Issue #12892: The utf-16* and utf-32* codecs now reject (lone) surrogates.

The utf-16* and utf-32* encoders no longer allow surrogate code points
(U+D800-U+DFFF) to be encoded.
The utf-32* decoders no longer decode byte sequences that correspond to
surrogate code points.
The surrogatepass error handler now works with the utf-16* and utf-32* codecs.

Based on patches by Victor Stinner and Kang-Hao (Kenny) Lu.

Doc/library/codecs.rst

@@ -365,18 +365,23 @@ and implemented by all standard Python codecs:
 |                         | in :pep:`383`.                                |
 +-------------------------+-----------------------------------------------+
 
-In addition, the following error handlers are specific to a single codec:
+In addition, the following error handlers are specific to Unicode encoding
+schemes:
 
-+-------------------+---------+-------------------------------------------+
-| Value             | Codec   | Meaning                                   |
-+===================+=========+===========================================+
-|``'surrogatepass'``| utf-8   | Allow encoding and decoding of surrogate  |
-|                   |         | codes in UTF-8.                           |
-+-------------------+---------+-------------------------------------------+
++-------------------+------------------------+-------------------------------------------+
+| Value             | Codec                  | Meaning                                   |
++===================+========================+===========================================+
+|``'surrogatepass'``| utf-8, utf-16, utf-32, | Allow encoding and decoding of surrogate  |
+|                   | utf-16-be, utf-16-le,  | codes in all the Unicode encoding schemes.|
+|                   | utf-32-be, utf-32-le   |                                           |
++-------------------+------------------------+-------------------------------------------+
 
 .. versionadded:: 3.1
    The ``'surrogateescape'`` and ``'surrogatepass'`` error handlers.
 
+.. versionchanged:: 3.4
+   The ``'surrogatepass'`` error handlers now works with utf-16\* and utf-32\* codecs.
+
 The set of allowed values can be extended via :meth:`register_error`.
 
 
@@ -1167,6 +1172,12 @@ particular, the following variants typically exist:
 | utf_8_sig       |                                | all languages                  |
 +-----------------+--------------------------------+--------------------------------+
 
+.. versionchanged:: 3.4
+   The utf-16\* and utf-32\* encoders no longer allow surrogate code points
+   (U+D800--U+DFFF) to be encoded.  The utf-32\* decoders no longer decode
+   byte sequences that correspond to surrogate code points.
+
+
 Python Specific Encodings
 -------------------------
 

Doc/whatsnew/3.4.rst

@@ -253,6 +253,13 @@ Some smaller changes made to the core Python language are:
   ``__main__.__file__`` when a script has been executed directly using
   a relative path (Contributed by Brett Cannon in :issue:`18416`).
 
+* Now all the UTF-\* codecs (except UTF-7) reject surrogates during both
+  encoding and decoding unless the ``surrogatepass`` error handler is used,
+  with the exception of the UTF-16 decoder that accepts valid surrogate pairs,
+  and the UTF-16 encoder that produces them while encoding non-BMP characters.
+  Contributed by Victor Stinner, Kang-Hao (Kenny) Lu and Serhiy Storchaka in
+  :issue:`12892`.
+
 
 New Modules
 ===========

Lib/test/test_codecs.py

@@ -300,8 +300,46 @@ class ReadTest(MixInCheckStateHandling):
         self.assertEqual(reader.readline(), s5)
         self.assertEqual(reader.readline(), "")
 
