Improve GUC USERLIMIT code

I have just applied the attached patch:

Improve handling of GUC USERLIMIT variables by reorganizing code.  Also,
handle new postgresql.conf values with SIGHUP better by better enforcing
USERLIMIT settings on existing non-super-user backends.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
Index: src/backend/utils/misc/guc.c
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/utils/misc/guc.c,v
retrieving revision 1.195
diff -c -c -r1.195 guc.c
*** src/backend/utils/misc/guc.c	1 Apr 2004 21:28:45 -0000	1.195
--- src/backend/utils/misc/guc.c	5 Apr 2004 02:35:08 -0000
***************
*** 2571,2578 ****
  {
  	struct config_generic *record;
  	int			elevel;
! 	bool		makeDefault;
! 	bool		changeVal_orig;
  
  	if (context == PGC_SIGHUP || source == PGC_S_DEFAULT)
  		elevel = DEBUG2;
--- 2571,2577 ----
  {
  	struct config_generic *record;
  	int			elevel;
! 	bool		makeDefault, changeValOrig = changeVal;
  
  	if (context == PGC_SIGHUP || source == PGC_S_DEFAULT)
  		elevel = DEBUG2;
***************
*** 2694,2700 ****
  	 * to set the reset/session values even if we can't set the variable
  	 * itself.
  	 */
- 	changeVal_orig = changeVal;			/* we might have to reverse this later */
  	if (record->source > source)
  	{
  		if (changeVal && !makeDefault)
--- 2693,2698 ----
***************
*** 2703,2713 ****
  				 name);
  			return true;
  		}
! 		changeVal = false;			/* we won't change the variable itself */
  	}
  
  	/*
! 	 * Evaluate value and set variable
  	 */
  	switch (record->vartype)
  	{
--- 2701,2715 ----
  				 name);
  			return true;
  		}
! 		changeVal = false;			/* this might be reset in USERLIMIT */
  	}
  
  	/*
! 	 * Evaluate value and set variable.
! 	 * USERLIMIT checks two things:  1) is the user making a change
! 	 * that is blocked by an administrator setting.  2) is the administrator
! 	 * changing a setting and doing a SIGHUP that requires us to override
! 	 * a user setting.
  	 */
  	switch (record->vartype)
  	{
***************
*** 2726,2751 ****
  										name)));
  						return false;
  					}
- 					/* Limit non-superuser changes */
  					if (record->context == PGC_USERLIMIT &&
! 						source > PGC_S_UNPRIVILEGED &&
! 						newval < conf->reset_val &&
! 						!superuser())
  					{
! 						ereport(elevel,
! 								(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
! 						 errmsg("permission denied to set parameter \"%s\"",
! 								name),
! 								 errhint("Must be superuser to change this value to false.")));
! 						return false;
  					}
- 					/* Honor change to config file with SIGHUP */
- 					if (record->context == PGC_USERLIMIT &&
- 						source < PGC_S_UNPRIVILEGED &&
- 						record->reset_source > PGC_S_UNPRIVILEGED &&
- 						newval > conf->reset_val &&
- 						!superuser())
- 						changeVal = changeVal_orig;
  				}
  				else
  				{
--- 2728,2757 ----
  										name)));
  						return false;
  					}
  					if (record->context == PGC_USERLIMIT &&
! 						IsUnderPostmaster && !superuser())
  					{
! 						if (newval < conf->reset_val)
! 						{
! 							/* Limit non-superuser changes */
! 							if (source > PGC_S_UNPRIVILEGED)
! 							{
! 								ereport(elevel,
! 										(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
! 								 errmsg("permission denied to set parameter \"%s\"",
! 										name),
! 										 errhint("Must be superuser to change this value to false.")));
! 								return false;
! 							}
! 						}
! 						if (newval > *conf->variable)
! 						{
! 							/* Allow change if admin should override */
! 							if (source < PGC_S_UNPRIVILEGED &&
! 								record->source > PGC_S_UNPRIVILEGED)
! 								changeVal = changeValOrig;
! 						}
  					}
  				}
  				else
  				{
***************
*** 2822,2848 ****
  								   newval, name, conf->min, conf->max)));
  						return false;
  					}
- 					/* Limit non-superuser changes */
  					if (record->context == PGC_USERLIMIT &&
! 						source > PGC_S_UNPRIVILEGED &&
! 						conf->reset_val != 0 &&
! 						(newval > conf->reset_val || newval == 0) &&
! 						!superuser())
  					{
! 						ereport(elevel,
! 								(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
! 						 errmsg("permission denied to set parameter \"%s\"",
! 								name),
! 								 errhint("Must be superuser to increase this value or set it to zero.")));
! 						return false;
  					}
- 					/* Honor change to config file with SIGHUP */
- 					if (record->context == PGC_USERLIMIT &&
- 						source < PGC_S_UNPRIVILEGED &&
- 						record->reset_source > PGC_S_UNPRIVILEGED &&
- 						newval < conf->reset_val && newval != 0 &&
- 						!superuser())
- 						changeVal = changeVal_orig;
  				}
  				else
  				{
--- 2828,2862 ----
  								   newval, name, conf->min, conf->max)));
  						return false;
  					}
  					if (record->context == PGC_USERLIMIT &&
! 						IsUnderPostmaster && !superuser())
  					{
! 						/* handle log_min_duration_statement, -1=disable */
! 						if ((newval != -1 && conf->reset_val != -1 &&
! 							 newval > conf->reset_val) || /* increase duration */
! 						 	(newval == -1 && conf->reset_val != -1)) /* turn off */
! 						{
! 							/* Limit non-superuser changes */
! 							if (source > PGC_S_UNPRIVILEGED)
! 							{
! 								ereport(elevel,
! 										(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
! 								 errmsg("permission denied to set parameter \"%s\"",
! 										name),
! 										 errhint("Must be superuser to increase this value or turn it off.")));
! 								return false;
! 							}
! 						}
! 						/* Allow change if admin should override */
! 						if ((newval != -1 && *conf->variable != -1 &&
! 							 newval < *conf->variable) || /* decrease duration */
! 							(newval != -1 && *conf->variable == -1)) /* turn on */
! 						{
! 							if (source < PGC_S_UNPRIVILEGED &&
! 								record->source > PGC_S_UNPRIVILEGED)
! 								changeVal = changeValOrig;
! 						}
  					}
  				}
  				else
  				{
***************
*** 2919,2944 ****
  								   newval, name, conf->min, conf->max)));
  						return false;
  					}
- 					/* Limit non-superuser changes */
  					if (record->context == PGC_USERLIMIT &&
! 						source > PGC_S_UNPRIVILEGED &&
! 						newval > conf->reset_val &&
! 						!superuser())
  					{
! 						ereport(elevel,
! 								(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
! 						 errmsg("permission denied to set parameter \"%s\"",
! 								name),
! 								 errhint("Must be superuser to increase this value.")));
! 						return false;
  					}
- 					/* Honor change to config file with SIGHUP */
- 					if (record->context == PGC_USERLIMIT &&
- 						source < PGC_S_UNPRIVILEGED &&
- 						record->reset_source > PGC_S_UNPRIVILEGED &&
- 						newval < conf->reset_val &&
- 						!superuser())
- 						changeVal = changeVal_orig;
  				}
  				else
  				{
--- 2933,2957 ----
  								   newval, name, conf->min, conf->max)));
  						return false;
  					}
  					if (record->context == PGC_USERLIMIT &&
! 						IsUnderPostmaster && !superuser())
! 					/* No REAL PGC_USERLIMIT */
  					{
! 						/* Limit non-superuser changes */
! 						if (source > PGC_S_UNPRIVILEGED)
! 						{
! 							ereport(elevel,
! 									(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
! 							 errmsg("permission denied to set parameter \"%s\"",
! 									name),
! 									 errhint("Must be superuser to increase this value or turn it off.")));
! 							return false;
! 						}
! 						/* Allow change if admin should override */
! 						if (source < PGC_S_UNPRIVILEGED &&
! 							record->source > PGC_S_UNPRIVILEGED)
! 							changeVal = false;
  					}
  				}
  				else
  				{
***************
*** 3009,3042 ****
  					}
  
