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Fix LIKE's special-case code for % followed by _. I'm not entirely sure that
this case is worth a special code path, but a special code path that gets the boundary condition wrong is definitely no good. Per bug #4821 from Andrew Gierth. In passing, clean up some minor code formatting issues (excess parentheses and blank lines in odd places). Back-patch to 8.3, where the bug was introduced.
This commit is contained in:
Tom Lane
parent
8e4862b422
commit
6b4a3a7700
@ -9,7 +9,7 @@
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* UTF8 is a special case because we can use a much more efficient version
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* of NextChar than can be used for other multi-byte encodings.
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*
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* Before the inclusion, we need to define following macros:
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* Before the inclusion, we need to define the following macros:
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*
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* NextChar
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* MatchText - to name of function wanted
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@ -19,47 +19,46 @@
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* Copyright (c) 1996-2008, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/adt/like_match.c,v 1.20.2.2 2008/09/27 16:57:43 adunstan Exp $
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* $PostgreSQL: pgsql/src/backend/utils/adt/like_match.c,v 1.20.2.3 2009/05/24 18:10:47 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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/*
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** Originally written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
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** Rich $alz is now <rsalz@bbn.com>.
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** Special thanks to Lars Mathiesen <thorinn@diku.dk> for the LABORT code.
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**
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** This code was shamelessly stolen from the "pql" code by myself and
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** slightly modified :)
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**
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** All references to the word "star" were replaced by "percent"
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** All references to the word "wild" were replaced by "like"
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**
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** All the nice shell RE matching stuff was replaced by just "_" and "%"
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**
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** As I don't have a copy of the SQL standard handy I wasn't sure whether
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** to leave in the '\' escape character handling.
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**
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** Keith Parks. <keith@mtcc.demon.co.uk>
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**
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** SQL92 lets you specify the escape character by saying
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** LIKE <pattern> ESCAPE <escape character>. We are a small operation
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** so we force you to use '\'. - ay 7/95
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**
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** Now we have the like_escape() function that converts patterns with
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** any specified escape character (or none at all) to the internal
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** default escape character, which is still '\'. - tgl 9/2000
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**
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** The code is rewritten to avoid requiring null-terminated strings,
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** which in turn allows us to leave out some memcpy() operations.
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** This code should be faster and take less memory, but no promises...
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** - thomas 2000-08-06
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**
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*/
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* Originally written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
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* Rich $alz is now <rsalz@bbn.com>.
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* Special thanks to Lars Mathiesen <thorinn@diku.dk> for the LABORT code.
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*
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* This code was shamelessly stolen from the "pql" code by myself and
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* slightly modified :)
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*
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* All references to the word "star" were replaced by "percent"
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* All references to the word "wild" were replaced by "like"
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*
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* All the nice shell RE matching stuff was replaced by just "_" and "%"
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*
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* As I don't have a copy of the SQL standard handy I wasn't sure whether
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* to leave in the '\' escape character handling.
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*
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* Keith Parks. <keith@mtcc.demon.co.uk>
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*
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* SQL92 lets you specify the escape character by saying
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* LIKE <pattern> ESCAPE <escape character>. We are a small operation
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* so we force you to use '\'. - ay 7/95
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*
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* Now we have the like_escape() function that converts patterns with
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* any specified escape character (or none at all) to the internal
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* default escape character, which is still '\'. - tgl 9/2000
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*
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* The code is rewritten to avoid requiring null-terminated strings,
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* which in turn allows us to leave out some memcpy() operations.
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* This code should be faster and take less memory, but no promises...
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* - thomas 2000-08-06
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*/
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/*--------------------
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* Match text and p, return LIKE_TRUE, LIKE_FALSE, or LIKE_ABORT.
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* Match text and pattern, return LIKE_TRUE, LIKE_FALSE, or LIKE_ABORT.
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*
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* LIKE_TRUE: they match
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* LIKE_FALSE: they don't match
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@ -80,19 +79,18 @@ static int
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MatchText(char *t, int tlen, char *p, int plen)
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{
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/* Fast path for match-everything pattern */
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if ((plen == 1) && (*p == '%'))
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if (plen == 1 && *p == '%')
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return LIKE_TRUE;
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/*
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* In this loop, we advance by char when matching wildcards (and thus on
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* recursive entry to this function we are properly char-synced). On other
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* occasions it is safe to advance by byte, as the text and pattern will
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* be in lockstep. This allows us to perform all comparisons between the
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* be in lockstep. This allows us to perform all comparisons between the
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* text and pattern on a byte by byte basis, even for multi-byte
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* encodings.
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*/
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while ((tlen > 0) && (plen > 0))
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while (tlen > 0 && plen > 0)
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{
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if (*p == '\\')
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{
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@ -111,7 +109,7 @@ MatchText(char *t, int tlen, char *p, int plen)
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/* %% is the same as % according to the SQL standard */
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/* Advance past all %'s */
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while ((plen > 0) && (*p == '%'))
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while (plen > 0 && *p == '%')
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NextByte(p, plen);
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/* Trailing percent matches everything. */
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if (plen <= 0)
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@ -122,22 +120,24 @@ MatchText(char *t, int tlen, char *p, int plen)
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* rest of the pattern.