+    ill_formed_sequence_replace = "\ufffd"
+
+    def test_lone_surrogates(self):
+        self.assertRaises(UnicodeEncodeError, "\ud800".encode, self.encoding)
+        self.assertEqual("[\uDC80]".encode(self.encoding, "backslashreplace"),
+                         "[\\udc80]".encode(self.encoding))
+        self.assertEqual("[\uDC80]".encode(self.encoding, "xmlcharrefreplace"),
+                         "[�]".encode(self.encoding))
+        self.assertEqual("[\uDC80]".encode(self.encoding, "ignore"),
+                         "[]".encode(self.encoding))
+        self.assertEqual("[\uDC80]".encode(self.encoding, "replace"),
+                         "[?]".encode(self.encoding))
+
+        bom = "".encode(self.encoding)
+        for before, after in [("\U00010fff", "A"), ("[", "]"),
+                              ("A", "\U00010fff")]:
+            before_sequence = before.encode(self.encoding)[len(bom):]
+            after_sequence = after.encode(self.encoding)[len(bom):]
+            test_string = before + "\uDC80" + after
+            test_sequence = (bom + before_sequence +
+                             self.ill_formed_sequence + after_sequence)
+            self.assertRaises(UnicodeDecodeError, test_sequence.decode,
+                              self.encoding)
+            self.assertEqual(test_string.encode(self.encoding,
+                                                "surrogatepass"),
+                             test_sequence)
+            self.assertEqual(test_sequence.decode(self.encoding,
+                                                  "surrogatepass"),
+                             test_string)
+            self.assertEqual(test_sequence.decode(self.encoding, "ignore"),
+                             before + after)
+            self.assertEqual(test_sequence.decode(self.encoding, "replace"),
+                             before + self.ill_formed_sequence_replace + after)
+
 class UTF32Test(ReadTest, unittest.TestCase):
     encoding = "utf-32"
+    if sys.byteorder == 'little':
+        ill_formed_sequence = b"\x80\xdc\x00\x00"
+    else:
+        ill_formed_sequence = b"\x00\x00\xdc\x80"
 
     spamle = (b'\xff\xfe\x00\x00'
               b's\x00\x00\x00p\x00\x00\x00a\x00\x00\x00m\x00\x00\x00'
@@ -393,6 +431,7 @@ class UTF32Test(ReadTest, unittest.TestCase):
 
 class UTF32LETest(ReadTest, unittest.TestCase):
     encoding = "utf-32-le"
+    ill_formed_sequence = b"\x80\xdc\x00\x00"
 
     def test_partial(self):
         self.check_partial(
@@ -437,6 +476,7 @@ class UTF32LETest(ReadTest, unittest.TestCase):
 
 class UTF32BETest(ReadTest, unittest.TestCase):
     encoding = "utf-32-be"
+    ill_formed_sequence = b"\x00\x00\xdc\x80"
 
     def test_partial(self):
         self.check_partial(
@@ -482,6 +522,10 @@ class UTF32BETest(ReadTest, unittest.TestCase):
 
 class UTF16Test(ReadTest, unittest.TestCase):
     encoding = "utf-16"
+    if sys.byteorder == 'little':
+        ill_formed_sequence = b"\x80\xdc"
+    else:
+        ill_formed_sequence = b"\xdc\x80"
 
     spamle = b'\xff\xfes\x00p\x00a\x00m\x00s\x00p\x00a\x00m\x00'
     spambe = b'\xfe\xff\x00s\x00p\x00a\x00m\x00s\x00p\x00a\x00m'
@@ -562,6 +606,7 @@ class UTF16Test(ReadTest, unittest.TestCase):
 
 class UTF16LETest(ReadTest, unittest.TestCase):
     encoding = "utf-16-le"
+    ill_formed_sequence = b"\x80\xdc"
 
     def test_partial(self):
         self.check_partial(
@@ -605,6 +650,7 @@ class UTF16LETest(ReadTest, unittest.TestCase):
 
 class UTF16BETest(ReadTest, unittest.TestCase):
     encoding = "utf-16-be"
+    ill_formed_sequence = b"\xdc\x80"
 
     def test_partial(self):
         self.check_partial(
@@ -648,6 +694,8 @@ class UTF16BETest(ReadTest, unittest.TestCase):
 
 class UTF8Test(ReadTest, unittest.TestCase):
     encoding = "utf-8"
+    ill_formed_sequence = b"\xed\xb2\x80"
+    ill_formed_sequence_replace = "\ufffd" * 3
 
     def test_partial(self):
         self.check_partial(
@@ -677,18 +725,11 @@ class UTF8Test(ReadTest, unittest.TestCase):
                                          u, u.encode(self.encoding))
 
