Re-apply guc cleanup patch, with memory allocation bugs fixed.

src/backend/utils/misc/guc-file.l

@@ -4,7 +4,7 @@
  *
  * Copyright (c) 2000-2006, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/backend/utils/misc/guc-file.l,v 1.42 2006/08/12 04:12:41 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/misc/guc-file.l,v 1.43 2006/08/13 01:30:17 momjian Exp $
  */
 
 %{
@@ -50,7 +50,8 @@ int GUC_yylex(void);
 static bool ParseConfigFile(const char *config_file, const char *calling_file,
 							int depth, GucContext context, int elevel,
 							struct name_value_pair **head_p,
-							struct name_value_pair **tail_p);
+							struct name_value_pair **tail_p,
+							int *varcount);
 static void free_name_value_list(struct name_value_pair * list);
 static char *GUC_scanstr(const char *s);
 
@@ -114,8 +115,10 @@ STRING          \'([^'\\\n]|\\.|\'\')*\'
 void
 ProcessConfigFile(GucContext context)
 {
-	int			elevel;
+	int			elevel, i;
 	struct name_value_pair *item, *head, *tail;
+	bool	   *apply_list = NULL;
+	int			varcount = 0;
 
 	Assert(context == PGC_POSTMASTER || context == PGC_SIGHUP);
 
@@ -134,25 +137,56 @@ ProcessConfigFile(GucContext context)
 
 	if (!ParseConfigFile(ConfigFileName, NULL,
 						 0, context, elevel,
-						 &head, &tail))
+						 &head, &tail, &varcount))
 		goto cleanup_list;
 
+	/* Can we allocate memory here, what about leaving here prematurely? */
+	apply_list = (bool *) palloc(sizeof(bool) * varcount);
+
 	/* Check if all options are valid */
-	for (item = head; item; item = item->next)
+	for (item = head, i = 0; item; item = item->next, i++)
+	{
+		bool isEqual, isContextOk;
+
+		if (!verify_config_option(item->name, item->value, context,
+						  PGC_S_FILE, &isEqual, &isContextOk))
 		{
-		if (!set_config_option(item->name, item->value, context,
-							   PGC_S_FILE, false, false))
+			ereport(elevel,
+				(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+				errmsg("configuration file is invalid")));
 			goto cleanup_list;
 		}
 
-	/* If we got here all the options checked out okay, so apply them. */
-	for (item = head; item; item = item->next)
+		if (isContextOk == false)
 		{
+			apply_list[i] = false;
+			if (context == PGC_SIGHUP)
+			{
+				if (isEqual == false)
+					ereport(elevel,
+						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+						errmsg("parameter \"%s\" cannot be changed after server start; configuration file change ignored",
+						item->name)));
+			}
+			else
+				/* if it is boot phase, context must be valid for all
+				 * configuration item. */
+				goto cleanup_list;
+		}
+		else
+			apply_list[i] = true;
+	}
+
+	/* If we got here all the options checked out okay, so apply them. */
+	for (item = head, i = 0; item; item = item->next, i++)
+		if (apply_list[i])
 			set_config_option(item->name, item->value, context,
 							  PGC_S_FILE, false, true);
-	}
 
- cleanup_list:
+
+cleanup_list:
+	if (apply_list)
+		pfree(apply_list);
 	free_name_value_list(head);
 }
 
@@ -189,7 +223,8 @@ static bool
 ParseConfigFile(const char *config_file, const char *calling_file,
 				int depth, GucContext context, int elevel,
 				struct name_value_pair **head_p,
-				struct name_value_pair **tail_p)
+				struct name_value_pair **tail_p,
+				int *varcount)
 {
 	bool			OK = true;
 	char			abs_path[MAXPGPATH];
@@ -289,7 +324,7 @@ ParseConfigFile(const char *config_file, const char *calling_file,
 
 			if (!ParseConfigFile(opt_value, config_file,
 								 depth + 1, context, elevel,
-								 head_p, tail_p))
+								 head_p, tail_p, varcount))
 			{
 				pfree(opt_name);
 				pfree(opt_value);
@@ -333,6 +368,7 @@ ParseConfigFile(const char *config_file, const char *calling_file,
 			else
 				(*tail_p)->next = item;
 			*tail_p = item;
+			(*varcount)++;
 		}
 
