Date: Fri, 30 Jul 2004 07:20:13 GMT From: Steven Smith <sos22@cantab.net> To: freebsd-bugs@FreeBSD.org Subject: Re: misc/69788: The processing result of strtoul() cannot judge whether it is an error. Message-ID: <200407300720.i6U7KDix069001@freefall.freebsd.org>
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The following reply was made to PR misc/69788; it has been noted by GNATS.
From: Steven Smith <sos22@cantab.net>
To: Takayuki Sakuma <takayuki@finet.fujitsu.com>
Cc: freebsd-gnats-submit@FreeBSD.org, sos22@srcf.ucam.org
Subject: Re: misc/69788: The processing result of strtoul() cannot judge whether it is an error.
Date: Fri, 30 Jul 2004 08:12:42 +0100
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> errno=3D0;
> ul =3D strtoul("4294967295", &p, 10);
> printf("ul=3D%lu,*p=3D%x,errno=3D%d(%s)\n", ul, *p, errno, strerr=
or(errno));
>=20
> result:
> ul=3D4294967295,*p=3D0,errno=3D22(Unknown error: 0)
In my tests, strtoul correctly leaves errno at 0:
errno=3D0;
ul =3D strtoul("4294967295", &p, 10);
o_errno =3D errno;=09
printf("ul=3D%lu,*p=3D%x,errno=3D%d(%s)\n", ul, *p, o_errno,strerror(errno=
));
=20
gives the result ``ul=3D4294967295,*p=3D0,errno=3D0(Unknown error: 0)'', as
expected. The problem with the original test case is that strerror()
is setting errno to EINVAL (because 0 isn't a valid error number)
before errno is pushed on the stack for printf (the order in which
function arguments are evaluated is undefined in C).
Steven Smith,
sos22@cantab.net.
--=20
One day, I'm going to get an Alice-bot to answer all my email for me,
and see how long it takes people to notice.
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