regc_pg_locale.c

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/*-------------------------------------------------------------------------
 *
 * regc_pg_locale.c
 *    ctype functions adapted to work on pg_wchar (a/k/a chr),
 *    and functions to cache the results of wholesale ctype probing.
 *
 * This file is #included by regcomp.c; it's not meant to compile standalone.
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/regex/regc_pg_locale.c
 *
 *-------------------------------------------------------------------------
 */
 
#include "catalog/pg_collation.h"
#include "common/unicode_case.h"
#include "common/unicode_category.h"
#include "utils/pg_locale.h"
#include "utils/pg_locale_c.h"
 
static pg_locale_t pg_regex_locale;
 
 
/*
 * pg_set_regex_collation: set collation for these functions to obey
 *
 * This is called when beginning compilation or execution of a regexp.
 * Since there's no need for reentrancy of regexp operations, it's okay
 * to store the results in static variables.
 */
void
pg_set_regex_collation(Oid collation)
{
    pg_locale_t locale = 0;
 
    if (!OidIsValid(collation))
    {
        /*
         * This typically means that the parser could not resolve a conflict
         * of implicit collations, so report it that way.
         */
        ereport(ERROR,
                (errcode(ERRCODE_INDETERMINATE_COLLATION),
                 errmsg("could not determine which collation to use for regular expression"),
                 errhint("Use the COLLATE clause to set the collation explicitly.")));
    }
 
    locale = pg_newlocale_from_collation(collation);
 
    if (!locale->deterministic)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("nondeterministic collations are not supported for regular expressions")));
 
    pg_regex_locale = locale;
}
 
/*
 * The following functions overlap with those defined in pg_locale.c. XXX:
 * consider refactor.
 */
 
static int
regc_wc_isdigit(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
        return (c <= (pg_wchar) 127 &&
                (pg_char_properties[c] & PG_ISDIGIT));
    else
        return pg_regex_locale->ctype->wc_isdigit(c, pg_regex_locale);
}
 
static int
regc_wc_isalpha(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
        return (c <= (pg_wchar) 127 &&
                (pg_char_properties[c] & PG_ISALPHA));
    else
        return pg_regex_locale->ctype->wc_isalpha(c, pg_regex_locale);
}
 
static int
regc_wc_isalnum(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
        return (c <= (pg_wchar) 127 &&
                (pg_char_properties[c] & PG_ISALNUM));
    else
        return pg_regex_locale->ctype->wc_isalnum(c, pg_regex_locale);
}
 
static int
regc_wc_isword(pg_wchar c)
{
    /* We define word characters as alnum class plus underscore */
    if (c == CHR('_'))
        return 1;
    return regc_wc_isalnum(c);
}
 
static int
regc_wc_isupper(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
        return (c <= (pg_wchar) 127 &&
                (pg_char_properties[c] & PG_ISUPPER));
    else
        return pg_regex_locale->ctype->wc_isupper(c, pg_regex_locale);
}
 
static int
regc_wc_islower(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
        return (c <= (pg_wchar) 127 &&
                (pg_char_properties[c] & PG_ISLOWER));
    else
        return pg_regex_locale->ctype->wc_islower(c, pg_regex_locale);
}
 
static int
regc_wc_isgraph(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
        return (c <= (pg_wchar) 127 &&
                (pg_char_properties[c] & PG_ISGRAPH));
    else
        return pg_regex_locale->ctype->wc_isgraph(c, pg_regex_locale);
}
 
static int
regc_wc_isprint(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
        return (c <= (pg_wchar) 127 &&
                (pg_char_properties[c] & PG_ISPRINT));
    else
        return pg_regex_locale->ctype->wc_isprint(c, pg_regex_locale);
}
 
static int
regc_wc_ispunct(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
        return (c <= (pg_wchar) 127 &&
                (pg_char_properties[c] & PG_ISPUNCT));
    else
        return pg_regex_locale->ctype->wc_ispunct(c, pg_regex_locale);
}
 
static int
regc_wc_isspace(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
        return (c <= (pg_wchar) 127 &&
                (pg_char_properties[c] & PG_ISSPACE));
    else
        return pg_regex_locale->ctype->wc_isspace(c, pg_regex_locale);
}
 
