Age Owner Branch data TLA Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * like_match.c
4 : : * LIKE pattern matching internal code.
5 : : *
6 : : * This file is included by like.c four times, to provide matching code for
7 : : * (1) single-byte encodings, (2) UTF8, (3) other multi-byte encodings,
8 : : * and (4) case insensitive matches in single-byte encodings.
9 : : * (UTF8 is a special case because we can use a much more efficient version
10 : : * of NextChar than can be used for general multi-byte encodings.)
11 : : *
12 : : * Before the inclusion, we need to define the following macros:
13 : : *
14 : : * NextChar
15 : : * MatchText - to name of function wanted
16 : : * do_like_escape - name of function if wanted - needs CHAREQ and CopyAdvChar
17 : : * MATCH_LOWER - define for case (4) to specify case folding for 1-byte chars
18 : : *
19 : : * Copyright (c) 1996-2025, PostgreSQL Global Development Group
20 : : *
21 : : * IDENTIFICATION
22 : : * src/backend/utils/adt/like_match.c
23 : : *
24 : : *-------------------------------------------------------------------------
25 : : */
26 : :
27 : : /*
28 : : * Originally written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
29 : : * Rich $alz is now <rsalz@bbn.com>.
30 : : * Special thanks to Lars Mathiesen <thorinn@diku.dk> for the
31 : : * LIKE_ABORT code.
32 : : *
33 : : * This code was shamelessly stolen from the "pql" code by myself and
34 : : * slightly modified :)
35 : : *
36 : : * All references to the word "star" were replaced by "percent"
37 : : * All references to the word "wild" were replaced by "like"
38 : : *
39 : : * All the nice shell RE matching stuff was replaced by just "_" and "%"
40 : : *
41 : : * As I don't have a copy of the SQL standard handy I wasn't sure whether
42 : : * to leave in the '\' escape character handling.
43 : : *
44 : : * Keith Parks. <keith@mtcc.demon.co.uk>
45 : : *
46 : : * SQL lets you specify the escape character by saying
47 : : * LIKE <pattern> ESCAPE <escape character>. We are a small operation
48 : : * so we force you to use '\'. - ay 7/95
49 : : *
50 : : * Now we have the like_escape() function that converts patterns with
51 : : * any specified escape character (or none at all) to the internal
52 : : * default escape character, which is still '\'. - tgl 9/2000
53 : : *
54 : : * The code is rewritten to avoid requiring null-terminated strings,
55 : : * which in turn allows us to leave out some memcpy() operations.
56 : : * This code should be faster and take less memory, but no promises...
57 : : * - thomas 2000-08-06
58 : : */
59 : :
60 : :
61 : : /*--------------------
62 : : * Match text and pattern, return LIKE_TRUE, LIKE_FALSE, or LIKE_ABORT.
63 : : *
64 : : * LIKE_TRUE: they match
65 : : * LIKE_FALSE: they don't match
66 : : * LIKE_ABORT: not only don't they match, but the text is too short.
67 : : *
68 : : * If LIKE_ABORT is returned, then no suffix of the text can match the
69 : : * pattern either, so an upper-level % scan can stop scanning now.
70 : : *--------------------
71 : : */
72 : :
73 : : #ifdef MATCH_LOWER
74 : : #define GETCHAR(t, locale) MATCH_LOWER(t, locale)
75 : : #else
76 : : #define GETCHAR(t, locale) (t)
77 : : #endif
78 : :
79 : : static int
358 peter@eisentraut.org 80 :CBC 641447 : MatchText(const char *t, int tlen, const char *p, int plen, pg_locale_t locale)
81 : : {
82 : : /* Fast path for match-everything pattern */
5949 tgl@sss.pgh.pa.us 83 [ + + + + ]: 641447 : if (plen == 1 && *p == '%')
8738 ishii@postgresql.org 84 : 122 : return LIKE_TRUE;
85 : :
86 : : /* Since this function recurses, it could be driven to stack overflow */
3627 tgl@sss.pgh.pa.us 87 : 641325 : check_stack_depth();
88 : :
89 : : /*
90 : : * In this loop, we advance by char when matching wildcards (and thus on
91 : : * recursive entry to this function we are properly char-synced). On other
92 : : * occasions it is safe to advance by byte, as the text and pattern will
93 : : * be in lockstep. This allows us to perform all comparisons between the
94 : : * text and pattern on a byte by byte basis, even for multi-byte
95 : : * encodings.
