python/py313/Lib/site-packages/defusedxml/common.py

# defusedxml
#
# Copyright (c) 2013 by Christian Heimes <christian@python.org>
# Licensed to PSF under a Contributor Agreement.
# See https://www.python.org/psf/license for licensing details.
"""Common constants, exceptions and helpe functions
"""
import sys
import xml.parsers.expat

PY3 = sys.version_info[0] == 3

# Fail early when pyexpat is not installed correctly
if not hasattr(xml.parsers.expat, "ParserCreate"):
    raise ImportError("pyexpat")  # pragma: no cover


class DefusedXmlException(ValueError):
    """Base exception"""

    def __repr__(self):
        return str(self)


class DTDForbidden(DefusedXmlException):
    """Document type definition is forbidden"""

    def __init__(self, name, sysid, pubid):
        super(DTDForbidden, self).__init__()
        self.name = name
        self.sysid = sysid
        self.pubid = pubid

    def __str__(self):
        tpl = "DTDForbidden(name='{}', system_id={!r}, public_id={!r})"
        return tpl.format(self.name, self.sysid, self.pubid)


class EntitiesForbidden(DefusedXmlException):
    """Entity definition is forbidden"""

    def __init__(self, name, value, base, sysid, pubid, notation_name):
        super(EntitiesForbidden, self).__init__()
        self.name = name
        self.value = value
        self.base = base
        self.sysid = sysid
        self.pubid = pubid
        self.notation_name = notation_name

    def __str__(self):
        tpl = "EntitiesForbidden(name='{}', system_id={!r}, public_id={!r})"
        return tpl.format(self.name, self.sysid, self.pubid)


class ExternalReferenceForbidden(DefusedXmlException):
    """Resolving an external reference is forbidden"""

    def __init__(self, context, base, sysid, pubid):
        super(ExternalReferenceForbidden, self).__init__()
        self.context = context
        self.base = base
        self.sysid = sysid
        self.pubid = pubid

    def __str__(self):
        tpl = "ExternalReferenceForbidden(system_id='{}', public_id={})"
        return tpl.format(self.sysid, self.pubid)


class NotSupportedError(DefusedXmlException):
    """The operation is not supported"""


def _apply_defusing(defused_mod):
    assert defused_mod is sys.modules[defused_mod.__name__]
    stdlib_name = defused_mod.__origin__
    __import__(stdlib_name, {}, {}, ["*"])
    stdlib_mod = sys.modules[stdlib_name]
    stdlib_names = set(dir(stdlib_mod))
    for name, obj in vars(defused_mod).items():
        if name.startswith("_") or name not in stdlib_names:
            continue
        setattr(stdlib_mod, name, obj)
    return stdlib_mod


def _generate_etree_functions(DefusedXMLParser, _TreeBuilder, _parse, _iterparse):
    """Factory for functions needed by etree, dependent on whether
    cElementTree or ElementTree is used."""

    def parse(source, parser=None, forbid_dtd=False, forbid_entities=True, forbid_external=True):
        if parser is None:
            parser = DefusedXMLParser(
                target=_TreeBuilder(),
                forbid_dtd=forbid_dtd,
                forbid_entities=forbid_entities,
                forbid_external=forbid_external,
            )
        return _parse(source, parser)

    def iterparse(
        source,
        events=None,
        parser=None,
        forbid_dtd=False,
        forbid_entities=True,
        forbid_external=True,
    ):
        if parser is None:
            parser = DefusedXMLParser(
                target=_TreeBuilder(),
                forbid_dtd=forbid_dtd,
                forbid_entities=forbid_entities,
                forbid_external=forbid_external,
            )
        return _iterparse(source, events, parser)

    def fromstring(text, forbid_dtd=False, forbid_entities=True, forbid_external=True):
        parser = DefusedXMLParser(
            target=_TreeBuilder(),
            forbid_dtd=forbid_dtd,
            forbid_entities=forbid_entities,
            forbid_external=forbid_external,
        )
        parser.feed(text)
        return parser.close()

    return parse, iterparse, fromstring