_join(element_base_url(element), value,
|
||
'<%s %s="%s"> at line %s', element.tag, attr_name,
|
||
value, element.sourceline)
|
||
|
||
|
||
def url_join(base_url, url, context, *args):
|
||
"""Like urllib.urljoin, but issue a warning and return None 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))
|
||
else:
|
||
LOGGER.warn('Relative URI reference without a base URI: ' + context,
|
||
*args)
|
||
return None
|
||
|
||
|
||
def get_link_attribute(element, attr_name):
|
||
"""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 'internal', unquote(attr_value[1:])
|
||
uri = get_url_attribute(element, attr_name)
|
||
if uri:
|
||
document_url = element_base_url(element)
|
||
if document_url:
|
||
parsed = urlsplit(uri)
|
||
# Compare with fragments removed
|
||
if parsed[:-1] == urlsplit(document_url)[:-1]:
|
||
return 'internal', unquote(parsed.fragment)
|
||
return '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_base64_decode(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 base64_decode(data)
|
||
|
||
|
||
def open_data_url(url):
|
||
"""Decode URLs with the 'data' scheme. urllib can handle them
|
||
in Python 2, but that is broken in Python 3.
|
||
|
||
Inspired from Python 2.7.2’s urllib.py.
|
||
|
||
"""
|
||
# syntax of data URLs:
|
||
# dataurl := "data:" [ mediatype ] [ ";base64" ] "," data
|
||
# mediatype := [ type "/" subtype ] *( ";" parameter )
|
||
# data := *urlchar
|
||
# parameter := attribute "=" value
|
||
try:
|
||
header, data = url.split(',', 1)
|
||
except ValueError:
|
||
raise IOError('bad data URL')
|
||
header = header[5:] # len('data:') == 5
|
||
if header:
|
||
semi = header.rfind(';')
|
||
if semi >= 0 and '=' not in header[semi:]:
|
||
content_type = header[:semi]
|
||
encoding = header[semi + 1:]
|
||
else:
|
||
content_type = header
|
||
encoding = ''
|
||
message = parse_email('Content-type: ' + content_type)
|
||
mime_type = message.get_content_type()
|
||
charset = message.get_content_charset()
|
||
else:
|
||
mime_type = 'text/plain'
|
||
charset = 'US-ASCII'
|
||
encoding = ''
|
||
|
||
data = unquote_to_bytes(data)
|
||
if encoding == 'base64':
|
||
data = safe_base64_decode(data)
|
||
|
||
return dict(string=data, mime_type=mime_type, encoding=charset,
|
||
redirected_url=url)
|
||
|
||
|
||
def default_url_fetcher(url):
|
||
"""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: Unicode string
|
||
:param url: The URL of the resource to fetch
|
||
:raises: any exception to indicate failure. Failures are logged
|
||
as warnings, with the string representation of the exception
|
||
in the message.
|
||
:returns: In case of success, a dict with the following keys:
|
||
|
||
* One of ``string`` (a byte string) or ``file_obj``
|
||
(a file-like object)
|
||
* Optionally: ``mime_type``, a MIME type extracted eg. 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 eg. from a
|
||
*charset* parameter in a *Content-Type* header
|
||
* Optionally: ``redirected_url``, the actual URL of the ressource
|
||
in case there were eg. HTTP redirects.
|
||
|
||
If a ``file_obj`` key is given, it is the caller’s responsability
|
||
to call ``file_obj.close()``.
|
||
|
||
"""
|
||
if url.lower().startswith('data:'):
|
||
return open_data_url(url)
|
||
elif UNICODE_SCHEME_RE.match(url):
|
||
url = iri_to_uri(url)
|
||
result, mime_type, charset = urlopen_contenttype(Request(
|
||
url, headers={'User-Agent': VERSION_STRING}))
|
||
return dict(file_obj=result, redirected_url=result.geturl(),
|
||
mime_type=mime_type, encoding=charset)
|
||
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:
|
||
name = type(exc).__name__
|
||
value = str(exc)
|
||
raise URLFetchingError('%s: %s' % (name, value) if value else name)
|
||
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: # pragma: no cover
|
||
# May already be closed or something.
|
||
# This is just cleanup anyway.
|
||
pass
|
||
else:
|
||
yield result
|