Stop "dd if=/dev/zero of=/dev/null bs=1 count=2 skip=0x7fffffffffffffff"

from erroring out with "dd: skip: Undefined error: 0", mostly for
consistency and to avoid the unidiomatic, wrong looking code.
Patch from Bulat Musin <mbulatka at yandex dot ru>.
OK guenther@ millert@

diff --git a/bin/dd/args.c b/bin/dd/args.c
index a59f320..6cd6de9 100644 (file)
--- a/bin/dd/args.c
+++ b/bin/dd/args.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: args.c,v 1.28 2016/08/16 16:44:55 krw Exp $   */
+/*     $OpenBSD: args.c,v 1.29 2018/01/03 19:12:20 schwarze Exp $      */
 /*     $NetBSD: args.c,v 1.7 1996/03/01 01:18:58 jtc Exp $     */
 
 /*-
@@ -406,8 +406,9 @@ get_off(char *val)
        off_t num, t;
        char *expr;
 
+       errno = 0;
        num = strtoll(val, &expr, 0);
-       if (num == LLONG_MAX)                   /* Overflow. */
+       if (num == LLONG_MAX && errno == ERANGE)        /* Overflow. */
                err(1, "%s", oper);
        if (expr == val)                        /* No digits. */
                errx(1, "%s: illegal numeric value", oper);