Yeah I thought of that. But if making it a critical section is cheap then it's probably a better approach. The problem with restoring the locale for the palloc is that if the user is unlucky he might sort a table of thousands of strings that all trigger the exception case.
What about something like this? 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);
PG_RETURN_BYTEA_P(GET_BYTEA(trans)); }
8<--------------------------------
Joe
---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives?
http://archives.postgresql.org