96 : : */
5949 97 [ + + + + ]: 957000 : while (tlen > 0 && plen > 0)
98 : : {
8738 ishii@postgresql.org 99 [ + + ]: 951726 : if (*p == '\\')
100 : : {
101 : : /* Next pattern byte must match literally, whatever it is */
6671 andrew@dunslane.net 102 : 6437 : NextByte(p, plen);
103 : : /* ... and there had better be one, per SQL standard */
6189 tgl@sss.pgh.pa.us 104 [ - + ]: 6437 : if (plen <= 0)
6189 tgl@sss.pgh.pa.us 105 [ # # ]:UBC 0 : ereport(ERROR,
106 : : (errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
107 : : errmsg("LIKE pattern must not end with escape character")));
358 peter@eisentraut.org 108 [ + + ]:CBC 6437 : if (GETCHAR(*p, locale) != GETCHAR(*t, locale))
8738 ishii@postgresql.org 109 : 1716 : return LIKE_FALSE;
110 : : }
111 [ + + ]: 945289 : else if (*p == '%')
112 : : {
113 : : char firstpat;
114 : :
115 : : /*
116 : : * % processing is essentially a search for a text position at
117 : : * which the remainder of the text matches the remainder of the
118 : : * pattern, using a recursive call to check each potential match.
119 : : *
120 : : * If there are wildcards immediately following the %, we can skip
121 : : * over them first, using the idea that any sequence of N _'s and
122 : : * one or more %'s is equivalent to N _'s and one % (ie, it will
123 : : * match any sequence of at least N text characters). In this way
124 : : * we will always run the recursive search loop using a pattern
125 : : * fragment that begins with a literal character-to-match, thereby
126 : : * not recursing more than we have to.
127 : : */
5580 tgl@sss.pgh.pa.us 128 : 83914 : NextByte(p, plen);
129 : :
130 [ + + ]: 84167 : while (plen > 0)
131 : : {
132 [ + + ]: 65980 : if (*p == '%')
133 : 9 : NextByte(p, plen);
134 [ + + ]: 65971 : else if (*p == '_')
135 : : {
136 : : /* If not enough text left to match the pattern, ABORT */
137 [ + + ]: 247 : if (tlen <= 0)
138 : 3 : return LIKE_ABORT;
139 [ + + - + ]: 244 : NextChar(t, tlen);
140 : 244 : NextByte(p, plen);
141 : : }
142 : : else
143 : 65724 : break; /* Reached a non-wildcard pattern char */
144 : : }
145 : :
146 : : /*
147 : : * If we're at end of pattern, match: we have a trailing % which
148 : : * matches any remaining text string.
149 : : */
8738 ishii@postgresql.org 150 [ + + ]: 83911 : if (plen <= 0)
151 : 18187 : return LIKE_TRUE;
152 : :
153 : : /*
154 : : * Otherwise, scan for a text position at which we can match the
155 : : * rest of the pattern. The first remaining pattern char is known
156 : : * to be a regular or escaped literal character, so we can compare
157 : : * the first pattern byte to each text byte to avoid recursing
158 : : * more than we have to. This fact also guarantees that we don't
159 : : * have to consider a match to the zero-length substring at the
160 : : * end of the text. With a nondeterministic collation, we can't
161 : : * rely on the first bytes being equal, so we have to recurse in
162 : : * any case.
163 : : */
5580 tgl@sss.pgh.pa.us 164 [ + + ]: 65724 : if (*p == '\\')
165 : : {
166 [ - + ]: 2 : if (plen < 2)
5580 tgl@sss.pgh.pa.us 167 [ # # ]:UBC 0 : ereport(ERROR,
168 : : (errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
169 : : errmsg("LIKE pattern must not end with escape character")));
358 peter@eisentraut.org 170 :CBC 2 : firstpat = GETCHAR(p[1], locale);
171 : : }
172 : : else
173 : 65722 : firstpat = GETCHAR(*p, locale);
174 : :
5580 tgl@sss.pgh.pa.us 175 [ + + ]: 1917085 : while (tlen > 0)
176 : : {
283 peter@eisentraut.org 177 [ + + + + : 1865871 : if (GETCHAR(*t, locale) == firstpat || (locale && !locale->deterministic))
+ + ]
178 : : {
358 179 : 53774 : int matched = MatchText(t, tlen, p, plen, locale);
180 : :
6671 andrew@dunslane.net 181 [ + + ]: 53774 : if (matched != LIKE_FALSE)
5541 bruce@momjian.us 182 : 14510 : return matched; /* TRUE or ABORT */
183 : : }
184 : :
5580 tgl@sss.pgh.pa.us 185 [ + + + + ]: 1851385 : NextChar(t, tlen);
186 : : }
187 : :
188 : : /*
189 : : * End of text with no match, so no point in trying later places
190 : : * to start matching this pattern.
