bpo-29591: Upgrade Modules/expat to libexpat 2.2 (#2164)

* bpo-29591: Upgrade Modules/expat to libexpat 2.2

* bpo-29591: Restore Python changes on expat

* bpo-29591: Remove expat config of unsupported platforms

Remove the configuration (Modules/expat/*config.h) of unsupported
platforms:

* Amiga
* MacOS Classic on PPC32
* Open Watcom

* bpo-29591: Remove useless XML_HAS_SET_HASH_SALT

The XML_HAS_SET_HASH_SALT define of Modules/expat/expat.h became
useless since our local expat copy was upgrade to expat 2.1 (it's now
expat 2.2.0).

14 files changed, 527 insertions, 476 deletions

diff --git a/Misc/NEWS b/Misc/NEWS
index 7452b25bcf..985d6c0041 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -362,6 +362,10 @@ Extension Modules
 Library
 -------
 
+- [Security] bpo-29591: Update expat copy from 2.1.1 to 2.2.0 to get fixes
+  of CVE-2016-0718 and CVE-2016-4472. See
+  https://sourceforge.net/p/expat/bugs/537/ for more information.
+
 - bpo-24744: pkgutil.walk_packages function now raises ValueError if *path*
   is a string. Patch by Sanyam Khurana.
 
diff --git a/Modules/expat/COPYING b/Modules/expat/COPYING
index dcb4506429..092c83baee 100644
--- a/Modules/expat/COPYING
+++ b/Modules/expat/COPYING
@@ -1,6 +1,5 @@
-Copyright (c) 1998, 1999, 2000 Thai Open Source Software Center Ltd
-                               and Clark Cooper
-Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006 Expat maintainers.
+Copyright (c) 1998-2000 Thai Open Source Software Center Ltd and Clark Cooper
+Copyright (c) 2001-2016 Expat maintainers
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
diff --git a/Modules/expat/amigaconfig.h b/Modules/expat/amigaconfig.h
deleted file mode 100644
index 86c6115040..0000000000
--- a/Modules/expat/amigaconfig.h
+++ /dev/null
@@ -1,32 +0,0 @@
-#ifndef AMIGACONFIG_H
-#define AMIGACONFIG_H
-
-/* 1234 = LIL_ENDIAN, 4321 = BIGENDIAN */
-#define BYTEORDER 4321
-
-/* Define to 1 if you have the `bcopy' function. */
-#define HAVE_BCOPY 1
-
-/* Define to 1 if you have the <check.h> header file. */
-#undef HAVE_CHECK_H
-
-/* Define to 1 if you have the `memmove' function. */
-#define HAVE_MEMMOVE 1
-
-/* Define to 1 if you have the <unistd.h> header file. */
-#define HAVE_UNISTD_H 1
-
-/* whether byteorder is bigendian */
-#define WORDS_BIGENDIAN
-
-/* Define to specify how much context to retain around the current parse
-   point. */
-#define XML_CONTEXT_BYTES 1024
-
-/* Define to make parameter entity parsing functionality available. */
-#define XML_DTD
-
-/* Define to make XML Namespaces functionality available. */
-#define XML_NS
-
-#endif  /* AMIGACONFIG_H */
diff --git a/Modules/expat/expat.h b/Modules/expat/expat.h
index e8eefddc6d..086e24b39c 100644
--- a/Modules/expat/expat.h
+++ b/Modules/expat/expat.h
@@ -342,7 +342,7 @@ XML_SetEntityDeclHandler(XML_Parser parser,
                          XML_EntityDeclHandler handler);
 
 /* OBSOLETE -- OBSOLETE -- OBSOLETE
-   This handler has been superceded by the EntityDeclHandler above.
+   This handler has been superseded by the EntityDeclHandler above.
    It is provided here for backward compatibility.
 
    This is called for a declaration of an unparsed (NDATA) entity.
@@ -915,8 +915,6 @@ XMLPARSEAPI(int)
 XML_SetHashSalt(XML_Parser parser,
                 unsigned long hash_salt);
 
-#define XML_HAS_SET_HASH_SALT  /* Python Only: Defined for pyexpat.c. */
-
 /* If XML_Parse or XML_ParseBuffer have returned XML_STATUS_ERROR, then
    XML_GetErrorCode returns information about the error.
 */
@@ -975,9 +973,12 @@ XML_FreeContentModel(XML_Parser parser, XML_Content *model);
 
 /* Exposing the memory handling functions used in Expat */
 XMLPARSEAPI(void *)
+XML_ATTR_MALLOC
+XML_ATTR_ALLOC_SIZE(2)
 XML_MemMalloc(XML_Parser parser, size_t size);
 
 XMLPARSEAPI(void *)
+XML_ATTR_ALLOC_SIZE(3)
 XML_MemRealloc(XML_Parser parser, void *ptr, size_t size);
 
 XMLPARSEAPI(void)
@@ -1033,14 +1034,12 @@ XMLPARSEAPI(const XML_Feature *)
 XML_GetFeatureList(void);
 
 
-/* Expat follows the GNU/Linux convention of odd number minor version for
-   beta/development releases and even number minor version for stable
-   releases. Micro is bumped with each release, and set to 0 with each
-   change to major or minor version.
+/* Expat follows the semantic versioning convention.
+   See http://semver.org.
 */
 #define XML_MAJOR_VERSION 2
-#define XML_MINOR_VERSION 1
-#define XML_MICRO_VERSION 1
+#define XML_MINOR_VERSION 2
+#define XML_MICRO_VERSION 0
 
 #ifdef __cplusplus
 }
diff --git a/Modules/expat/expat_external.h b/Modules/expat/expat_external.h
index f337e1c562..4860c5777a 100644
--- a/Modules/expat/expat_external.h
+++ b/Modules/expat/expat_external.h
@@ -69,12 +69,26 @@
 #endif
 #endif  /* not defined XML_STATIC */
 
+#if !defined(XMLIMPORT) && defined(__GNUC__) && (__GNUC__ >= 4)
+#define XMLIMPORT __attribute__ ((visibility ("default")))
+#endif
 
 /* If we didn't define it above, define it away: */
 #ifndef XMLIMPORT
 #define XMLIMPORT
 #endif
 
+#if defined(__GNUC__) && (__GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96))
+#define XML_ATTR_MALLOC __attribute__((__malloc__))
+#else
+#define XML_ATTR_MALLOC
+#endif
+
+#if defined(__GNUC__) && ((__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))
+#define XML_ATTR_ALLOC_SIZE(x)  __attribute__((__alloc_size__(x)))
+#else
+#define XML_ATTR_ALLOC_SIZE(x)
+#endif
 
 #define XMLPARSEAPI(type) XMLIMPORT type XMLCALL
 
diff --git a/Modules/expat/internal.h b/Modules/expat/internal.h
index dd5454831d..94cb98e15c 100644
--- a/Modules/expat/internal.h
+++ b/Modules/expat/internal.h
@@ -71,3 +71,25 @@
 #define inline
 #endif
 #endif
+
+#ifndef UNUSED_P
+# ifdef __GNUC__
+#  define UNUSED_P(p) UNUSED_ ## p __attribute__((__unused__))
+# else
+#  define UNUSED_P(p) UNUSED_ ## p
+# endif
+#endif
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+void
+align_limit_to_full_utf8_characters(const char * from, const char ** fromLimRef);
+
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/Modules/expat/macconfig.h b/Modules/expat/macconfig.h
deleted file mode 100644
index 2725caaf54..0000000000
--- a/Modules/expat/macconfig.h
+++ /dev/null
@@ -1,53 +0,0 @@
-/*================================================================
-** Copyright 2000, Clark Cooper
-** All rights reserved.
-**
-** This is free software. You are permitted to copy, distribute, or modify
-** it under the terms of the MIT/X license (contained in the COPYING file
-** with this distribution.)
-**
-*/
-
-#ifndef MACCONFIG_H
-#define MACCONFIG_H
-
-
-/* 1234 = LIL_ENDIAN, 4321 = BIGENDIAN */
-#define BYTEORDER  4321
-
-/* Define to 1 if you have the `bcopy' function. */
-#undef HAVE_BCOPY
-
-/* Define to 1 if you have the `memmove' function. */
-#define HAVE_MEMMOVE
-
-/* Define to 1 if you have a working `mmap' system call. */
-#undef HAVE_MMAP
-
-/* Define to 1 if you have the <unistd.h> header file. */
-#undef HAVE_UNISTD_H
-
-/* whether byteorder is bigendian */
-#define WORDS_BIGENDIAN
-
-/* Define to specify how much context to retain around the current parse
-   point. */
-#undef XML_CONTEXT_BYTES
-
-/* Define to make parameter entity parsing functionality available. */
-#define XML_DTD
-
-/* Define to make XML Namespaces functionality available. */
-#define XML_NS
-
-/* Define to empty if `const' does not conform to ANSI C. */
-#undef const
-
-/* Define to `long' if <sys/types.h> does not define. */
-#define off_t  long
-
-/* Define to `unsigned' if <sys/types.h> does not define. */
-#undef size_t
-
-
-#endif /* ifndef MACCONFIG_H */
diff --git a/Modules/expat/watcomconfig.h b/Modules/expat/watcomconfig.h
deleted file mode 100644
index 2f05e3f227..0000000000
--- a/Modules/expat/watcomconfig.h
+++ /dev/null
@@ -1,47 +0,0 @@
-/* expat_config.h for use with Open Watcom 1.5 and above.  */
-
-#ifndef WATCOMCONFIG_H
-#define WATCOMCONFIG_H
-
-#ifdef __NT__
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
-#undef WIN32_LEAN_AND_MEAN
-#endif
-
-/* 1234 = LIL_ENDIAN, 4321 = BIGENDIAN */
-#define BYTEORDER 1234
-
-/* Define to 1 if you have the `memmove' function. */
-#define HAVE_MEMMOVE 1
-
-/* Define to 1 if you have the <unistd.h> header file. */
-#define HAVE_UNISTD_H 1
-
-/* Define to the address where bug reports for this package should be sent. */
-#define PACKAGE_BUGREPORT "expat-bugs@mail.libexpat.org"
-
-/* Define to the full name of this package. */
-#define PACKAGE_NAME "expat"
-
-/* Define to the full name and version of this package. */
-#define PACKAGE_STRING "expat 2.0.0"
-
-/* Define to the one symbol short name of this package. */
-#undef PACKAGE_TARNAME
-
-/* Define to the version of this package. */
-#define PACKAGE_VERSION "2.0.0"
-
-/* Define to specify how much context to retain around the current parse
-   point. */
-#define XML_CONTEXT_BYTES 1024
-
-/* Define to make parameter entity parsing functionality available. */
-#define XML_DTD 1
-
-/* Define to make XML Namespaces functionality available. */
-#define XML_NS 1
-
-#endif
-
diff --git a/Modules/expat/xmlparse.c b/Modules/expat/xmlparse.c
index 412838794d..b308e67e2d 100644
--- a/Modules/expat/xmlparse.c
+++ b/Modules/expat/xmlparse.c
@@ -2,9 +2,22 @@
    See the file COPYING for copying permission.
 */
 
