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[3.7] bpo-44394: Update libexpat copy to 2.4.1 (pythonGH-26945)
Update the vendored copy of libexpat to 2.4.1 (from 2.2.8) to get the fix for the CVE-2013-0340 "Billion Laughs" vulnerability. This copy is most used on Windows and macOS. Co-authored-by: Łukasz Langa <[email protected]>. (cherry picked from commit 3fc5d84) Co-authored-by: Victor Stinner <[email protected]>
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‎Doc/library/xml.rst

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@@ -60,22 +60,26 @@ circumvent firewalls.
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The following table gives an overview of the known attacks and whether
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the various modules are vulnerable to them.
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========================= ============== =============== ============== ============== ==============
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kind sax etree minidom pulldom xmlrpc
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========================= ============== =============== ============== ============== ==============
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billion laughs **Vulnerable** **Vulnerable** **Vulnerable** **Vulnerable** **Vulnerable**
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quadratic blowup **Vulnerable** **Vulnerable** **Vulnerable** **Vulnerable** **Vulnerable**
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external entity expansion Safe (4) Safe (1) Safe (2) Safe (4) Safe (3)
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`DTD`_ retrieval Safe (4) Safe Safe Safe (4) Safe
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decompression bomb Safe Safe Safe Safe **Vulnerable**
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========================= ============== =============== ============== ============== ==============
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1. :mod:`xml.etree.ElementTree` doesn't expand external entities and raises a
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========================= ================== ================== ================== ================== ==================
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kind sax etree minidom pulldom xmlrpc
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========================= ================== ================== ================== ================== ==================
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billion laughs **Vulnerable** (1) **Vulnerable** (1) **Vulnerable** (1) **Vulnerable** (1) **Vulnerable** (1)
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quadratic blowup **Vulnerable** (1) **Vulnerable** (1) **Vulnerable** (1) **Vulnerable** (1) **Vulnerable** (1)
68+
external entity expansion Safe (5) Safe (2) Safe (3) Safe (5) Safe (4)
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`DTD`_ retrieval Safe (5) Safe Safe Safe (5) Safe
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decompression bomb Safe Safe Safe Safe **Vulnerable**
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========================= ================== ================== ================== ================== ==================
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1. Expat 2.4.1 and newer is not vulnerable to the "billion laughs" and
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"quadratic blowup" vulnerabilities. Items still listed as vulnerable due to
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potential reliance on system-provided libraries. Check
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:data:`pyexpat.EXPAT_VERSION`.
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2. :mod:`xml.etree.ElementTree` doesn't expand external entities and raises a
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:exc:`ParserError` when an entity occurs.
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2. :mod:`xml.dom.minidom` doesn't expand external entities and simply returns
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3. :mod:`xml.dom.minidom` doesn't expand external entities and simply returns
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the unexpanded entity verbatim.
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3. :mod:`xmlrpclib` doesn't expand external entities and omits them.
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4. Since Python 3.7.1, external general entities are no longer processed by
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4. :mod:`xmlrpclib` doesn't expand external entities and omits them.
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5. Since Python 3.7.1, external general entities are no longer processed by
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default.
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‎Misc/NEWS.d/next/Security/2021-06-29-02-45-53.bpo-44394.A220N1.rst

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Update the vendored copy of libexpat to 2.4.1 (from 2.2.8) to get the fix
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for the CVE-2013-0340 "Billion Laughs" vulnerability. This copy is most used
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on Windows and macOS.

‎Modules/expat/COPYING

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@@ -1,5 +1,5 @@
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Copyright (c) 1998-2000 Thai Open Source Software Center Ltd and Clark Cooper
2-
Copyright (c) 2001-2017 Expat maintainers
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Copyright (c) 2001-2019 Expat maintainers
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Permission is hereby granted, free of charge, to any person obtaining
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a copy of this software and associated documentation files (the

‎Modules/expat/ascii.h

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@@ -6,8 +6,11 @@
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\___/_/\_\ .__/ \__,_|\__|
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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
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Copyright (c) 2000-2017 Expat development team
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Copyright (c) 1999-2000 Thai Open Source Software Center Ltd
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Copyright (c) 2000 Clark Cooper <[email protected]>
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Copyright (c) 2002 Fred L. Drake, Jr. <[email protected]>
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Copyright (c) 2007 Karl Waclawek <[email protected]>
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Copyright (c) 2017 Sebastian Pipping <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining

‎Modules/expat/asciitab.h

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@@ -7,7 +7,9 @@
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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
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Copyright (c) 2000-2017 Expat development team
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Copyright (c) 2000 Clark Cooper <[email protected]>
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Copyright (c) 2002 Fred L. Drake, Jr. <[email protected]>
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Copyright (c) 2017 Sebastian Pipping <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining

‎Modules/expat/expat.h

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@@ -7,7 +7,14 @@
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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
10-
Copyright (c) 2000-2017 Expat development team
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Copyright (c) 2000 Clark Cooper <[email protected]>
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Copyright (c) 2000-2005 Fred L. Drake, Jr. <[email protected]>
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Copyright (c) 2001-2002 Greg Stein <[email protected]>
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Copyright (c) 2002-2016 Karl Waclawek <[email protected]>
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Copyright (c) 2016-2021 Sebastian Pipping <[email protected]>
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Copyright (c) 2016 Cristian Rodríguez <[email protected]>
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Copyright (c) 2016 Thomas Beutlich <[email protected]>
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Copyright (c) 2017 Rhodri James <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining
@@ -115,7 +122,11 @@ enum XML_Error {
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XML_ERROR_RESERVED_PREFIX_XMLNS,
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XML_ERROR_RESERVED_NAMESPACE_URI,
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/* Added in 2.2.1. */
118-
XML_ERROR_INVALID_ARGUMENT
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XML_ERROR_INVALID_ARGUMENT,
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/* Added in 2.3.0. */
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XML_ERROR_NO_BUFFER,
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/* Added in 2.4.0. */
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XML_ERROR_AMPLIFICATION_LIMIT_BREACH
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};
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enum XML_Content_Type {
@@ -318,7 +329,7 @@ typedef void(XMLCALL *XML_EndDoctypeDeclHandler)(void *userData);
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319330
For internal entities (<!ENTITY foo "bar">), value will
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be non-NULL and systemId, publicID, and notationName will be NULL.
321-
The value string is NOT nul-terminated; the length is provided in
332+
The value string is NOT null-terminated; the length is provided in
322333
the value_length argument. Since it is legal to have zero-length
323334
values, do not use this argument to test for internal entities.
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@@ -513,7 +524,7 @@ typedef struct {
513524
Otherwise it must return XML_STATUS_ERROR.
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515526
If info does not describe a suitable encoding, then the parser will
516-
return an XML_UNKNOWN_ENCODING error.
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return an XML_ERROR_UNKNOWN_ENCODING error.
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*/
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typedef int(XMLCALL *XML_UnknownEncodingHandler)(void *encodingHandlerData,
519530
const XML_Char *name,
@@ -707,7 +718,7 @@ XML_GetBase(XML_Parser parser);
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/* Returns the number of the attribute/value pairs passed in last call
708719
to the XML_StartElementHandler that were specified in the start-tag
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rather than defaulted. Each attribute/value pair counts as 2; thus
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this correspondds to an index into the atts array passed to the
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this corresponds to an index into the atts array passed to the
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XML_StartElementHandler. Returns -1 if parser == NULL.
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*/
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XMLPARSEAPI(int)
@@ -716,7 +727,7 @@ XML_GetSpecifiedAttributeCount(XML_Parser parser);
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/* Returns the index of the ID attribute passed in the last call to
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XML_StartElementHandler, or -1 if there is no ID attribute or
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parser == NULL. Each attribute/value pair counts as 2; thus this
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correspondds to an index into the atts array passed to the
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corresponds to an index into the atts array passed to the
720731
XML_StartElementHandler.
721732
*/
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XMLPARSEAPI(int)
@@ -997,7 +1008,10 @@ enum XML_FeatureEnum {
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XML_FEATURE_SIZEOF_XML_LCHAR,
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XML_FEATURE_NS,
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XML_FEATURE_LARGE_SIZE,
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XML_FEATURE_ATTR_INFO
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XML_FEATURE_ATTR_INFO,
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/* Added in Expat 2.4.0. */
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XML_FEATURE_BILLION_LAUGHS_ATTACK_PROTECTION_MAXIMUM_AMPLIFICATION_DEFAULT,
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XML_FEATURE_BILLION_LAUGHS_ATTACK_PROTECTION_ACTIVATION_THRESHOLD_DEFAULT
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/* Additional features must be added to the end of this enum. */
10021016
};
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@@ -1010,12 +1024,24 @@ typedef struct {
10101024
XMLPARSEAPI(const XML_Feature *)
10111025
XML_GetFeatureList(void);
10121026