191 : : */
8738 ishii@postgresql.org 192 : 51214 : return LIKE_ABORT;
193 : : }
6671 andrew@dunslane.net 194 [ + + ]: 861375 : else if (*p == '_')
195 : : {
196 : : /* _ matches any single character, and we know there is one */
197 [ + + + + ]: 7226 : NextChar(t, tlen);
198 : 7217 : NextByte(p, plen);
199 : 7217 : continue;
200 : : }
283 peter@eisentraut.org 201 [ + + + + ]: 854158 : else if (locale && !locale->deterministic)
202 : : {
203 : : /*
204 : : * For nondeterministic locales, we find the next substring of the
205 : : * pattern that does not contain wildcards and try to find a
206 : : * matching substring in the text. Crucially, we cannot do this
207 : : * character by character, as in the normal case, but must do it
208 : : * substring by substring, partitioned by the wildcard characters.
209 : : * (This is per SQL standard.)
210 : : */
211 : : const char *p1;
212 : : size_t p1len;
213 : : const char *t1;
214 : : size_t t1len;
215 : : bool found_escape;
216 : : const char *subpat;
217 : : size_t subpatlen;
218 : 141 : char *buf = NULL;
219 : :
220 : : /*
221 : : * Determine next substring of pattern without wildcards. p is
222 : : * the start of the subpattern, p1 is one past the last byte. Also
223 : : * track if we found an escape character.
224 : : */
225 : 141 : p1 = p;
226 : 141 : p1len = plen;
227 : 141 : found_escape = false;
228 [ + + ]: 417 : while (p1len > 0)
229 : : {
230 [ + + ]: 345 : if (*p1 == '\\')
231 : : {
232 : 6 : found_escape = true;
233 : 6 : NextByte(p1, p1len);
234 [ + + ]: 6 : if (p1len == 0)
235 [ + - ]: 3 : ereport(ERROR,
236 : : (errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
237 : : errmsg("LIKE pattern must not end with escape character")));
238 : : }
239 [ + + + + ]: 339 : else if (*p1 == '_' || *p1 == '%')
240 : : break;
241 : 276 : NextByte(p1, p1len);
242 : : }
243 : :
244 : : /*
245 : : * If we found an escape character, then make an unescaped copy of
246 : : * the subpattern.
247 : : */
248 [ + + ]: 138 : if (found_escape)
249 : : {
250 : : char *b;
251 : :
252 : 3 : b = buf = palloc(p1 - p);
253 [ + + ]: 15 : for (const char *c = p; c < p1; c++)
254 : : {
255 [ + + ]: 12 : if (*c == '\\')
256 : : ;
257 : : else
258 : 9 : *(b++) = *c;
259 : : }
260 : :
261 : 3 : subpat = buf;
262 : 3 : subpatlen = b - buf;
263 : : }
264 : : else
265 : : {
266 : 135 : subpat = p;
267 : 135 : subpatlen = p1 - p;
268 : : }
269 : :
270 : : /*
271 : : * Shortcut: If this is the end of the pattern, then the rest of
272 : : * the text has to match the rest of the pattern.
273 : : */
274 [ + + ]: 138 : if (p1len == 0)
275 : : {
276 : : int cmp;
277 : :
278 : 72 : cmp = pg_strncoll(subpat, subpatlen, t, tlen, locale);
279 : :
280 [ + + ]: 72 : if (buf)
281 : 3 : pfree(buf);
282 [ + + ]: 72 : if (cmp == 0)
283 : 45 : return LIKE_TRUE;
284 : : else
285 : 27 : return LIKE_FALSE;
286 : : }
287 : :
288 : : /*
289 : : * Now build a substring of the text and try to match it against
290 : : * the subpattern. t is the start of the text, t1 is one past the
291 : : * last byte. We start with a zero-length string.
292 : : */
293 : 66 : t1 = t;
294 : 66 : t1len = tlen;
295 : : for (;;)
296 : 129 : {
297 : : int cmp;
298 : :
299 [ - + ]: 195 : CHECK_FOR_INTERRUPTS();
300 : :
301 : 195 : cmp = pg_strncoll(subpat, subpatlen, t, (t1 - t), locale);
302 : :
303 : : /*
304 : : * If we found a match, we have to test if the rest of pattern
305 : : * can match against the rest of the string. Otherwise we
306 : : * have to continue here try matching with a longer substring.
