Rationalize code placement between wchar.c, encnames.c, and mbutils.c.

Move all the backend-only code that'd crept into wchar.c and encnames.c
into mbutils.c.

To remove the last few #ifdef dependencies from wchar.c and encnames.c,
also make the following changes:

* Adjust get_encoding_name_for_icu to return NULL, not throw an error,
for unsupported encodings.  Its sole caller can perfectly well throw an
error instead.  (While at it, I also made this function and its sibling
is_encoding_supported_by_icu proof against out-of-range encoding IDs.)

* Remove the overlength-name error condition from pg_char_to_encoding.
It's completely silly not to treat that just like any other
the-name-is-not-in-the-table case.

Also, get rid of pg_mic_mblen --- there's no obvious reason why
conv.c shouldn't call pg_mule_mblen instead.

Other than that, this is just code movement and comment-polishing with
no functional changes.  Notably, I reordered declarations in pg_wchar.h
to show which functions are frontend-accessible and which are not.

Discussion: https://postgr.es/m/CA+TgmoYO8oq-iy8E02rD8eX25T-9SmyxKWqqks5OMHxKvGXpXQ@mail.gmail.com

1 files changed, 2 insertions, 449 deletions

diff --git a/src/common/wchar.c b/src/common/wchar.c
index 74a88239a1d..efaf1c155bb 100644
--- a/src/common/wchar.c
+++ b/src/common/wchar.c
@@ -10,11 +10,7 @@
  *
  *-------------------------------------------------------------------------
  */
-#ifdef FRONTEND
-#include "postgres_fe.h"
-#else
-#include "postgres.h"
-#endif
+#include "c.h"
 
 #include "mb/pg_wchar.h"
 
@@ -838,6 +834,7 @@ pg_wchar2mule_with_len(const pg_wchar *from, unsigned char *to, int len)
 	return cnt;
 }
 
+/* exported for direct use by conv.c */
 int
 pg_mule_mblen(const unsigned char *s)
 {
@@ -1498,214 +1495,6 @@ pg_utf8_islegal(const unsigned char *source, int length)
 	return true;
 }
 
-#ifndef FRONTEND
-
-/*
- * 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;
-}
-#endif							/* !FRONTEND */
-
 
 /*
  *-------------------------------------------------------------------
@@ -1758,13 +1547,6 @@ const pg_wchar_tbl pg_wchar_table[] = {
 	{0, 0, pg_sjis_mblen, pg_sjis_dsplen, pg_sjis_verifier, 2}	/* PG_SHIFT_JIS_2004 */
 };
 
-/* returns the byte length of a word for mule internal code */
-int
-pg_mic_mblen(const unsigned char *mbstr)
-{
-	return pg_mule_mblen(mbstr);
-}
-
 /*
  * Returns the byte length of a multibyte character.
  */
@@ -1810,232 +1592,3 @@ pg_encoding_max_length(int encoding)
 
 	return pg_wchar_table[encoding].maxmblen;
 }
-
-#ifndef FRONTEND
-
-/*
- * fetch maximum length of the encoding for the current database
- */
-int
-pg_database_encoding_max_length(void)
-{
-	return pg_wchar_table[GetDatabaseEncoding()].maxmblen;
-}
-
-/*
- * 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;
-	}
-}
-
-/*
- * 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)));
-}
-
-#endif							/* !FRONTEND */