1 files changed, 450 insertions, 1 deletions

diff --git a/src/backend/utils/mb/mbutils.c b/src/backend/utils/mb/mbutils.c
index 5d7cc74ad6c..86787bcb319 100644
--- a/src/backend/utils/mb/mbutils.c
+++ b/src/backend/utils/mb/mbutils.c
@@ -1066,6 +1066,23 @@ pg_client_encoding(PG_FUNCTION_ARGS)
 	return DirectFunctionCall1(namein, CStringGetDatum(ClientEncoding->name));
 }
 
+Datum
+PG_char_to_encoding(PG_FUNCTION_ARGS)
+{
+	Name		s = PG_GETARG_NAME(0);
+
+	PG_RETURN_INT32(pg_char_to_encoding(NameStr(*s)));
+}
+
+Datum
+PG_encoding_to_char(PG_FUNCTION_ARGS)
+{
+	int32		encoding = PG_GETARG_INT32(0);
+	const char *encoding_name = pg_encoding_to_char(encoding);
+
+	return DirectFunctionCall1(namein, CStringGetDatum(encoding_name));
+}
+
 /*
  * gettext() returns messages in this encoding.  This often matches the
  * database encoding, but it differs for SQL_ASCII databases, for processes
@@ -1078,6 +1095,438 @@ GetMessageEncoding(void)
 	return MessageEncoding->encoding;
 }
 
+
+/*
+ * Generic character incrementer function.
+ *
+ * Not knowing anything about the properties of the encoding in use, we just
+ * keep incrementing the last byte until we get a validly-encoded result,
+ * or we run out of values to try.  We don't bother to try incrementing
+ * higher-order bytes, so there's no growth in runtime for wider characters.
+ * (If we did try to do that, we'd need to consider the likelihood that 255
+ * is not a valid final byte in the encoding.)
+ */
+static bool
+pg_generic_charinc(unsigned char *charptr, int len)
+{
+	unsigned char *lastbyte = charptr + len - 1;
+	mbverifier	mbverify;
+
+	/* We can just invoke the character verifier directly. */
+	mbverify = pg_wchar_table[GetDatabaseEncoding()].mbverify;
+
+	while (*lastbyte < (unsigned char) 255)
+	{
+		(*lastbyte)++;
+		if ((*mbverify) (charptr, len) == len)
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * UTF-8 character incrementer function.
+ *
+ * For a one-byte character less than 0x7F, we just increment the byte.
+ *
+ * For a multibyte character, every byte but the first must fall between 0x80
+ * and 0xBF; and the first byte must be between 0xC0 and 0xF4.  We increment
+ * the last byte that's not already at its maximum value.  If we can't find a
+ * byte that's less than the maximum allowable value, we simply fail.  We also
+ * need some special-case logic to skip regions used for surrogate pair
+ * handling, as those should not occur in valid UTF-8.
+ *
+ * Note that we don't reset lower-order bytes back to their minimums, since
+ * we can't afford to make an exhaustive search (see make_greater_string).
+ */
+static bool
+pg_utf8_increment(unsigned char *charptr, int length)
+{
+	unsigned char a;
+	unsigned char limit;
+
+	switch (length)
+	{
+		default:
+			/* reject lengths 5 and 6 for now */
+			return false;
+		case 4:
+			a = charptr[3];
+			if (a < 0xBF)
+			{
+				charptr[3]++;
+				break;
+			}
+			/* FALL THRU */
+		case 3:
+			a = charptr[2];
+			if (a < 0xBF)
+			{
+				charptr[2]++;
+				break;
+			}
+			/* FALL THRU */
+		case 2:
+			a = charptr[1];
+			switch (*charptr)
+			{
+				case 0xED:
+					limit = 0x9F;
+					break;
+				case 0xF4:
+					limit = 0x8F;
+					break;
+				default:
+					limit = 0xBF;
+					break;
+			}
+			if (a < limit)
+			{
+				charptr[1]++;
+				break;
+			}
+			/* FALL THRU */
+		case 1:
+			a = *charptr;
+			if (a == 0x7F || a == 0xDF || a == 0xEF || a == 0xF4)
+				return false;
+			charptr[0]++;
+			break;
+	}
+
+	return true;
+}
+
+/*
+ * EUC-JP character incrementer function.
+ *
+ * If the sequence starts with SS2 (0x8e), it must be a two-byte sequence
+ * representing JIS X 0201 characters with the second byte ranging between
+ * 0xa1 and 0xdf.  We just increment the last byte if it's less than 0xdf,
+ * and otherwise rewrite the whole sequence to 0xa1 0xa1.
+ *
+ * If the sequence starts with SS3 (0x8f), it must be a three-byte sequence
+ * in which the last two bytes range between 0xa1 and 0xfe.  The last byte
+ * is incremented if possible, otherwise the second-to-last byte.
