[src/trunk]: src/usr.bin/printf A truly ancient bug found by Edgar Fuss

[kre <kre%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d5c86375d14c
branches:  trunk
changeset: 433370:d5c86375d14c
user:      kre <kre%NetBSD.org@localhost>
date:      Mon Sep 10 14:42:29 2018 +0000

description:
A truly ancient bug found by Edgar Fuss

When printf is running builtin in a sh, global vars aren't reset to
0 between invocations.   This affects "rval" which remembers state
from a previous %b \c and thereafter always exits after the first
format conversion, until we get a conversion that generates an
error (which resets the flag almost by accident)

        printf %b abc\\c
        abc                             (no \n)
        printf %s%s hello world
        hello                           (no \n, of course, no world ...)
        printf %s%s hello world
        hello
        printf %s%s hello world
        hello
        printf %d hello
        printf: hello: expected numeric value
        0                               (no \n)
        printf %s%s hello world
        helloworld                      (no \n, and we are back!)

This affects both /bin/sh and /bin/csh (and has for a very long time).

XXX pullup -8

diffstat:

 usr.bin/printf/printf.c |  6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diffs (27 lines):

diff -r 75b612b75c1d -r d5c86375d14c usr.bin/printf/printf.c
--- a/usr.bin/printf/printf.c   Mon Sep 10 13:11:05 2018 +0000
+++ b/usr.bin/printf/printf.c   Mon Sep 10 14:42:29 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: printf.c,v 1.45 2018/09/04 01:13:50 kre Exp $  */
+/*     $NetBSD: printf.c,v 1.46 2018/09/10 14:42:29 kre Exp $  */
 
 /*
  * Copyright (c) 1989, 1993
@@ -41,7 +41,7 @@
 #if 0
 static char sccsid[] = "@(#)printf.c   8.2 (Berkeley) 3/22/95";
 #else
-__RCSID("$NetBSD: printf.c,v 1.45 2018/09/04 01:13:50 kre Exp $");
+__RCSID("$NetBSD: printf.c,v 1.46 2018/09/10 14:42:29 kre Exp $");
 #endif
 #endif /* not lint */
 
@@ -136,6 +136,8 @@
        (void)setlocale (LC_ALL, "");
 #endif
 
+       rval = 0;       /* clear for builtin versions (avoid holdover) */
+
        while ((o = getopt(argc, argv, "")) != -1) {
                switch (o) {
                case '?':