 		/* break out of loop if read EOF, else loop for next line */

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 1.337 2006/08/12 04:12:41 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.338 2006/08/13 01:30:17 momjian Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -2313,7 +2313,7 @@ guc_strdup(int elevel, const char *src)
  * states).
  */
 static void
-set_string_field(struct config_string * conf, char **field, char *newval)
+set_string_field(struct config_string *conf, char **field, char *newval)
 {
 	char	   *oldval = *field;
 	GucStack   *stack;
@@ -2535,8 +2535,7 @@ add_placeholder_variable(const char *name, int elevel)
 	gen = &var->gen;
 	memset(var, 0, sz);
 
-	gen->name = guc_strdup(elevel, name);
-	if (gen->name == NULL)
+	if ((gen->name = guc_strdup(elevel, name)) == NULL)
 	{
 		free(var);
 		return NULL;
@@ -3690,96 +3689,254 @@ call_string_assign_hook(GucStringAssignHook assign_hook,
 	return result;
 }
 
-
 /*
- * Sets option `name' to given value. The value should be a string
- * which is going to be parsed and converted to the appropriate data
- * type.  The context and source parameters indicate in which context this
- * function is being called so it can apply the access restrictions
- * properly.
- *
- * If value is NULL, set the option to its default value. If the
- * parameter changeVal is false then don't really set the option but do all
- * the checks to see if it would work.
- *
- * If there is an error (non-existing option, invalid value) then an
- * ereport(ERROR) is thrown *unless* this is called in a context where we
- * don't want to ereport (currently, startup or SIGHUP config file reread).
- * In that case we write a suitable error message via ereport(DEBUG) and
- * return false. This is working around the deficiencies in the ereport
- * mechanism, so don't blame me.  In all other cases, the function
- * returns true, including cases where the input is valid but we chose
- * not to apply it because of context or source-priority considerations.
- *
- * See also SetConfigOption for an external interface.
+ * Try to parse value. Determine what is type and call related
+ * parsing function or if newval is equal to NULL, reset value 
+ * to default or bootval. If the value parsed okay return true,
+ * else false.
  */
-bool
-set_config_option(const char *name, const char *value,
-				  GucContext context, GucSource source,
-				  bool isLocal, bool changeVal)
+static bool
+parse_value(int elevel, const struct config_generic *record, 
+		const char *value, GucSource *source, bool changeVal, 
+		union config_var_value *retval)
 {
-	struct config_generic *record;
-	int			elevel;
-	bool		makeDefault;
+	/*
+	 * Evaluate value and set variable.
+	 */
+	switch (record->vartype)
+	{
+		case PGC_BOOL:
+			{
+				struct config_bool *conf = (struct config_bool *) record;
+				bool		newval;
 