+#include <stddef.h>
+#include <string.h>                     /* memset(), memcpy() */
+#include <assert.h>
+#include <limits.h>                     /* UINT_MAX */
+
+#ifdef WIN32
+#define getpid GetCurrentProcessId
+#else
+#include <sys/time.h>                   /* gettimeofday() */
+#include <sys/types.h>                  /* getpid() */
+#include <unistd.h>                     /* getpid() */
+#endif
+
 #define XML_BUILDING_EXPAT 1
 
-#ifdef COMPILED_FROM_DSP
+#ifdef WIN32
 #include "winconfig.h"
 #elif defined(MACOS_CLASSIC)
 #include "macconfig.h"
@@ -14,13 +27,7 @@
 #include "watcomconfig.h"
 #elif defined(HAVE_EXPAT_CONFIG_H)
 #include <expat_config.h>
-#endif /* ndef COMPILED_FROM_DSP */
-
-#include <stddef.h>
-#include <string.h>                     /* memset(), memcpy() */
-#include <assert.h>
-#include <limits.h>                     /* UINT_MAX */
-#include <time.h>                       /* time() */
+#endif /* ndef WIN32 */
 
 #include "ascii.h"
 #include "expat.h"
@@ -432,7 +439,7 @@ static ELEMENT_TYPE *
 getElementType(XML_Parser parser, const ENCODING *enc,
                const char *ptr, const char *end);
 
-static unsigned long generate_hash_secret_salt(void);
+static unsigned long generate_hash_secret_salt(XML_Parser parser);
 static XML_Bool startParsing(XML_Parser parser);
 
 static XML_Parser
@@ -691,11 +698,38 @@ static const XML_Char implicitContext[] = {
 };
 
 static unsigned long
-generate_hash_secret_salt(void)
+gather_time_entropy(void)
 {
-  unsigned int seed = time(NULL) % UINT_MAX;
-  srand(seed);
-  return rand();
+#ifdef WIN32
+  FILETIME ft;
+  GetSystemTimeAsFileTime(&ft); /* never fails */
+  return ft.dwHighDateTime ^ ft.dwLowDateTime;
+#else
+  struct timeval tv;
+  int gettimeofday_res;
+
+  gettimeofday_res = gettimeofday(&tv, NULL);
+  assert (gettimeofday_res == 0);
+
+  /* Microseconds time is <20 bits entropy */
+  return tv.tv_usec;
+#endif
+}
+
+static unsigned long
+generate_hash_secret_salt(XML_Parser parser)
+{
+  /* Process ID is 0 bits entropy if attacker has local access
+   * XML_Parser address is few bits of entropy if attacker has local access */
+  const unsigned long entropy =
+      gather_time_entropy() ^ getpid() ^ (unsigned long)parser;
+
+  /* Factors are 2^31-1 and 2^61-1 (Mersenne primes M31 and M61) */
+  if (sizeof(unsigned long) == 4) {
+    return entropy * 2147483647;
+  } else {
+    return entropy * (unsigned long)2305843009213693951;
+  }
 }
 
 static XML_Bool  /* only valid for root parser */
@@ -703,7 +737,7 @@ startParsing(XML_Parser parser)
 {
     /* hash functions must be initialized before setContext() is called */
     if (hash_secret_salt == 0)
-      hash_secret_salt = generate_hash_secret_salt();
+      hash_secret_salt = generate_hash_secret_salt(parser);
     if (ns) {
       /* implicit context only set for root parser, since child
          parsers (i.e. external entity parsers) will inherit it
@@ -1695,15 +1729,15 @@ XML_GetBuffer(XML_Parser parser, int len)
   if (len > bufferLim - bufferEnd) {
 #ifdef XML_CONTEXT_BYTES
     int keep;
-#endif
-    int neededSize = len + (int)(bufferEnd - bufferPtr);
+#endif  /* defined XML_CONTEXT_BYTES */
+    /* Do not invoke signed arithmetic overflow: */
+    int neededSize = (int) ((unsigned)len + (unsigned)(bufferEnd - bufferPtr));
     if (neededSize < 0) {
       errorCode = XML_ERROR_NO_MEMORY;
       return NULL;
     }
 #ifdef XML_CONTEXT_BYTES
     keep = (int)(bufferPtr - buffer);
-
     if (keep > XML_CONTEXT_BYTES)
       keep = XML_CONTEXT_BYTES;
     neededSize += keep;
@@ -1728,7 +1762,8 @@ XML_GetBuffer(XML_Parser parser, int len)
       if (bufferSize == 0)
         bufferSize = INIT_BUFFER_SIZE;
       do {
-        bufferSize *= 2;
+        /* Do not invoke signed arithmetic overflow: */
+        bufferSize = (int) (2U * (unsigned) bufferSize);
       } while (bufferSize < neededSize && bufferSize > 0);
       if (bufferSize <= 0) {
         errorCode = XML_ERROR_NO_MEMORY;
@@ -1855,7 +1890,7 @@ XML_Index XMLCALL
 XML_GetCurrentByteIndex(XML_Parser parser)
 {
   if (eventPtr)
-    return parseEndByteIndex - (parseEndPtr - eventPtr);
+    return (XML_Index)(parseEndByteIndex - (parseEndPtr - eventPtr));
   return -1;
 }
 
@@ -2429,11 +2464,11 @@ doContent(XML_Parser parser,
           for (;;) {
             int bufSize;
             int convLen;
-            XmlConvert(enc,
+            const enum XML_Convert_Result convert_res = XmlConvert(enc,
                        &fromPtr, rawNameEnd,
                        (ICHAR **)&toPtr, (ICHAR *)tag->bufEnd - 1);
             convLen = (int)(toPtr - (XML_Char *)tag->buf);
-            if (fromPtr == rawNameEnd) {
+            if ((convert_res == XML_CONVERT_COMPLETED) || (convert_res == XML_CONVERT_INPUT_INCOMPLETE)) {
               tag->name.strLen = convLen;
               break;
             }
@@ -2654,11 +2689,11 @@ doContent(XML_Parser parser,
           if (MUST_CONVERT(enc, s)) {
             for (;;) {
               ICHAR *dataPtr = (ICHAR *)dataBuf;
-              XmlConvert(enc, &s, next, &dataPtr, (ICHAR *)dataBufEnd);
+              const enum XML_Convert_Result convert_res = XmlConvert(enc, &s, next, &dataPtr, (ICHAR *)dataBufEnd);
               *eventEndPP = s;
               charDataHandler(handlerArg, dataBuf,
                               (int)(dataPtr - (ICHAR *)dataBuf));
-              if (s == next)
+              if ((convert_res == XML_CONVERT_COMPLETED) || (convert_res == XML_CONVERT_INPUT_INCOMPLETE))
                 break;
               *eventPP = s;
             }
@@ -3264,11 +3299,11 @@ doCdataSection(XML_Parser parser,
           if (MUST_CONVERT(enc, s)) {
             for (;;) {
               ICHAR *dataPtr = (ICHAR *)dataBuf;
-              XmlConvert(enc, &s, next, &dataPtr, (ICHAR *)dataBufEnd);
+              const enum XML_Convert_Result convert_res = XmlConvert(enc, &s, next, &dataPtr, (ICHAR *)dataBufEnd);
               *eventEndPP = next;
               charDataHandler(handlerArg, dataBuf,
                               (int)(dataPtr - (ICHAR *)dataBuf));
-              if (s == next)
+              if ((convert_res == XML_CONVERT_COMPLETED) || (convert_res == XML_CONVERT_INPUT_INCOMPLETE))
                 break;
               *eventPP = s;
             }
@@ -4927,9 +4962,9 @@ internalEntityProcessor(XML_Parser parser,
 
 static enum XML_Error PTRCALL
 errorProcessor(XML_Parser parser,
-               const char *s,
-               const char *end,
-               const char **nextPtr)
+               const char *UNUSED_P(s),
+               const char *UNUSED_P(end),
+               const char **UNUSED_P(nextPtr))
 {
   return errorCode;
 }
@@ -5345,6 +5380,7 @@ reportDefault(XML_Parser parser, const ENCODING *enc,
               const char *s, const char *end)
 {
   if (MUST_CONVERT(enc, s)) {
+    enum XML_Convert_Result convert_res;
     const char **eventPP;
     const char **eventEndPP;
     if (enc == encoding) {
@@ -5357,11 +5393,11 @@ reportDefault(XML_Parser parser, const ENCODING *enc,
     }
     do {
       ICHAR *dataPtr = (ICHAR *)dataBuf;
-      XmlConvert(enc, &s, end, &dataPtr, (ICHAR *)dataBufEnd);
+      convert_res = XmlConvert(enc, &s, end, &dataPtr, (ICHAR *)dataBufEnd);
       *eventEndPP = s;
       defaultHandler(handlerArg, dataBuf, (int)(dataPtr - (ICHAR *)dataBuf));
       *eventPP = s;
-    } while (s != end);
+    } while ((convert_res != XML_CONVERT_COMPLETED) && (convert_res != XML_CONVERT_INPUT_INCOMPLETE));
   }
   else
     defaultHandler(handlerArg, (XML_Char *)s, (int)((XML_Char *)end - (XML_Char *)s));
@@ -6166,8 +6202,8 @@ poolAppend(STRING_POOL *pool, const ENCODING *enc,
   if (!pool->ptr && !poolGrow(pool))
     return NULL;
   for (;;) {
-    XmlConvert(enc, &ptr, end, (ICHAR **)&(pool->ptr), (ICHAR *)pool->end);
-    if (ptr == end)
+    const enum XML_Convert_Result convert_res = XmlConvert(enc, &ptr, end, (ICHAR **)&(pool->ptr), (ICHAR *)pool->end);
+    if ((convert_res == XML_CONVERT_COMPLETED) || (convert_res == XML_CONVERT_INPUT_INCOMPLETE))
       break;
     if (!poolGrow(pool))
       return NULL;
@@ -6251,8 +6287,13 @@ poolGrow(STRING_POOL *pool)
     }
   }
   if (pool->blocks && pool->start == pool->blocks->s) {
-    int blockSize = (int)(pool->end - pool->start)*2;
-    BLOCK *temp = (BLOCK *)
+    BLOCK *temp;
+    int blockSize = (int)((unsigned)(pool->end - pool->start)*2U);
+
+    if (blockSize < 0)
+      return XML_FALSE;
+
+    temp = (BLOCK *)
       pool->mem->realloc_fcn(pool->blocks,
                              (offsetof(BLOCK, s)
                               + blockSize * sizeof(XML_Char)));
@@ -6267,6 +6308,10 @@ poolGrow(STRING_POOL *pool)
   else {
     BLOCK *tem;
     int blockSize = (int)(pool->end - pool->start);
+
+    if (blockSize < 0)
+      return XML_FALSE;
+
     if (blockSize < INIT_BLOCK_SIZE)
       blockSize = INIT_BLOCK_SIZE;
     else
diff --git a/Modules/expat/xmlrole.c b/Modules/expat/xmlrole.c
index 44772e21dd..fcd0dc6948 100644
--- a/Modules/expat/xmlrole.c
+++ b/Modules/expat/xmlrole.c
@@ -4,7 +4,7 @@
 
