pg_locale_builtin.c

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/*-----------------------------------------------------------------------
 *
 * PostgreSQL locale utilities for builtin provider
 *
 * Portions Copyright (c) 2002-2025, PostgreSQL Global Development Group
 *
 * src/backend/utils/adt/pg_locale_builtin.c
 *
 *-----------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "catalog/pg_database.h"
#include "catalog/pg_collation.h"
#include "common/unicode_case.h"
#include "common/unicode_category.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/memutils.h"
#include "utils/pg_locale.h"
#include "utils/syscache.h"
 
extern pg_locale_t create_pg_locale_builtin(Oid collid,
                                            MemoryContext context);
extern char *get_collation_actual_version_builtin(const char *collcollate);
extern size_t strlower_builtin(char *dest, size_t destsize, const char *src,
                               ssize_t srclen, pg_locale_t locale);
extern size_t strtitle_builtin(char *dest, size_t destsize, const char *src,
                               ssize_t srclen, pg_locale_t locale);
extern size_t strupper_builtin(char *dest, size_t destsize, const char *src,
                               ssize_t srclen, pg_locale_t locale);
extern size_t strfold_builtin(char *dest, size_t destsize, const char *src,
                              ssize_t srclen, pg_locale_t locale);
 
 
struct WordBoundaryState
{
    const char *str;
    size_t      len;
    size_t      offset;
    bool        posix;
    bool        init;
    bool        prev_alnum;
};
 
/*
 * Simple word boundary iterator that draws boundaries each time the result of
 * pg_u_isalnum() changes.
 */
static size_t
initcap_wbnext(void *state)
{
    struct WordBoundaryState *wbstate = (struct WordBoundaryState *) state;
 
    while (wbstate->offset < wbstate->len &&
           wbstate->str[wbstate->offset] != '\0')
    {
        pg_wchar    u = utf8_to_unicode((unsigned char *) wbstate->str +
                                        wbstate->offset);
        bool        curr_alnum = pg_u_isalnum(u, wbstate->posix);
 
        if (!wbstate->init || curr_alnum != wbstate->prev_alnum)
        {
            size_t      prev_offset = wbstate->offset;
 
            wbstate->init = true;
            wbstate->offset += unicode_utf8len(u);
            wbstate->prev_alnum = curr_alnum;
            return prev_offset;
        }
 
        wbstate->offset += unicode_utf8len(u);
    }
 
    return wbstate->len;
}
 
size_t
strlower_builtin(char *dest, size_t destsize, const char *src, ssize_t srclen,
                 pg_locale_t locale)
{
    return unicode_strlower(dest, destsize, src, srclen,
                            locale->info.builtin.casemap_full);
}
 
size_t
strtitle_builtin(char *dest, size_t destsize, const char *src, ssize_t srclen,
                 pg_locale_t locale)
{
    struct WordBoundaryState wbstate = {
        .str = src,
        .len = srclen,
        .offset = 0,
        .posix = !locale->info.builtin.casemap_full,
        .init = false,
        .prev_alnum = false,
    };
 
    return unicode_strtitle(dest, destsize, src, srclen,
                            locale->info.builtin.casemap_full,
                            initcap_wbnext, &wbstate);
}
 
size_t
strupper_builtin(char *dest, size_t destsize, const char *src, ssize_t srclen,
                 pg_locale_t locale)
{
    return unicode_strupper(dest, destsize, src, srclen,
                            locale->info.builtin.casemap_full);
}
 
size_t
strfold_builtin(char *dest, size_t destsize, const char *src, ssize_t srclen,
                pg_locale_t locale)
{
    return unicode_strfold(dest, destsize, src, srclen,
                           locale->info.builtin.casemap_full);
}
 
pg_locale_t
create_pg_locale_builtin(Oid collid, MemoryContext context)
{
    const char *locstr;
    pg_locale_t result;
 
    if (collid == DEFAULT_COLLATION_OID)
    {
        HeapTuple   tp;
        Datum       datum;
 
        tp = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId));
        if (!HeapTupleIsValid(tp))
            elog(ERROR, "cache lookup failed for database %u", MyDatabaseId);
        datum = SysCacheGetAttrNotNull(DATABASEOID, tp,
                                       Anum_pg_database_datlocale);
        locstr = TextDatumGetCString(datum);
        ReleaseSysCache(tp);
    }
    else
    {
        HeapTuple   tp;
        Datum       datum;
 
        tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collid));
        if (!HeapTupleIsValid(tp))
            elog(ERROR, "cache lookup failed for collation %u", collid);
        datum = SysCacheGetAttrNotNull(COLLOID, tp,
                                       Anum_pg_collation_colllocale);
        locstr = TextDatumGetCString(datum);
        ReleaseSysCache(tp);
    }
 
    builtin_validate_locale(GetDatabaseEncoding(), locstr);
 
    result = MemoryContextAllocZero(context, sizeof(struct pg_locale_struct));
 
    result->info.builtin.locale = MemoryContextStrdup(context, locstr);
    result->info.builtin.casemap_full = (strcmp(locstr, "PG_UNICODE_FAST") == 0);
    result->provider = COLLPROVIDER_BUILTIN;
    result->deterministic = true;
    result->collate_is_c = true;
    result->ctype_is_c = (strcmp(locstr, "C") == 0);
 
    return result;
}
 
char *
get_collation_actual_version_builtin(const char *collcollate)
{
    /*
     * The only two supported locales (C and C.UTF-8) are both based on memcmp
     * and are not expected to change, but track the version anyway.
     *
     * Note that the character semantics may change for some locales, but the
     * collation version only tracks changes to sort order.
     */
    if (strcmp(collcollate, "C") == 0)
        return "1";
    else if (strcmp(collcollate, "C.UTF-8") == 0)
        return "1";
    else if (strcmp(collcollate, "PG_UNICODE_FAST") == 0)
        return "1";
    else
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("invalid locale name \"%s\" for builtin provider",
                        collcollate)));
 
    return NULL;                /* keep compiler quiet */
}