     def test_lone_surrogates(self):
-        self.assertRaises(UnicodeEncodeError, "\ud800".encode, "utf-8")
-        self.assertRaises(UnicodeDecodeError, b"\xed\xa0\x80".decode, "utf-8")
-        self.assertEqual("[\uDC80]".encode("utf-8", "backslashreplace"),
-                         b'[\\udc80]')
-        self.assertEqual("[\uDC80]".encode("utf-8", "xmlcharrefreplace"),
-                         b'[�]')
-        self.assertEqual("[\uDC80]".encode("utf-8", "surrogateescape"),
+        super().test_lone_surrogates()
+        # not sure if this is making sense for
+        # UTF-16 and UTF-32
+        self.assertEqual("[\uDC80]".encode('utf-8', "surrogateescape"),
                          b'[\x80]')
-        self.assertEqual("[\uDC80]".encode("utf-8", "ignore"),
-                         b'[]')
-        self.assertEqual("[\uDC80]".encode("utf-8", "replace"),
-                         b'[?]')
 
     def test_surrogatepass_handler(self):
         self.assertEqual("abc\ud800def".encode("utf-8", "surrogatepass"),
@@ -851,6 +892,9 @@ class UTF7Test(ReadTest, unittest.TestCase):
         self.assertEqual('\ud801\udca0'.encode(self.encoding), b'+2AHcoA-')
         self.assertEqual(b'+2AHcoA-'.decode(self.encoding), '\U000104A0')
 
+    test_lone_surrogates = None
+
+
 class UTF16ExTest(unittest.TestCase):
 
     def test_errors(self):
@@ -875,7 +919,7 @@ class ReadBufferTest(unittest.TestCase):
         self.assertRaises(TypeError, codecs.readbuffer_encode)
         self.assertRaises(TypeError, codecs.readbuffer_encode, 42)
 
-class UTF8SigTest(ReadTest, unittest.TestCase):
+class UTF8SigTest(UTF8Test, unittest.TestCase):
     encoding = "utf-8-sig"
 
     def test_partial(self):

Misc/ACKS

@@ -783,6 +783,7 @@ Ned Jackson Lovely
 Jason Lowe
 Tony Lownds
 Ray Loyzaga
+Kang-Hao (Kenny) Lu
 Lukas Lueg
 Loren Luke
 Fredrik Lundh

Misc/NEWS

@@ -10,6 +10,12 @@ Projected release date: 2013-11-24
 Core and Builtins
 -----------------
 
+- Issue #12892: The utf-16* and utf-32* encoders no longer allow surrogate code
+  points (U+D800-U+DFFF) to be encoded.  The utf-32* decoders no longer decode
+  byte sequences that correspond to surrogate code points.  The surrogatepass
+  error handler now works with the utf-16* and utf-32* codecs.  Based on
+  patches by Victor Stinner and Kang-Hao (Kenny) Lu.
+
 - Issue #17806: Added keyword-argument support for "tabsize" to
   str/bytes.expandtabs().
 