 #include <stddef.h>
 
-#ifdef COMPILED_FROM_DSP
+#ifdef WIN32
 #include "winconfig.h"
 #elif defined(MACOS_CLASSIC)
 #include "macconfig.h"
@@ -16,7 +16,7 @@
 #ifdef HAVE_EXPAT_CONFIG_H
 #include <expat_config.h>
 #endif
-#endif /* ndef COMPILED_FROM_DSP */
+#endif /* ndef WIN32 */
 
 #include "expat_external.h"
 #include "internal.h"
@@ -195,9 +195,9 @@ prolog1(PROLOG_STATE *state,
 static int PTRCALL
 prolog2(PROLOG_STATE *state,
         int tok,
-        const char *ptr,
-        const char *end,
-        const ENCODING *enc)
+        const char *UNUSED_P(ptr),
+        const char *UNUSED_P(end),
+        const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -216,9 +216,9 @@ prolog2(PROLOG_STATE *state,
 static int PTRCALL
 doctype0(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -264,9 +264,9 @@ doctype1(PROLOG_STATE *state,
 static int PTRCALL
 doctype2(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -281,9 +281,9 @@ doctype2(PROLOG_STATE *state,
 static int PTRCALL
 doctype3(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -298,9 +298,9 @@ doctype3(PROLOG_STATE *state,
 static int PTRCALL
 doctype4(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -318,9 +318,9 @@ doctype4(PROLOG_STATE *state,
 static int PTRCALL
 doctype5(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -437,9 +437,9 @@ externalSubset1(PROLOG_STATE *state,
 static int PTRCALL
 entity0(PROLOG_STATE *state,
         int tok,
-        const char *ptr,
-        const char *end,
-        const ENCODING *enc)
+        const char *UNUSED_P(ptr),
+        const char *UNUSED_P(end),
+        const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -457,9 +457,9 @@ entity0(PROLOG_STATE *state,
 static int PTRCALL
 entity1(PROLOG_STATE *state,
         int tok,
-        const char *ptr,
-        const char *end,
-        const ENCODING *enc)
+        const char *UNUSED_P(ptr),
+        const char *UNUSED_P(end),
+        const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -502,9 +502,9 @@ entity2(PROLOG_STATE *state,
 static int PTRCALL
 entity3(PROLOG_STATE *state,
         int tok,
-        const char *ptr,
-        const char *end,
-        const ENCODING *enc)
+        const char *UNUSED_P(ptr),
+        const char *UNUSED_P(end),
+        const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -519,9 +519,9 @@ entity3(PROLOG_STATE *state,
 static int PTRCALL
 entity4(PROLOG_STATE *state,
         int tok,
-        const char *ptr,
-        const char *end,
-        const ENCODING *enc)
+        const char *UNUSED_P(ptr),
+        const char *UNUSED_P(end),
+        const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -559,9 +559,9 @@ entity5(PROLOG_STATE *state,
 static int PTRCALL
 entity6(PROLOG_STATE *state,
         int tok,
-        const char *ptr,
-        const char *end,
-        const ENCODING *enc)
+        const char *UNUSED_P(ptr),
+        const char *UNUSED_P(end),
+        const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -605,9 +605,9 @@ entity7(PROLOG_STATE *state,
 static int PTRCALL
 entity8(PROLOG_STATE *state,
         int tok,
-        const char *ptr,
-        const char *end,
-        const ENCODING *enc)
+        const char *UNUSED_P(ptr),
+        const char *UNUSED_P(end),
+        const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -622,9 +622,9 @@ entity8(PROLOG_STATE *state,
 static int PTRCALL
 entity9(PROLOG_STATE *state,
         int tok,
-        const char *ptr,
-        const char *end,
-        const ENCODING *enc)
+        const char *UNUSED_P(ptr),
+        const char *UNUSED_P(end),
+        const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -639,9 +639,9 @@ entity9(PROLOG_STATE *state,
 static int PTRCALL
 entity10(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -656,9 +656,9 @@ entity10(PROLOG_STATE *state,
 static int PTRCALL
 notation0(PROLOG_STATE *state,
           int tok,
-          const char *ptr,
-          const char *end,
-          const ENCODING *enc)
+          const char *UNUSED_P(ptr),
+          const char *UNUSED_P(end),
+          const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -697,9 +697,9 @@ notation1(PROLOG_STATE *state,
 static int PTRCALL
 notation2(PROLOG_STATE *state,
           int tok,
-          const char *ptr,
-          const char *end,
-          const ENCODING *enc)
+          const char *UNUSED_P(ptr),
+          const char *UNUSED_P(end),
+          const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -714,9 +714,9 @@ notation2(PROLOG_STATE *state,
 static int PTRCALL
 notation3(PROLOG_STATE *state,
           int tok,
-          const char *ptr,
-          const char *end,
-          const ENCODING *enc)
+          const char *UNUSED_P(ptr),
+          const char *UNUSED_P(end),
+          const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -732,9 +732,9 @@ notation3(PROLOG_STATE *state,
 static int PTRCALL
 notation4(PROLOG_STATE *state,
           int tok,
-          const char *ptr,
-          const char *end,
-          const ENCODING *enc)
+          const char *UNUSED_P(ptr),
+          const char *UNUSED_P(end),
+          const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -753,9 +753,9 @@ notation4(PROLOG_STATE *state,
 static int PTRCALL
 attlist0(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -771,9 +771,9 @@ attlist0(PROLOG_STATE *state,
 static int PTRCALL
 attlist1(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -833,9 +833,9 @@ attlist2(PROLOG_STATE *state,
 static int PTRCALL
 attlist3(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -852,9 +852,9 @@ attlist3(PROLOG_STATE *state,
 static int PTRCALL
 attlist4(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -872,9 +872,9 @@ attlist4(PROLOG_STATE *state,
 static int PTRCALL
 attlist5(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -889,9 +889,9 @@ attlist5(PROLOG_STATE *state,
 static int PTRCALL
 attlist6(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -906,9 +906,9 @@ attlist6(PROLOG_STATE *state,
 static int PTRCALL
 attlist7(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -967,9 +967,9 @@ attlist8(PROLOG_STATE *state,
 static int PTRCALL
 attlist9(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -984,9 +984,9 @@ attlist9(PROLOG_STATE *state,
 static int PTRCALL
 element0(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -1072,9 +1072,9 @@ element2(PROLOG_STATE *state,
 static int PTRCALL
 element3(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -1097,9 +1097,9 @@ element3(PROLOG_STATE *state,
 static int PTRCALL
 element4(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -1115,9 +1115,9 @@ element4(PROLOG_STATE *state,
 static int PTRCALL
 element5(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -1136,9 +1136,9 @@ element5(PROLOG_STATE *state,
 static int PTRCALL
 element6(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -1166,9 +1166,9 @@ element6(PROLOG_STATE *state,
 static int PTRCALL
 element7(PROLOG_STATE *state,
          int tok,
-         const char *ptr,
-         const char *end,
-         const ENCODING *enc)
+         const char *UNUSED_P(ptr),
+         const char *UNUSED_P(end),
+         const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -1240,9 +1240,9 @@ condSect0(PROLOG_STATE *state,
 static int PTRCALL
 condSect1(PROLOG_STATE *state,
           int tok,
-          const char *ptr,
-          const char *end,
-          const ENCODING *enc)
+          const char *UNUSED_P(ptr),
+          const char *UNUSED_P(end),
+          const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -1258,9 +1258,9 @@ condSect1(PROLOG_STATE *state,
 static int PTRCALL
 condSect2(PROLOG_STATE *state,
           int tok,
-          const char *ptr,
-          const char *end,
-          const ENCODING *enc)
+          const char *UNUSED_P(ptr),
+          const char *UNUSED_P(end),
+          const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -1277,9 +1277,9 @@ condSect2(PROLOG_STATE *state,
 static int PTRCALL
 declClose(PROLOG_STATE *state,
           int tok,
-          const char *ptr,
-          const char *end,
-          const ENCODING *enc)
+          const char *UNUSED_P(ptr),
+          const char *UNUSED_P(end),
+          const ENCODING *UNUSED_P(enc))
 {
   switch (tok) {
   case XML_TOK_PROLOG_S:
@@ -1292,11 +1292,11 @@ declClose(PROLOG_STATE *state,
 }
 
 static int PTRCALL
-error(PROLOG_STATE *state,
-      int tok,
-      const char *ptr,
-      const char *end,
-      const ENCODING *enc)
+error(PROLOG_STATE *UNUSED_P(state),
+      int UNUSED_P(tok),
+      const char *UNUSED_P(ptr),
+      const char *UNUSED_P(end),
+      const ENCODING *UNUSED_P(enc))
 {
   return XML_ROLE_NONE;
 }
diff --git a/Modules/expat/xmltok.c b/Modules/expat/xmltok.c
index bf09dfc72b..a29d9e2f8a 100644
--- a/Modules/expat/xmltok.c
+++ b/Modules/expat/xmltok.c
@@ -4,7 +4,7 @@
 
 #include <stddef.h>
 
-#ifdef COMPILED_FROM_DSP
+#ifdef WIN32
 #include "winconfig.h"
 #elif defined(MACOS_CLASSIC)
 #include "macconfig.h"
@@ -16,7 +16,7 @@
 #ifdef HAVE_EXPAT_CONFIG_H
 #include <expat_config.h>
 #endif
-#endif /* ndef COMPILED_FROM_DSP */
+#endif /* ndef WIN32 */
 
 #include "expat_external.h"
 #include "internal.h"
@@ -46,7 +46,7 @@
 #define VTABLE VTABLE1, PREFIX(toUtf8), PREFIX(toUtf16)
 
 #define UCS2_GET_NAMING(pages, hi, lo) \
-   (namingBitmap[(pages[hi] << 3) + ((lo) >> 5)] & (1 << ((lo) & 0x1F)))
+   (namingBitmap[(pages[hi] << 3) + ((lo) >> 5)] & (1u << ((lo) & 0x1F)))
 
 /* A 2 byte UTF-8 representation splits the characters 11 bits between
    the bottom 5 and 6 bits of the bytes.  We need 8 bits to index into
@@ -56,7 +56,7 @@
     (namingBitmap[((pages)[(((byte)[0]) >> 2) & 7] << 3) \
                       + ((((byte)[0]) & 3) << 1) \
                       + ((((byte)[1]) >> 5) & 1)] \
-         & (1 << (((byte)[1]) & 0x1F)))
+         & (1u << (((byte)[1]) & 0x1F)))
 
