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Fix breakage that had crept into setlocale() usage: once again we've

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been bit by the fact that the locale functions return pointers to
modifiable variables.  I added some comments that might help us avoid
the mistake in future.
This commit is contained in:
Tom Lane
2002-10-18 20:44:02 +00:00
parent 6c06bc2644
commit 0d17ce92ac
1 changed files with 50 additions and 25 deletions
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75
src/backend/utils/adt/pg_locale.c
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@ -2,14 +2,14 @@
*
* PostgreSQL locale utilities
*
* $Header: /cvsroot/pgsql/src/backend/utils/adt/pg_locale.c,v 1.19 2002/09/04 20:31:28 momjian Exp $
*
* Portions Copyright (c) 2002, PostgreSQL Global Development Group
*
* $Header: /cvsroot/pgsql/src/backend/utils/adt/pg_locale.c,v 1.20 2002/10/18 20:44:02 tgl Exp $
*
*-----------------------------------------------------------------------
*/
/*
/*----------
* Here is how the locale stuff is handled: LC_COLLATE and LC_CTYPE
* are fixed by initdb, stored in pg_control, and cannot be changed.
* Thus, the effects of strcoll(), strxfrm(), isupper(), toupper(),
@ -20,14 +20,29 @@
*
* The other categories, LC_MONETARY, LC_NUMERIC, and LC_TIME are also
* settable at run-time. However, we don't actually set those locale
* categories permanently. This would have bizzare effects like no
* categories permanently. This would have bizarre effects like no
* longer accepting standard floating-point literals in some locales.
* Instead, we only set the locales briefly when needed, cache the
* required information obtained from localeconv(), and set them back.
* The information is only used by the formatting functions (to_char,
* etc.) and the money type. For the user, this should all be
* The cached information is only used by the formatting functions
* (to_char, etc.) and the money type. For the user, this should all be
* transparent. (Actually, LC_TIME doesn't do anything at all right
* now.)
*
* !!! NOW HEAR THIS !!!
*
* We've been bitten repeatedly by this bug, so let's try to keep it in
* mind in future: on some platforms, the locale functions return pointers
* to static data that will be overwritten by any later locale function.
* Thus, for example, the obvious-looking sequence
* save = setlocale(category, NULL);
* if (!setlocale(category, value))
* fail = true;
* setlocale(category, save);
* DOES NOT WORK RELIABLY: on some platforms the second setlocale() call
* will change the memory save is pointing at. To do this sort of thing
* safely, you *must* pstrdup what setlocale returns the first time.
*----------
*/
@ -64,15 +79,19 @@ locale_xxx_assign(int category, const char *value, bool doit, bool interactive)
save = setlocale(category, NULL);
if (!save)
return NULL;
return NULL; /* won't happen, we hope */
/* save may be pointing at a modifiable scratch variable, see above */
save = pstrdup(save);
if (!setlocale(category, value))
return NULL;
value = NULL; /* set failure return marker */
setlocale(category, save);
setlocale(category, save); /* assume this won't fail */
pfree(save);
/* need to reload cache next time */
if (doit)
/* need to reload cache next time? */
if (doit && value != NULL)
CurrentLocaleConvValid = false;
return value;
@ -99,7 +118,7 @@ locale_time_assign(const char *value, bool doit, bool interactive)
/*
* lc_messages takes effect immediately
* We allow LC_MESSAGES to actually be set globally.
*/
const char *
locale_messages_assign(const char *value, bool doit, bool interactive)
@ -116,16 +135,7 @@ locale_messages_assign(const char *value, bool doit, bool interactive)
}
else
{
char *save;
save = setlocale(LC_MESSAGES, NULL);
if (!save)
return NULL;
if (!setlocale(LC_MESSAGES, value))
return NULL;
setlocale(LC_MESSAGES, save);
value = locale_xxx_assign(LC_MESSAGES, value, false, interactive);
}
#endif
return value;
@ -210,8 +220,13 @@ PGLC_localeconv(void)
free_struct_lconv(&CurrentLocaleConv);
/* Set user's values of monetary and numeric locales */
save_lc_monetary = setlocale(LC_MONETARY, NULL);
if (save_lc_monetary)
save_lc_monetary = pstrdup(save_lc_monetary);
save_lc_numeric = setlocale(LC_NUMERIC, NULL);
if (save_lc_numeric)
save_lc_numeric = pstrdup(save_lc_numeric);
setlocale(LC_MONETARY, locale_monetary);
setlocale(LC_NUMERIC, locale_numeric);
@ -221,7 +236,7 @@ PGLC_localeconv(void)
/*
* Must copy all values since restoring internal settings may
* overwrite
* overwrite localeconv()'s results.
*/
CurrentLocaleConv = *extlconv;
CurrentLocaleConv.currency_symbol = strdup(extlconv->currency_symbol);
@ -236,8 +251,18 @@ PGLC_localeconv(void)
CurrentLocaleConv.positive_sign = strdup(extlconv->positive_sign);
CurrentLocaleConv.n_sign_posn = extlconv->n_sign_posn;
setlocale(LC_MONETARY, save_lc_monetary);
setlocale(LC_NUMERIC, save_lc_numeric);
/* Try to restore internal settings */
if (save_lc_monetary)
{
setlocale(LC_MONETARY, save_lc_monetary);
pfree(save_lc_monetary);
}
if (save_lc_numeric)
{
setlocale(LC_NUMERIC, save_lc_numeric);
pfree(save_lc_numeric);
}
CurrentLocaleConvValid = true;
return &CurrentLocaleConv;