-	if (context == PGC_SIGHUP || source == PGC_S_DEFAULT)
+				if (value)
+				{
+					if (!parse_bool(value, &newval))
+					{
+						ereport(elevel,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						  errmsg("parameter \"%s\" requires a Boolean value",
+								 record->name)));
+						return false;
+					}
+				}
+				else
+				{
+					newval = conf->reset_val;
+					*source = conf->gen.reset_source;
+				}
+
+				if (conf->assign_hook)
+					if (!(*conf->assign_hook) (newval, changeVal, *source))
+					{
+						ereport(elevel,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("invalid value for parameter \"%s\": %d",
+									record->name, (int) newval)));
+						return false;
+					}
+				if (retval)
+					retval->boolval = newval;
+				break;
+			}
+
+		case PGC_INT:
+			{
+				struct config_int *conf = (struct config_int *) record;
+				int			newval;
+
+				if (value)
+				{
+					if (!parse_int(value, &newval, conf->gen.flags))
+					{
+						ereport(elevel,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						 errmsg("parameter \"%s\" requires an integer value",
+								record->name)));
+						return false;
+					}
+					if (newval < conf->min || newval > conf->max)
+					{
+						ereport(elevel,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+								 errmsg("%d is outside the valid range for parameter \"%s\" (%d .. %d)",
+										newval, record->name, conf->min, conf->max)));
+						return false;
+					}
+				}
+				else
+				{
+					newval = conf->reset_val;
+					*source = conf->gen.reset_source;
+				}
+
+				if (conf->assign_hook)
+					if (!(*conf->assign_hook) (newval, changeVal, *source))
+					{
+						ereport(elevel,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("invalid value for parameter \"%s\": %d",
+									record->name, newval)));
+						return false;
+					}
+				if (retval)
+					retval->intval = newval;
+				break;
+			}
+
+		case PGC_REAL:
+			{
+				struct config_real *conf = (struct config_real *) record;
+				double		newval;
+
+				if (value)
+				{
+					if (!parse_real(value, &newval))
+					{
+						ereport(elevel,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						  errmsg("parameter \"%s\" requires a numeric value",
+								 record->name)));
+						return false;
+					}
+					if (newval < conf->min || newval > conf->max)
 					{
+						ereport(elevel,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+								 errmsg("%g is outside the valid range for parameter \"%s\" (%g .. %g)",
+										newval, record->name, conf->min, conf->max)));
+						return false;
+					}
+				}
+				else
+				{
+					newval = conf->reset_val;
+					*source = conf->gen.reset_source;
+				}
+
+				if (conf->assign_hook)
+					if (!(*conf->assign_hook) (newval, changeVal, *source))
+					{
+						ereport(elevel,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("invalid value for parameter \"%s\": %g",
+									record->name, newval)));
+						return false;
+					}
+				if (retval)
+					retval->realval = newval;
+				break;
+			}
+
+		case PGC_STRING:
+			{
+				struct config_string *conf = (struct config_string *) record;
+				char	   *newval;
+
+				if (value)
+				{
+					if ((newval = guc_strdup(elevel, value)) == NULL)
+						return false;
 					/*
-		 * To avoid cluttering the log, only the postmaster bleats loudly
-		 * about problems with the config file.
+					 * The only sort of "parsing" check we need to do is
+					 * apply truncation if GUC_IS_NAME.
 					 */
-		elevel = IsUnderPostmaster ? DEBUG2 : LOG;
+					if (conf->gen.flags & GUC_IS_NAME)
+						truncate_identifier(newval, strlen(newval), true);
+				}
+				else if (conf->reset_val)
+				{
+					/*
+					 * We could possibly avoid strdup here, but easier to make
+					 * this case work the same as the normal assignment case.
+					 */
+					if ((newval = guc_strdup(elevel, conf->reset_val)) == NULL)
+						return false;
+					*source = conf->gen.reset_source;
 				}
-	else if (source == PGC_S_DATABASE || source == PGC_S_USER)
-		elevel = INFO;
 				else
-		elevel = ERROR;
+				{
+					/* Nothing to reset to, as yet; so do nothing */
+					break;
+				}
 
-	record = find_option(name, elevel);
-	if (record == NULL)
+				if (conf->assign_hook)
 				{
+					const char *hookresult;
+
+					/*
+					 * If the hook ereports, we have to make sure we free
+					 * newval, else it will be a permanent memory leak.
+					 */
+					hookresult = call_string_assign_hook(conf->assign_hook,
+														 newval,
+														 changeVal,
+														 *source);
+					if (hookresult == NULL)
+					{
+						free(newval);
 						ereport(elevel,
-				(errcode(ERRCODE_UNDEFINED_OBJECT),
-			   errmsg("unrecognized configuration parameter \"%s\"", name)));
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						 errmsg("invalid value for parameter \"%s\": \"%s\"",
+								record->name, value ? value : "")));
 						return false;
 					}
+					else if (hookresult != newval)
+					{
+						free(newval);
 
 						/*
+						 * Having to cast away const here is annoying, but the
+						 * alternative is to declare assign_hooks as returning
+						 * char*, which would mean they'd have to cast away
+						 * const, or as both taking and returning char*, which
+						 * doesn't seem attractive either --- we don't want
+						 * them to scribble on the passed str.
+						 */
+						newval = (char *) hookresult;
+					}
+				}
+
+				if (retval)
+					retval->stringval = newval;
+				else
+					free(newval);
+				break;
+			}
+	}
+	return true;
+}
+
+/*
  * Check if the option can be set at this time. See guc.h for the precise
-	 * rules. Note that we don't want to throw errors if we're in the SIGHUP
-	 * context. In that case we just ignore the attempt and return true.
+ * rules. 
  */
+static bool
+checkContext(int elevel, struct config_generic *record, GucContext context)
+{
 	switch (record->context)
 	{
 		case PGC_INTERNAL:
-			if (context == PGC_SIGHUP)
-				return true;
 			if (context != PGC_INTERNAL)
 			{
 				ereport(elevel,
 						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
 						 errmsg("parameter \"%s\" cannot be changed",
-								name)));
+								record->name)));
 				return false;
 			}
 			break;
 		case PGC_POSTMASTER:
 			if (context == PGC_SIGHUP)
-			{
-				if (changeVal && !is_newvalue_equal(record, value))
-					ereport(elevel,
-							(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
-							 errmsg("parameter \"%s\" cannot be changed after server start; configuration file change ignored",
-									name)));
+				return false;
 