 /* A 3 byte UTF-8 representation splits the characters 16 bits between
    the bottom 4, 6 and 6 bits of the bytes.  We need 8 bits to index
@@ -69,7 +69,7 @@
                        << 3) \
                       + ((((byte)[1]) & 3) << 1) \
                       + ((((byte)[2]) >> 5) & 1)] \
-         & (1 << (((byte)[2]) & 0x1F)))
+         & (1u << (((byte)[2]) & 0x1F)))
 
 #define UTF8_GET_NAMING(pages, p, n) \
   ((n) == 2 \
@@ -122,19 +122,19 @@
     ((*p) == 0xF4 ? (p)[1] > 0x8F : ((p)[1] & 0xC0) == 0xC0)))
 
 static int PTRFASTCALL
-isNever(const ENCODING *enc, const char *p)
+isNever(const ENCODING *UNUSED_P(enc), const char *UNUSED_P(p))
 {
   return 0;
 }
 
 static int PTRFASTCALL
-utf8_isName2(const ENCODING *enc, const char *p)
+utf8_isName2(const ENCODING *UNUSED_P(enc), const char *p)
 {
   return UTF8_GET_NAMING2(namePages, (const unsigned char *)p);
 }
 
 static int PTRFASTCALL
-utf8_isName3(const ENCODING *enc, const char *p)
+utf8_isName3(const ENCODING *UNUSED_P(enc), const char *p)
 {
   return UTF8_GET_NAMING3(namePages, (const unsigned char *)p);
 }
@@ -142,13 +142,13 @@ utf8_isName3(const ENCODING *enc, const char *p)
 #define utf8_isName4 isNever
 
 static int PTRFASTCALL
-utf8_isNmstrt2(const ENCODING *enc, const char *p)
+utf8_isNmstrt2(const ENCODING *UNUSED_P(enc), const char *p)
 {
   return UTF8_GET_NAMING2(nmstrtPages, (const unsigned char *)p);
 }
 
 static int PTRFASTCALL
-utf8_isNmstrt3(const ENCODING *enc, const char *p)
+utf8_isNmstrt3(const ENCODING *UNUSED_P(enc), const char *p)
 {
   return UTF8_GET_NAMING3(nmstrtPages, (const unsigned char *)p);
 }
@@ -156,19 +156,19 @@ utf8_isNmstrt3(const ENCODING *enc, const char *p)
 #define utf8_isNmstrt4 isNever
 
 static int PTRFASTCALL
-utf8_isInvalid2(const ENCODING *enc, const char *p)
+utf8_isInvalid2(const ENCODING *UNUSED_P(enc), const char *p)
 {
   return UTF8_INVALID2((const unsigned char *)p);
 }
 
 static int PTRFASTCALL
-utf8_isInvalid3(const ENCODING *enc, const char *p)
+utf8_isInvalid3(const ENCODING *UNUSED_P(enc), const char *p)
 {
   return UTF8_INVALID3((const unsigned char *)p);
 }
 
 static int PTRFASTCALL
-utf8_isInvalid4(const ENCODING *enc, const char *p)
+utf8_isInvalid4(const ENCODING *UNUSED_P(enc), const char *p)
 {
   return UTF8_INVALID4((const unsigned char *)p);
 }
@@ -222,6 +222,17 @@ struct normal_encoding {
  E ## isInvalid3, \
  E ## isInvalid4
 
+#define NULL_VTABLE \
+ /* isName2 */ NULL, \
+ /* isName3 */ NULL, \
+ /* isName4 */ NULL, \
+ /* isNmstrt2 */ NULL, \
+ /* isNmstrt3 */ NULL, \
+ /* isNmstrt4 */ NULL, \
+ /* isInvalid2 */ NULL, \
+ /* isInvalid3 */ NULL, \
+ /* isInvalid4 */ NULL
+
 static int FASTCALL checkCharRefNumber(int);
 
 #include "xmltok_impl.h"
@@ -318,39 +329,89 @@ enum {  /* UTF8_cvalN is value of masked first byte of N byte sequence */
   UTF8_cval4 = 0xf0
 };
 
-static void PTRCALL
-utf8_toUtf8(const ENCODING *enc,
+void
+align_limit_to_full_utf8_characters(const char * from, const char ** fromLimRef)
+{
+  const char * fromLim = *fromLimRef;
+  size_t walked = 0;
+  for (; fromLim > from; fromLim--, walked++) {
+    const unsigned char prev = (unsigned char)fromLim[-1];
+    if ((prev & 0xf8u) == 0xf0u) { /* 4-byte character, lead by 0b11110xxx byte */
+      if (walked + 1 >= 4) {
+        fromLim += 4 - 1;
+        break;
+      } else {
+        walked = 0;
+      }
+    } else if ((prev & 0xf0u) == 0xe0u) { /* 3-byte character, lead by 0b1110xxxx byte */
+      if (walked + 1 >= 3) {
+        fromLim += 3 - 1;
+        break;
+      } else {
+        walked = 0;
+      }
+    } else if ((prev & 0xe0u) == 0xc0u) { /* 2-byte character, lead by 0b110xxxxx byte */
+      if (walked + 1 >= 2) {
+        fromLim += 2 - 1;
+        break;
+      } else {
+        walked = 0;
+      }
+    } else if ((prev & 0x80u) == 0x00u) { /* 1-byte character, matching 0b0xxxxxxx */
+      break;
+    }
+  }
+  *fromLimRef = fromLim;
+}
+
+static enum XML_Convert_Result PTRCALL
+utf8_toUtf8(const ENCODING *UNUSED_P(enc),
             const char **fromP, const char *fromLim,
             char **toP, const char *toLim)
 {
+  enum XML_Convert_Result res = XML_CONVERT_COMPLETED;
   char *to;
   const char *from;
   if (fromLim - *fromP > toLim - *toP) {
     /* Avoid copying partial characters. */
-    for (fromLim = *fromP + (toLim - *toP); fromLim > *fromP; fromLim--)
-      if (((unsigned char)fromLim[-1] & 0xc0) != 0x80)
-        break;
+    res = XML_CONVERT_OUTPUT_EXHAUSTED;
+    fromLim = *fromP + (toLim - *toP);
+    align_limit_to_full_utf8_characters(*fromP, &fromLim);
   }
-  for (to = *toP, from = *fromP; from != fromLim; from++, to++)
+  for (to = *toP, from = *fromP; (from < fromLim) && (to < toLim); from++, to++)
     *to = *from;
   *fromP = from;
   *toP = to;
+
+  if ((to == toLim) && (from < fromLim))
+    return XML_CONVERT_OUTPUT_EXHAUSTED;
+  else
+    return res;
 }
 
-static void PTRCALL
+static enum XML_Convert_Result PTRCALL
 utf8_toUtf16(const ENCODING *enc,
              const char **fromP, const char *fromLim,
              unsigned short **toP, const unsigned short *toLim)
 {
+  enum XML_Convert_Result res = XML_CONVERT_COMPLETED;
   unsigned short *to = *toP;
   const char *from = *fromP;
-  while (from != fromLim && to != toLim) {
+  while (from < fromLim && to < toLim) {
     switch (((struct normal_encoding *)enc)->type[(unsigned char)*from]) {
     case BT_LEAD2:
+      if (fromLim - from < 2) {
+        res = XML_CONVERT_INPUT_INCOMPLETE;
+        break;
+      }
       *to++ = (unsigned short)(((from[0] & 0x1f) << 6) | (from[1] & 0x3f));
       from += 2;
       break;
     case BT_LEAD3:
+      if (fromLim - from < 3) {
+        res = XML_CONVERT_INPUT_INCOMPLETE;
+        break;
+      }
       *to++ = (unsigned short)(((from[0] & 0xf) << 12)
                                | ((from[1] & 0x3f) << 6) | (from[2] & 0x3f));
       from += 3;
@@ -358,8 +419,14 @@ utf8_toUtf16(const ENCODING *enc,
     case BT_LEAD4:
       {
         unsigned long n;
-        if (to + 1 == toLim)
+        if (toLim - to < 2) {
+          res = XML_CONVERT_OUTPUT_EXHAUSTED;
           goto after;
+        }
+        if (fromLim - from < 4) {
+          res = XML_CONVERT_INPUT_INCOMPLETE;
+          goto after;
+        }
         n = ((from[0] & 0x7) << 18) | ((from[1] & 0x3f) << 12)
             | ((from[2] & 0x3f) << 6) | (from[3] & 0x3f);
         n -= 0x10000;
@@ -377,6 +444,7 @@ utf8_toUtf16(const ENCODING *enc,
 after:
   *fromP = from;
   *toP = to;
+  return res;
 }
 
 #ifdef XML_NS
@@ -425,38 +493,43 @@ static const struct normal_encoding internal_utf8_encoding = {
   STANDARD_VTABLE(sb_) NORMAL_VTABLE(utf8_)
 };
 
-static void PTRCALL
-latin1_toUtf8(const ENCODING *enc,
+static enum XML_Convert_Result PTRCALL
+latin1_toUtf8(const ENCODING *UNUSED_P(enc),
               const char **fromP, const char *fromLim,
               char **toP, const char *toLim)
 {
   for (;;) {
     unsigned char c;
     if (*fromP == fromLim)
-      break;
+      return XML_CONVERT_COMPLETED;
     c = (unsigned char)**fromP;
     if (c & 0x80) {
       if (toLim - *toP < 2)
-        break;
+        return XML_CONVERT_OUTPUT_EXHAUSTED;
       *(*toP)++ = (char)((c >> 6) | UTF8_cval2);
       *(*toP)++ = (char)((c & 0x3f) | 0x80);
       (*fromP)++;
     }
     else {
       if (*toP == toLim)
-        break;
+        return XML_CONVERT_OUTPUT_EXHAUSTED;
       *(*toP)++ = *(*fromP)++;
     }
   }
 }
 
-static void PTRCALL
-latin1_toUtf16(const ENCODING *enc,
+static enum XML_Convert_Result PTRCALL
+latin1_toUtf16(const ENCODING *UNUSED_P(enc),
                const char **fromP, const char *fromLim,
                unsigned short **toP, const unsigned short *toLim)
 {
-  while (*fromP != fromLim && *toP != toLim)
+  while (*fromP < fromLim && *toP < toLim)
     *(*toP)++ = (unsigned char)*(*fromP)++;
+
+  if ((*toP == toLim) && (*fromP < fromLim))
+    return XML_CONVERT_OUTPUT_EXHAUSTED;
+  else
+    return XML_CONVERT_COMPLETED;
 }
 
 #ifdef XML_NS
@@ -467,7 +540,7 @@ static const struct normal_encoding latin1_encoding_ns = {
 #include "asciitab.h"
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(sb_)
+  STANDARD_VTABLE(sb_) NULL_VTABLE
 };
 