1027+
#ifdef XML_DTD
1028+
/* Added in Expat 2.4.0. */
1029+
XMLPARSEAPI(XML_Bool)
1030+
XML_SetBillionLaughsAttackProtectionMaximumAmplification(
1031+
XML_Parser parser, float maximumAmplificationFactor);
1032+
1033+
/* Added in Expat 2.4.0. */
1034+
XMLPARSEAPI(XML_Bool)
1035+
XML_SetBillionLaughsAttackProtectionActivationThreshold(
1036+
XML_Parser parser, unsigned long long activationThresholdBytes);
1037+
#endif
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/* Expat follows the semantic versioning convention.
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See http://semver.org.
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*/
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#define XML_MAJOR_VERSION 2
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#define XML_MINOR_VERSION 2
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#define XML_MICRO_VERSION 8
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#define XML_MINOR_VERSION 4
1044+
#define XML_MICRO_VERSION 1
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#ifdef __cplusplus
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}

‎Modules/expat/expat_external.h

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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
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Copyright (c) 2000-2017 Expat development team
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Copyright (c) 2000 Clark Cooper <[email protected]>
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Copyright (c) 2000-2004 Fred L. Drake, Jr. <[email protected]>
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Copyright (c) 2001-2002 Greg Stein <[email protected]>
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Copyright (c) 2002-2006 Karl Waclawek <[email protected]>
14+
Copyright (c) 2016 Cristian Rodríguez <[email protected]>
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Copyright (c) 2016-2019 Sebastian Pipping <[email protected]>
16+
Copyright (c) 2017 Rhodri James <[email protected]>
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Copyright (c) 2018 Yury Gribov <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining

‎Modules/expat/iasciitab.h

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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
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Copyright (c) 2000-2017 Expat development team
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Copyright (c) 2000 Clark Cooper <[email protected]>
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Copyright (c) 2002 Fred L. Drake, Jr. <[email protected]>
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Copyright (c) 2017 Sebastian Pipping <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining

‎Modules/expat/internal.h

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\___/_/\_\ .__/ \__,_|\__|
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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
29-
Copyright (c) 2000-2017 Expat development team
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Copyright (c) 2002-2003 Fred L. Drake, Jr. <[email protected]>
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Copyright (c) 2002-2006 Karl Waclawek <[email protected]>
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Copyright (c) 2003 Greg Stein <[email protected]>
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Copyright (c) 2016-2021 Sebastian Pipping <[email protected]>
32+
Copyright (c) 2018 Yury Gribov <[email protected]>
33+
Copyright (c) 2019 David Loffredo <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining
@@ -101,22 +105,58 @@
101105
# endif
102106
#endif
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108+
#include <limits.h> // ULONG_MAX
109+
110+
#if defined(_WIN32) && ! defined(__USE_MINGW_ANSI_STDIO)
111+
# define EXPAT_FMT_ULL(midpart) "%" midpart "I64u"
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# if defined(_WIN64) // Note: modifiers "td" and "zu" do not work for MinGW
113+
# define EXPAT_FMT_PTRDIFF_T(midpart) "%" midpart "I64d"
114+
# define EXPAT_FMT_SIZE_T(midpart) "%" midpart "I64u"
115+
# else
116+
# define EXPAT_FMT_PTRDIFF_T(midpart) "%" midpart "d"
117+
# define EXPAT_FMT_SIZE_T(midpart) "%" midpart "u"
118+
# endif
119+
#else
120+
# define EXPAT_FMT_ULL(midpart) "%" midpart "llu"
121+
# if ! defined(ULONG_MAX)
122+
# error Compiler did not define ULONG_MAX for us
123+
# elif ULONG_MAX == 18446744073709551615u // 2^64-1
124+
# define EXPAT_FMT_PTRDIFF_T(midpart) "%" midpart "ld"
125+
# define EXPAT_FMT_SIZE_T(midpart) "%" midpart "lu"
126+
# else
127+
# define EXPAT_FMT_PTRDIFF_T(midpart) "%" midpart "d"
128+
# define EXPAT_FMT_SIZE_T(midpart) "%" midpart "u"
129+
# endif
130+
#endif
131+
104132
#ifndef UNUSED_P
105133
# define UNUSED_P(p) (void)p
106134
#endif
107135

136+
/* NOTE BEGIN If you ever patch these defaults to greater values
137+
for non-attack XML payload in your environment,
138+
please file a bug report with libexpat. Thank you!
139+
*/
140+
#define EXPAT_BILLION_LAUGHS_ATTACK_PROTECTION_MAXIMUM_AMPLIFICATION_DEFAULT \
141+
100.0f
142+
#define EXPAT_BILLION_LAUGHS_ATTACK_PROTECTION_ACTIVATION_THRESHOLD_DEFAULT \
143+
8388608 // 8 MiB, 2^23
144+
/* NOTE END */
145+
146+
#include "expat.h" // so we can use type XML_Parser below
147+
108148
#ifdef __cplusplus
109149
extern "C" {
110150
#endif
111151

