Re: Allow commenting of variables in postgresql.conf to - - Mailing list pgsql-patches

From Zdenek Kotala
Subject Re: Allow commenting of variables in postgresql.conf to -
Date
Msg-id 44B6C693.2010106@sun.com
Whole thread Raw
In response to Re: Allow commenting of variables in postgresql.conf to -  (Zdenek Kotala <Zdenek.Kotala@Sun.COM>)
Responses Re: Allow commenting of variables in postgresql.conf to - try 4  (Joachim Wieland <joe@mcknight.de>)
List pgsql-patches
There is last version of patch with following changes/improvements:

1) I divide set_config_option to more smaller functions without backside
effect.

2) Behavior of reconfiguration is "same" in SIG_HUP context (exclude
elevel). All errors are reported and full validity of file is checked too.

    Zdenek


Index: src/backend/utils/misc/guc-file.l
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/utils/misc/guc-file.l,v
retrieving revision 1.37
diff -c -r1.37 guc-file.l
*** src/backend/utils/misc/guc-file.l    7 Mar 2006 01:03:12 -0000    1.37
--- src/backend/utils/misc/guc-file.l    13 Jul 2006 21:55:28 -0000
***************
*** 112,119 ****
  void
  ProcessConfigFile(GucContext context)
  {
!     int            elevel;
      struct name_value_pair *item, *head, *tail;

      Assert(context == PGC_POSTMASTER || context == PGC_SIGHUP);

--- 112,120 ----
  void
  ProcessConfigFile(GucContext context)
  {
!     int            elevel, i;
      struct name_value_pair *item, *head, *tail;
+     char       *env;

      Assert(context == PGC_POSTMASTER || context == PGC_SIGHUP);

***************
*** 137,146 ****

      /* Check if all options are valid */
      for (item = head; item; item = item->next)
!     {
!         if (!set_config_option(item->name, item->value, context,
!                                PGC_S_FILE, false, false))
              goto cleanup_list;
      }

      /* If we got here all the options checked out okay, so apply them. */
--- 138,173 ----

      /* Check if all options are valid */
      for (item = head; item; item = item->next)
!     {
!         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 )
+         {
+             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 loading context must be valid for all configuration item.
+                 goto cleanup_list;
+             }
+         }
      }

      /* If we got here all the options checked out okay, so apply them. */
***************
*** 150,155 ****
--- 177,233 ----
                            PGC_S_FILE, false, true);
      }

+     if( context == PGC_SIGHUP)
+     {
+     /* Revert all "untouched" options with reset source PGC_S_FILE to
+      * default/boot value.
+      */
+         for (i = 0; i < num_guc_variables; i++)
+         {
+             struct config_generic *gconf = guc_variables[i];
+             if ( gconf->context != PGC_INTERNAL && gconf->context != PGC_POSTMASTER &&
+                 !( gconf->context == PGC_BACKEND && IsUnderPostmaster) &&
+                  (gconf->reset_source == PGC_S_FILE) && ( (gconf->status & GUC_JUST_RELOAD) == 0) )
+             {
+                 if( set_config_option(gconf->name, NULL, context,
+                       PGC_S_FILE, false, true) )
+                 {
+                     GucStack   *stack;
+                     /* set correctly source */
+                     gconf->reset_source = PGC_S_DEFAULT;
+                     for (stack = gconf->stack; stack; stack = stack->prev)
+                     {
+                         if (stack->source == PGC_S_FILE)
+                         {
+                             stack->source = PGC_S_DEFAULT;
+                         }
+                     }
+
+                     ereport(elevel,
+                             (errcode(ERRCODE_SUCCESSFUL_COMPLETION),
+                             errmsg("configuration option %s has been revert to the boot value", gconf->name)));
+                 }
+             }
+             gconf->status &= ~GUC_JUST_RELOAD;
+         }
+
+         /* Revert to environment variable. PGPORT is ignored, because it cannot be
+          * set in running state.
+          */
+         env = getenv("PGDATESTYLE");
+         if (env != NULL)
+         {
+             set_config_option("datestyle", env, context,
+                             PGC_S_ENV_VAR, false, true);
+         }
+
+         env = getenv("PGCLIENTENCODING");
+         if (env != NULL)
+         {
+             set_config_option("client_encoding", env, context,
+                             PGC_S_ENV_VAR, false, true);
+         }
+     }
   cleanup_list:
      free_name_value_list(head);
  }
Index: src/backend/utils/misc/guc.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/utils/misc/guc.c,v
retrieving revision 1.319
diff -c -r1.319 guc.c
*** src/backend/utils/misc/guc.c    11 May 2006 19:15:35 -0000    1.319
--- src/backend/utils/misc/guc.c    13 Jul 2006 21:55:28 -0000
***************
*** 2648,2686 ****
                      struct config_bool *conf = (struct config_bool *) gconf;