 #endif
@@ -480,16 +553,21 @@ static const struct normal_encoding latin1_encoding = {
 #undef BT_COLON
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(sb_)
+  STANDARD_VTABLE(sb_) NULL_VTABLE
 };
 
-static void PTRCALL
-ascii_toUtf8(const ENCODING *enc,
+static enum XML_Convert_Result PTRCALL
+ascii_toUtf8(const ENCODING *UNUSED_P(enc),
              const char **fromP, const char *fromLim,
              char **toP, const char *toLim)
 {
-  while (*fromP != fromLim && *toP != toLim)
+  while (*fromP < fromLim && *toP < toLim)
     *(*toP)++ = *(*fromP)++;
+
+  if ((*toP == toLim) && (*fromP < fromLim))
+    return XML_CONVERT_OUTPUT_EXHAUSTED;
+  else
+    return XML_CONVERT_COMPLETED;
 }
 
 #ifdef XML_NS
@@ -500,7 +578,7 @@ static const struct normal_encoding ascii_encoding_ns = {
 #include "asciitab.h"
 /* BT_NONXML == 0 */
   },
-  STANDARD_VTABLE(sb_)
+  STANDARD_VTABLE(sb_) NULL_VTABLE
 };
 
 #endif
@@ -513,7 +591,7 @@ static const struct normal_encoding ascii_encoding = {
 #undef BT_COLON
 /* BT_NONXML == 0 */
   },
-  STANDARD_VTABLE(sb_)
+  STANDARD_VTABLE(sb_) NULL_VTABLE
 };
 
 static int PTRFASTCALL
@@ -536,13 +614,14 @@ unicode_byte_type(char hi, char lo)
 }
 
 #define DEFINE_UTF16_TO_UTF8(E) \
-static void  PTRCALL \
-E ## toUtf8(const ENCODING *enc, \
+static enum XML_Convert_Result  PTRCALL \
+E ## toUtf8(const ENCODING *UNUSED_P(enc), \
             const char **fromP, const char *fromLim, \
             char **toP, const char *toLim) \
 { \
-  const char *from; \
-  for (from = *fromP; from != fromLim; from += 2) { \
+  const char *from = *fromP; \
+  fromLim = from + (((fromLim - from) >> 1) << 1);  /* shrink to even */ \
+  for (; from < fromLim; from += 2) { \
     int plane; \
     unsigned char lo2; \
     unsigned char lo = GET_LO(from); \
@@ -552,7 +631,7 @@ E ## toUtf8(const ENCODING *enc, \
       if (lo < 0x80) { \
         if (*toP == toLim) { \
           *fromP = from; \
-          return; \
+          return XML_CONVERT_OUTPUT_EXHAUSTED; \
         } \
         *(*toP)++ = lo; \
         break; \
@@ -562,7 +641,7 @@ E ## toUtf8(const ENCODING *enc, \
     case 0x4: case 0x5: case 0x6: case 0x7: \
       if (toLim -  *toP < 2) { \
         *fromP = from; \
-        return; \
+        return XML_CONVERT_OUTPUT_EXHAUSTED; \
       } \
       *(*toP)++ = ((lo >> 6) | (hi << 2) |  UTF8_cval2); \
       *(*toP)++ = ((lo & 0x3f) | 0x80); \
@@ -570,7 +649,7 @@ E ## toUtf8(const ENCODING *enc, \
     default: \
       if (toLim -  *toP < 3)  { \
         *fromP = from; \
-        return; \
+        return XML_CONVERT_OUTPUT_EXHAUSTED; \
       } \
       /* 16 bits divided 4, 6, 6 amongst 3 bytes */ \
       *(*toP)++ = ((hi >> 4) | UTF8_cval3); \
@@ -580,7 +659,11 @@ E ## toUtf8(const ENCODING *enc, \
     case 0xD8: case 0xD9: case 0xDA: case 0xDB: \
       if (toLim -  *toP < 4) { \
         *fromP = from; \
-        return; \
+        return XML_CONVERT_OUTPUT_EXHAUSTED; \
+      } \
+      if (fromLim - from < 4) { \
+        *fromP = from; \
+        return XML_CONVERT_INPUT_INCOMPLETE; \
       } \
       plane = (((hi & 0x3) << 2) | ((lo >> 6) & 0x3)) + 1; \
       *(*toP)++ = ((plane >> 2) | UTF8_cval4); \
@@ -596,20 +679,32 @@ E ## toUtf8(const ENCODING *enc, \
     } \
   } \
   *fromP = from; \
+  if (from < fromLim) \
+    return XML_CONVERT_INPUT_INCOMPLETE; \
+  else \
+    return XML_CONVERT_COMPLETED; \
 }
 
 #define DEFINE_UTF16_TO_UTF16(E) \
-static void  PTRCALL \
-E ## toUtf16(const ENCODING *enc, \
+static enum XML_Convert_Result  PTRCALL \
+E ## toUtf16(const ENCODING *UNUSED_P(enc), \
              const char **fromP, const char *fromLim, \
              unsigned short **toP, const unsigned short *toLim) \
 { \
+  enum XML_Convert_Result res = XML_CONVERT_COMPLETED; \
+  fromLim = *fromP + (((fromLim - *fromP) >> 1) << 1);  /* shrink to even */ \
   /* Avoid copying first half only of surrogate */ \
   if (fromLim - *fromP > ((toLim - *toP) << 1) \
-      && (GET_HI(fromLim - 2) & 0xF8) == 0xD8) \
+      && (GET_HI(fromLim - 2) & 0xF8) == 0xD8) { \
     fromLim -= 2; \
-  for (; *fromP != fromLim && *toP != toLim; *fromP += 2) \
+    res = XML_CONVERT_INPUT_INCOMPLETE; \
+  } \
+  for (; *fromP < fromLim && *toP < toLim; *fromP += 2) \
     *(*toP)++ = (GET_HI(*fromP) << 8) | GET_LO(*fromP); \
+  if ((*toP == toLim) && (*fromP < fromLim)) \
+    return XML_CONVERT_OUTPUT_EXHAUSTED; \
+  else \
+    return res; \
 }
 
 #define SET2(ptr, ch) \
@@ -726,7 +821,7 @@ static const struct normal_encoding little2_encoding_ns = {
 #include "asciitab.h"
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(little2_)
+  STANDARD_VTABLE(little2_) NULL_VTABLE
 };
 
 #endif
@@ -745,7 +840,7 @@ static const struct normal_encoding little2_encoding = {
 #undef BT_COLON
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(little2_)
+  STANDARD_VTABLE(little2_) NULL_VTABLE
 };
 
 #if BYTEORDER != 4321
@@ -758,7 +853,7 @@ static const struct normal_encoding internal_little2_encoding_ns = {
 #include "iasciitab.h"
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(little2_)
+  STANDARD_VTABLE(little2_) NULL_VTABLE
 };
 
 #endif
@@ -771,7 +866,7 @@ static const struct normal_encoding internal_little2_encoding = {
 #undef BT_COLON
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(little2_)
+  STANDARD_VTABLE(little2_) NULL_VTABLE
 };
 
 #endif
@@ -867,7 +962,7 @@ static const struct normal_encoding big2_encoding_ns = {
 #include "asciitab.h"
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(big2_)
+  STANDARD_VTABLE(big2_) NULL_VTABLE
 };
 
 #endif
@@ -886,7 +981,7 @@ static const struct normal_encoding big2_encoding = {
 #undef BT_COLON
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(big2_)
+  STANDARD_VTABLE(big2_) NULL_VTABLE
 };
 
 #if BYTEORDER != 1234
@@ -899,7 +994,7 @@ static const struct normal_encoding internal_big2_encoding_ns = {
 #include "iasciitab.h"
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(big2_)
+  STANDARD_VTABLE(big2_) NULL_VTABLE
 };
 
 #endif
@@ -912,7 +1007,7 @@ static const struct normal_encoding internal_big2_encoding = {
 #undef BT_COLON
 #include "latin1tab.h"
   },
-  STANDARD_VTABLE(big2_)
+  STANDARD_VTABLE(big2_) NULL_VTABLE
 };
 
 #endif
@@ -938,7 +1033,7 @@ streqci(const char *s1, const char *s2)
 }
 
 static void PTRCALL
-initUpdatePosition(const ENCODING *enc, const char *ptr,
+initUpdatePosition(const ENCODING *UNUSED_P(enc), const char *ptr,
                    const char *end, POSITION *pos)
 {
   normal_updatePosition(&utf8_encoding.enc, ptr, end, pos);
@@ -1288,7 +1383,7 @@ unknown_isInvalid(const ENCODING *enc, const char *p)
   return (c & ~0xFFFF) || checkCharRefNumber(c) < 0;
 }
 
-static void PTRCALL
+static enum XML_Convert_Result PTRCALL
 unknown_toUtf8(const ENCODING *enc,
                const char **fromP, const char *fromLim,
                char **toP, const char *toLim)
@@ -1299,21 +1394,21 @@ unknown_toUtf8(const ENCODING *enc,
     const char *utf8;
     int n;
     if (*fromP == fromLim)
-      break;
+      return XML_CONVERT_COMPLETED;
     utf8 = uenc->utf8[(unsigned char)**fromP];
     n = *utf8++;
     if (n == 0) {
       int c = uenc->convert(uenc->userData, *fromP);
       n = XmlUtf8Encode(c, buf);
       if (n > toLim - *toP)
-        break;
+        return XML_CONVERT_OUTPUT_EXHAUSTED;
       utf8 = buf;
       *fromP += (AS_NORMAL_ENCODING(enc)->type[(unsigned char)**fromP]
                  - (BT_LEAD2 - 2));
     }
     else {
       if (n > toLim - *toP)
-        break;
+        return XML_CONVERT_OUTPUT_EXHAUSTED;
       (*fromP)++;
     }
     do {
@@ -1322,13 +1417,13 @@ unknown_toUtf8(const ENCODING *enc,
   }
 }
 
-static void PTRCALL
+static enum XML_Convert_Result PTRCALL
 unknown_toUtf16(const ENCODING *enc,
                 const char **fromP, const char *fromLim,
                 unsigned short **toP, const unsigned short *toLim)
 {
   const struct unknown_encoding *uenc = AS_UNKNOWN_ENCODING(enc);
-  while (*fromP != fromLim && *toP != toLim) {
+  while (*fromP < fromLim && *toP < toLim) {
     unsigned short c = uenc->utf16[(unsigned char)**fromP];
     if (c == 0) {
       c = (unsigned short)
@@ -1340,6 +1435,11 @@ unknown_toUtf16(const ENCODING *enc,
       (*fromP)++;
     *(*toP)++ = c;
   }
+
+  if ((*toP == toLim) && (*fromP < fromLim))
+    return XML_CONVERT_OUTPUT_EXHAUSTED;
+  else
+    return XML_CONVERT_COMPLETED;
 }
 
