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form '^(foo)$'. Before, these could never be optimized into indexscans. The recent changes to make psql and pg_dump generate such patterns (for \d commands and -t and related switches, respectively) therefore represented a big performance hit for people with large pg_class catalogs, as seen in recent gripe from Erik Jones. While at it, be more paranoid about case-sensitivity checking in multibyte encodings, and fix some other corner cases in which a regex might be interpreted too liberally.
636 lines
16 KiB
C
636 lines
16 KiB
C
/*-------------------------------------------------------------------------
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*
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* regexp.c
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* Postgres' interface to the regular expression package.
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*
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* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/adt/regexp.c,v 1.67 2007/01/03 22:39:26 tgl Exp $
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*
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* Alistair Crooks added the code for the regex caching
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* agc - cached the regular expressions used - there's a good chance
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* that we'll get a hit, so this saves a compile step for every
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* attempted match. I haven't actually measured the speed improvement,
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* but it `looks' a lot quicker visually when watching regression
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* test output.
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*
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* agc - incorporated Keith Bostic's Berkeley regex code into
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* the tree for all ports. To distinguish this regex code from any that
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* is existent on a platform, I've prepended the string "pg_" to
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* the functions regcomp, regerror, regexec and regfree.
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* Fixed a bug that was originally a typo by me, where `i' was used
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* instead of `oldest' when compiling regular expressions - benign
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* results mostly, although occasionally it bit you...
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "regex/regex.h"
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#include "utils/builtins.h"
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#include "utils/guc.h"
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/* GUC-settable flavor parameter */
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static int regex_flavor = REG_ADVANCED;
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/*
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* We cache precompiled regular expressions using a "self organizing list"
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* structure, in which recently-used items tend to be near the front.
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* Whenever we use an entry, it's moved up to the front of the list.
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* Over time, an item's average position corresponds to its frequency of use.
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*
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* When we first create an entry, it's inserted at the front of
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* the array, dropping the entry at the end of the array if necessary to
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* make room. (This might seem to be weighting the new entry too heavily,
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* but if we insert new entries further back, we'll be unable to adjust to
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* a sudden shift in the query mix where we are presented with MAX_CACHED_RES
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* never-before-seen items used circularly. We ought to be able to handle
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* that case, so we have to insert at the front.)
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*
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* Knuth mentions a variant strategy in which a used item is moved up just
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* one place in the list. Although he says this uses fewer comparisons on
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* average, it seems not to adapt very well to the situation where you have
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* both some reusable patterns and a steady stream of non-reusable patterns.
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* A reusable pattern that isn't used at least as often as non-reusable
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* patterns are seen will "fail to keep up" and will drop off the end of the
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* cache. With move-to-front, a reusable pattern is guaranteed to stay in
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* the cache as long as it's used at least once in every MAX_CACHED_RES uses.
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*/
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/* this is the maximum number of cached regular expressions */
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#ifndef MAX_CACHED_RES
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#define MAX_CACHED_RES 32
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#endif
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/* this structure describes one cached regular expression */
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typedef struct cached_re_str
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{
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text *cre_pat; /* original RE (untoasted TEXT form) */
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int cre_flags; /* compile flags: extended,icase etc */
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regex_t cre_re; /* the compiled regular expression */
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} cached_re_str;
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static int num_res = 0; /* # of cached re's */
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static cached_re_str re_array[MAX_CACHED_RES]; /* cached re's */
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/*
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* RE_compile_and_cache - compile a RE, caching if possible
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*
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* Returns regex_t *
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*
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* text_re --- the pattern, expressed as an *untoasted* TEXT object
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* cflags --- compile options for the pattern
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*
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* Pattern is given in the database encoding. We internally convert to
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* array of pg_wchar which is what Spencer's regex package wants.
