Prevent ALTER USER f RESET ALL from removing the settings that were put there

by a superuser -- "ALTER USER f RESET setting" already disallows removing such a
setting.

Apply the same treatment to ALTER DATABASE d RESET ALL when run by a database
owner that's not superuser.

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.299.2.8 2010/02/25 23:44:27 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.299.2.9 2010/03/25 14:45:36 alvherre Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -5439,6 +5439,7 @@ ProcessGUCArray(ArrayType *array, GucSource source)
 		free(name);
 		if (value)
 			free(value);
+		pfree(s);
 	}
 }
 
@@ -5574,6 +5575,85 @@ GUCArrayDelete(ArrayType *array, const char *name)
 			&& val[strlen(name)] == '=')
 			continue;
 
+
+		/* else add it to the output array */
+		if (newarray)
+		{
+			newarray = array_set(newarray, 1, &index,
+								 d,
+								 false,
+								 -1 /* varlenarray */ ,
+								 -1 /* TEXT's typlen */ ,
+								 false /* TEXT's typbyval */ ,
+								 'i' /* TEXT's typalign */ );
+		}
+		else
+			newarray = construct_array(&d, 1,
+									   TEXTOID,
+									   -1, false, 'i');
+
+		index++;
+	}
+
+	return newarray;
+}
+
+/*
+ * Given a GUC array, delete all settings from it that our permission
+ * level allows: if superuser, delete them all; if regular user, only
+ * those that are PGC_USERSET
+ */
+ArrayType *
+GUCArrayReset(ArrayType *array)
+{
+	ArrayType  *newarray;
+	int			i;
+	int			index;
+
+	/* if array is currently null, nothing to do */
+	if (!array)
+		return NULL;
+
+	/* if we're superuser, we can delete everything */
+	if (superuser())
+		return NULL;
+
+	newarray = NULL;
+	index = 1;
+
+	for (i = 1; i <= ARR_DIMS(array)[0]; i++)
+	{
+		Datum		d;
+		char	   *val;
+		char	   *eqsgn;
+		bool		isnull;
+		struct config_generic *gconf;
+
+		d = array_ref(array, 1, &i,
+					  -1 /* varlenarray */ ,
+					  -1 /* TEXT's typlen */ ,
+					  false /* TEXT's typbyval */ ,
+					  'i' /* TEXT's typalign */ ,
+					  &isnull);
+
+		if (isnull)
+			continue;
+		val = DatumGetCString(DirectFunctionCall1(textout, d));
+
+		eqsgn = strchr(val, '=');
+		*eqsgn = '\0';
+
+		gconf = find_option(val, WARNING);
+		if (!gconf)
+			continue;
+
+		/* note: superuser-ness was already checked above */
+		/* skip entry if OK to delete */
+		if (gconf->context == PGC_USERSET)
+			continue;
+
+		/* XXX do we need to worry about database owner? */
+
 		/* else add it to the output array */
 		if (newarray)
 		{
@@ -5592,6 +5672,7 @@ GUCArrayDelete(ArrayType *array, const char *name)
 									   -1, false, 'i');
 
 		index++;
+		pfree(val);
 	}
 
 	return newarray;