  					if (record->context == PGC_USERLIMIT &&
! 						*conf->variable)
  					{
  						int			old_int_value,
  									new_int_value;
  
  						/* all USERLIMIT strings are message levels */
- 						assign_msglvl(&old_int_value, conf->reset_val,
- 									  true, source);
  						assign_msglvl(&new_int_value, newval,
  									  true, source);
! 						/* Limit non-superuser changes */
! 						if (source > PGC_S_UNPRIVILEGED &&
! 							new_int_value > old_int_value &&
! 							!superuser())
  						{
! 							ereport(elevel,
! 								(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  								 errmsg("permission denied to set parameter \"%s\"",
  										name),
! 								 errhint("Must be superuser to increase this value.")));
! 							return false;
  						}
- 						/* Honor change to config file with SIGHUP */
- 						if (source < PGC_S_UNPRIVILEGED &&
- 							record->reset_source > PGC_S_UNPRIVILEGED &&
- 							newval < conf->reset_val &&
- 							!superuser())
- 							changeVal = changeVal_orig;
  					}
  				}
  				else if (conf->reset_val)
--- 3022,3059 ----
  					}
  
  					if (record->context == PGC_USERLIMIT &&
! 						IsUnderPostmaster && !superuser())
  					{
  						int			old_int_value,
  									new_int_value;
  
  						/* all USERLIMIT strings are message levels */
  						assign_msglvl(&new_int_value, newval,
  									  true, source);
! 						assign_msglvl(&old_int_value, conf->reset_val,
! 									  true, source);
! 						if (new_int_value > old_int_value)
  						{
! 							/* Limit non-superuser changes */
! 							if (source > PGC_S_UNPRIVILEGED)
! 							{
! 								ereport(elevel,
! 										(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
  								 errmsg("permission denied to set parameter \"%s\"",
  										name),
! 										 errhint("Must be superuser to increase this value.")));
! 								return false;
! 							}
! 						}
! 							/* Allow change if admin should override */
! 						assign_msglvl(&old_int_value, *conf->variable,
! 									  true, source);
! 						if (new_int_value < old_int_value)
! 						{
! 							if (source < PGC_S_UNPRIVILEGED &&
! 								record->source > PGC_S_UNPRIVILEGED)
! 								changeVal = changeValOrig;
  						}
  					}
  				}
  				else if (conf->reset_val)