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*/
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static regex_t *
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RE_compile_and_cache(text *text_re, int cflags)
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{
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int text_re_len = VARSIZE(text_re);
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pg_wchar *pattern;
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size_t pattern_len;
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int i;
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int regcomp_result;
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cached_re_str re_temp;
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char errMsg[100];
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/*
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* Look for a match among previously compiled REs. Since the data
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* structure is self-organizing with most-used entries at the front, our
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* search strategy can just be to scan from the front.
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*/
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for (i = 0; i < num_res; i++)
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{
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if (VARSIZE(re_array[i].cre_pat) == text_re_len &&
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memcmp(re_array[i].cre_pat, text_re, text_re_len) == 0 &&
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re_array[i].cre_flags == cflags)
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{
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/*
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* Found a match; move it to front if not there already.
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*/
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if (i > 0)
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{
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re_temp = re_array[i];
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memmove(&re_array[1], &re_array[0], i * sizeof(cached_re_str));
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re_array[0] = re_temp;
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}
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return &re_array[0].cre_re;
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}
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}
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/*
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* Couldn't find it, so try to compile the new RE. To avoid leaking
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* resources on failure, we build into the re_temp local.
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*/
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/* Convert pattern string to wide characters */
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pattern = (pg_wchar *) palloc((text_re_len - VARHDRSZ + 1) * sizeof(pg_wchar));
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pattern_len = pg_mb2wchar_with_len(VARDATA(text_re),
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pattern,
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text_re_len - VARHDRSZ);
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regcomp_result = pg_regcomp(&re_temp.cre_re,
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pattern,
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pattern_len,
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cflags);
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pfree(pattern);
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if (regcomp_result != REG_OKAY)
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{
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/* re didn't compile */
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pg_regerror(regcomp_result, &re_temp.cre_re, errMsg, sizeof(errMsg));
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/* XXX should we pg_regfree here? */
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
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errmsg("invalid regular expression: %s", errMsg)));
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}
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/*
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* use malloc/free for the cre_pat field because the storage has to
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* persist across transactions
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*/
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re_temp.cre_pat = malloc(text_re_len);
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if (re_temp.cre_pat == NULL)
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{
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pg_regfree(&re_temp.cre_re);
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ereport(ERROR,
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(errcode(ERRCODE_OUT_OF_MEMORY),
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errmsg("out of memory")));
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}
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memcpy(re_temp.cre_pat, text_re, text_re_len);
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re_temp.cre_flags = cflags;
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/*
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* Okay, we have a valid new item in re_temp; insert it into the storage
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* array. Discard last entry if needed.
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*/
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if (num_res >= MAX_CACHED_RES)
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{
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--num_res;
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Assert(num_res < MAX_CACHED_RES);
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pg_regfree(&re_array[num_res].cre_re);
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free(re_array[num_res].cre_pat);
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}
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if (num_res > 0)
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memmove(&re_array[1], &re_array[0], num_res * sizeof(cached_re_str));
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re_array[0] = re_temp;
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num_res++;
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return &re_array[0].cre_re;
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}
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/*
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* RE_compile_and_execute - compile and execute a RE
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*
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* Returns TRUE on match, FALSE on no match
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*
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* text_re --- the pattern, expressed as an *untoasted* TEXT object
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* dat --- the data to match against (need not be null-terminated)
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* dat_len --- the length of the data string
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* cflags --- compile options for the pattern
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* nmatch, pmatch --- optional return area for match details
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*
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* Both pattern and data are given in the database encoding. We internally
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* convert to array of pg_wchar which is what Spencer's regex package wants.
