fc without arguments dereferences argv[1]; from Christos

[unix-history] / usr / src / bin / expr / expr.y

diff --git a/usr/src/bin/expr/expr.y b/usr/src/bin/expr/expr.y
index f9af96c..cf3fa84 100644 (file)
--- a/usr/src/bin/expr/expr.y
+++ b/usr/src/bin/expr/expr.y
@@ -2,7 +2,7 @@
  * Copyright (c) 1991 The Regents of the University of California.
  * All rights reserved.
  *
  * Copyright (c) 1991 The Regents of the University of California.
  * All rights reserved.
  *

- * %sccs.include.redist.c%
+ * %sccs.include.proprietary.c%

  */
 
 /* Yacc productions for "expr" command: */
  */
 
 /* Yacc productions for "expr" command: */


@@ -66,7 +66,7 @@ char copyright[] =
 #endif /* not lint */
 
 #ifndef lint
 #endif /* not lint */
 
 #ifndef lint

-static char sccsid[] = "@(#)expr.y     5.1 (Berkeley) %G%";
+static char sccsid[] = "@(#)expr.y     5.3 (Berkeley) %G%";

 #endif /* not lint */
 
 #include <stdio.h>
 #endif /* not lint */
 
 #include <stdio.h>


@@ -145,8 +145,18 @@ char *arith(op, r1, r2) char *r1, *r2; {
        case ADD: i1 = i1 + i2; break;
        case SUBT: i1 = i1 - i2; break;
        case MULT: i1 = i1 * i2; break;
        case ADD: i1 = i1 + i2; break;
        case SUBT: i1 = i1 - i2; break;
        case MULT: i1 = i1 * i2; break;

-       case DIV: i1 = i1 / i2; break;
-       case REM: i1 = i1 % i2; break;
+       case DIV:
+               if (i2 != 0)
+                       i1 = i1 / i2;
+               else
+                       yyerror("Divide by zero");
+               break;
+       case REM:
+               if (i2 != 0)
+                       i1 = i1 % i2;
+               else
+                       yyerror("Remainder by zero");
+               break;

        }
        rv = malloc(16);
        (void)sprintf(rv, "%ld", i1);
        }
        rv = malloc(16);
        (void)sprintf(rv, "%ld", i1);