                      if (conf->assign_hook)
!                         if (!(*conf->assign_hook) (conf->reset_val, true,
                                                     PGC_S_DEFAULT))
                              elog(FATAL, "failed to initialize %s to %d",
!                                  conf->gen.name, (int) conf->reset_val);
!                     *conf->variable = conf->reset_val;
                      break;
                  }
              case PGC_INT:
                  {
                      struct config_int *conf = (struct config_int *) gconf;

!                     Assert(conf->reset_val >= conf->min);
!                     Assert(conf->reset_val <= conf->max);
                      if (conf->assign_hook)
!                         if (!(*conf->assign_hook) (conf->reset_val, true,
                                                     PGC_S_DEFAULT))
                              elog(FATAL, "failed to initialize %s to %d",
!                                  conf->gen.name, conf->reset_val);
!                     *conf->variable = conf->reset_val;
                      break;
                  }
              case PGC_REAL:
                  {
                      struct config_real *conf = (struct config_real *) gconf;

!                     Assert(conf->reset_val >= conf->min);
!                     Assert(conf->reset_val <= conf->max);
                      if (conf->assign_hook)
!                         if (!(*conf->assign_hook) (conf->reset_val, true,
                                                     PGC_S_DEFAULT))
                              elog(FATAL, "failed to initialize %s to %g",
!                                  conf->gen.name, conf->reset_val);
!                     *conf->variable = conf->reset_val;
                      break;
                  }
              case PGC_STRING:
--- 2648,2686 ----
                      struct config_bool *conf = (struct config_bool *) gconf;

                      if (conf->assign_hook)
!                         if (!(*conf->assign_hook) (conf->boot_val, true,
                                                     PGC_S_DEFAULT))
                              elog(FATAL, "failed to initialize %s to %d",
!                                  conf->gen.name, (int) conf->boot_val);
!                     *conf->variable = conf->reset_val = conf->boot_val;
                      break;
                  }
              case PGC_INT:
                  {
                      struct config_int *conf = (struct config_int *) gconf;

!                     Assert(conf->boot_val >= conf->min);
!                     Assert(conf->boot_val <= conf->max);
                      if (conf->assign_hook)
!                         if (!(*conf->assign_hook) (conf->boot_val, true,
                                                     PGC_S_DEFAULT))
                              elog(FATAL, "failed to initialize %s to %d",
!                                  conf->gen.name, conf->boot_val);
!                     *conf->variable = conf->reset_val = conf->boot_val;
                      break;
                  }
              case PGC_REAL:
                  {
                      struct config_real *conf = (struct config_real *) gconf;

!                     Assert(conf->boot_val >= conf->min);
!                     Assert(conf->boot_val <= conf->max);
                      if (conf->assign_hook)
!                         if (!(*conf->assign_hook) (conf->boot_val, true,
                                                     PGC_S_DEFAULT))
                              elog(FATAL, "failed to initialize %s to %g",
!                                  conf->gen.name, conf->boot_val);
!                     *conf->variable = conf->reset_val = conf->boot_val;
                      break;
                  }
              case PGC_STRING:
***************
*** 3133,3139 ****
      for (i = 0; i < num_guc_variables; i++)
      {
          struct config_generic *gconf = guc_variables[i];
!         int            my_status = gconf->status;
          GucStack   *stack = gconf->stack;
          bool        useTentative;
          bool        changed;
--- 3133,3139 ----
      for (i = 0; i < num_guc_variables; i++)
      {
          struct config_generic *gconf = guc_variables[i];
!         int            my_status = gconf->status & (~GUC_JUST_RELOAD);
          GucStack   *stack = gconf->stack;
          bool        useTentative;
          bool        changed;
***************
*** 3571,3630 ****
      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.
   */
! 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;

!     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;

