@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $ PostgreSQL : pgsql / src / backend / tcop / postgres . c , v 1.396 2004 / 03 / 21 22 : 29 : 11 tgl Exp $
* $ PostgreSQL : pgsql / src / backend / tcop / postgres . c , v 1.397 2004 / 03 / 24 22 : 40 : 29 tgl Exp $
*
* NOTES
* this is the " main " module of the postgres backend and
@ -92,11 +92,22 @@ bool Log_disconnections = false;
*/
int XfuncMode = 0 ;
/* GUC variable for maximum stack depth (measured in kilobytes) */
int max_stack_depth = 2048 ;
/* ----------------
* private variables
* - - - - - - - - - - - - - - - -
*/
/* max_stack_depth converted to bytes for speed of checking */
static int max_stack_depth_bytes = 2048 * 1024 ;
/* stack base pointer (initialized by PostgresMain) */
static char * stack_base_ptr = NULL ;
/*
* Flag to mark SIGHUP . Whenever the main loop comes around it
* will reread the configuration file . ( Better than doing the
@ -1970,6 +1981,64 @@ ProcessInterrupts(void)
}
/*
* check_stack_depth : check for excessively deep recursion
*
* This should be called someplace in any recursive routine that might possibly
* recurse deep enough to overflow the stack . Most Unixen treat stack
* overflow as an unrecoverable SIGSEGV , so we want to error out ourselves
* before hitting the hardware limit . Unfortunately we have no direct way
* to detect the hardware limit , so we have to rely on the admin to set a
* GUC variable for it . . .
*/
void
check_stack_depth ( void )
{
char stack_top_loc ;
int stack_depth ;
/*
* Compute distance from PostgresMain ' s local variables to my own
*
* Note : in theory stack_depth should be ptrdiff_t or some such , but
* since the whole point of this code is to bound the value to something
* much less than integer - sized , int should work fine .
*/
stack_depth = ( int ) ( stack_base_ptr - & stack_top_loc ) ;
/*
* Take abs value , since stacks grow up on some machines , down on others
*/
if ( stack_depth < 0 )
stack_depth = - stack_depth ;
/*
* Trouble ?
*
* The test on stack_base_ptr prevents us from erroring out if called
* during process setup or in a non - backend process . Logically it should
* be done first , but putting it here avoids wasting cycles during normal
* cases .
*/
if ( stack_depth > max_stack_depth_bytes & &
stack_base_ptr ! = NULL )
{
ereport ( ERROR ,
( errcode ( ERRCODE_STATEMENT_TOO_COMPLEX ) ,
errmsg ( " stack depth limit exceeded " ) ,
errhint ( " Increase the configuration parameter \" max_stack_depth \" . " ) ) ) ;
}
}
/* GUC assign hook to update max_stack_depth_bytes from max_stack_depth */
bool
assign_max_stack_depth ( int newval , bool doit , GucSource source )
{
/* Range check was already handled by guc.c */
if ( doit )
max_stack_depth_bytes = newval * 1024 ;
return true ;
}
static void
usage ( char * progname )
{
@ -2030,6 +2099,7 @@ PostgresMain(int argc, char *argv[], const char *username)
GucSource gucsource ;
char * tmp ;
int firstchar ;
char stack_base ;
StringInfoData input_message ;
volatile bool send_rfq = true ;
@ -2069,6 +2139,9 @@ PostgresMain(int argc, char *argv[], const char *username)
SetProcessingMode ( InitProcessing ) ;
/* Set up reference point for stack depth checking */
stack_base_ptr = & stack_base ;
/*
* Set default values for command - line options .
*/
Tom Lane
22 years ago