-				return true;
-			}
 			if (context != PGC_POSTMASTER)
 			{
 				ereport(elevel,
 						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
 						 errmsg("parameter \"%s\" cannot be changed after server start",
-								name)));
+								record->name)));
 				return false;
 			}
 			break;
@@ -3789,7 +3946,7 @@ set_config_option(const char *name, const char *value,
 				ereport(elevel,
 						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
 						 errmsg("parameter \"%s\" cannot be changed now",
-								name)));
+								record->name)));
 				return false;
 			}
 
@@ -3812,14 +3969,16 @@ set_config_option(const char *name, const char *value,
 				 * backend start.
 				 */
 				if (IsUnderPostmaster)
-					return true;
+				{
+					return false;
+				}
 			}
 			else if (context != PGC_BACKEND && context != PGC_POSTMASTER)
 			{
 				ereport(elevel,
 						(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
 						 errmsg("parameter \"%s\" cannot be set after connection start",
-								name)));
+								record->name)));
 				return false;
 			}
 			break;
@@ -3829,7 +3988,7 @@ set_config_option(const char *name, const char *value,
 				ereport(elevel,
 						(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 						 errmsg("permission denied to set parameter \"%s\"",
-								name)));
+								record->name)));
 				return false;
 			}
 			break;
@@ -3837,6 +3996,114 @@ set_config_option(const char *name, const char *value,
 			/* always okay */
 			break;
 	}
+	return true;
+}
+
+/*
+ * Get error level for different sources and context.
+ */
+static int
+get_elevel(GucContext context, GucSource source)
+{
+	int elevel;
+	if (context == PGC_SIGHUP || source == PGC_S_DEFAULT)
+	{
+		/*
+		 * To avoid cluttering the log, only the postmaster bleats loudly
+		 * about problems with the config file.
+		 */
+		elevel = IsUnderPostmaster ? DEBUG2 : LOG;
+	}
+	else if (source == PGC_S_DATABASE || source == PGC_S_USER)
+		elevel = INFO;
+	else
+		elevel = ERROR;
+
+	return elevel;
+}
+
+/*
+ * Verify if option exists and value is valid.
+ * It is primary used for validation of items in configuration file.
+ */
+bool
+verify_config_option(const char *name, const char *value,
+				GucContext context, GucSource source,
+				bool *isNewEqual, bool *isContextOK)
+{
+	int					   elevel;
+	struct config_generic *record;
+
+	elevel = get_elevel(context, source);
+
+	record = find_option(name, elevel);
+	if (record == NULL)
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+			   errmsg("unrecognized configuration parameter \"%s\"", name)));
+		return false;
+	}
+
+	if (parse_value(elevel, record, value, &source, false, NULL))
+	{
+		if (isNewEqual != NULL)
+			*isNewEqual = is_newvalue_equal(record, value);
+		if (isContextOK != NULL)
+			*isContextOK = checkContext(elevel, record, context);
+	}
+	else 
+		return false;
+
+    return true;
+}
+
+
+/*
+ * Sets option `name' to given value. The value should be a string
+ * which is going to be parsed and converted to the appropriate data
+ * type.  The context and source parameters indicate in which context this
+ * function is being called so it can apply the access restrictions
+ * properly.
+ *
+ * If value is NULL, set the option to its default value. If the
+ * parameter changeVal is false then don't really set the option but do all
+ * the checks to see if it would work.
+ *
+ * If there is an error (non-existing option, invalid value) then an
+ * ereport(ERROR) is thrown *unless* this is called in a context where we
+ * don't want to ereport (currently, startup or SIGHUP config file reread).
+ * In that case we write a suitable error message via ereport(DEBUG) and
+ * return false. This is working around the deficiencies in the ereport
+ * mechanism, so don't blame me.  In all other cases, the function
+ * returns true, including cases where the input is valid but we chose
+ * not to apply it because of context or source-priority considerations.
+ *
+ * See also SetConfigOption for an external interface.
+ */
+bool
+set_config_option(const char *name, const char *value,
+				  GucContext context, GucSource source,
+				  bool isLocal, bool changeVal)
+{
+	struct config_generic *record;
+	int			elevel;
+	bool		makeDefault;
+
+	elevel = get_elevel(context, source);
+
+	record = find_option(name, elevel);
+	if (record == NULL)
+	{
+		ereport(elevel,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+			   errmsg("unrecognized configuration parameter \"%s\"", name)));
+		return false;
+	}
+
+	/* Check if change is allowed in the running context. */
+	if (!checkContext(elevel, record, context))
+		return false;
 