!     record = find_option(name, elevel);
!     if (record == NULL)
!     {
!         ereport(elevel,
!                 (errcode(ERRCODE_UNDEFINED_OBJECT),
!                errmsg("unrecognized configuration parameter \"%s\"", name)));
!         return false;
      }

      /*
       * 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
--- 3571,3852 ----
      return result;
  }

  /*
!  * 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.
   */
! static bool
! parse_value(int elevel, const struct config_generic *record,
!         const char *value, GucSource *source, bool changeVal,
!         union config_var_value *retval)
  {

!     Assert( !(changeVal && retval==NULL) );
!     /*
!      * Evaluate value and set variable.
!      */
!     switch (record->vartype)
      {
!         case PGC_BOOL:
!             {
!                 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",
!                                  record->name)));
!                         return false;
!                     }
!                 }
!                 else
!                 {
!                     /* Revert value to default if source is configuration file. It is used when
!                      * configuration parameter is removed/commented out in the config file. Else
!                      * RESET or SET TO DEFAULT command is called and reset_val is used.
!                      */
!                     if( *source == PGC_S_FILE )
!                     {
!                         newval =  conf->boot_val;
!                     }
!                     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 != NULL )
!                     retval->boolval = newval;
!                 break;
!             }
!
!         case PGC_INT:
!             {
!                 struct config_int *conf = (struct config_int *) record;
!                 int            newval;
!
!                 if (value)
!                 {
!                     if (!parse_int(value, &newval))
!                     {
!                         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
!                 {
!                     /* Revert value to default if source is configuration file. It is used when
!                      * configuration parameter is removed/commented out in the config file. Else
!                      * RESET or SET TO DEFAULT command is called and reset_val is used.
!                      */
!                     if( *source == PGC_S_FILE )
!                     {
!                         newval =  conf->boot_val;
!                     }
!                     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 != NULL )
!                     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
!                 {
!                     /* Revert value to default if source is configuration file. It is used when
!                      * configuration parameter is removed/commented out in the config file. Else
!                      * RESET or SET TO DEFAULT command is called and reset_val is used.
!                      */
!                     if( *source == PGC_S_FILE )
!                     {
!                         newval =  conf->boot_val;
!                     }
!                     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 != NULL )
!                     retval->realval = newval;
!                 break;
!             }
!
!         case PGC_STRING:
!             {
!                 struct config_string *conf = (struct config_string *) record;
!                 char       *newval;
!
!                 if (value)
!                 {
!                     newval = guc_strdup(elevel, value);
!                     if (newval == NULL)
!                         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 (*source == PGC_S_FILE)
!                 {
!                     /* Revert value to default when item is removed from config file. */
!                     if ( conf->boot_val != NULL )
!                     {
!                         newval = guc_strdup(elevel, conf->boot_val);
!                         if (newval == NULL)
!                             return false;
!                     }
!                     else
!                     {
!                         return false;
!                     }
!                 }
!                 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\"",
!                                 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 ( !changeVal )
!                     free(newval);
!                 if( retval != NULL )
!                     retval->stringval= newval;
!                 break;
!             }
      }
+     return true;
+ }

+ /*
+  *
+  */
+ bool
+ checkContext(int elevel, struct config_generic *record, GucContext context)
+ {
      /*
       * 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
***************
*** 3633,3666 ****
      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)));
                  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 true;
-             }
              if (context != PGC_POSTMASTER)
              {
                  ereport(elevel,
                          (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
                           errmsg("parameter \"%s\" cannot be changed after server start",
!                                 name)));
                  return false;
              }
              break;
--- 3855,3879 ----
      switch (record->context)
      {
          case PGC_INTERNAL:
              if (context != PGC_INTERNAL)
              {
                  ereport(elevel,
                          (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
                           errmsg("parameter \"%s\" cannot be changed",
!                                 record->name)));
                  return false;
              }
              break;
          case PGC_POSTMASTER:
              if (context == PGC_SIGHUP)
!                 return false;

              if (context != PGC_POSTMASTER)
              {
                  ereport(elevel,
                          (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
                           errmsg("parameter \"%s\" cannot be changed after server start",
!                                 record->name)));
                  return false;
              }
              break;
***************
*** 3670,3676 ****
                  ereport(elevel,
                          (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
                           errmsg("parameter \"%s\" cannot be changed now",
!                                 name)));
                  return false;
              }