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*/
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static bool
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RE_compile_and_execute(text *text_re, char *dat, int dat_len,
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int cflags, int nmatch, regmatch_t *pmatch)
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{
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pg_wchar *data;
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size_t data_len;
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int regexec_result;
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regex_t *re;
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char errMsg[100];
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/* Convert data string to wide characters */
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data = (pg_wchar *) palloc((dat_len + 1) * sizeof(pg_wchar));
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data_len = pg_mb2wchar_with_len(dat, data, dat_len);
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/* Compile RE */
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re = RE_compile_and_cache(text_re, cflags);
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/* Perform RE match and return result */
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regexec_result = pg_regexec(re,
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data,
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data_len,
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0,
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NULL, /* no details */
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nmatch,
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pmatch,
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0);
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pfree(data);
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if (regexec_result != REG_OKAY && regexec_result != REG_NOMATCH)
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{
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/* re failed??? */
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pg_regerror(regexec_result, re, errMsg, sizeof(errMsg));
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_REGULAR_EXPRESSION),
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errmsg("regular expression failed: %s", errMsg)));
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}
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return (regexec_result == REG_OKAY);
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}
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/*
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* assign_regex_flavor - GUC hook to validate and set REGEX_FLAVOR
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*/
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const char *
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assign_regex_flavor(const char *value,
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bool doit, GucSource source)
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{
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if (pg_strcasecmp(value, "advanced") == 0)
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{
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if (doit)
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regex_flavor = REG_ADVANCED;
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}
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else if (pg_strcasecmp(value, "extended") == 0)
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{
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if (doit)
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regex_flavor = REG_EXTENDED;
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}
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else if (pg_strcasecmp(value, "basic") == 0)
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{
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if (doit)
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regex_flavor = REG_BASIC;
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}
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else
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return NULL; /* fail */
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return value; /* OK */
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}
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/*
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* interface routines called by the function manager
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*/
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Datum
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nameregexeq(PG_FUNCTION_ARGS)
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{
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Name n = PG_GETARG_NAME(0);
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text *p = PG_GETARG_TEXT_P(1);
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PG_RETURN_BOOL(RE_compile_and_execute(p,
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NameStr(*n),
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strlen(NameStr(*n)),
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regex_flavor,
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0, NULL));
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}
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Datum
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nameregexne(PG_FUNCTION_ARGS)
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{
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Name n = PG_GETARG_NAME(0);
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text *p = PG_GETARG_TEXT_P(1);
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PG_RETURN_BOOL(!RE_compile_and_execute(p,
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NameStr(*n),
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strlen(NameStr(*n)),
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regex_flavor,
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0, NULL));
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}
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Datum
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textregexeq(PG_FUNCTION_ARGS)
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{
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text *s = PG_GETARG_TEXT_P(0);
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text *p = PG_GETARG_TEXT_P(1);
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PG_RETURN_BOOL(RE_compile_and_execute(p,
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VARDATA(s),
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VARSIZE(s) - VARHDRSZ,
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regex_flavor,
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0, NULL));
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}
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Datum
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textregexne(PG_FUNCTION_ARGS)
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{
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text *s = PG_GETARG_TEXT_P(0);
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text *p = PG_GETARG_TEXT_P(1);
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PG_RETURN_BOOL(!RE_compile_and_execute(p,
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VARDATA(s),
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VARSIZE(s) - VARHDRSZ,
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regex_flavor,
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0, NULL));
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}
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/*
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* routines that use the regexp stuff, but ignore the case.
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* for this, we use the REG_ICASE flag to pg_regcomp
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*/
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Datum
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nameicregexeq(PG_FUNCTION_ARGS)
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{
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Name n = PG_GETARG_NAME(0);
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text *p = PG_GETARG_TEXT_P(1);
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PG_RETURN_BOOL(RE_compile_and_execute(p,
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NameStr(*n),
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strlen(NameStr(*n)),
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regex_flavor | REG_ICASE,
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0, NULL));
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}
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Datum
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nameicregexne(PG_FUNCTION_ARGS)
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{
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Name n = PG_GETARG_NAME(0);
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text *p = PG_GETARG_TEXT_P(1);
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PG_RETURN_BOOL(!RE_compile_and_execute(p,
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NameStr(*n),
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strlen(NameStr(*n)),
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regex_flavor | REG_ICASE,
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0, NULL));
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}
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Datum
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texticregexeq(PG_FUNCTION_ARGS)
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{
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text *s = PG_GETARG_TEXT_P(0);
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text *p = PG_GETARG_TEXT_P(1);
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PG_RETURN_BOOL(RE_compile_and_execute(p,
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VARDATA(s),
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VARSIZE(s) - VARHDRSZ,
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regex_flavor | REG_ICASE,
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0, NULL));
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}
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Datum
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texticregexne(PG_FUNCTION_ARGS)
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{
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text *s = PG_GETARG_TEXT_P(0);
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text *p = PG_GETARG_TEXT_P(1);
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PG_RETURN_BOOL(!RE_compile_and_execute(p,
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VARDATA(s),
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VARSIZE(s) - VARHDRSZ,
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regex_flavor | REG_ICASE,
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0, NULL));
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}
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/*
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* textregexsubstr()
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* Return a substring matched by a regular expression.