112-
#ifdef XML_ENABLE_VISIBILITY
113-
# if XML_ENABLE_VISIBILITY
114-
__attribute__((visibility("default")))
115-
# endif
152+
void _INTERNAL_trim_to_complete_utf8_characters(const char *from,
153+
const char **fromLimRef);
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155+
#if defined(XML_DTD)
156+
unsigned long long testingAccountingGetCountBytesDirect(XML_Parser parser);
157+
unsigned long long testingAccountingGetCountBytesIndirect(XML_Parser parser);
158+
const char *unsignedCharToPrintable(unsigned char c);
116159
#endif
117-
void
118-
_INTERNAL_trim_to_complete_utf8_characters(const char *from,
119-
const char **fromLimRef);
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#ifdef __cplusplus
122162
}

‎Modules/expat/latin1tab.h

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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
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Copyright (c) 2000-2017 Expat development team
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Copyright (c) 2000 Clark Cooper <[email protected]>
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Copyright (c) 2002 Fred L. Drake, Jr. <[email protected]>
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Copyright (c) 2017 Sebastian Pipping <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining

‎Modules/expat/nametab.h

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\___/_/\_\ .__/ \__,_|\__|
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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
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Copyright (c) 2000-2017 Expat development team
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Copyright (c) 2000 Clark Cooper <[email protected]>
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Copyright (c) 2017 Sebastian Pipping <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining

‎Modules/expat/siphash.h

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* --------------------------------------------------------------------------
1212
* HISTORY:
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*
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* 2020-10-03 (Sebastian Pipping)
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* - Drop support for Visual Studio 9.0/2008 and earlier
16+
*
1417
* 2019-08-03 (Sebastian Pipping)
1518
* - Mark part of sip24_valid as to be excluded from clang-format
1619
* - Re-format code using clang-format 9
@@ -96,15 +99,7 @@
9699
#define SIPHASH_H
97100

98101
#include <stddef.h> /* size_t */
99-
100-
#if defined(_WIN32) && defined(_MSC_VER) && (_MSC_VER < 1600)
101-
/* For vs2003/7.1 up to vs2008/9.0; _MSC_VER 1600 is vs2010/10.0 */
102-
typedef unsigned __int8 uint8_t;
103-
typedef unsigned __int32 uint32_t;
104-
typedef unsigned __int64 uint64_t;
105-
#else
106-
# include <stdint.h> /* uint64_t uint32_t uint8_t */
107-
#endif
102+
#include <stdint.h> /* uint64_t uint32_t uint8_t */
108103

109104
/*
110105
* Workaround to not require a C++11 compiler for using ULL suffix

‎Modules/expat/utf8tab.h

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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
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Copyright (c) 2000-2017 Expat development team
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Copyright (c) 2000 Clark Cooper <[email protected]>
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Copyright (c) 2002 Fred L. Drake, Jr. <[email protected]>
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Copyright (c) 2017 Sebastian Pipping <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining

‎Modules/expat/winconfig.h

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\___/_/\_\ .__/ \__,_|\__|
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|_| XML parser
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Copyright (c) 1997-2000 Thai Open Source Software Center Ltd
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Copyright (c) 2000-2017 Expat development team
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Copyright (c) 2000 Clark Cooper <[email protected]>
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Copyright (c) 2002 Greg Stein <[email protected]>
11+
Copyright (c) 2005 Karl Waclawek <[email protected]>
12+
Copyright (c) 2017-2021 Sebastian Pipping <[email protected]>
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Licensed under the MIT license:
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Permission is hereby granted, free of charge, to any person obtaining
@@ -40,17 +42,4 @@
4042
#include <memory.h>
4143
#include <string.h>
4244

43-
#if defined(HAVE_EXPAT_CONFIG_H) /* e.g. MinGW */
44-
# include <expat_config.h>
45-
#else /* !defined(HAVE_EXPAT_CONFIG_H) */
46-
47-
# define XML_NS 1
48-
# define XML_DTD 1
49-
# define XML_CONTEXT_BYTES 1024
50-
51-
/* we will assume all Windows platforms are little endian */
52-
# define BYTEORDER 1234
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#endif /* !defined(HAVE_EXPAT_CONFIG_H) */
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5645
#endif /* ndef WINCONFIG_H */

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