sys.[ch]:

handle SIGFPE and allow the registered signal handler to do recovery
	rather than bail
progs.h, pr_exec.c, pr_load.c:
	if pr_faultchecks is 1 (0 is default), handle division by 0 gracefully
	by loading the maximum representable number into the answer
	Closes: #58
the rest:
	kill the SIGFPE stuff

include/QF/progs.h

@@ -249,6 +249,7 @@ extern struct cvar_s *pr_debug;
 extern struct cvar_s *pr_deadbeef_ents;
 extern struct cvar_s *pr_deadbeef_locals;
 extern struct cvar_s *pr_boundscheck;
+extern struct cvar_s *pr_faultchecks;
 
 extern const char *pr_gametype;
 

include/QF/sys.h

@@ -71,7 +71,7 @@ int Sys_TimeID (void);
 // not to hog cpu when paused or debugging
 
 void Sys_MaskFPUExceptions (void);
-void Sys_PushSignalHook (void (*hook)(int, void*), void *data);
+void Sys_PushSignalHook (int (*hook)(int, void*), void *data);
 void Sys_PopSignalHook (void);
 
 // send text to the console

libs/gamecode/engine/pr_exec.c

@@ -36,7 +36,7 @@ static const char rcsid[] =
 #ifdef HAVE_STRINGS_H
 # include <strings.h>
 #endif
-
+#include <signal.h>
 #include <stdarg.h>
 
 #include "QF/cvar.h"
@@ -168,13 +168,6 @@ PR_LeaveFunction (progs_t * pr)
 	pr->pr_xstatement = pr->pr_stack[pr->pr_depth].s;
 }
 
-static void
-signal_hook (int sig, void *data)
-{
-	progs_t    *pr = (progs_t *) data;
-	PR_DumpState (pr);
-}
-
 #define OPA (*op_a)
 #define OPB (*op_b)
 #define OPC (*op_c)
@@ -186,6 +179,42 @@ signal_hook (int sig, void *data)
 #define FNZ(x) ((x).integer_var && (x).integer_var != 0x80000000)
 
 
+static int
+signal_hook (int sig, void *data)
+{
+	progs_t    *pr = (progs_t *) data;
+	
+	if (sig == SIGFPE && pr_faultchecks->int_val) {
+		dstatement_t *st;
+		pr_type_t  *op_a, *op_b, *op_c;
+
+		st = pr->pr_statements + pr->pr_xstatement;
+		op_a = pr->pr_globals + st->a;
+		op_b = pr->pr_globals + st->b;
+		op_c = pr->pr_globals + st->c;
+
+		switch (st->op) {
+			case OP_DIV_F:
+				if ((OPA.integer_var & 0x80000000)
+					^ (OPB.integer_var & 0x80000000))
+					OPC.integer_var = 0xff7fffff;
+				else
+					OPC.integer_var = 0x7f7fffff;
+				return 1;
+			case OP_DIV_I:
+				if (OPA.integer_var & 0x80000000)
+					OPC.integer_var = -0x80000000;
+				else
+					OPC.integer_var = 0x7fffffff;
+				return 1;
+			default:
+				break;
+		}
+	}
+	PR_DumpState (pr);
+	return 0;
+}
+
 /*
 	PR_ExecuteProgram
 

libs/gamecode/engine/pr_load.c

@@ -53,6 +53,8 @@ static const char rcsid[] =
 
 #include "compat.h"
 
+cvar_t     *pr_faultchecks;
+
 static const char *
 function_get_key (void *f, void *_pr)
 {
@@ -294,6 +296,8 @@ PR_Init_Cvars (void)
 	pr_deadbeef_locals = Cvar_Get ("pr_deadbeef_locals", "0", CVAR_NONE, NULL,
 								   "set to clear uninitialized local vars to "
 								   "0xdeadbeef");
+	pr_faultchecks = Cvar_Get ("pr_faultchecks", "0", CVAR_NONE, NULL,
+							   "capture and handle division by 0 in progs");
 	PR_Debug_Init_Cvars ();
 }
 

libs/util/sys.c

@@ -583,17 +583,17 @@ static jmp_buf  aiee_abort;
 
 typedef struct sh_stack_s {
 	struct sh_stack_s *next;
-	void (*signal_hook)(int,void*);
+	int (*signal_hook)(int,void*);
 	void *data;
 } sh_stack_t;
 
 static sh_stack_t *sh_stack;
 static sh_stack_t *free_sh;
-static void (*signal_hook)(int,void*);
+static int (*signal_hook)(int,void*);
 static void *signal_hook_data;
 
 void
-Sys_PushSignalHook (void (*hook)(int, void *), void *data)
+Sys_PushSignalHook (int (*hook)(int, void *), void *data)
 {
 	sh_stack_t *s;
 