Objects/stringlib/codecs.h

@@ -596,66 +596,232 @@ IllegalSurrogate:
 #undef SWAB
 
 
-Py_LOCAL_INLINE(void)
-STRINGLIB(utf16_encode)(unsigned short *out,
-                        const STRINGLIB_CHAR *in,
+#if STRINGLIB_MAX_CHAR >= 0x80
+Py_LOCAL_INLINE(Py_ssize_t)
+STRINGLIB(utf16_encode_)(const STRINGLIB_CHAR *in,
                         Py_ssize_t len,
+                        unsigned short **outptr,
                         int native_ordering)
 {
+    unsigned short *out = *outptr;
     const STRINGLIB_CHAR *end = in + len;
 #if STRINGLIB_SIZEOF_CHAR == 1
 # define SWAB2(CH)  ((CH) << 8)
 #else
 # define SWAB2(CH)  (((CH) << 8) | ((CH) >> 8))
 #endif
-#if STRINGLIB_MAX_CHAR < 0x10000
     if (native_ordering) {
-# if STRINGLIB_SIZEOF_CHAR == 2
-        Py_MEMCPY(out, in, 2 * len);
-# else
-        _PyUnicode_CONVERT_BYTES(STRINGLIB_CHAR, unsigned short, in, end, out);
+#if STRINGLIB_MAX_CHAR < 0x10000
+        const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
+        while (in < unrolled_end) {
+# if STRINGLIB_MAX_CHAR >= 0xd800
+            if (((in[0] ^ 0xd800) &
+                 (in[1] ^ 0xd800) &
+                 (in[2] ^ 0xd800) &
+                 (in[3] ^ 0xd800) & 0xf800) == 0)
+                break;
 # endif
+            out[0] = in[0];
+            out[1] = in[1];
+            out[2] = in[2];
+            out[3] = in[3];
+            in += 4; out += 4;
+        }
+#endif
+        while (in < end) {
+            Py_UCS4 ch;
+            ch = *in++;
+#if STRINGLIB_MAX_CHAR >= 0xd800
+            if (ch < 0xd800)
+                *out++ = ch;
+            else if (ch < 0xe000)
+                /* reject surrogate characters (U+DC800-U+DFFF) */
+                goto fail;
+# if STRINGLIB_MAX_CHAR >= 0x10000
+            else if (ch >= 0x10000) {
+                out[0] = Py_UNICODE_HIGH_SURROGATE(ch);
+                out[1] = Py_UNICODE_LOW_SURROGATE(ch);
+                out += 2;
+            }
+# endif
+            else
+#endif
+                *out++ = ch;
+        }
     } else {
+#if STRINGLIB_MAX_CHAR < 0x10000
         const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
         while (in < unrolled_end) {
+# if STRINGLIB_MAX_CHAR >= 0xd800
+            if (((in[0] ^ 0xd800) &
+                 (in[1] ^ 0xd800) &
+                 (in[2] ^ 0xd800) &
+                 (in[3] ^ 0xd800) & 0xf800) == 0)
+                break;
+# endif
             out[0] = SWAB2(in[0]);
             out[1] = SWAB2(in[1]);
             out[2] = SWAB2(in[2]);
             out[3] = SWAB2(in[3]);
             in += 4; out += 4;
         }
+#endif
         while (in < end) {
-            *out++ = SWAB2(*in);
-            ++in;
+            Py_UCS4 ch = *in++;
+#if STRINGLIB_MAX_CHAR >= 0xd800
+            if (ch < 0xd800)
+                *out++ = SWAB2((Py_UCS2)ch);
+            else if (ch < 0xe000)
+                /* reject surrogate characters (U+DC800-U+DFFF) */
+                goto fail;
+# if STRINGLIB_MAX_CHAR >= 0x10000
+            else if (ch >= 0x10000) {
+                Py_UCS2 ch1 = Py_UNICODE_HIGH_SURROGATE(ch);
+                Py_UCS2 ch2 = Py_UNICODE_LOW_SURROGATE(ch);
+                out[0] = SWAB2(ch1);
+                out[1] = SWAB2(ch2);
+                out += 2;
+            }
+# endif
+            else
+#endif
+                *out++ = SWAB2((Py_UCS2)ch);
         }
     }
-#else
+    *outptr = out;
+    return len;
+#if STRINGLIB_MAX_CHAR >= 0xd800
+  fail:
+#endif
+    *outptr = out;
+    return len - (end - in + 1);
+}
+#endif
+
+#undef SWAB2
+
+#if STRINGLIB_MAX_CHAR >= 0x80
+Py_LOCAL_INLINE(Py_ssize_t)
+STRINGLIB(utf16_encode)(const STRINGLIB_CHAR *in,
+                        Py_ssize_t len,
+                        unsigned short **outptr,
+                        int native_ordering)
