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Commit8167a38

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Allow multibyte characters as escape in SIMILAR TO and SUBSTRING.
Previously, only a single-byte character was allowed as anescape. This patch allows it to be a multi-byte character, though itstill must be a single character.Reviewed by Heikki Linnakangas and Tom Lane.
1 parent1c9701c commit8167a38

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1 file changed

+58
-5
lines changed

1 file changed

+58
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lines changed

‎src/backend/utils/adt/regexp.c‎

Lines changed: 58 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -688,11 +688,16 @@ similar_escape(PG_FUNCTION_ARGS)
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elen=VARSIZE_ANY_EXHDR(esc_text);
689689
if (elen==0)
690690
e=NULL;/* no escape character */
691-
elseif (elen!=1)
692-
ereport(ERROR,
693-
(errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
694-
errmsg("invalid escape string"),
695-
errhint("Escape string must be empty or one character.")));
691+
else
692+
{
693+
intescape_mblen=pg_mbstrlen_with_len(e,elen);
694+
695+
if (escape_mblen>1)
696+
ereport(ERROR,
697+
(errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
698+
errmsg("invalid escape string"),
699+
errhint("Escape string must be empty or one character.")));
700+
}
696701
}
697702

698703
/*----------
@@ -724,6 +729,54 @@ similar_escape(PG_FUNCTION_ARGS)
724729
{
725730
charpchar=*p;
726731

732+
/*
733+
* If both the escape character and the current character from the
734+
* pattern are multi-byte, we need to take the slow path.
735+
*
736+
* But if one of them is single-byte, we can process the pattern one
737+
* byte at a time, ignoring multi-byte characters. (This works
738+
* because all server-encodings have the property that a valid
739+
* multi-byte character representation cannot contain the
740+
* representation of a valid single-byte character.)
741+
*/
742+
743+
if (elen>1)
744+
{
745+
intmblen=pg_mblen(p);
746+
if (mblen>1)
747+
{
748+
/* slow, multi-byte path */
749+
if (afterescape)
750+
{
751+
*r++='\\';
752+
memcpy(r,p,mblen);
753+
r+=mblen;
754+
afterescape= false;
755+
}
756+
elseif (e&&elen==mblen&&memcmp(e,p,mblen)==0)
757+
{
758+
/* SQL99 escape character; do not send to output */
759+
afterescape= true;
760+
}
761+
else
762+
{
763+
/*
764+
* We know it's a multi-byte character, so we don't need
765+
* to do all the comparisons to single-byte characters
766+
* that we do below.
767+
*/
768+
memcpy(r,p,mblen);
769+
r+=mblen;
770+
}
771+
772+
p+=mblen;
773+
plen-=mblen;
774+
775+
continue;
776+
}
777+
}
778+
779+
/* fast path */
727780
if (afterescape)
728781
{
729782
if (pchar=='"'&& !incharclass)/* for SUBSTRING patterns */

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