 	/*
 	 * Should we set reset/stacked values?	(If so, the behavior is not
@@ -3872,43 +4139,22 @@ set_config_option(const char *name, const char *value,
 				struct config_bool *conf = (struct config_bool *) record;
 				bool		newval;
 				
-				if (value)
-				{
-					if (!parse_bool(value, &newval))
-					{
-						ereport(elevel,
-								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-						  errmsg("parameter \"%s\" requires a Boolean value",
-								 name)));
-						return false;
-					}
-				}
-				else
-				{
-					newval = conf->reset_val;
-					source = conf->gen.reset_source;
-				}
-
-				if (conf->assign_hook)
-					if (!(*conf->assign_hook) (newval, changeVal, source))
-					{
-						ereport(elevel,
-								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-							 errmsg("invalid value for parameter \"%s\": %d",
-									name, (int) newval)));
+				if (!parse_value(elevel, record, value, &source, changeVal,
+					(union config_var_value*) &newval))
 					return false;
-					}
 
 				if (changeVal || makeDefault)
 				{
 					/* Save old value to support transaction abort */
 					if (!makeDefault)
 						push_old_value(&conf->gen);
+
 					if (changeVal)
 					{
 						*conf->variable = newval;
 						conf->gen.source = source;
 					}
+
 					if (makeDefault)
 					{
 						GucStack   *stack;
@@ -3948,51 +4194,22 @@ set_config_option(const char *name, const char *value,
 				struct config_int *conf = (struct config_int *) record;
 				int			newval;
 
-				if (value)
-				{
-					if (!parse_int(value, &newval, conf->gen.flags))
-					{
-						ereport(elevel,
-								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-						 errmsg("parameter \"%s\" requires an integer value",
-								name)));
-						return false;
-					}
-					if (newval < conf->min || newval > conf->max)
-					{
-						ereport(elevel,
-								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-								 errmsg("%d is outside the valid range for parameter \"%s\" (%d .. %d)",
-										newval, name, conf->min, conf->max)));
-						return false;
-					}
-				}
-				else
-				{
-					newval = conf->reset_val;
-					source = conf->gen.reset_source;
-				}
-
-				if (conf->assign_hook)
-					if (!(*conf->assign_hook) (newval, changeVal, source))
-					{
-						ereport(elevel,
-								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-							 errmsg("invalid value for parameter \"%s\": %d",
-									name, newval)));
+ 				if (!parse_value(elevel, record, value, &source, changeVal,
+					(union config_var_value*) &newval))
  					return false;
-					}
 
 				if (changeVal || makeDefault)
 				{
 					/* Save old value to support transaction abort */
 					if (!makeDefault)
 						push_old_value(&conf->gen);
+
 					if (changeVal)
 					{
 						*conf->variable = newval;
 						conf->gen.source = source;
 					}
+
 					if (makeDefault)
 					{
 						GucStack   *stack;
@@ -4032,51 +4249,22 @@ set_config_option(const char *name, const char *value,
 				struct config_real *conf = (struct config_real *) record;
 				double		newval;
 
-				if (value)
-				{
-					if (!parse_real(value, &newval))
-					{
-						ereport(elevel,
-								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-						  errmsg("parameter \"%s\" requires a numeric value",
-								 name)));
-						return false;
-					}
-					if (newval < conf->min || newval > conf->max)
-					{
-						ereport(elevel,
-								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-								 errmsg("%g is outside the valid range for parameter \"%s\" (%g .. %g)",
-										newval, name, conf->min, conf->max)));
-						return false;
-					}
-				}
-				else
-				{
-					newval = conf->reset_val;
-					source = conf->gen.reset_source;
-				}
-
-				if (conf->assign_hook)
-					if (!(*conf->assign_hook) (newval, changeVal, source))
-					{
-						ereport(elevel,
-								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-							 errmsg("invalid value for parameter \"%s\": %g",
-									name, newval)));
+				if (!parse_value(elevel, record, value, &source, changeVal,
+					(union config_var_value*) &newval))
 					return false; 
-					}
 
 				if (changeVal || makeDefault)
 				{
 					/* Save old value to support transaction abort */
 					if (!makeDefault)
 						push_old_value(&conf->gen);
+
 					if (changeVal)
 					{
 						*conf->variable = newval;
 						conf->gen.source = source;
 					}
+
 					if (makeDefault)
 					{
 						GucStack   *stack;
@@ -4116,82 +4304,22 @@ set_config_option(const char *name, const char *value,
 				struct config_string *conf = (struct config_string *) record;
 				char	   *newval;
 