+{
+    unsigned short *out = *outptr;
+    const STRINGLIB_CHAR *end = in + len;
+#if STRINGLIB_SIZEOF_CHAR == 1
     if (native_ordering) {
+        const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
+        while (in < unrolled_end) {
+            out[0] = in[0];
+            out[1] = in[1];
+            out[2] = in[2];
+            out[3] = in[3];
+            in += 4; out += 4;
+        }
+        while (in < end) {
+            *out++ = *in++;
+        }
+    } else {
+# define SWAB2(CH)  ((CH) << 8) /* high byte is zero */
+        const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
+        while (in < unrolled_end) {
+            out[0] = SWAB2(in[0]);
+            out[1] = SWAB2(in[1]);
+            out[2] = SWAB2(in[2]);
+            out[3] = SWAB2(in[3]);
+            in += 4; out += 4;
+        }
         while (in < end) {
             Py_UCS4 ch = *in++;
-            if (ch < 0x10000)
+            *out++ = SWAB2((Py_UCS2)ch);
+        }
+#undef SWAB2
+    }
+    *outptr = out;
+    return len;
+#else
+    if (native_ordering) {
+#if STRINGLIB_MAX_CHAR < 0x10000
+        const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
+        while (in < unrolled_end) {
+            /* check if any character is a surrogate character */
+            if (((in[0] ^ 0xd800) &
+                 (in[1] ^ 0xd800) &
+                 (in[2] ^ 0xd800) &
+                 (in[3] ^ 0xd800) & 0xf800) == 0)
+                break;
+            out[0] = in[0];
+            out[1] = in[1];
+            out[2] = in[2];
+            out[3] = in[3];
+            in += 4; out += 4;
+        }
+#endif
+        while (in < end) {
+            Py_UCS4 ch;
+            ch = *in++;
+            if (ch < 0xd800)
                 *out++ = ch;
-            else {
+            else if (ch < 0xe000)
+                /* reject surrogate characters (U+DC800-U+DFFF) */
+                goto fail;
+#if STRINGLIB_MAX_CHAR >= 0x10000
+            else if (ch >= 0x10000) {
                 out[0] = Py_UNICODE_HIGH_SURROGATE(ch);
                 out[1] = Py_UNICODE_LOW_SURROGATE(ch);
                 out += 2;
             }
+#endif
+            else
+                *out++ = ch;
         }
     } else {
+#define SWAB2(CH)  (((CH) << 8) | ((CH) >> 8))
+#if STRINGLIB_MAX_CHAR < 0x10000
+        const STRINGLIB_CHAR *unrolled_end = in + _Py_SIZE_ROUND_DOWN(len, 4);
+        while (in < unrolled_end) {
+            /* check if any character is a surrogate character */
+            if (((in[0] ^ 0xd800) &
+                 (in[1] ^ 0xd800) &
+                 (in[2] ^ 0xd800) &
+                 (in[3] ^ 0xd800) & 0xf800) == 0)
+                break;
+            out[0] = SWAB2(in[0]);
+            out[1] = SWAB2(in[1]);
+            out[2] = SWAB2(in[2]);
+            out[3] = SWAB2(in[3]);
+            in += 4; out += 4;
+        }
+#endif
         while (in < end) {
             Py_UCS4 ch = *in++;
-            if (ch < 0x10000)
+            if (ch < 0xd800)
                 *out++ = SWAB2((Py_UCS2)ch);
-            else {
+            else if (ch < 0xe000)
+                /* reject surrogate characters (U+DC800-U+DFFF) */
+                goto fail;
+#if STRINGLIB_MAX_CHAR >= 0x10000
+            else if (ch >= 0x10000) {
                 Py_UCS2 ch1 = Py_UNICODE_HIGH_SURROGATE(ch);
                 Py_UCS2 ch2 = Py_UNICODE_LOW_SURROGATE(ch);
                 out[0] = SWAB2(ch1);
                 out[1] = SWAB2(ch2);
                 out += 2;
             }
+#endif
+            else
+                *out++ = SWAB2((Py_UCS2)ch);
         }
+#undef SWAB2
     }
+    *outptr = out;
+    return len;
+  fail:
+    *outptr = out;
+    return len - (end - in + 1);
 #endif
-#undef SWAB2
 }
+#endif
+
 #endif /* STRINGLIB_IS_UNICODE */