 ENCODING *
@@ -1503,7 +1603,7 @@ initScan(const ENCODING * const *encodingTable,
 {
   const ENCODING **encPtr;
 
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   encPtr = enc->encPtr;
   if (ptr + 1 == end) {
diff --git a/Modules/expat/xmltok.h b/Modules/expat/xmltok.h
index ca867aa6b4..752007e8b9 100644
--- a/Modules/expat/xmltok.h
+++ b/Modules/expat/xmltok.h
@@ -130,6 +130,12 @@ typedef int (PTRCALL *SCANNER)(const ENCODING *,
                                const char *,
                                const char **);
 
+enum XML_Convert_Result {
+  XML_CONVERT_COMPLETED = 0,
+  XML_CONVERT_INPUT_INCOMPLETE = 1,
+  XML_CONVERT_OUTPUT_EXHAUSTED = 2  /* and therefore potentially input remaining as well */
+};
+
 struct encoding {
   SCANNER scanners[XML_N_STATES];
   SCANNER literalScanners[XML_N_LITERAL_TYPES];
@@ -158,12 +164,12 @@ struct encoding {
                             const char *ptr,
                             const char *end,
                             const char **badPtr);
-  void (PTRCALL *utf8Convert)(const ENCODING *enc,
+  enum XML_Convert_Result (PTRCALL *utf8Convert)(const ENCODING *enc,
                               const char **fromP,
                               const char *fromLim,
                               char **toP,
                               const char *toLim);
-  void (PTRCALL *utf16Convert)(const ENCODING *enc,
+  enum XML_Convert_Result (PTRCALL *utf16Convert)(const ENCODING *enc,
                                const char **fromP,
                                const char *fromLim,
                                unsigned short **toP,
diff --git a/Modules/expat/xmltok_impl.c b/Modules/expat/xmltok_impl.c
index 9c2895b877..5f779c0571 100644
--- a/Modules/expat/xmltok_impl.c
+++ b/Modules/expat/xmltok_impl.c
@@ -87,27 +87,45 @@
 #define PREFIX(ident) ident
 #endif
 
+
+#define HAS_CHARS(enc, ptr, end, count) \
+    (end - ptr >= count * MINBPC(enc))
+
+#define HAS_CHAR(enc, ptr, end) \
+    HAS_CHARS(enc, ptr, end, 1)
+
+#define REQUIRE_CHARS(enc, ptr, end, count) \
+    { \
+      if (! HAS_CHARS(enc, ptr, end, count)) { \
+        return XML_TOK_PARTIAL; \
+      } \
+    }
+
+#define REQUIRE_CHAR(enc, ptr, end) \
+    REQUIRE_CHARS(enc, ptr, end, 1)
+
+
 /* ptr points to character following "<!-" */
 
 static int PTRCALL
 PREFIX(scanComment)(const ENCODING *enc, const char *ptr,
                     const char *end, const char **nextTokPtr)
 {
-  if (ptr != end) {
+  if (HAS_CHAR(enc, ptr, end)) {
     if (!CHAR_MATCHES(enc, ptr, ASCII_MINUS)) {
       *nextTokPtr = ptr;
       return XML_TOK_INVALID;
     }
     ptr += MINBPC(enc);
-    while (ptr != end) {
+    while (HAS_CHAR(enc, ptr, end)) {
       switch (BYTE_TYPE(enc, ptr)) {
       INVALID_CASES(ptr, nextTokPtr)
       case BT_MINUS:
-        if ((ptr += MINBPC(enc)) == end)
-          return XML_TOK_PARTIAL;
+        ptr += MINBPC(enc);
+        REQUIRE_CHAR(enc, ptr, end);
         if (CHAR_MATCHES(enc, ptr, ASCII_MINUS)) {
-          if ((ptr += MINBPC(enc)) == end)
-            return XML_TOK_PARTIAL;
+          ptr += MINBPC(enc);
+          REQUIRE_CHAR(enc, ptr, end);
           if (!CHAR_MATCHES(enc, ptr, ASCII_GT)) {
             *nextTokPtr = ptr;
             return XML_TOK_INVALID;
@@ -131,8 +149,7 @@ static int PTRCALL
 PREFIX(scanDecl)(const ENCODING *enc, const char *ptr,
                  const char *end, const char **nextTokPtr)
 {
-  if (ptr == end)
-    return XML_TOK_PARTIAL;
+  REQUIRE_CHAR(enc, ptr, end);
   switch (BYTE_TYPE(enc, ptr)) {
   case BT_MINUS:
     return PREFIX(scanComment)(enc, ptr + MINBPC(enc), end, nextTokPtr);
@@ -147,11 +164,10 @@ PREFIX(scanDecl)(const ENCODING *enc, const char *ptr,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     case BT_PERCNT:
-      if (ptr + MINBPC(enc) == end)
-        return XML_TOK_PARTIAL;
+      REQUIRE_CHARS(enc, ptr, end, 2);
       /* don't allow <!ENTITY% foo "whatever"> */
       switch (BYTE_TYPE(enc, ptr + MINBPC(enc))) {
       case BT_S: case BT_CR: case BT_LF: case BT_PERCNT:
@@ -175,7 +191,7 @@ PREFIX(scanDecl)(const ENCODING *enc, const char *ptr,
 }
 
 static int PTRCALL
-PREFIX(checkPiTarget)(const ENCODING *enc, const char *ptr,
+PREFIX(checkPiTarget)(const ENCODING *UNUSED_P(enc), const char *ptr,
                       const char *end, int *tokPtr)
 {
   int upper = 0;
@@ -225,15 +241,14 @@ PREFIX(scanPi)(const ENCODING *enc, const char *ptr,
 {
   int tok;
   const char *target = ptr;
-  if (ptr == end)
-    return XML_TOK_PARTIAL;
+  REQUIRE_CHAR(enc, ptr, end);
   switch (BYTE_TYPE(enc, ptr)) {
   CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
   default:
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_S: case BT_CR: case BT_LF:
@@ -242,13 +257,12 @@ PREFIX(scanPi)(const ENCODING *enc, const char *ptr,
         return XML_TOK_INVALID;
       }
       ptr += MINBPC(enc);
-      while (ptr != end) {
+      while (HAS_CHAR(enc, ptr, end)) {
         switch (BYTE_TYPE(enc, ptr)) {
         INVALID_CASES(ptr, nextTokPtr)
         case BT_QUEST:
           ptr += MINBPC(enc);
-          if (ptr == end)
-            return XML_TOK_PARTIAL;
+          REQUIRE_CHAR(enc, ptr, end);
           if (CHAR_MATCHES(enc, ptr, ASCII_GT)) {
             *nextTokPtr = ptr + MINBPC(enc);
             return tok;
@@ -266,8 +280,7 @@ PREFIX(scanPi)(const ENCODING *enc, const char *ptr,
         return XML_TOK_INVALID;
       }
       ptr += MINBPC(enc);
-      if (ptr == end)
-        return XML_TOK_PARTIAL;
+      REQUIRE_CHAR(enc, ptr, end);
       if (CHAR_MATCHES(enc, ptr, ASCII_GT)) {
         *nextTokPtr = ptr + MINBPC(enc);
         return tok;
@@ -282,15 +295,14 @@ PREFIX(scanPi)(const ENCODING *enc, const char *ptr,
 }
 
 static int PTRCALL
-PREFIX(scanCdataSection)(const ENCODING *enc, const char *ptr,
+PREFIX(scanCdataSection)(const ENCODING *UNUSED_P(enc), const char *ptr,
                          const char *end, const char **nextTokPtr)
 {
   static const char CDATA_LSQB[] = { ASCII_C, ASCII_D, ASCII_A,
                                      ASCII_T, ASCII_A, ASCII_LSQB };
   int i;
   /* CDATA[ */
-  if (end - ptr < 6 * MINBPC(enc))
-    return XML_TOK_PARTIAL;
+  REQUIRE_CHARS(enc, ptr, end, 6);
   for (i = 0; i < 6; i++, ptr += MINBPC(enc)) {
     if (!CHAR_MATCHES(enc, ptr, CDATA_LSQB[i])) {
       *nextTokPtr = ptr;
@@ -305,7 +317,7 @@ static int PTRCALL
 PREFIX(cdataSectionTok)(const ENCODING *enc, const char *ptr,
                         const char *end, const char **nextTokPtr)
 {
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   if (MINBPC(enc) > 1) {
     size_t n = end - ptr;
@@ -319,13 +331,11 @@ PREFIX(cdataSectionTok)(const ENCODING *enc, const char *ptr,
   switch (BYTE_TYPE(enc, ptr)) {
   case BT_RSQB:
     ptr += MINBPC(enc);
-    if (ptr == end)
-      return XML_TOK_PARTIAL;
+    REQUIRE_CHAR(enc, ptr, end);
     if (!CHAR_MATCHES(enc, ptr, ASCII_RSQB))
       break;
     ptr += MINBPC(enc);
-    if (ptr == end)
-      return XML_TOK_PARTIAL;
+    REQUIRE_CHAR(enc, ptr, end);
     if (!CHAR_MATCHES(enc, ptr, ASCII_GT)) {
       ptr -= MINBPC(enc);
       break;
@@ -334,8 +344,7 @@ PREFIX(cdataSectionTok)(const ENCODING *enc, const char *ptr,
     return XML_TOK_CDATA_SECT_CLOSE;
   case BT_CR:
     ptr += MINBPC(enc);
-    if (ptr == end)
-      return XML_TOK_PARTIAL;
+    REQUIRE_CHAR(enc, ptr, end);
     if (BYTE_TYPE(enc, ptr) == BT_LF)
       ptr += MINBPC(enc);
     *nextTokPtr = ptr;
@@ -348,7 +357,7 @@ PREFIX(cdataSectionTok)(const ENCODING *enc, const char *ptr,
     ptr += MINBPC(enc);
     break;
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: \
@@ -383,19 +392,18 @@ static int PTRCALL
 PREFIX(scanEndTag)(const ENCODING *enc, const char *ptr,
                    const char *end, const char **nextTokPtr)
 {
-  if (ptr == end)
-    return XML_TOK_PARTIAL;
+  REQUIRE_CHAR(enc, ptr, end);
   switch (BYTE_TYPE(enc, ptr)) {
   CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
   default:
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_S: case BT_CR: case BT_LF:
-      for (ptr += MINBPC(enc); ptr != end; ptr += MINBPC(enc)) {
+      for (ptr += MINBPC(enc); HAS_CHAR(enc, ptr, end); ptr += MINBPC(enc)) {
         switch (BYTE_TYPE(enc, ptr)) {
         case BT_S: case BT_CR: case BT_LF:
           break;
@@ -432,7 +440,7 @@ static int PTRCALL
 PREFIX(scanHexCharRef)(const ENCODING *enc, const char *ptr,
                        const char *end, const char **nextTokPtr)
 {
-  if (ptr != end) {
+  if (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     case BT_DIGIT:
     case BT_HEX:
@@ -441,7 +449,7 @@ PREFIX(scanHexCharRef)(const ENCODING *enc, const char *ptr,
       *nextTokPtr = ptr;
       return XML_TOK_INVALID;
     }
-    for (ptr += MINBPC(enc); ptr != end; ptr += MINBPC(enc)) {
+    for (ptr += MINBPC(enc); HAS_CHAR(enc, ptr, end); ptr += MINBPC(enc)) {
       switch (BYTE_TYPE(enc, ptr)) {
       case BT_DIGIT:
       case BT_HEX:
@@ -464,7 +472,7 @@ static int PTRCALL
 PREFIX(scanCharRef)(const ENCODING *enc, const char *ptr,
                     const char *end, const char **nextTokPtr)
 {
-  if (ptr != end) {
+  if (HAS_CHAR(enc, ptr, end)) {
     if (CHAR_MATCHES(enc, ptr, ASCII_x))
       return PREFIX(scanHexCharRef)(enc, ptr + MINBPC(enc), end, nextTokPtr);
     switch (BYTE_TYPE(enc, ptr)) {
@@ -474,7 +482,7 @@ PREFIX(scanCharRef)(const ENCODING *enc, const char *ptr,
       *nextTokPtr = ptr;
       return XML_TOK_INVALID;
     }
-    for (ptr += MINBPC(enc); ptr != end; ptr += MINBPC(enc)) {
+    for (ptr += MINBPC(enc); HAS_CHAR(enc, ptr, end); ptr += MINBPC(enc)) {
       switch (BYTE_TYPE(enc, ptr)) {
       case BT_DIGIT:
         break;
@@ -496,8 +504,7 @@ static int PTRCALL
 PREFIX(scanRef)(const ENCODING *enc, const char *ptr, const char *end,
                 const char **nextTokPtr)
 {
-  if (ptr == end)
-    return XML_TOK_PARTIAL;
+  REQUIRE_CHAR(enc, ptr, end);
   switch (BYTE_TYPE(enc, ptr)) {
   CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
   case BT_NUM:
@@ -506,7 +513,7 @@ PREFIX(scanRef)(const ENCODING *enc, const char *ptr, const char *end,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_SEMI:
@@ -529,7 +536,7 @@ PREFIX(scanAtts)(const ENCODING *enc, const char *ptr, const char *end,
 #ifdef XML_NS
   int hadColon = 0;
 #endif
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
 #ifdef XML_NS
@@ -540,8 +547,7 @@ PREFIX(scanAtts)(const ENCODING *enc, const char *ptr, const char *end,
       }
       hadColon = 1;
       ptr += MINBPC(enc);
-      if (ptr == end)
-        return XML_TOK_PARTIAL;
+      REQUIRE_CHAR(enc, ptr, end);
       switch (BYTE_TYPE(enc, ptr)) {
       CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
       default:
@@ -555,8 +561,7 @@ PREFIX(scanAtts)(const ENCODING *enc, const char *ptr, const char *end,
         int t;
 