307 : : * (This is similar to the recursion for the '%' wildcard
308 : : * above.)
309 : : *
310 : : * Note that we can't just wind forward p and t and continue
311 : : * with the main loop. This would fail for example with
312 : : *
313 : : * U&'\0061\0308bc' LIKE U&'\00E4_c' COLLATE ignore_accents
314 : : *
315 : : * You'd find that t=\0061 matches p=\00E4, but then the rest
316 : : * won't match; but t=\0061\0308 also matches p=\00E4, and
317 : : * then the rest will match.
318 : : */
319 [ + + ]: 195 : if (cmp == 0)
320 : : {
321 : 51 : int matched = MatchText(t1, t1len, p1, p1len, locale);
322 : :
323 [ + + ]: 51 : if (matched == LIKE_TRUE)
324 : : {
325 [ - + ]: 45 : if (buf)
283 peter@eisentraut.org 326 :UBC 0 : pfree(buf);
283 peter@eisentraut.org 327 :CBC 45 : return matched;
328 : : }
329 : : }
330 : :
331 : : /*
332 : : * Didn't match. If we used up the whole text, then the match
333 : : * fails. Otherwise, try again with a longer substring.
334 : : */
335 [ + + ]: 150 : if (t1len == 0)
336 : : {
276 337 [ - + ]: 21 : if (buf)
276 peter@eisentraut.org 338 :UBC 0 : pfree(buf);
283 peter@eisentraut.org 339 :CBC 21 : return LIKE_FALSE;
340 : : }
341 : : else
342 [ + + + + ]: 144 : NextChar(t1, t1len);
343 : : }
344 : : }
358 345 [ + + ]: 854017 : else if (GETCHAR(*p, locale) != GETCHAR(*t, locale))
346 : : {
347 : : /* non-wildcard pattern char fails to match text char */
8738 ishii@postgresql.org 348 : 550280 : return LIKE_FALSE;
349 : : }
350 : :
351 : : /*
352 : : * Pattern and text match, so advance.
353 : : *
354 : : * It is safe to use NextByte instead of NextChar here, even for
355 : : * multi-byte character sets, because we are not following immediately
356 : : * after a wildcard character. If we are in the middle of a multibyte
357 : : * character, we must already have matched at least one byte of the
358 : : * character from both text and pattern; so we cannot get out-of-sync
359 : : * on character boundaries. And we know that no backend-legal
360 : : * encoding allows ASCII characters such as '%' to appear as non-first
361 : : * bytes of characters, so we won't mistakenly detect a new wildcard.
362 : : */
6671 andrew@dunslane.net 363 : 308458 : NextByte(t, tlen);
364 : 308458 : NextByte(p, plen);
365 : : }
366 : :
8738 ishii@postgresql.org 367 [ + + ]: 5274 : if (tlen > 0)
368 : 159 : return LIKE_FALSE; /* end of pattern, but not of text */
369 : :
370 : : /*
371 : : * End of text, but perhaps not of pattern. Match iff the remaining
372 : : * pattern can match a zero-length string, ie, it's zero or more %'s.
373 : : */
5580 tgl@sss.pgh.pa.us 374 [ + + + + ]: 5410 : while (plen > 0 && *p == '%')
6671 andrew@dunslane.net 375 : 295 : NextByte(p, plen);
8738 ishii@postgresql.org 376 [ + + ]: 5115 : if (plen <= 0)
377 : 2331 : return LIKE_TRUE;
378 : :
379 : : /*
380 : : * End of text with no match, so no point in trying later places to start
381 : : * matching this pattern.
382 : : */
383 : 2784 : return LIKE_ABORT;
384 : : } /* MatchText() */
385 : :
386 : : /*
387 : : * like_escape() --- given a pattern and an ESCAPE string,
388 : : * convert the pattern to use Postgres' standard backslash escape convention.