Python/codecs.c

@@ -753,6 +753,65 @@ PyObject *PyCodec_BackslashReplaceErrors(PyObject *exc)
     }
 }
 
+#define ENC_UTF8        0
+#define ENC_UTF16BE     1
+#define ENC_UTF16LE     2
+#define ENC_UTF32BE     3
+#define ENC_UTF32LE     4
+
+static int
+get_standard_encoding(const char *encoding, int *bytelength)
+{
+    if (Py_TOLOWER(encoding[0]) == 'u' &&
+        Py_TOLOWER(encoding[1]) == 't' &&
+        Py_TOLOWER(encoding[2]) == 'f') {
+        encoding += 3;
+        if (*encoding == '-' || *encoding == '_' )
+            encoding++;
+        if (encoding[0] == '1' && encoding[1] == '6') {
+            encoding += 2;
+            *bytelength = 2;
+            if (*encoding == '\0') {
+#ifdef WORDS_BIGENDIAN
+                return ENC_UTF16BE;
+#else
+                return ENC_UTF16LE;
+#endif
+            }
+            if (*encoding == '-' || *encoding == '_' )
+                encoding++;
+            if (Py_TOLOWER(encoding[1]) == 'e' && encoding[2] == '\0') {
+                if (Py_TOLOWER(encoding[0]) == 'b')
+                    return ENC_UTF16BE;
+                if (Py_TOLOWER(encoding[0]) == 'l')
+                    return ENC_UTF16LE;
+            }
+        }
+        else if (encoding[0] == '3' && encoding[1] == '2') {
+            encoding += 2;
+            *bytelength = 4;
+            if (*encoding == '\0') {
+#ifdef WORDS_BIGENDIAN
+                return ENC_UTF32BE;
+#else
+                return ENC_UTF32LE;
+#endif
+            }
+            if (*encoding == '-' || *encoding == '_' )
+                encoding++;
+            if (Py_TOLOWER(encoding[1]) == 'e' && encoding[2] == '\0') {
+                if (Py_TOLOWER(encoding[0]) == 'b')
+                    return ENC_UTF32BE;
+                if (Py_TOLOWER(encoding[0]) == 'l')
+                    return ENC_UTF32LE;
+            }
+        }
+    }
+    /* utf-8 */
+    *bytelength = 3;
+    return ENC_UTF8;
+}
+
 /* This handler is declared static until someone demonstrates
    a need to call it directly. */
 static PyObject *
@@ -760,24 +819,40 @@ PyCodec_SurrogatePassErrors(PyObject *exc)
 {
     PyObject *restuple;
     PyObject *object;
+    PyObject *encode;
+    char *encoding;
+    int code;
+    int bytelength;
     Py_ssize_t i;
     Py_ssize_t start;
     Py_ssize_t end;
     PyObject *res;
     if (PyObject_IsInstance(exc, PyExc_UnicodeEncodeError)) {
-        char *outp;
+        unsigned char *outp;
         if (PyUnicodeEncodeError_GetStart(exc, &start))
             return NULL;
         if (PyUnicodeEncodeError_GetEnd(exc, &end))
             return NULL;
         if (!(object = PyUnicodeEncodeError_GetObject(exc)))
             return NULL;
-        res = PyBytes_FromStringAndSize(NULL, 3*(end-start));
+        if (!(encode = PyUnicodeEncodeError_GetEncoding(exc))) {
+            Py_DECREF(object);
+            return NULL;
+        }
+        if (!(encoding = PyUnicode_AsUTF8(encode))) {
+            Py_DECREF(object);
+            Py_DECREF(encode);
+            return NULL;
+        }
+        code = get_standard_encoding(encoding, &bytelength);
+        Py_DECREF(encode);
+
+        res = PyBytes_FromStringAndSize(NULL, bytelength*(end-start));
         if (!res) {
             Py_DECREF(object);
             return NULL;
         }
-        outp = PyBytes_AsString(res);
+        outp = (unsigned char*)PyBytes_AsString(res);
         for (i = start; i < end; i++) {
             /* object is guaranteed to be "ready" */
             Py_UCS4 ch = PyUnicode_READ_CHAR(object, i);
@@ -788,9 +863,33 @@ PyCodec_SurrogatePassErrors(PyObject *exc)
                 Py_DECREF(object);
                 return NULL;
             }
-            *outp++ = (char)(0xe0 | (ch >> 12));
-            *outp++ = (char)(0x80 | ((ch >> 6) & 0x3f));
-            *outp++ = (char)(0x80 | (ch & 0x3f));
+            switch (code) {
+            case ENC_UTF8:
+                *outp++ = (unsigned char)(0xe0 | (ch >> 12));
