Re: Collation rules and multi-lingual databases

Joe Conway wrote:
> What about something like this?

Oops! Forgot to restrore error handling. See below:

Joe

> 8<--------------------------------
>
> #include <setjmp.h>
> #include <string.h>
>
> #include "postgres.h"
> #include "fmgr.h"
> #include "tcop/tcopprot.h"
> #include "utils/builtins.h"
>
> #define GET_STR(textp) \
> DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(textp)))
> #define GET_BYTEA(str_) \
> DatumGetTextP(DirectFunctionCall1(byteain, CStringGetDatum(str_)))
> #define MAX_BYTEA_LEN 0x3fffffff
>
> /*
> * pg_strxfrm - Function to convert string similar to the strxfrm C
> * function using a specified locale.
> */
> extern Datum pg_strxfrm(PG_FUNCTION_ARGS);
> PG_FUNCTION_INFO_V1(pg_strxfrm);
>
> Datum
> pg_strxfrm(PG_FUNCTION_ARGS)
> {
> char *str = GET_STR(PG_GETARG_TEXT_P(0));
> size_t str_len = strlen(str);
> char *localestr = GET_STR(PG_GETARG_TEXT_P(1));
> size_t approx_trans_len = 4 + (str_len * 3);
> char *trans = (char *) palloc(approx_trans_len + 1);
> size_t actual_trans_len;
> char *oldlocale;
> char *newlocale;
> sigjmp_buf save_restart;
>
> if (approx_trans_len > MAX_BYTEA_LEN)
> elog(ERROR, "source string too long to transform");
>
> oldlocale = setlocale(LC_COLLATE, NULL);
> if (!oldlocale)
> elog(ERROR, "setlocale failed to return a locale");
>
> /* catch elog while locale is set other than the default */
> memcpy(&save_restart, &Warn_restart, sizeof(save_restart));
> if (sigsetjmp(Warn_restart, 1) != 0)
> {
> memcpy(&Warn_restart, &save_restart, sizeof(Warn_restart));
> newlocale = setlocale(LC_COLLATE, oldlocale);
> if (!newlocale)
> elog(PANIC, "setlocale failed to reset locale: %s", localestr);
> siglongjmp(Warn_restart, 1);
> }
>
> newlocale = setlocale(LC_COLLATE, localestr);
> if (!newlocale)
> elog(ERROR, "setlocale failed to set a locale: %s", localestr);
>
> actual_trans_len = strxfrm(trans, str, approx_trans_len + 1);
>
> /* if the buffer was not large enough, resize it and try again */
> if (actual_trans_len >= approx_trans_len)
> {
> approx_trans_len = actual_trans_len + 1;
> if (approx_trans_len > MAX_BYTEA_LEN)
> elog(ERROR, "source string too long to transform");
>
> trans = (char *) repalloc(trans, approx_trans_len + 1);
> actual_trans_len = strxfrm(trans, str, approx_trans_len + 1);
>
> /* if the buffer still not large enough, punt */
> if (actual_trans_len >= approx_trans_len)
> elog(ERROR, "strxfrm failed, buffer insufficient");
> }
>
> newlocale = setlocale(LC_COLLATE, oldlocale);
> if (!newlocale)
> elog(PANIC, "setlocale failed to reset locale: %s", localestr);

/* restore normal error handling */
memcpy(&Warn_restart, &save_restart, sizeof(Warn_restart));

>
> PG_RETURN_BYTEA_P(GET_BYTEA(trans));
> }
>
> 8<--------------------------------
>