Be more careful with error paths in pg_set_regex_collation().

Set global variables after error paths so that they don't end up in an
inconsistent state.

The inconsistent state doesn't lead to an actual problem, because
after an error, pg_set_regex_collation() will be called again before
the globals are accessed.

Change extracted from patch by Andreas Karlsson, though not discussed
explicitly.

Discussion: https://postgr.es/m/60929555-4709-40a7-b136-bcb44cff5a3c@proxel.se

diff --git a/src/backend/regex/regc_pg_locale.c b/src/backend/regex/regc_pg_locale.c
index 554a71e75a56d047f1a988923da058a6556621d1..35361c46a60ed8103a88870c89ed13e300e5aa2d 100644 (file)
--- a/src/backend/regex/regc_pg_locale.c
+++ b/src/backend/regex/regc_pg_locale.c
@@ -231,6 +231,9 @@ static const unsigned char pg_char_properties[128] = {
 void
 pg_set_regex_collation(Oid collation)
 {
+       pg_locale_t locale = 0;
+       PG_Locale_Strategy strategy;
+
        if (!OidIsValid(collation))
        {
                /*
@@ -246,40 +249,41 @@ pg_set_regex_collation(Oid collation)
        if (lc_ctype_is_c(collation))
        {
                /* C/POSIX collations use this path regardless of database encoding */
-               pg_regex_strategy = PG_REGEX_STRATEGY_C;
-               pg_regex_locale = 0;
-               pg_regex_collation = C_COLLATION_OID;
+               strategy = PG_REGEX_STRATEGY_C;
+               collation = C_COLLATION_OID;
        }
        else
        {
-               pg_regex_locale = pg_newlocale_from_collation(collation);
+               locale = pg_newlocale_from_collation(collation);
 
-               if (!pg_locale_deterministic(pg_regex_locale))
+               if (!pg_locale_deterministic(locale))
                        ereport(ERROR,
                                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                                         errmsg("nondeterministic collations are not supported for regular expressions")));
 
-               if (pg_regex_locale->provider == COLLPROVIDER_BUILTIN)
+               if (locale->provider == COLLPROVIDER_BUILTIN)
                {
                        Assert(GetDatabaseEncoding() == PG_UTF8);
-                       pg_regex_strategy = PG_REGEX_STRATEGY_BUILTIN;
+                       strategy = PG_REGEX_STRATEGY_BUILTIN;
                }
 #ifdef USE_ICU
-               else if (pg_regex_locale->provider == COLLPROVIDER_ICU)
+               else if (locale->provider == COLLPROVIDER_ICU)
                {
-                       pg_regex_strategy = PG_REGEX_STRATEGY_ICU;
+                       strategy = PG_REGEX_STRATEGY_ICU;
                }
 #endif
                else
                {
                        if (GetDatabaseEncoding() == PG_UTF8)
-                               pg_regex_strategy = PG_REGEX_STRATEGY_LIBC_WIDE;
+                               strategy = PG_REGEX_STRATEGY_LIBC_WIDE;
                        else
-                               pg_regex_strategy = PG_REGEX_STRATEGY_LIBC_1BYTE;
+                               strategy = PG_REGEX_STRATEGY_LIBC_1BYTE;
                }
-
-               pg_regex_collation = collation;
        }
+
+       pg_regex_strategy = strategy;
+       pg_regex_locale = locale;
+       pg_regex_collation = collation;
 }
 
 static int