--- 3883,3889 ----
                  ereport(elevel,
                          (errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
                           errmsg("parameter \"%s\" cannot be changed now",
!                                 record->name)));
                  return false;
              }

***************
*** 3693,3706 ****
                   * backend start.
                   */
                  if (IsUnderPostmaster)
!                     return true;
              }
              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)));
                  return false;
              }
              break;
--- 3906,3921 ----
                   * backend start.
                   */
                  if (IsUnderPostmaster)
!                 {
!                     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",
!                                 record->name)));
                  return false;
              }
              break;
***************
*** 3710,3716 ****
                  ereport(elevel,
                          (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                           errmsg("permission denied to set parameter \"%s\"",
!                                 name)));
                  return false;
              }
              break;
--- 3925,3931 ----
                  ereport(elevel,
                          (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                           errmsg("permission denied to set parameter \"%s\"",
!                                 record->name)));
                  return false;
              }
              break;
***************
*** 3718,3729 ****
              /* always okay */
              break;
      }

      /*
       * Should we set reset/stacked values?    (If so, the behavior is not
       * transactional.)
       */
!     makeDefault = changeVal && (source <= PGC_S_OVERRIDE) && (value != NULL);

      /*
       * Ignore attempted set if overridden by previously processed setting.
--- 3933,4052 ----
              /* always okay */
              break;
      }
+     return true;
+ }
+ /*
+  * Get error level for different sources and context.
+  */
+ 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)
+ {
+     union config_var_value newval;
+     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,  &newval) )
+     {
+         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 )
+     {
+         return false;
+     }

      /*
       * Should we set reset/stacked values?    (If so, the behavior is not
       * transactional.)
       */
!     makeDefault = changeVal && (source <= PGC_S_OVERRIDE) && (value != NULL || source == PGC_S_FILE);

      /*
       * Ignore attempted set if overridden by previously processed setting.
***************
*** 3752,3784 ****
              {
                  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)));
!                         return false;
!                     }

                  if (changeVal || makeDefault)
                  {
--- 4075,4083 ----
              {
                  struct config_bool *conf = (struct config_bool *) record;
                  bool        newval;
!
!                 if( !parse_value(elevel, record, value, &source, changeVal, (union config_var_value*) &newval) )
!                     return false;

                  if (changeVal || makeDefault)
                  {
***************
*** 3829,3868 ****
                  struct config_int *conf = (struct config_int *) record;
                  int            newval;

!                 if (value)
!                 {
!                     if (!parse_int(value, &newval))
!                     {
!                         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)));
!                         return false;
!                     }

                  if (changeVal || makeDefault)
                  {
--- 4128,4135 ----
                  struct config_int *conf = (struct config_int *) record;
                  int            newval;

!                 if( !parse_value(elevel, record, value, &source, changeVal, (union config_var_value*) &newval) )
!                     return false;

                  if (changeVal || makeDefault)
                  {
***************
*** 3913,3952 ****
                  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)));
!                         return false;
!                     }

                  if (changeVal || makeDefault)
                  {
--- 4180,4187 ----
                  struct config_real *conf = (struct config_real *) record;
                  double        newval;

!                 if( !parse_value(elevel, record, value, &source, changeVal, (union config_var_value*) &newval) )
!                     return false;

                  if (changeVal || makeDefault)
                  {
***************
*** 3997,4067 ****
                  struct config_string *conf = (struct config_string *) record;
                  char       *newval;

!                 if (value)
!                 {
!                     newval = guc_strdup(elevel, value);
!                     if (newval == NULL)
!                         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)
                  {
--- 4232,4239 ----
                  struct config_string *conf = (struct config_string *) record;
                  char       *newval;

!                 if( !parse_value(elevel, record, value, &source, changeVal, (union config_var_value*) &newval) )
!                     return false;

                  if (changeVal || makeDefault)
                  {
***************
*** 4109,4115 ****
                      }
                  }
                  else
!                     free(newval);
                  break;
              }
      }
--- 4281,4288 ----
                      }
                  }
                  else
!                     if( newval != NULL )
!                         free(newval);
                  break;
              }
      }
***************
*** 4117,4122 ****
--- 4290,4298 ----
      if (changeVal && (record->flags & GUC_REPORT))
          ReportGUCOption(record);

+     if(changeVal && record->source == PGC_S_FILE && value != NULL)
+         record->status |= GUC_JUST_RELOAD;
+
      return true;
  }

