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Allow multibyte characters as escape in SIMILAR TO and SUBSTRING.

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Previously, only a single-byte character was allowed as an
escape. This patch allows it to be a multi-byte character, though it
still must be a single character.

Reviewed by Heikki Linnakangas and Tom Lane.
This commit is contained in:
Jeff Davis 2014-08-27 21:07:36 -07:00
parent 1c9701cfe5
commit 8167a3883a
1 changed files with 58 additions and 5 deletions
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63
src/backend/utils/adt/regexp.c
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@ -688,11 +688,16 @@ similar_escape(PG_FUNCTION_ARGS)
elen = VARSIZE_ANY_EXHDR(esc_text);
if (elen == 0)
e = NULL; /* no escape character */
else if (elen != 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
errmsg("invalid escape string"),
errhint("Escape string must be empty or one character.")));
else
{
int escape_mblen = pg_mbstrlen_with_len(e, elen);
if (escape_mblen > 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
errmsg("invalid escape string"),
errhint("Escape string must be empty or one character.")));
}
}
/*----------
@ -724,6 +729,54 @@ similar_escape(PG_FUNCTION_ARGS)
{
char pchar = *p;
/*
* If both the escape character and the current character from the
* pattern are multi-byte, we need to take the slow path.
*
* But if one of them is single-byte, we can process the pattern one
* byte at a time, ignoring multi-byte characters. (This works
* because all server-encodings have the property that a valid
* multi-byte character representation cannot contain the
* representation of a valid single-byte character.)
*/
if (elen > 1)
{
int mblen = pg_mblen(p);
if (mblen > 1)
{
/* slow, multi-byte path */
if (afterescape)
{
*r++ = '\\';
memcpy(r, p, mblen);
r += mblen;
afterescape = false;
}
else if (e && elen == mblen && memcmp(e, p, mblen) == 0)
{
/* SQL99 escape character; do not send to output */
afterescape = true;
}
else
{
/*
* We know it's a multi-byte character, so we don't need
* to do all the comparisons to single-byte characters
* that we do below.
*/
memcpy(r, p, mblen);
r += mblen;
}
p += mblen;
plen -= mblen;
continue;
}
}
/* fast path */
if (afterescape)
{
if (pchar == '"' && !incharclass) /* for SUBSTRING patterns */