389 : : */
390 : : #ifdef do_like_escape
391 : :
392 : : static text *
393 : 112 : do_like_escape(text *pat, text *esc)
394 : : {
395 : : text *result;
396 : : char *p,
397 : : *e,
398 : : *r;
399 : : int plen,
400 : : elen;
401 : : bool afterescape;
402 : :
6560 tgl@sss.pgh.pa.us 403 [ + + ]: 112 : p = VARDATA_ANY(pat);
404 [ - + - - : 112 : plen = VARSIZE_ANY_EXHDR(pat);
- - - - +
+ ]
405 [ - + ]: 112 : e = VARDATA_ANY(esc);
406 [ - + - - : 112 : elen = VARSIZE_ANY_EXHDR(esc);
- - - - -
+ ]
407 : :
408 : : /*
409 : : * Worst-case pattern growth is 2x --- unlikely, but it's hardly worth
410 : : * trying to calculate the size more accurately than that.
411 : : */
8738 ishii@postgresql.org 412 : 112 : result = (text *) palloc(plen * 2 + VARHDRSZ);
413 : 112 : r = VARDATA(result);
414 : :
415 [ + + ]: 112 : if (elen == 0)
416 : : {
417 : : /*
418 : : * No escape character is wanted. Double any backslashes in the
419 : : * pattern to make them act like ordinary characters.
420 : : */
421 [ + + ]: 64 : while (plen > 0)
422 : : {
423 [ - + ]: 48 : if (*p == '\\')
8738 ishii@postgresql.org 424 :UBC 0 : *r++ = '\\';
8738 ishii@postgresql.org 425 [ + + ]:CBC 96 : CopyAdvChar(r, p, plen);
426 : : }
427 : : }
428 : : else
429 : : {
430 : : /*
431 : : * The specified escape must be only a single character.
432 : : */
433 : 96 : NextChar(e, elen);
434 [ - + ]: 96 : if (elen != 0)
8077 tgl@sss.pgh.pa.us 435 [ # # ]:UBC 0 : ereport(ERROR,
436 : : (errcode(ERRCODE_INVALID_ESCAPE_SEQUENCE),
437 : : errmsg("invalid escape string"),
438 : : errhint("Escape string must be empty or one character.")));
439 : :
6560 tgl@sss.pgh.pa.us 440 [ - + ]:CBC 96 : e = VARDATA_ANY(esc);
441 : :
442 : : /*
443 : : * If specified escape is '\', just copy the pattern as-is.
444 : : */
8738 ishii@postgresql.org 445 [ - + ]: 96 : if (*e == '\\')
446 : : {
6560 tgl@sss.pgh.pa.us 447 [ # # # # :UBC 0 : memcpy(result, pat, VARSIZE_ANY(pat));
# # # # #
# ]
8738 ishii@postgresql.org 448 : 0 : return result;
449 : : }
450 : :
451 : : /*
452 : : * Otherwise, convert occurrences of the specified escape character to
453 : : * '\', and double occurrences of '\' --- unless they immediately
454 : : * follow an escape character!
455 : : */
8738 ishii@postgresql.org 456 :CBC 96 : afterescape = false;
457 [ + + ]: 582 : while (plen > 0)
458 : : {
459 [ + + + + ]: 486 : if (CHAREQ(p, e) && !afterescape)
460 : : {
461 : 96 : *r++ = '\\';
462 : 96 : NextChar(p, plen);
463 : 96 : afterescape = true;
464 : : }
465 [ - + ]: 390 : else if (*p == '\\')
466 : : {
8738 ishii@postgresql.org 467 :UBC 0 : *r++ = '\\';
468 [ # # ]: 0 : if (!afterescape)
469 : 0 : *r++ = '\\';
470 : 0 : NextChar(p, plen);
471 : 0 : afterescape = false;
472 : : }
473 : : else
474 : : {
8738 ishii@postgresql.org 475 [ + + ]:CBC 762 : CopyAdvChar(r, p, plen);
476 : 390 : afterescape = false;
477 : : }
478 : : }
479 : : }
480 : :
6766 tgl@sss.pgh.pa.us 481 : 112 : SET_VARSIZE(result, r - ((char *) result));
482 : :
8738 ishii@postgresql.org 483 : 112 : return result;
484 : : }
485 : : #endif /* do_like_escape */
486 : :
487 : : #ifdef CHAREQ
488 : : #undef CHAREQ
489 : : #endif
490 : :
491 : : #undef NextChar
492 : : #undef CopyAdvChar
493 : : #undef MatchText
494 : :
495 : : #ifdef do_like_escape
496 : : #undef do_like_escape
497 : : #endif
498 : :
499 : : #undef GETCHAR
500 : :
501 : : #ifdef MATCH_LOWER
502 : : #undef MATCH_LOWER
503 : :
504 : : #endif
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