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e04fa58dcd
to explicitly cast the output back to char before comparing it to a char value, else we get the wrong result for high-bit-set characters. Found by Rolf Jentsch. Also, fix several places where <ctype.h> functions were being called without casting the argument to unsigned char; this is likewise unportable, but we keep making that mistake :-(. These found by buildfarm member salamander, which I will desperately miss if it ever goes belly-up.
354 lines
8.6 KiB
C
354 lines
8.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* like_match.c
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* like expression handling internal code.
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*
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* This file is included by like.c four times, to provide natching code for
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* single-byte encodings, UTF8, and for other multi-byte encodings,
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* and case insensitive matches for single byte encodings.
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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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*
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* NextChar
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* MatchText - to name of function wanted
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* do_like_escape - name of function if wanted - needs CHAREQ and CopyAdvChar
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* MATCH_LOWER - define iff using to_lower on text chars
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*
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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 1.21 2008/03/01 03:26:34 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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/*--------------------
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* Match text and p, 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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* LIKE_ABORT: not only don't they match, but the text is too short.
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*
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* If LIKE_ABORT is returned, then no suffix of the text can match the
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* pattern either, so an upper-level % scan can stop scanning now.
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*--------------------
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*/
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#ifdef MATCH_LOWER
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#define TCHAR(t) ((char) tolower((unsigned char) (t)))
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#else
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#define TCHAR(t) (t)
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#endif
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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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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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* 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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{
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if (*p == '\\')
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{
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/* Next byte must match literally, whatever it is */
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NextByte(p, plen);
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if ((plen <= 0) || *p != *t)
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return LIKE_FALSE;
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}
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else if (*p == '%')
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{
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/*
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* % processing is essentially a search for a match for what
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* follows the %, plus a recursive match of the remainder. We
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* succeed if and only if both conditions are met.
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*/
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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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NextByte(p, plen);
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/* Trailing percent matches everything. */
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if (plen <= 0)
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return LIKE_TRUE;
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/*
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* Otherwise, scan for a text position at which we can match the
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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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{
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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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while (tlen > 0)
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{
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int matched = MatchText(t, tlen, p, plen);
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if (matched != LIKE_FALSE)
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return matched; /* TRUE or ABORT */
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NextChar(t, tlen);
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}
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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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{
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if (plen < 2)
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return LIKE_FALSE;
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firstpat = TCHAR(p[1]);
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}
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while (tlen > 0)
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{
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/*
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* Optimization to prevent most recursion: don't recurse
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* unless first pattern byte matches first text byte.
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*/
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if (TCHAR(*t) == firstpat)
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{
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int matched = MatchText(t, tlen, p, plen);
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if (matched != LIKE_FALSE)
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return matched; /* TRUE or ABORT */
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}
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NextChar(t, tlen);
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}
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}
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/*
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* End of text with no match, so no point in trying later places
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* to start matching this pattern.
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*/
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return LIKE_ABORT;
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}
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else if (*p == '_')
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{
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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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{
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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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return LIKE_FALSE;
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}
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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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* character, we must already have matched at least one byte of the
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* character from both text and pattern; so we cannot get out-of-sync
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* on character boundaries. And we know that no backend-legal
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* encoding allows ASCII characters such as '%' to appear as non-first
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* bytes of characters, so we won't mistakenly detect a new wildcard.
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*/
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NextByte(t, tlen);
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NextByte(p, plen);
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}
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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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NextByte(p, plen);
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if (plen <= 0)
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return LIKE_TRUE;
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/*
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* End of text with no match, so no point in trying later places to start
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* matching this pattern.
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*/
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return LIKE_ABORT;
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} /* MatchText() */
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/*
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* like_escape() --- given a pattern and an ESCAPE string,
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* convert the pattern to use Postgres' standard backslash escape convention.
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*/
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#ifdef do_like_escape
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static text *
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do_like_escape(text *pat, text *esc)
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{
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text *result;
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char *p,
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*e,
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*r;
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int plen,
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elen;
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bool afterescape;
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p = VARDATA_ANY(pat);
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plen = VARSIZE_ANY_EXHDR(pat);
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e = VARDATA_ANY(esc);
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elen = VARSIZE_ANY_EXHDR(esc);
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/*
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* Worst-case pattern growth is 2x --- unlikely, but it's hardly worth
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* trying to calculate the size more accurately than that.
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*/
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result = (text *) palloc(plen * 2 + VARHDRSZ);
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r = VARDATA(result);
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if (elen == 0)
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{
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/*
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* No escape character is wanted. Double any backslashes in the
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* pattern to make them act like ordinary characters.
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*/
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while (plen > 0)
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{
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if (*p == '\\')
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*r++ = '\\';
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CopyAdvChar(r, p, plen);
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}
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}
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else
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{
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/*
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* The specified escape must be only a single character.
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*/
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NextChar(e, elen);
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if (elen != 0)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
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errmsg("invalid escape string"),
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errhint("Escape string must be empty or one character.")));
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e = VARDATA_ANY(esc);
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/*
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* If specified escape is '\', just copy the pattern as-is.
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*/
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if (*e == '\\')
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{
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memcpy(result, pat, VARSIZE_ANY(pat));
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return result;
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}
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/*
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* Otherwise, convert occurrences of the specified escape character to
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* '\', and double occurrences of '\' --- unless they immediately
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* follow an escape character!
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*/
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afterescape = false;
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while (plen > 0)
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{
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if (CHAREQ(p, e) && !afterescape)
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{
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*r++ = '\\';
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NextChar(p, plen);
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afterescape = true;
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}
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else if (*p == '\\')
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{
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*r++ = '\\';
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if (!afterescape)
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*r++ = '\\';
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NextChar(p, plen);
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afterescape = false;
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}
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else
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{
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CopyAdvChar(r, p, plen);
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afterescape = false;
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}
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}
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}
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SET_VARSIZE(result, r - ((char *) result));
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return result;
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}
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#endif /* do_like_escape */
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#ifdef CHAREQ
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#undef CHAREQ
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#endif
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#undef NextChar
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#undef CopyAdvChar
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#undef MatchText
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#ifdef do_like_escape
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#undef do_like_escape
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#endif
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#undef TCHAR
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#ifdef MATCH_LOWER
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#undef MATCH_LOWER
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#endif
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