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*/
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if (*p == '_')
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{
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/* %_ is the same as _% - avoid matching _ repeatedly */
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NextChar(t, tlen);
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NextByte(p, plen);
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if (tlen <= 0)
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do
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{
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return (plen <= 0) ? LIKE_TRUE : LIKE_ABORT;
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}
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else if (plen <= 0)
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{
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return LIKE_FALSE;
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}
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NextChar(t, tlen);
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NextByte(p, plen);
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} while (tlen > 0 && plen > 0 && *p == '_');
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/*
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* If we are at the end of the pattern, succeed: % followed
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* by n _'s matches any string of at least n characters, and
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* we have now found there are at least n characters.
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*/
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if (plen <= 0)
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return LIKE_TRUE;
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/* Look for a place that matches the rest of the pattern */
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while (tlen > 0)
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{
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int matched = MatchText(t, tlen, p, plen);
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@ -150,7 +150,6 @@ MatchText(char *t, int tlen, char *p, int plen)
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}
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else
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{
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char firstpat = TCHAR(*p);
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if (*p == '\\')
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@ -175,7 +174,6 @@ MatchText(char *t, int tlen, char *p, int plen)
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}
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NextChar(t, tlen);
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}
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}
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@ -187,20 +185,20 @@ MatchText(char *t, int tlen, char *p, int plen)
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}
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else if (*p == '_')
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{
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/* _ matches any single character, and we know there is one */
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NextChar(t, tlen);
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NextByte(p, plen);
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continue;
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}
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else if (TCHAR(*t) != TCHAR(*p))
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else if (TCHAR(*p) != TCHAR(*t))
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{
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/*
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* Not the single-character wildcard and no explicit match? Then
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* time to quit...
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*/
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/* non-wildcard pattern char fails to match text char */
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return LIKE_FALSE;
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}
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/*
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* Pattern and text match, so advance.
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*
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* It is safe to use NextByte instead of NextChar here, even for
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* multi-byte character sets, because we are not following immediately
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* after a wildcard character. If we are in the middle of a multibyte
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@ -217,9 +215,8 @@ MatchText(char *t, int tlen, char *p, int plen)
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if (tlen > 0)
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return LIKE_FALSE; /* end of pattern, but not of text */
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/* End of input string. Do we have matching pattern remaining? */
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while ((plen > 0) && (*p == '%')) /* allow multiple %'s at end of
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* pattern */
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/* End of text string. Do we have matching pattern remaining? */
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while (plen > 0 && *p == '%') /* allow multiple %'s at end of pattern */
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NextByte(p, plen);
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if (plen <= 0)
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@ -349,5 +346,4 @@ do_like_escape(text *pat, text *esc)
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#ifdef MATCH_LOWER
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#undef MATCH_LOWER
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#endif
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@ -826,6 +826,33 @@ SELECT 'Hawkeye' NOT ILIKE 'h%' AS "false";
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f
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(1 row)
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--
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-- test %/_ combination cases, cf bug #4821
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--
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SELECT 'foo' LIKE '_%' as t, 'f' LIKE '_%' as t, '' LIKE '_%' as f;
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t | t | f
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---+---+---
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t | t | f
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(1 row)
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SELECT 'foo' LIKE '%_' as t, 'f' LIKE '%_' as t, '' LIKE '%_' as f;
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t | t | f
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---+---+---
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t | t | f
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(1 row)
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SELECT 'foo' LIKE '__%' as t, 'foo' LIKE '___%' as t, 'foo' LIKE '____%' as f;
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t | t | f
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---+---+---
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t | t | f
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(1 row)
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SELECT 'foo' LIKE '%__' as t, 'foo' LIKE '%___' as t, 'foo' LIKE '%____' as f;
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t | t | f
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---+---+---
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t | t | f
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(1 row)
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--
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-- test implicit type conversion
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--
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@ -252,6 +252,17 @@ SELECT 'hawkeye' NOT ILIKE 'H%Eye' AS "false";
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SELECT 'Hawkeye' ILIKE 'h%' AS "true";
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SELECT 'Hawkeye' NOT ILIKE 'h%' AS "false";
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--
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-- test %/_ combination cases, cf bug #4821
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--
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SELECT 'foo' LIKE '_%' as t, 'f' LIKE '_%' as t, '' LIKE '_%' as f;
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SELECT 'foo' LIKE '%_' as t, 'f' LIKE '%_' as t, '' LIKE '%_' as f;
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SELECT 'foo' LIKE '__%' as t, 'foo' LIKE '___%' as t, 'foo' LIKE '____%' as f;
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SELECT 'foo' LIKE '%__' as t, 'foo' LIKE '%___' as t, 'foo' LIKE '%____' as f;
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--
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-- test implicit type conversion
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--
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