***************
*** 5111,5116 ****
--- 5287,5297 ----
  static bool
  is_newvalue_equal(struct config_generic *record, const char *newvalue)
  {
+     if( !newvalue )
+     {
+         return false;
+     }
+
      switch (record->vartype)
      {
          case PGC_BOOL:
Index: src/include/utils/guc.h
===================================================================
RCS file: /projects/cvsroot/pgsql/src/include/utils/guc.h,v
retrieving revision 1.68
diff -c -r1.68 guc.h
*** src/include/utils/guc.h    11 May 2006 19:15:35 -0000    1.68
--- src/include/utils/guc.h    13 Jul 2006 21:55:29 -0000
***************
*** 17,23 ****
  #include "tcop/dest.h"
  #include "utils/array.h"

-
  /*
   * Certain options can only be set at certain times. The rules are
   * like this:
--- 17,22 ----
***************
*** 195,200 ****
--- 194,202 ----
  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);
Index: src/include/utils/guc_tables.h
===================================================================
RCS file: /projects/cvsroot/pgsql/src/include/utils/guc_tables.h,v
retrieving revision 1.22
diff -c -r1.22 guc_tables.h
*** src/include/utils/guc_tables.h    5 Mar 2006 15:59:07 -0000    1.22
--- src/include/utils/guc_tables.h    13 Jul 2006 21:55:29 -0000
***************
*** 132,138 ****
  #define GUC_HAVE_TENTATIVE    0x0001        /* tentative value is defined */
  #define GUC_HAVE_LOCAL        0x0002        /* a SET LOCAL has been executed */
  #define GUC_HAVE_STACK        0x0004        /* we have stacked prior value(s) */
!

  /* GUC records for specific variable types */

--- 132,138 ----
  #define GUC_HAVE_TENTATIVE    0x0001        /* tentative value is defined */
  #define GUC_HAVE_LOCAL        0x0002        /* a SET LOCAL has been executed */
  #define GUC_HAVE_STACK        0x0004        /* we have stacked prior value(s) */
! #define GUC_JUST_RELOAD     0x0008      /* value is just reload from configuration file */

  /* GUC records for specific variable types */

***************
*** 142,152 ****
      /* these fields must be set correctly in initial value: */
      /* (all but reset_val are constants) */
      bool       *variable;
!     bool        reset_val;
      GucBoolAssignHook assign_hook;
      GucShowHook show_hook;
      /* variable fields, initialized at runtime: */
      bool        tentative_val;
  };

  struct config_int
--- 142,153 ----
      /* these fields must be set correctly in initial value: */
      /* (all but reset_val are constants) */
      bool       *variable;
!     bool        boot_val;
      GucBoolAssignHook assign_hook;
      GucShowHook show_hook;
      /* variable fields, initialized at runtime: */
      bool        tentative_val;
+     bool        reset_val;
  };

  struct config_int
***************
*** 155,167 ****
      /* these fields must be set correctly in initial value: */
      /* (all but reset_val are constants) */
      int           *variable;
!     int            reset_val;
      int            min;
      int            max;
      GucIntAssignHook assign_hook;
      GucShowHook show_hook;
      /* variable fields, initialized at runtime: */
      int            tentative_val;
  };

  struct config_real
--- 156,169 ----
      /* these fields must be set correctly in initial value: */
      /* (all but reset_val are constants) */
      int           *variable;
!     int            boot_val;
      int            min;
      int            max;
      GucIntAssignHook assign_hook;
      GucShowHook show_hook;
      /* variable fields, initialized at runtime: */
      int            tentative_val;
+     int            reset_val;
  };

  struct config_real
***************
*** 170,182 ****
      /* these fields must be set correctly in initial value: */
      /* (all but reset_val are constants) */
      double       *variable;
!     double        reset_val;
      double        min;
      double        max;
      GucRealAssignHook assign_hook;
      GucShowHook show_hook;
      /* variable fields, initialized at runtime: */
      double        tentative_val;
  };

  struct config_string
--- 172,186 ----
      /* these fields must be set correctly in initial value: */
      /* (all but reset_val are constants) */
      double       *variable;
!     double        boot_val;
      double        min;
      double        max;
      GucRealAssignHook assign_hook;
      GucShowHook show_hook;
      /* variable fields, initialized at runtime: */
      double        tentative_val;
+       double        reset_val;
+
  };

  struct config_string


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