Code improvements for ALTER SYSTEM .. SET.

Move FreeConfigVariables() later to make sure ErrorConfFile is valid
when we use it, and get rid of an unnecessary string copy operation.

Amit Kapila, kibitzed by me.

diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index c452a0ac0dc938f1879a6a232bf4867582190de0..ec9e0322021b87fbeed9fa2c29eb1b0d3f3a76c1 100644 (file)
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -120,7 +120,6 @@ ProcessConfigFile(GucContext context)
                                   *head,
                                   *tail;
        int                     i;
-       char            ConfigAutoFileName[MAXPGPATH];
        char            *ErrorConfFile;
        char            *CallingFileName;
 
@@ -155,17 +154,16 @@ ProcessConfigFile(GucContext context)
         * data directory, however when called during initdb data directory is not
         * set till this point, so use ConfigFile path which will be same.
         */
-       snprintf(ConfigAutoFileName,sizeof(ConfigAutoFileName),"%s", PG_AUTOCONF_FILENAME);
        if (data_directory)
                CallingFileName = NULL;
        else
                CallingFileName = ConfigFileName;
 
-       if (!ParseConfigFile(ConfigAutoFileName, CallingFileName, false, 0, elevel, &head, &tail))
+       if (!ParseConfigFile(PG_AUTOCONF_FILENAME, CallingFileName, false, 0, elevel, &head, &tail))
        {
                /* Syntax error(s) detected in the file, so bail out */
                error = true;
-               ErrorConfFile = ConfigAutoFileName;
+               ErrorConfFile = PG_AUTOCONF_FILENAME;
                goto cleanup_list;
        }
 
@@ -368,8 +366,6 @@ ProcessConfigFile(GucContext context)
        PgReloadTime = GetCurrentTimestamp();
 
  cleanup_list:
-       FreeConfigVariables(head);
-
        if (error)
        {
                /* During postmaster startup, any error is fatal */
@@ -389,6 +385,13 @@ ProcessConfigFile(GucContext context)
                                         errmsg("configuration file \"%s\" contains errors; no changes were applied",
                                                        ErrorConfFile)));
        }
+
+       /*
+        * Calling FreeConfigVariables() any earlier than this can cause problems,
+        * because ErrorConfFile could be pointing to a string that will be freed
+        * here.
+        */
+       FreeConfigVariables(head);
 }
 
 /*