-				if (value)
-				{
-					newval = guc_strdup(elevel, value);
-					if (newval == NULL)
+				if (!parse_value(elevel, record, value, &source, changeVal,
+					(union config_var_value*) &newval))
 					return false;
-					/*
-					 * The only sort of "parsing" check we need to do is
-					 * apply truncation if GUC_IS_NAME.
-					 */
-					if (conf->gen.flags & GUC_IS_NAME)
-						truncate_identifier(newval, strlen(newval), true);
-				}
-				else if (conf->reset_val)
-				{
-					/*
-					 * We could possibly avoid strdup here, but easier to make
-					 * this case work the same as the normal assignment case.
-					 */
-					newval = guc_strdup(elevel, conf->reset_val);
-					if (newval == NULL)
-						return false;
-					source = conf->gen.reset_source;
-				}
-				else
-				{
-					/* Nothing to reset to, as yet; so do nothing */
-					break;
-				}
-
-				if (conf->assign_hook)
-				{
-					const char *hookresult;
-
-					/*
-					 * If the hook ereports, we have to make sure we free
-					 * newval, else it will be a permanent memory leak.
-					 */
-					hookresult = call_string_assign_hook(conf->assign_hook,
-														 newval,
-														 changeVal,
-														 source);
-					if (hookresult == NULL)
-					{
-						free(newval);
-						ereport(elevel,
-								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-						 errmsg("invalid value for parameter \"%s\": \"%s\"",
-								name, value ? value : "")));
-						return false;
-					}
-					else if (hookresult != newval)
-					{
-						free(newval);
-
-						/*
-						 * Having to cast away const here is annoying, but the
-						 * alternative is to declare assign_hooks as returning
-						 * char*, which would mean they'd have to cast away
-						 * const, or as both taking and returning char*, which
-						 * doesn't seem attractive either --- we don't want
-						 * them to scribble on the passed str.
-						 */
-						newval = (char *) hookresult;
-					}
-				}
 
 				if (changeVal || makeDefault)
 				{
 					/* Save old value to support transaction abort */
 					if (!makeDefault)
 						push_old_value(&conf->gen);
+
 					if (changeVal)
 					{
 						set_string_field(conf, conf->variable, newval);
 						conf->gen.source = source;
 					}
+
 					if (makeDefault)
 					{
 						GucStack   *stack;
@@ -4767,8 +4895,7 @@ GetPGVariableResultDesc(const char *name)
 
 		/* need a tuple descriptor representing a single TEXT column */
 		tupdesc = CreateTemplateTupleDesc(1, false);
-		TupleDescInitEntry(tupdesc, (AttrNumber) 1, varname,
-						   TEXTOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 1, varname, TEXTOID, -1, 0);
 	}
 	return tupdesc;
 }
@@ -4860,7 +4987,6 @@ ShowAllGUCConfig(DestReceiver *dest)
 		/* send it to dest */
 		do_tup_output(tstate, values);
 
-		/* clean up */
 		if (values[1] != NULL)
 			pfree(values[1]);
 	}
@@ -5314,6 +5440,9 @@ _ShowOption(struct config_generic * record, bool use_units)
 static bool
 is_newvalue_equal(struct config_generic *record, const char *newvalue)
 {
+	if (!newvalue)
+		return false;
+  
 	switch (record->vartype)
 	{
 		case PGC_BOOL:

src/include/utils/guc.h

@@ -7,7 +7,7 @@
  * Copyright (c) 2000-2006, PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
- * $PostgreSQL: pgsql/src/include/utils/guc.h,v 1.73 2006/08/12 04:12:41 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/guc.h,v 1.74 2006/08/13 01:30:17 momjian Exp $
  *--------------------------------------------------------------------
  */
 #ifndef GUC_H
@@ -193,6 +193,9 @@ extern void ParseLongOption(const char *string, char **name, char **value);
 extern bool set_config_option(const char *name, const char *value,
 				  GucContext context, GucSource source,
 				  bool isLocal, bool changeVal);
+extern bool verify_config_option(const char *name, const char *value,
+				GucContext context, GucSource source,
+				bool *isNewEqual, bool *isContextOK);
 extern char *GetConfigOptionByName(const char *name, const char **varname);
 extern void GetConfigOptionByNum(int varnum, const char **values, bool *noshow);
 extern int	GetNumConfigOptions(void);