common.py 3.9 KB

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  1. # defusedxml
  2. #
  3. # Copyright (c) 2013 by Christian Heimes <christian@python.org>
  4. # Licensed to PSF under a Contributor Agreement.
  5. # See https://www.python.org/psf/license for licensing details.
  6. """Common constants, exceptions and helpe functions
  7. """
  8. import sys
  9. import xml.parsers.expat
  10. PY3 = sys.version_info[0] == 3
  11. # Fail early when pyexpat is not installed correctly
  12. if not hasattr(xml.parsers.expat, "ParserCreate"):
  13. raise ImportError("pyexpat") # pragma: no cover
  14. class DefusedXmlException(ValueError):
  15. """Base exception"""
  16. def __repr__(self):
  17. return str(self)
  18. class DTDForbidden(DefusedXmlException):
  19. """Document type definition is forbidden"""
  20. def __init__(self, name, sysid, pubid):
  21. super(DTDForbidden, self).__init__()
  22. self.name = name
  23. self.sysid = sysid
  24. self.pubid = pubid
  25. def __str__(self):
  26. tpl = "DTDForbidden(name='{}', system_id={!r}, public_id={!r})"
  27. return tpl.format(self.name, self.sysid, self.pubid)
  28. class EntitiesForbidden(DefusedXmlException):
  29. """Entity definition is forbidden"""
  30. def __init__(self, name, value, base, sysid, pubid, notation_name):
  31. super(EntitiesForbidden, self).__init__()
  32. self.name = name
  33. self.value = value
  34. self.base = base
  35. self.sysid = sysid
  36. self.pubid = pubid
  37. self.notation_name = notation_name
  38. def __str__(self):
  39. tpl = "EntitiesForbidden(name='{}', system_id={!r}, public_id={!r})"
  40. return tpl.format(self.name, self.sysid, self.pubid)
  41. class ExternalReferenceForbidden(DefusedXmlException):
  42. """Resolving an external reference is forbidden"""
  43. def __init__(self, context, base, sysid, pubid):
  44. super(ExternalReferenceForbidden, self).__init__()
  45. self.context = context
  46. self.base = base
  47. self.sysid = sysid
  48. self.pubid = pubid
  49. def __str__(self):
  50. tpl = "ExternalReferenceForbidden(system_id='{}', public_id={})"
  51. return tpl.format(self.sysid, self.pubid)
  52. class NotSupportedError(DefusedXmlException):
  53. """The operation is not supported"""
  54. def _apply_defusing(defused_mod):
  55. assert defused_mod is sys.modules[defused_mod.__name__]
  56. stdlib_name = defused_mod.__origin__
  57. __import__(stdlib_name, {}, {}, ["*"])
  58. stdlib_mod = sys.modules[stdlib_name]
  59. stdlib_names = set(dir(stdlib_mod))
  60. for name, obj in vars(defused_mod).items():
  61. if name.startswith("_") or name not in stdlib_names:
  62. continue
  63. setattr(stdlib_mod, name, obj)
  64. return stdlib_mod
  65. def _generate_etree_functions(DefusedXMLParser, _TreeBuilder, _parse, _iterparse):
  66. """Factory for functions needed by etree, dependent on whether
  67. cElementTree or ElementTree is used."""
  68. def parse(source, parser=None, forbid_dtd=False, forbid_entities=True, forbid_external=True):
  69. if parser is None:
  70. parser = DefusedXMLParser(
  71. target=_TreeBuilder(),
  72. forbid_dtd=forbid_dtd,
  73. forbid_entities=forbid_entities,
  74. forbid_external=forbid_external,
  75. )
  76. return _parse(source, parser)
  77. def iterparse(
  78. source,
  79. events=None,
  80. parser=None,
  81. forbid_dtd=False,
  82. forbid_entities=True,
  83. forbid_external=True,
  84. ):
  85. if parser is None:
  86. parser = DefusedXMLParser(
  87. target=_TreeBuilder(),
  88. forbid_dtd=forbid_dtd,
  89. forbid_entities=forbid_entities,
  90. forbid_external=forbid_external,
  91. )
  92. return _iterparse(source, events, parser)
  93. def fromstring(text, forbid_dtd=False, forbid_entities=True, forbid_external=True):
  94. parser = DefusedXMLParser(
  95. target=_TreeBuilder(),
  96. forbid_dtd=forbid_dtd,
  97. forbid_entities=forbid_entities,
  98. forbid_external=forbid_external,
  99. )
  100. parser.feed(text)
  101. return parser.close()
  102. return parse, iterparse, fromstring