         ptr += MINBPC(enc);
-        if (ptr == end)
-          return XML_TOK_PARTIAL;
+        REQUIRE_CHAR(enc, ptr, end);
         t = BYTE_TYPE(enc, ptr);
         if (t == BT_EQUALS)
           break;
@@ -579,8 +584,7 @@ PREFIX(scanAtts)(const ENCODING *enc, const char *ptr, const char *end,
 #endif
         for (;;) {
           ptr += MINBPC(enc);
-          if (ptr == end)
-            return XML_TOK_PARTIAL;
+          REQUIRE_CHAR(enc, ptr, end);
           open = BYTE_TYPE(enc, ptr);
           if (open == BT_QUOT || open == BT_APOS)
             break;
@@ -598,8 +602,7 @@ PREFIX(scanAtts)(const ENCODING *enc, const char *ptr, const char *end,
         /* in attribute value */
         for (;;) {
           int t;
-          if (ptr == end)
-            return XML_TOK_PARTIAL;
+          REQUIRE_CHAR(enc, ptr, end);
           t = BYTE_TYPE(enc, ptr);
           if (t == open)
             break;
@@ -624,8 +627,7 @@ PREFIX(scanAtts)(const ENCODING *enc, const char *ptr, const char *end,
           }
         }
         ptr += MINBPC(enc);
-        if (ptr == end)
-          return XML_TOK_PARTIAL;
+        REQUIRE_CHAR(enc, ptr, end);
         switch (BYTE_TYPE(enc, ptr)) {
         case BT_S:
         case BT_CR:
@@ -642,8 +644,7 @@ PREFIX(scanAtts)(const ENCODING *enc, const char *ptr, const char *end,
         /* ptr points to closing quote */
         for (;;) {
           ptr += MINBPC(enc);
-          if (ptr == end)
-            return XML_TOK_PARTIAL;
+          REQUIRE_CHAR(enc, ptr, end);
           switch (BYTE_TYPE(enc, ptr)) {
           CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
           case BT_S: case BT_CR: case BT_LF:
@@ -655,8 +656,7 @@ PREFIX(scanAtts)(const ENCODING *enc, const char *ptr, const char *end,
           case BT_SOL:
           sol:
             ptr += MINBPC(enc);
-            if (ptr == end)
-              return XML_TOK_PARTIAL;
+            REQUIRE_CHAR(enc, ptr, end);
             if (!CHAR_MATCHES(enc, ptr, ASCII_GT)) {
               *nextTokPtr = ptr;
               return XML_TOK_INVALID;
@@ -688,13 +688,12 @@ PREFIX(scanLt)(const ENCODING *enc, const char *ptr, const char *end,
 #ifdef XML_NS
   int hadColon;
 #endif
-  if (ptr == end)
-    return XML_TOK_PARTIAL;
+  REQUIRE_CHAR(enc, ptr, end);
   switch (BYTE_TYPE(enc, ptr)) {
   CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
   case BT_EXCL:
-    if ((ptr += MINBPC(enc)) == end)
-      return XML_TOK_PARTIAL;
+    ptr += MINBPC(enc);
+    REQUIRE_CHAR(enc, ptr, end);
     switch (BYTE_TYPE(enc, ptr)) {
     case BT_MINUS:
       return PREFIX(scanComment)(enc, ptr + MINBPC(enc), end, nextTokPtr);
@@ -716,7 +715,7 @@ PREFIX(scanLt)(const ENCODING *enc, const char *ptr, const char *end,
   hadColon = 0;
 #endif
   /* we have a start-tag */
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
 #ifdef XML_NS
@@ -727,8 +726,7 @@ PREFIX(scanLt)(const ENCODING *enc, const char *ptr, const char *end,
       }
       hadColon = 1;
       ptr += MINBPC(enc);
-      if (ptr == end)
-        return XML_TOK_PARTIAL;
+      REQUIRE_CHAR(enc, ptr, end);
       switch (BYTE_TYPE(enc, ptr)) {
       CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
       default:
@@ -740,7 +738,7 @@ PREFIX(scanLt)(const ENCODING *enc, const char *ptr, const char *end,
     case BT_S: case BT_CR: case BT_LF:
       {
         ptr += MINBPC(enc);
-        while (ptr != end) {
+        while (HAS_CHAR(enc, ptr, end)) {
           switch (BYTE_TYPE(enc, ptr)) {
           CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
           case BT_GT:
@@ -765,8 +763,7 @@ PREFIX(scanLt)(const ENCODING *enc, const char *ptr, const char *end,
     case BT_SOL:
     sol:
       ptr += MINBPC(enc);
-      if (ptr == end)
-        return XML_TOK_PARTIAL;
+      REQUIRE_CHAR(enc, ptr, end);
       if (!CHAR_MATCHES(enc, ptr, ASCII_GT)) {
         *nextTokPtr = ptr;
         return XML_TOK_INVALID;
@@ -785,7 +782,7 @@ static int PTRCALL
 PREFIX(contentTok)(const ENCODING *enc, const char *ptr, const char *end,
                    const char **nextTokPtr)
 {
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   if (MINBPC(enc) > 1) {
     size_t n = end - ptr;
@@ -803,7 +800,7 @@ PREFIX(contentTok)(const ENCODING *enc, const char *ptr, const char *end,
     return PREFIX(scanRef)(enc, ptr + MINBPC(enc), end, nextTokPtr);
   case BT_CR:
     ptr += MINBPC(enc);
-    if (ptr == end)
+    if (! HAS_CHAR(enc, ptr, end))
       return XML_TOK_TRAILING_CR;
     if (BYTE_TYPE(enc, ptr) == BT_LF)
       ptr += MINBPC(enc);
@@ -814,12 +811,12 @@ PREFIX(contentTok)(const ENCODING *enc, const char *ptr, const char *end,
     return XML_TOK_DATA_NEWLINE;
   case BT_RSQB:
     ptr += MINBPC(enc);
-    if (ptr == end)
+    if (! HAS_CHAR(enc, ptr, end))
       return XML_TOK_TRAILING_RSQB;
     if (!CHAR_MATCHES(enc, ptr, ASCII_RSQB))
       break;
     ptr += MINBPC(enc);
-    if (ptr == end)
+    if (! HAS_CHAR(enc, ptr, end))
       return XML_TOK_TRAILING_RSQB;
     if (!CHAR_MATCHES(enc, ptr, ASCII_GT)) {
       ptr -= MINBPC(enc);
@@ -832,7 +829,7 @@ PREFIX(contentTok)(const ENCODING *enc, const char *ptr, const char *end,
     ptr += MINBPC(enc);
     break;
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: \
@@ -845,12 +842,12 @@ PREFIX(contentTok)(const ENCODING *enc, const char *ptr, const char *end,
     LEAD_CASE(2) LEAD_CASE(3) LEAD_CASE(4)
 #undef LEAD_CASE
     case BT_RSQB:
-      if (ptr + MINBPC(enc) != end) {
+      if (HAS_CHARS(enc, ptr, end, 2)) {
          if (!CHAR_MATCHES(enc, ptr + MINBPC(enc), ASCII_RSQB)) {
            ptr += MINBPC(enc);
            break;
          }
-         if (ptr + 2*MINBPC(enc) != end) {
+         if (HAS_CHARS(enc, ptr, end, 3)) {
            if (!CHAR_MATCHES(enc, ptr + 2*MINBPC(enc), ASCII_GT)) {
              ptr += MINBPC(enc);
              break;
@@ -884,8 +881,7 @@ static int PTRCALL
 PREFIX(scanPercent)(const ENCODING *enc, const char *ptr, const char *end,
                     const char **nextTokPtr)
 {
-  if (ptr == end)
-    return XML_TOK_PARTIAL;
+  REQUIRE_CHAR(enc, ptr, end);
   switch (BYTE_TYPE(enc, ptr)) {
   CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
   case BT_S: case BT_LF: case BT_CR: case BT_PERCNT:
@@ -895,7 +891,7 @@ PREFIX(scanPercent)(const ENCODING *enc, const char *ptr, const char *end,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_SEMI:
@@ -913,15 +909,14 @@ static int PTRCALL
 PREFIX(scanPoundName)(const ENCODING *enc, const char *ptr, const char *end,
                       const char **nextTokPtr)
 {
-  if (ptr == end)
-    return XML_TOK_PARTIAL;
+  REQUIRE_CHAR(enc, ptr, end);
   switch (BYTE_TYPE(enc, ptr)) {
   CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
   default:
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_CR: case BT_LF: case BT_S:
@@ -941,7 +936,7 @@ PREFIX(scanLit)(int open, const ENCODING *enc,
                 const char *ptr, const char *end,
                 const char **nextTokPtr)
 {
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     int t = BYTE_TYPE(enc, ptr);
     switch (t) {
     INVALID_CASES(ptr, nextTokPtr)
@@ -950,7 +945,7 @@ PREFIX(scanLit)(int open, const ENCODING *enc,
       ptr += MINBPC(enc);
       if (t != open)
         break;
-      if (ptr == end)
+      if (! HAS_CHAR(enc, ptr, end))
         return -XML_TOK_LITERAL;
       *nextTokPtr = ptr;
       switch (BYTE_TYPE(enc, ptr)) {
@@ -973,7 +968,7 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
                   const char **nextTokPtr)
 {
   int tok;
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   if (MINBPC(enc) > 1) {
     size_t n = end - ptr;
@@ -992,8 +987,7 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
   case BT_LT:
     {
       ptr += MINBPC(enc);
-      if (ptr == end)
-        return XML_TOK_PARTIAL;
+      REQUIRE_CHAR(enc, ptr, end);
       switch (BYTE_TYPE(enc, ptr)) {
       case BT_EXCL:
         return PREFIX(scanDecl)(enc, ptr + MINBPC(enc), end, nextTokPtr);
@@ -1021,7 +1015,7 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
   case BT_S: case BT_LF:
     for (;;) {
       ptr += MINBPC(enc);
-      if (ptr == end)
+      if (! HAS_CHAR(enc, ptr, end))
         break;
       switch (BYTE_TYPE(enc, ptr)) {
       case BT_S: case BT_LF:
@@ -1048,11 +1042,10 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
     return XML_TOK_OPEN_BRACKET;
   case BT_RSQB:
     ptr += MINBPC(enc);
-    if (ptr == end)
+    if (! HAS_CHAR(enc, ptr, end))
       return -XML_TOK_CLOSE_BRACKET;
     if (CHAR_MATCHES(enc, ptr, ASCII_RSQB)) {
-      if (ptr + MINBPC(enc) == end)
-        return XML_TOK_PARTIAL;
+      REQUIRE_CHARS(enc, ptr, end, 2);
       if (CHAR_MATCHES(enc, ptr + MINBPC(enc), ASCII_GT)) {
         *nextTokPtr = ptr + 2*MINBPC(enc);
         return XML_TOK_COND_SECT_CLOSE;
@@ -1065,7 +1058,7 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
     return XML_TOK_OPEN_PAREN;
   case BT_RPAR:
     ptr += MINBPC(enc);
-    if (ptr == end)
+    if (! HAS_CHAR(enc, ptr, end))
       return -XML_TOK_CLOSE_PAREN;
     switch (BYTE_TYPE(enc, ptr)) {
     case BT_AST:
@@ -1141,7 +1134,7 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_GT: case BT_RPAR: case BT_COMMA:
@@ -1154,8 +1147,7 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
       ptr += MINBPC(enc);
       switch (tok) {
       case XML_TOK_NAME:
-        if (ptr == end)
-          return XML_TOK_PARTIAL;
+        REQUIRE_CHAR(enc, ptr, end);
         tok = XML_TOK_PREFIXED_NAME;
         switch (BYTE_TYPE(enc, ptr)) {
         CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
@@ -1204,10 +1196,12 @@ PREFIX(attributeValueTok)(const ENCODING *enc, const char *ptr,
                           const char *end, const char **nextTokPtr)
 {
   const char *start;
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
+  else if (! HAS_CHAR(enc, ptr, end))
+    return XML_TOK_PARTIAL;
   start = ptr;
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: ptr += n; break;
@@ -1232,7 +1226,7 @@ PREFIX(attributeValueTok)(const ENCODING *enc, const char *ptr,
     case BT_CR:
       if (ptr == start) {
         ptr += MINBPC(enc);
-        if (ptr == end)
+        if (! HAS_CHAR(enc, ptr, end))
           return XML_TOK_TRAILING_CR;
         if (BYTE_TYPE(enc, ptr) == BT_LF)
           ptr += MINBPC(enc);
@@ -1262,10 +1256,12 @@ PREFIX(entityValueTok)(const ENCODING *enc, const char *ptr,
                        const char *end, const char **nextTokPtr)
 {
   const char *start;
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
+  else if (! HAS_CHAR(enc, ptr, end))
+    return XML_TOK_PARTIAL;
   start = ptr;
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: ptr += n; break;
@@ -1294,7 +1290,7 @@ PREFIX(entityValueTok)(const ENCODING *enc, const char *ptr,
     case BT_CR:
       if (ptr == start) {
         ptr += MINBPC(enc);
-        if (ptr == end)
+        if (! HAS_CHAR(enc, ptr, end))
           return XML_TOK_TRAILING_CR;
         if (BYTE_TYPE(enc, ptr) == BT_LF)
           ptr += MINBPC(enc);
@@ -1326,15 +1322,15 @@ PREFIX(ignoreSectionTok)(const ENCODING *enc, const char *ptr,
       end = ptr + n;
     }
   }
-  while (ptr != end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
     INVALID_CASES(ptr, nextTokPtr)
     case BT_LT:
-      if ((ptr += MINBPC(enc)) == end)
-        return XML_TOK_PARTIAL;
+      ptr += MINBPC(enc);
+      REQUIRE_CHAR(enc, ptr, end);
       if (CHAR_MATCHES(enc, ptr, ASCII_EXCL)) {
-        if ((ptr += MINBPC(enc)) == end)
-          return XML_TOK_PARTIAL;
+        ptr += MINBPC(enc);
+        REQUIRE_CHAR(enc, ptr, end);
         if (CHAR_MATCHES(enc, ptr, ASCII_LSQB)) {
           ++level;
           ptr += MINBPC(enc);
@@ -1342,11 +1338,11 @@ PREFIX(ignoreSectionTok)(const ENCODING *enc, const char *ptr,
       }
       break;
     case BT_RSQB:
-      if ((ptr += MINBPC(enc)) == end)
-        return XML_TOK_PARTIAL;
+      ptr += MINBPC(enc);
+      REQUIRE_CHAR(enc, ptr, end);
       if (CHAR_MATCHES(enc, ptr, ASCII_RSQB)) {
-        if ((ptr += MINBPC(enc)) == end)
-          return XML_TOK_PARTIAL;
+        ptr += MINBPC(enc);
+        REQUIRE_CHAR(enc, ptr, end);
         if (CHAR_MATCHES(enc, ptr, ASCII_GT)) {
           ptr += MINBPC(enc);
           if (level == 0) {
@@ -1373,7 +1369,7 @@ PREFIX(isPublicId)(const ENCODING *enc, const char *ptr, const char *end,
 {
   ptr += MINBPC(enc);
   end -= MINBPC(enc);
-  for (; ptr != end; ptr += MINBPC(enc)) {
+  for (; HAS_CHAR(enc, ptr, end); ptr += MINBPC(enc)) {
     switch (BYTE_TYPE(enc, ptr)) {
     case BT_DIGIT:
     case BT_HEX:
@@ -1521,7 +1517,7 @@ PREFIX(getAtts)(const ENCODING *enc, const char *ptr,
 }
 
