From ef246bd8e22ef6768bd4c613fac6c0f3aea8ec8f Mon Sep 17 00:00:00 2001
From: carl <cecodere@yahoo.ca>
Date: Sun, 16 Jun 2019 00:42:48 +0800
Subject: [PATCH] Closes #193 (signed integer shift left does not correctly
 check overflow in the interpreter when shifting by 0 bits), Closes #192
 (integer division overflow is not handled in the interpreter and crashes it)
 and closes #194 (lar instruction does not accept negative bounds in
 interpreter when doing array index checking).

---
 util/int/do_array.c |  7 ++++---
 util/int/do_intar.c | 39 +++++++++++++++++++++++++++++++++------
 util/int/main.c     | 23 ++++++++++++++++++++++-
 3 files changed, 59 insertions(+), 10 deletions(-)

diff --git a/util/int/do_array.c b/util/int/do_array.c
index 62112fbd7..9f850d4c7 100644
--- a/util/int/do_array.c
+++ b/util/int/do_array.c
@@ -58,12 +58,13 @@ PRIVATE void arr(int type, /* operation TYPE */
 {
 	register ptr desc = dppop();	/* array DESCriptor */
 	register size obj_size;		/* OBJect SIZE */
-	register long diff =		/* between index and lower bound */
-		spop(elm_size) - mem_lds(desc, elm_size);
+	long index = spop(elm_size);
+	long diff =		/* between index and lower bound */
+		index - mem_lds(desc, elm_size);
 	register ptr arr_addr = dppop();/* ARRay ADDRess */
 
 	if (must_test && !(IgnMask&BIT(EARRAY))) {
-		if (diff < 0 || diff > mem_lds(desc + elm_size, elm_size)) {
+		if (diff < 0 || index > mem_lds(desc + elm_size, elm_size)) {
 			trap(EARRAY);
 		}
 	}
diff --git a/util/int/do_intar.c b/util/int/do_intar.c
index e80f1ee3f..8d0e559ec 100644
--- a/util/int/do_intar.c
+++ b/util/int/do_intar.c
@@ -14,7 +14,7 @@
 #include	"text.h"
 #include	"fra.h"
 
-PRIVATE long adi(long, long, size), sbi(long, long, size), dvi(long, long);
+PRIVATE long adi(long, long, size), sbi(long, long, size), dvi(long, long, size);
 PRIVATE long mli(long, long, size), rmi(long, long), ngi(long, size);
 PRIVATE long sli(long, long, size), sri(long, long, size);
 
@@ -55,7 +55,7 @@ void DoDVI(register size l)
 
 	LOG(("@I6 DoDVI(%ld)", l));
 	spoilFRA();
-	npush(dvi(spop(l), t), l);
+	npush(dvi(spop(l), t, l), l);
 }
 
 /** RMI w: Remainder (*) */
@@ -162,7 +162,7 @@ PRIVATE long mli(long w1, long w2, size nbytes)
 	return (w1 * w2);
 }
 
-PRIVATE long dvi(long w1, long w2)
+PRIVATE long dvi(long w1, long w2, size nbytes)
 {
 	if (w2 == 0) {
 		if (!(IgnMask&BIT(EIDIVZ))) {
@@ -170,6 +170,20 @@ PRIVATE long dvi(long w1, long w2)
 		}
 		else	return (0L);
 	}
+
+	/* Check for division overflow. */
+	if ((w1 == i_mins(nbytes)) && (w2 == -1))
+	{
+		if (must_test && !(IgnMask&BIT(EIOVFL)))
+		{
+			trap(EIOVFL);
+		} else return i_mins(nbytes);
+	}
+
+
+	if (must_test && !(IgnMask&BIT(EIOVFL)))
+	{
+	}
 	return (w1 / w2);
 }
 
@@ -212,11 +226,24 @@ PRIVATE long sli(long w1, long w2, size nbytes)
 	
 		if (!(IgnMask&BIT(EIOVFL))) {
 			/* check overflow */
-			if (	(w1 >= 0 && (w1 >> (nbytes*8 - w2)) != 0)
-			||	(w1 < 0 && (w1 >> (nbytes*8 - w2)) != -1)
-			) {
+
+			/* If the value is positive, then check, this is taken
+			 * from rule INT32-C of SEI website.
+			 */
+			if ((w1 >= 0) && (w1 > (i_maxs(nbytes) >> w2)))
+			{
 				trap(EIOVFL);
 			}
+
+			if ((w1 < 0) && (w1 < (i_mins(nbytes) >> w2)))
+			{
+				trap(EIOVFL);
+			}
+
+/*			if ((w1 < 0) && (w2 != 0) && ((w1 >> (nbytes*8 - w2)) != -1))
+			{
+				trap(EIOVFL);
+			}*/
 		}
 	}	
 
diff --git a/util/int/main.c b/util/int/main.c
index 05d49e87f..5587a3112 100644
--- a/util/int/main.c
+++ b/util/int/main.c
@@ -45,15 +45,36 @@ extern void disassemble(void);
 extern void tally(void);
 extern void out_tally(void);
 
+/** Check dynamically that the interpreter can run on the target machine. */
+static void check_requirements(char *name)
+{
+	
+	/* Verify that shift right supported signed shifts. According to ISO C90,
+	 * this is not mandatory, we should not support it here!
+	 */
+	int shrv = -4;
+	if ((shrv >> 1) != -2)
+	{
+		fprintf(stderr,
+			"%s compiled with compiler that does not support signed right shifts. Aborted.",
+			name);
+		exit(1);
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	register int i;
 	register int nosetjmp = 1;
 	int must_disassemble = 0;
 	int must_tally = 0;
-	
+
+
 	prog_name = argv[0];
 
+	check_requirements(prog_name);
+
+
 	/* Initialize the EM machine */
 	PreIgnMask = 0;
 	FRALimit = FRALIMIT;