+                *outp++ = (unsigned char)(0x80 | ((ch >> 6) & 0x3f));
+                *outp++ = (unsigned char)(0x80 | (ch & 0x3f));
+                break;
+            case ENC_UTF16LE:
+                *outp++ = (unsigned char) ch;
+                *outp++ = (unsigned char)(ch >> 8);
+                break;
+            case ENC_UTF16BE:
+                *outp++ = (unsigned char)(ch >> 8);
+                *outp++ = (unsigned char) ch;
+                break;
+            case ENC_UTF32LE:
+                *outp++ = (unsigned char) ch;
+                *outp++ = (unsigned char)(ch >> 8);
+                *outp++ = (unsigned char)(ch >> 16);
+                *outp++ = (unsigned char)(ch >> 24);
+                break;
+            case ENC_UTF32BE:
+                *outp++ = (unsigned char)(ch >> 24);
+                *outp++ = (unsigned char)(ch >> 16);
+                *outp++ = (unsigned char)(ch >> 8);
+                *outp++ = (unsigned char) ch;
+                break;
+            }
         }
         restuple = Py_BuildValue("(On)", res, end);
         Py_DECREF(res);
@@ -802,34 +901,64 @@ PyCodec_SurrogatePassErrors(PyObject *exc)
         Py_UCS4 ch = 0;
         if (PyUnicodeDecodeError_GetStart(exc, &start))
             return NULL;
+        if (PyUnicodeDecodeError_GetEnd(exc, &end))
+            return NULL;
         if (!(object = PyUnicodeDecodeError_GetObject(exc)))
             return NULL;
         if (!(p = (unsigned char*)PyBytes_AsString(object))) {
             Py_DECREF(object);
             return NULL;
         }
+        if (!(encode = PyUnicodeDecodeError_GetEncoding(exc))) {
+            Py_DECREF(object);
+            return NULL;
+        }
+        if (!(encoding = PyUnicode_AsUTF8(encode))) {
+            Py_DECREF(object);
+            Py_DECREF(encode);
+            return NULL;
+        }
+        code = get_standard_encoding(encoding, &bytelength);
+        Py_DECREF(encode);
+
         /* Try decoding a single surrogate character. If
            there are more, let the codec call us again. */
         p += start;
-        if (PyBytes_GET_SIZE(object) - start >= 3 &&
-            (p[0] & 0xf0) == 0xe0 &&
-            (p[1] & 0xc0) == 0x80 &&
-            (p[2] & 0xc0) == 0x80) {
-            /* it's a three-byte code */
-            ch = ((p[0] & 0x0f) << 12) + ((p[1] & 0x3f) << 6) + (p[2] & 0x3f);
-            if (!Py_UNICODE_IS_SURROGATE(ch))
-                /* it's not a surrogate - fail */
-                ch = 0;
+        if (PyBytes_GET_SIZE(object) - start >= bytelength) {
+            switch (code) {
+            case ENC_UTF8:
+                if ((p[0] & 0xf0) == 0xe0 &&
+                    (p[1] & 0xc0) == 0x80 &&
+                    (p[2] & 0xc0) == 0x80) {
+                    /* it's a three-byte code */
+                    ch = ((p[0] & 0x0f) << 12) + ((p[1] & 0x3f) << 6) + (p[2] & 0x3f);
+                }
+                break;
+            case ENC_UTF16LE:
+                ch = p[1] << 8 | p[0];
+                break;
+            case ENC_UTF16BE:
+                ch = p[0] << 8 | p[1];
+                break;
+            case ENC_UTF32LE:
+                ch = (p[3] << 24) | (p[2] << 16) | (p[1] << 8) | p[0];
+                break;
+            case ENC_UTF32BE:
+                ch = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
+                break;
+            }
         }
+
         Py_DECREF(object);
-        if (ch == 0) {
+        if (!Py_UNICODE_IS_SURROGATE(ch)) {
+            /* it's not a surrogate - fail */
             PyErr_SetObject(PyExceptionInstance_Class(exc), exc);
             return NULL;
         }
         res = PyUnicode_FromOrdinal(ch);
         if (res == NULL)
             return NULL;
-        return Py_BuildValue("(Nn)", res, start+3);
+        return Py_BuildValue("(Nn)", res, start + bytelength);
     }
     else {
         wrong_exception_type(exc);