Refactor GUC set_config_option function:

The main reason for refactoring was that set_config_option() was too
overloaded function and its behavior did not consistent. Old version of
set_config_function hides some messages. For example if you type:

tcp_port = 5432.1

then old implementation ignore this error without any message to log
file in the signal context (configuration reload). Main problem was that
semantic analysis of postgresql.conf is not perform in the
ProcessConfigFile function, but in the set_config_options *after*
context check. This skipped check for variables with PG_POSTMASTER
context. There was request from Joachim Wieland to add more messages
about ignored changes in the config file as well.

Zdenek Kotala

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 1.38 2006/07/27 08:30:41 petere Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/misc/guc-file.l,v 1.39 2006/08/11 20:08:28 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++)
 	{
-		if (!set_config_option(item->name, item->value, context,
-							   PGC_S_FILE, false, false))
+		bool isEqual, isContextOk;
+
+		if (!verify_config_option(item->name, item->value, context,
+						  PGC_S_FILE, &isEqual, &isContextOk))
+		{
+			ereport(elevel,
+				(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+				errmsg("configuration file is invalid")));
 			goto cleanup_list;
+		}
+
+		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; item; item = item->next)
-	{
-		set_config_option(item->name, item->value, context,
-						  PGC_S_FILE, false, true);
-	}
+	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);
 }
 
@@ -189,13 +223,14 @@ 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];
-	FILE	   *fp;
+	bool			OK = true;
+	char			abs_path[MAXPGPATH];
+	FILE		   *fp;
 	YY_BUFFER_STATE lex_buffer;
-	int			token;
+	int				token;
 
 	/*
 	 * Reject too-deep include nesting depth.  This is just a safety check
@@ -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 */