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*/
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Datum
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textregexsubstr(PG_FUNCTION_ARGS)
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{
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text *s = PG_GETARG_TEXT_P(0);
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text *p = PG_GETARG_TEXT_P(1);
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bool match;
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regmatch_t pmatch[2];
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/*
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* We pass two regmatch_t structs to get info about the overall match and
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* the match for the first parenthesized subexpression (if any). If there
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* is a parenthesized subexpression, we return what it matched; else
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* return what the whole regexp matched.
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*/
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match = RE_compile_and_execute(p,
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VARDATA(s),
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VARSIZE(s) - VARHDRSZ,
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regex_flavor,
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2, pmatch);
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/* match? then return the substring matching the pattern */
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if (match)
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{
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int so,
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eo;
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so = pmatch[1].rm_so;
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eo = pmatch[1].rm_eo;
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if (so < 0 || eo < 0)
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{
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/* no parenthesized subexpression */
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so = pmatch[0].rm_so;
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eo = pmatch[0].rm_eo;
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}
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return DirectFunctionCall3(text_substr,
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PointerGetDatum(s),
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Int32GetDatum(so + 1),
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Int32GetDatum(eo - so));
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}
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PG_RETURN_NULL();
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}
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/*
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* textregexreplace_noopt()
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* Return a string matched by a regular expression, with replacement.
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*
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* This version doesn't have an option argument: we default to case
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* sensitive match, replace the first instance only.
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*/
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Datum
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textregexreplace_noopt(PG_FUNCTION_ARGS)
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{
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text *s = PG_GETARG_TEXT_P(0);
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text *p = PG_GETARG_TEXT_P(1);
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text *r = PG_GETARG_TEXT_P(2);
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regex_t *re;
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re = RE_compile_and_cache(p, regex_flavor);
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PG_RETURN_TEXT_P(replace_text_regexp(s, (void *) re, r, false));
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}
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|
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/*
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* textregexreplace()
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* Return a string matched by a regular expression, with replacement.
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*/
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Datum
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textregexreplace(PG_FUNCTION_ARGS)
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{
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text *s = PG_GETARG_TEXT_P(0);
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text *p = PG_GETARG_TEXT_P(1);
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text *r = PG_GETARG_TEXT_P(2);
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text *opt = PG_GETARG_TEXT_P(3);
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char *opt_p = VARDATA(opt);
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int opt_len = (VARSIZE(opt) - VARHDRSZ);
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int i;
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bool glob = false;
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bool ignorecase = false;
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regex_t *re;
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/* parse options */
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for (i = 0; i < opt_len; i++)
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{
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switch (opt_p[i])
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{
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case 'i':
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ignorecase = true;
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break;
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case 'g':
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glob = true;
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break;
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default:
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ereport(ERROR,
|
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("invalid option of regexp_replace: %c",
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opt_p[i])));
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break;
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}
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}
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if (ignorecase)
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re = RE_compile_and_cache(p, regex_flavor | REG_ICASE);
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else
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re = RE_compile_and_cache(p, regex_flavor);
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PG_RETURN_TEXT_P(replace_text_regexp(s, (void *) re, r, glob));
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}
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|
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/* similar_escape()
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* Convert a SQL99 regexp pattern to POSIX style, so it can be used by
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* our regexp engine.