+ *
+ * If the sequence starts with a value other than the above and its MSB
+ * is set, it must be a two-byte sequence representing JIS X 0208 characters
+ * with both bytes ranging between 0xa1 and 0xfe.  The last byte is
+ * incremented if possible, otherwise the second-to-last byte.
+ *
+ * Otherwise, the sequence is a single-byte ASCII character. It is
+ * incremented up to 0x7f.
+ */
+static bool
+pg_eucjp_increment(unsigned char *charptr, int length)
+{
+	unsigned char c1,
+				c2;
+	int			i;
+
+	c1 = *charptr;
+
+	switch (c1)
+	{
+		case SS2:				/* JIS X 0201 */
+			if (length != 2)
+				return false;
+
+			c2 = charptr[1];
+
+			if (c2 >= 0xdf)
+				charptr[0] = charptr[1] = 0xa1;
+			else if (c2 < 0xa1)
+				charptr[1] = 0xa1;
+			else
+				charptr[1]++;
+			break;
+
+		case SS3:				/* JIS X 0212 */
+			if (length != 3)
+				return false;
+
+			for (i = 2; i > 0; i--)
+			{
+				c2 = charptr[i];
+				if (c2 < 0xa1)
+				{
+					charptr[i] = 0xa1;
+					return true;
+				}
+				else if (c2 < 0xfe)
+				{
+					charptr[i]++;
+					return true;
+				}
+			}
+
+			/* Out of 3-byte code region */
+			return false;
+
+		default:
+			if (IS_HIGHBIT_SET(c1)) /* JIS X 0208? */
+			{
+				if (length != 2)
+					return false;
+
+				for (i = 1; i >= 0; i--)
+				{
+					c2 = charptr[i];
+					if (c2 < 0xa1)
+					{
+						charptr[i] = 0xa1;
+						return true;
+					}
+					else if (c2 < 0xfe)
+					{
+						charptr[i]++;
+						return true;
+					}
+				}
+
+				/* Out of 2 byte code region */
+				return false;
+			}
+			else
+			{					/* ASCII, single byte */
+				if (c1 > 0x7e)
+					return false;
+				(*charptr)++;
+			}
+			break;
+	}
+
+	return true;
+}
+
+/*
+ * get the character incrementer for the encoding for the current database
+ */
+mbcharacter_incrementer
+pg_database_encoding_character_incrementer(void)
+{
+	/*
+	 * Eventually it might be best to add a field to pg_wchar_table[], but for
+	 * now we just use a switch.
+	 */
+	switch (GetDatabaseEncoding())
+	{
+		case PG_UTF8:
+			return pg_utf8_increment;
+
+		case PG_EUC_JP:
+			return pg_eucjp_increment;
+
+		default:
+			return pg_generic_charinc;
+	}
+}
+
+/*
+ * fetch maximum length of the encoding for the current database
+ */
+int
+pg_database_encoding_max_length(void)
+{
+	return pg_wchar_table[GetDatabaseEncoding()].maxmblen;
+}
+
+/*
+ * Verify mbstr to make sure that it is validly encoded in the current
+ * database encoding.  Otherwise same as pg_verify_mbstr().
+ */
+bool
+pg_verifymbstr(const char *mbstr, int len, bool noError)
+{
+	return
+		pg_verify_mbstr_len(GetDatabaseEncoding(), mbstr, len, noError) >= 0;
+}
+
+/*
+ * Verify mbstr to make sure that it is validly encoded in the specified
+ * encoding.
+ */
+bool
+pg_verify_mbstr(int encoding, const char *mbstr, int len, bool noError)
+{
+	return pg_verify_mbstr_len(encoding, mbstr, len, noError) >= 0;
+}
+
+/*
+ * Verify mbstr to make sure that it is validly encoded in the specified
+ * encoding.
+ *
+ * mbstr is not necessarily zero terminated; length of mbstr is
+ * specified by len.
+ *
+ * If OK, return length of string in the encoding.
+ * If a problem is found, return -1 when noError is
+ * true; when noError is false, ereport() a descriptive message.
+ */
+int
+pg_verify_mbstr_len(int encoding, const char *mbstr, int len, bool noError)
+{
+	mbverifier	mbverify;
+	int			mb_len;
+
+	Assert(PG_VALID_ENCODING(encoding));
+
+	/*
+	 * In single-byte encodings, we need only reject nulls (\0).