@@ -639,6 +639,8 @@ aiee (int sig)
 static void
 signal_handler (int sig)
 {
+	int         recover = 0;
+
 	printf ("Received signal %d, exiting...\n", sig);
 
 	switch (sig) {
@@ -660,21 +662,35 @@ signal_handler (int sig)
 #endif
 			signal (SIGILL, aiee);
 			signal (SIGSEGV, aiee);
+			signal (SIGFPE, aiee);
 
 			if (!setjmp (aiee_abort)) {
 				if (signal_hook)
-					signal_hook (sig, signal_hook_data);
+					recover = signal_hook (sig, signal_hook_data);
 				Sys_Shutdown ();
 			}
 
+			if (recover) {
 #ifndef _WIN32
-			signal (SIGQUIT, SIG_DFL);
+				signal (SIGQUIT, signal_handler);
-			signal (SIGTRAP, SIG_DFL);
+				signal (SIGTRAP, signal_handler);
-			signal (SIGIOT, SIG_DFL);
+				signal (SIGIOT, signal_handler);
-			signal (SIGBUS, SIG_DFL);
+				signal (SIGBUS, signal_handler);
 #endif
-			signal (SIGILL, SIG_DFL);
+				signal (SIGILL, signal_handler);
-			signal (SIGSEGV, SIG_DFL);
+				signal (SIGSEGV, signal_handler);
+				signal (SIGFPE, signal_handler);
+			} else {
+#ifndef _WIN32
+				signal (SIGQUIT, SIG_DFL);
+				signal (SIGTRAP, SIG_DFL);
+				signal (SIGIOT, SIG_DFL);
+				signal (SIGBUS, SIG_DFL);
+#endif
+				signal (SIGILL, SIG_DFL);
+				signal (SIGSEGV, SIG_DFL);
+				signal (SIGFPE, SIG_DFL);
+			}
 	}
 }
 
@@ -693,5 +709,5 @@ Sys_Init (void)
 	signal (SIGILL, signal_handler);
 	signal (SIGSEGV, signal_handler);
 	signal (SIGTERM, signal_handler);
-//	signal (SIGFPE, signal_handler);
+	signal (SIGFPE, signal_handler);
 }

nq/source/sys_sdl.c

@@ -95,8 +95,6 @@ startup (void)
 		Sys_Error ("This version of " PROGRAM
 				   " requires at least Win95 or NT 4.0");
 	}
-#else
-	signal (SIGFPE, SIG_IGN);
 #endif
 }
 

nq/source/sys_unix.c

@@ -69,21 +69,12 @@ shutdown (void)
 	fcntl (0, F_SETFL, fcntl (0, F_GETFL, 0) & ~O_NONBLOCK);
 }
 
-void
-floating_point_exception_handler (int whatever)
-{
-//	Sys_Warn("floating point exception\n");
-	signal (SIGFPE, floating_point_exception_handler);
-}
-
 int
 main (int c, const char *v[])
 {
 
 	double      time, oldtime, newtime;
 
-	signal (SIGFPE, SIG_IGN);
-
 	memset (&host_parms, 0, sizeof (host_parms));
 
 	COM_InitArgv (c, v);

nq/source/sys_unixd.c

@@ -80,8 +80,6 @@ main (int argc, const char **argv)
 {
 	double      time, oldtime, newtime;
 
-	signal (SIGFPE, SIG_IGN);
-
 	memset (&host_parms, 0, sizeof (host_parms));
 
 	COM_InitArgv (argc, argv);

qw/source/cl_sys_sdl.c

@@ -96,8 +96,6 @@ startup (void)
 		Sys_Error ("This version of " PROGRAM
 				   " requires at least Win95 or NT 4.0");
 	}
-#else
-	signal (SIGFPE, SIG_IGN);
 #endif
 }
 

qw/source/cl_sys_unix.c

@@ -70,12 +70,6 @@ shutdown (void)
 	fcntl (0, F_SETFL, fcntl (0, F_GETFL, 0) & ~O_NONBLOCK);
 }
 
-void
-floating_point_exception_handler (int whatever)
-{
-	signal (SIGFPE, floating_point_exception_handler);
-}
-
 int         skipframes;
 
 int
@@ -84,9 +78,6 @@ main (int c, const char *v[])
 //	static char cwd[1024];
 	double      time, oldtime, newtime;
 
-//	signal(SIGFPE, floating_point_exception_handler);
-	signal (SIGFPE, SIG_IGN);
-
 	memset (&host_parms, 0, sizeof (host_parms));
 
 	COM_InitArgv (c, v);