static pg_wchar
regc_wc_toupper(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
    {
        if (c <= (pg_wchar) 127)
            return pg_ascii_toupper((unsigned char) c);
        return c;
    }
    else
        return pg_regex_locale->ctype->wc_toupper(c, pg_regex_locale);
}
 
static pg_wchar
regc_wc_tolower(pg_wchar c)
{
    if (pg_regex_locale->ctype_is_c)
    {
        if (c <= (pg_wchar) 127)
            return pg_ascii_tolower((unsigned char) c);
        return c;
    }
    else
        return pg_regex_locale->ctype->wc_tolower(c, pg_regex_locale);
}
 
 
/*
 * These functions cache the results of probing libc's ctype behavior for
 * all character codes of interest in a given encoding/collation.  The
 * result is provided as a "struct cvec", but notice that the representation
 * is a touch different from a cvec created by regc_cvec.c: we allocate the
 * chrs[] and ranges[] arrays separately from the struct so that we can
 * realloc them larger at need.  This is okay since the cvecs made here
 * should never be freed by freecvec().
 *
 * We use malloc not palloc since we mustn't lose control on out-of-memory;
 * the main regex code expects us to return a failure indication instead.
 */
 
typedef int (*regc_wc_probefunc) (pg_wchar c);
 
typedef struct pg_ctype_cache
{
    regc_wc_probefunc probefunc;    /* regc_wc_isalpha or a sibling */
    pg_locale_t locale;         /* locale this entry is for */
    struct cvec cv;             /* cache entry contents */
    struct pg_ctype_cache *next;    /* chain link */
} pg_ctype_cache;
 
static pg_ctype_cache *pg_ctype_cache_list = NULL;
 
/*
 * Add a chr or range to pcc->cv; return false if run out of memory
 */
static bool
store_match(pg_ctype_cache *pcc, pg_wchar chr1, int nchrs)
{
    chr        *newchrs;
 
    if (nchrs > 1)
    {
        if (pcc->cv.nranges >= pcc->cv.rangespace)
        {
            pcc->cv.rangespace *= 2;
            newchrs = (chr *) realloc(pcc->cv.ranges,
                                      pcc->cv.rangespace * sizeof(chr) * 2);
            if (newchrs == NULL)
                return false;
            pcc->cv.ranges = newchrs;
        }
        pcc->cv.ranges[pcc->cv.nranges * 2] = chr1;
        pcc->cv.ranges[pcc->cv.nranges * 2 + 1] = chr1 + nchrs - 1;
        pcc->cv.nranges++;
    }
    else
    {
        assert(nchrs == 1);
        if (pcc->cv.nchrs >= pcc->cv.chrspace)
        {
            pcc->cv.chrspace *= 2;
            newchrs = (chr *) realloc(pcc->cv.chrs,
                                      pcc->cv.chrspace * sizeof(chr));
            if (newchrs == NULL)
                return false;
            pcc->cv.chrs = newchrs;
        }
        pcc->cv.chrs[pcc->cv.nchrs++] = chr1;
    }
    return true;
}
 
/*
 * Given a probe function (e.g., regc_wc_isalpha) get a struct cvec for all
 * chrs satisfying the probe function.  The active collation is the one
 * previously set by pg_set_regex_collation.  Return NULL if out of memory.
 *
 * Note that the result must not be freed or modified by caller.
 */
static struct cvec *
regc_ctype_get_cache(regc_wc_probefunc probefunc, int cclasscode)
{
    pg_ctype_cache *pcc;
    pg_wchar    max_chr;
    pg_wchar    cur_chr;
    int         nmatches;
    chr        *newchrs;
 
    /*
     * Do we already have the answer cached?
     */
    for (pcc = pg_ctype_cache_list; pcc != NULL; pcc = pcc->next)
    {
        if (pcc->probefunc == probefunc &&
            pcc->locale == pg_regex_locale)
            return &pcc->cv;
    }
 