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*/
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Datum
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similar_escape(PG_FUNCTION_ARGS)
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{
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text *pat_text;
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text *esc_text;
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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 = false;
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int nquotes = 0;
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/* This function is not strict, so must test explicitly */
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if (PG_ARGISNULL(0))
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PG_RETURN_NULL();
|
|
pat_text = PG_GETARG_TEXT_P(0);
|
|
p = VARDATA(pat_text);
|
|
plen = (VARSIZE(pat_text) - VARHDRSZ);
|
|
if (PG_ARGISNULL(1))
|
|
{
|
|
/* No ESCAPE clause provided; default to backslash as escape */
|
|
e = "\\";
|
|
elen = 1;
|
|
}
|
|
else
|
|
{
|
|
esc_text = PG_GETARG_TEXT_P(1);
|
|
e = VARDATA(esc_text);
|
|
elen = (VARSIZE(esc_text) - VARHDRSZ);
|
|
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.")));
|
|
}
|
|
|
|
/*----------
|
|
* We surround the transformed input string with
|
|
* ***:^(?: ... )$
|
|
* which is bizarre enough to require some explanation. "***:" is a
|
|
* director prefix to force the regex to be treated as an ARE regardless
|
|
* of the current regex_flavor setting. We need "^" and "$" to force
|
|
* the pattern to match the entire input string as per SQL99 spec. The
|
|
* "(?:" and ")" are a non-capturing set of parens; we have to have
|
|
* parens in case the string contains "|", else the "^" and "$" will
|
|
* be bound into the first and last alternatives which is not what we
|
|
* want, and the parens must be non capturing because we don't want them
|
|
* to count when selecting output for SUBSTRING.
|
|
*----------
|
|
*/
|
|
|
|
/*
|
|
* We need room for the prefix/postfix plus as many as 2 output bytes per
|
|
* input byte
|
|
*/
|
|
result = (text *) palloc(VARHDRSZ + 10 + 2 * plen);
|
|
r = VARDATA(result);
|
|
|
|
*r++ = '*';
|
|
*r++ = '*';
|
|
*r++ = '*';
|
|
*r++ = ':';
|
|
*r++ = '^';
|
|
*r++ = '(';
|
|
*r++ = '?';
|
|
*r++ = ':';
|
|
|
|
while (plen > 0)
|
|
{
|
|
char pchar = *p;
|
|
|
|
if (afterescape)
|
|
{
|
|
if (pchar == '"') /* for SUBSTRING patterns */
|
|
*r++ = ((nquotes++ % 2) == 0) ? '(' : ')';
|
|
else
|
|
{
|
|
*r++ = '\\';
|
|
*r++ = pchar;
|
|
}
|
|
afterescape = false;
|
|
}
|
|
else if (e && pchar == *e)
|
|
{
|
|
/* SQL99 escape character; do not send to output */
|
|
afterescape = true;
|
|
}
|
|
else if (pchar == '%')
|
|
{
|
|
*r++ = '.';
|
|
*r++ = '*';
|
|
}
|
|
else if (pchar == '_')
|
|
*r++ = '.';
|
|
else if (pchar == '\\' || pchar == '.' || pchar == '?' ||
|
|
pchar == '{')
|
|
{
|
|
*r++ = '\\';
|
|
*r++ = pchar;
|
|
}
|
|
else
|
|
*r++ = pchar;
|
|
p++, plen--;
|
|
}
|
|
|
|
*r++ = ')';
|
|
*r++ = '$';
|
|
|
|
VARATT_SIZEP(result) = r - ((char *) result);
|
|
|
|
PG_RETURN_TEXT_P(result);
|
|
}
|
|
|
|
/*
|
|
* report whether regex_flavor is currently BASIC
|
|
*/
|
|
bool
|
|
regex_flavor_is_basic(void)
|
|
{
|
|
return (regex_flavor == REG_BASIC);
|
|
}
|