+	 */
+	if (pg_encoding_max_length(encoding) <= 1)
+	{
+		const char *nullpos = memchr(mbstr, 0, len);
+
+		if (nullpos == NULL)
+			return len;
+		if (noError)
+			return -1;
+		report_invalid_encoding(encoding, nullpos, 1);
+	}
+
+	/* fetch function pointer just once */
+	mbverify = pg_wchar_table[encoding].mbverify;
+
+	mb_len = 0;
+
+	while (len > 0)
+	{
+		int			l;
+
+		/* fast path for ASCII-subset characters */
+		if (!IS_HIGHBIT_SET(*mbstr))
+		{
+			if (*mbstr != '\0')
+			{
+				mb_len++;
+				mbstr++;
+				len--;
+				continue;
+			}
+			if (noError)
+				return -1;
+			report_invalid_encoding(encoding, mbstr, len);
+		}
+
+		l = (*mbverify) ((const unsigned char *) mbstr, len);
+
+		if (l < 0)
+		{
+			if (noError)
+				return -1;
+			report_invalid_encoding(encoding, mbstr, len);
+		}
+
+		mbstr += l;
+		len -= l;
+		mb_len++;
+	}
+	return mb_len;
+}
+
+/*
+ * check_encoding_conversion_args: check arguments of a conversion function
+ *
+ * "expected" arguments can be either an encoding ID or -1 to indicate that
+ * the caller will check whether it accepts the ID.
+ *
+ * Note: the errors here are not really user-facing, so elog instead of
+ * ereport seems sufficient.  Also, we trust that the "expected" encoding
+ * arguments are valid encoding IDs, but we don't trust the actuals.
+ */
+void
+check_encoding_conversion_args(int src_encoding,
+							   int dest_encoding,
+							   int len,
+							   int expected_src_encoding,
+							   int expected_dest_encoding)
+{
+	if (!PG_VALID_ENCODING(src_encoding))
+		elog(ERROR, "invalid source encoding ID: %d", src_encoding);
+	if (src_encoding != expected_src_encoding && expected_src_encoding >= 0)
+		elog(ERROR, "expected source encoding \"%s\", but got \"%s\"",
+			 pg_enc2name_tbl[expected_src_encoding].name,
+			 pg_enc2name_tbl[src_encoding].name);
+	if (!PG_VALID_ENCODING(dest_encoding))
+		elog(ERROR, "invalid destination encoding ID: %d", dest_encoding);
+	if (dest_encoding != expected_dest_encoding && expected_dest_encoding >= 0)
+		elog(ERROR, "expected destination encoding \"%s\", but got \"%s\"",
+			 pg_enc2name_tbl[expected_dest_encoding].name,
+			 pg_enc2name_tbl[dest_encoding].name);
+	if (len < 0)
+		elog(ERROR, "encoding conversion length must not be negative");
+}
+
+/*
+ * report_invalid_encoding: complain about invalid multibyte character
+ *
+ * note: len is remaining length of string, not length of character;
+ * len must be greater than zero, as we always examine the first byte.
+ */
+void
+report_invalid_encoding(int encoding, const char *mbstr, int len)
+{
+	int			l = pg_encoding_mblen(encoding, mbstr);
+	char		buf[8 * 5 + 1];
+	char	   *p = buf;
+	int			j,
+				jlimit;
+
+	jlimit = Min(l, len);
+	jlimit = Min(jlimit, 8);	/* prevent buffer overrun */
+
+	for (j = 0; j < jlimit; j++)
+	{
+		p += sprintf(p, "0x%02x", (unsigned char) mbstr[j]);
+		if (j < jlimit - 1)
+			p += sprintf(p, " ");
+	}
+
+	ereport(ERROR,
+			(errcode(ERRCODE_CHARACTER_NOT_IN_REPERTOIRE),
+			 errmsg("invalid byte sequence for encoding \"%s\": %s",
+					pg_enc2name_tbl[encoding].name,
+					buf)));
+}
+
+/*
+ * report_untranslatable_char: complain about untranslatable character
+ *
+ * note: len is remaining length of string, not length of character;
+ * len must be greater than zero, as we always examine the first byte.
+ */
+void
+report_untranslatable_char(int src_encoding, int dest_encoding,
+						   const char *mbstr, int len)
+{
+	int			l = pg_encoding_mblen(src_encoding, mbstr);
+	char		buf[8 * 5 + 1];
+	char	   *p = buf;
+	int			j,
+				jlimit;
+
+	jlimit = Min(l, len);
+	jlimit = Min(jlimit, 8);	/* prevent buffer overrun */
+
+	for (j = 0; j < jlimit; j++)
+	{
+		p += sprintf(p, "0x%02x", (unsigned char) mbstr[j]);
+		if (j < jlimit - 1)
+			p += sprintf(p, " ");
+	}
+
+	ereport(ERROR,
+			(errcode(ERRCODE_UNTRANSLATABLE_CHARACTER),
+			 errmsg("character with byte sequence %s in encoding \"%s\" has no equivalent in encoding \"%s\"",
+					buf,
+					pg_enc2name_tbl[src_encoding].name,
+					pg_enc2name_tbl[dest_encoding].name)));
+}
+
+
 #ifdef WIN32
 /*
  * Convert from MessageEncoding to a palloc'ed, null-terminated utf16
@@ -1149,4 +1598,4 @@ pgwin32_message_to_UTF16(const char *str, int len, int *utf16len)
 	return utf16;
 }
 
-#endif
+#endif							/* WIN32 */