    /*
     * Nope, so initialize some workspace ...
     */
    pcc = (pg_ctype_cache *) malloc(sizeof(pg_ctype_cache));
    if (pcc == NULL)
        return NULL;
    pcc->probefunc = probefunc;
    pcc->locale = pg_regex_locale;
    pcc->cv.nchrs = 0;
    pcc->cv.chrspace = 128;
    pcc->cv.chrs = (chr *) malloc(pcc->cv.chrspace * sizeof(chr));
    pcc->cv.nranges = 0;
    pcc->cv.rangespace = 64;
    pcc->cv.ranges = (chr *) malloc(pcc->cv.rangespace * sizeof(chr) * 2);
    if (pcc->cv.chrs == NULL || pcc->cv.ranges == NULL)
        goto out_of_memory;
    pcc->cv.cclasscode = cclasscode;
 
    /*
     * Decide how many character codes we ought to look through.  In general
     * we don't go past MAX_SIMPLE_CHR; chr codes above that are handled at
     * runtime using the "high colormap" mechanism.  However, in C locale
     * there's no need to go further than 127, and if we only have a 1-byte
     * <ctype.h> API there's no need to go further than that can handle.
     *
     * If it's not MAX_SIMPLE_CHR that's constraining the search, mark the
     * output cvec as not having any locale-dependent behavior, since there
     * will be no need to do any run-time locale checks.  (The #if's here
     * would always be true for production values of MAX_SIMPLE_CHR, but it's
     * useful to allow it to be small for testing purposes.)
     */
    if (pg_regex_locale->ctype_is_c)
    {
#if MAX_SIMPLE_CHR >= 127
        max_chr = (pg_wchar) 127;
        pcc->cv.cclasscode = -1;
#else
        max_chr = (pg_wchar) MAX_SIMPLE_CHR;
#endif
    }
    else if (GetDatabaseEncoding() == PG_UTF8)
    {
        max_chr = (pg_wchar) MAX_SIMPLE_CHR;
    }
    else
    {
#if MAX_SIMPLE_CHR >= UCHAR_MAX
        max_chr = (pg_wchar) UCHAR_MAX;
        pcc->cv.cclasscode = -1;
#else
        max_chr = (pg_wchar) MAX_SIMPLE_CHR;
#endif
    }
 
    /*
     * And scan 'em ...
     */
    nmatches = 0;               /* number of consecutive matches */
 
    for (cur_chr = 0; cur_chr <= max_chr; cur_chr++)
    {
        if ((*probefunc) (cur_chr))
            nmatches++;
        else if (nmatches > 0)
        {
            if (!store_match(pcc, cur_chr - nmatches, nmatches))
                goto out_of_memory;
            nmatches = 0;
        }
    }
 
    if (nmatches > 0)
        if (!store_match(pcc, cur_chr - nmatches, nmatches))
            goto out_of_memory;
 
    /*
     * We might have allocated more memory than needed, if so free it
     */
    if (pcc->cv.nchrs == 0)
    {
        free(pcc->cv.chrs);
        pcc->cv.chrs = NULL;
        pcc->cv.chrspace = 0;
    }
    else if (pcc->cv.nchrs < pcc->cv.chrspace)
    {
        newchrs = (chr *) realloc(pcc->cv.chrs,
                                  pcc->cv.nchrs * sizeof(chr));
        if (newchrs == NULL)
            goto out_of_memory;
        pcc->cv.chrs = newchrs;
        pcc->cv.chrspace = pcc->cv.nchrs;
    }
    if (pcc->cv.nranges == 0)
    {
        free(pcc->cv.ranges);
        pcc->cv.ranges = NULL;
        pcc->cv.rangespace = 0;
    }
    else if (pcc->cv.nranges < pcc->cv.rangespace)
    {
        newchrs = (chr *) realloc(pcc->cv.ranges,
                                  pcc->cv.nranges * sizeof(chr) * 2);
        if (newchrs == NULL)
            goto out_of_memory;
        pcc->cv.ranges = newchrs;
        pcc->cv.rangespace = pcc->cv.nranges;
    }
 
    /*
     * Success, link it into cache chain
     */
    pcc->next = pg_ctype_cache_list;
    pg_ctype_cache_list = pcc;
 
    return &pcc->cv;
 
    /*
     * Failure, clean up
     */
out_of_memory:
    free(pcc->cv.chrs);
    free(pcc->cv.ranges);
    free(pcc);
 
    return NULL;
}