Do bounds check before assignment

As reported by alf (alf.schlichting lemarit com) on bugs@, a bounds check
didn't trigger because it was performed after assignment, so truncation
would happen for large ranges. Fix this and clean up and simplify the code
a bit.

ok deraadt millert

diff --git a/usr.bin/jot/jot.c b/usr.bin/jot/jot.c
index c84a8cb..bd1f364 100644 (file)
--- a/usr.bin/jot/jot.c
+++ b/usr.bin/jot/jot.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: jot.c,v 1.49 2019/06/27 18:03:36 deraadt Exp $        */
+/*     $OpenBSD: jot.c,v 1.50 2021/07/30 02:46:53 tb Exp $     */
 /*     $NetBSD: jot.c,v 1.3 1994/12/02 20:29:43 pk Exp $       */
 
 /*-
@@ -244,7 +244,7 @@ main(int argc, char *argv[])
                        if (putdata(x, reps == i && !infinity))
                                errx(1, "range error in conversion: %f", x);
        } else { /* Random output: use defaults for omitted values. */
-               bool            use_unif;
+               bool            use_unif = 0;
                uint32_t        pow10 = 1;
                uint32_t        uintx = 0; /* Initialized to make gcc happy. */
 
@@ -261,18 +261,19 @@ main(int argc, char *argv[])
                if (prec == 0 && (fmod(ender, 1) != 0 || fmod(begin, 1) != 0))
                        use_unif = 0;
                else {
+                       double range;
+
                        while (prec-- > 0)
                                pow10 *= 10;
-                       /*
-                        * If pow10 * (ender - begin) is an integer, use
-                        * arc4random_uniform().
-                        */
-                       use_unif = fmod(pow10 * (ender - begin), 1) == 0;
-                       if (use_unif) {
-                               uintx = pow10 * (ender - begin);
-                               if (uintx >= UINT32_MAX)
+
+                       range = pow10 * (ender - begin);
+
+                       /* If range is an integer, use arc4random_uniform(). */
+                       if (fmod(range, 1) == 0) {
+                               if (range >= UINT32_MAX)
                                        errx(1, "requested range too large");
-                               uintx++;
+                               use_unif = 1;
+                               uintx = range + 1;
                        }
                }