 static int PTRFASTCALL
-PREFIX(charRefNumber)(const ENCODING *enc, const char *ptr)
+PREFIX(charRefNumber)(const ENCODING *UNUSED_P(enc), const char *ptr)
 {
   int result = 0;
   /* skip &# */
@@ -1565,7 +1561,7 @@ PREFIX(charRefNumber)(const ENCODING *enc, const char *ptr)
 }
 
 static int PTRCALL
-PREFIX(predefinedEntityName)(const ENCODING *enc, const char *ptr,
+PREFIX(predefinedEntityName)(const ENCODING *UNUSED_P(enc), const char *ptr,
                              const char *end)
 {
   switch ((end - ptr)/MINBPC(enc)) {
@@ -1683,11 +1679,11 @@ PREFIX(sameName)(const ENCODING *enc, const char *ptr1, const char *ptr2)
 }
 
 static int PTRCALL
-PREFIX(nameMatchesAscii)(const ENCODING *enc, const char *ptr1,
+PREFIX(nameMatchesAscii)(const ENCODING *UNUSED_P(enc), const char *ptr1,
                          const char *end1, const char *ptr2)
 {
   for (; *ptr2; ptr1 += MINBPC(enc), ptr2++) {
-    if (ptr1 == end1)
+    if (end1 - ptr1 < MINBPC(enc))
       return 0;
     if (!CHAR_MATCHES(enc, ptr1, *ptr2))
       return 0;
@@ -1744,7 +1740,7 @@ PREFIX(updatePosition)(const ENCODING *enc,
                        const char *end,
                        POSITION *pos)
 {
-  while (ptr < end) {
+  while (HAS_CHAR(enc, ptr, end)) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: \
@@ -1760,7 +1756,7 @@ PREFIX(updatePosition)(const ENCODING *enc,
     case BT_CR:
       pos->lineNumber++;
       ptr += MINBPC(enc);
-      if (ptr != end && BYTE_TYPE(enc, ptr) == BT_LF)
+      if (HAS_CHAR(enc, ptr, end) && BYTE_TYPE(enc, ptr) == BT_LF)
         ptr += MINBPC(enc);
       pos->columnNumber = (XML_Size)-1;
       break;
diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index ec7a60b6e9..d9cfa3e208 100644
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -1188,10 +1188,8 @@ newxmlparseobject(const char *encoding, const char *namespace_separator, PyObjec
         Py_DECREF(self);
         return NULL;
     }
-#if XML_COMBINED_VERSION >= 20100 || defined(XML_HAS_SET_HASH_SALT)
-    /* This feature was added upstream in libexpat 2.1.0.  Our expat copy
-     * has a backport of this feature where we also define XML_HAS_SET_HASH_SALT
-     * to indicate that we can still use it. */
+#if XML_COMBINED_VERSION >= 20100
+    /* This feature was added upstream in libexpat 2.1.0. */
     XML_SetHashSalt(self->itself,
                     (unsigned long)_Py_HashSecret.expat.hashsalt);
 #endif