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From: Cyril Hrubis <chrubis@suse.cz>
To: Jan Stancek <jstancek@redhat.com>
Cc: ltp-list@lists.sourceforge.net
Subject: Re: [LTP] [PATCH] diotest: set errno with zero before test with zero
Date: Mon, 8 Dec 2014 13:13:04 +0100	[thread overview]
Message-ID: <20141208121304.GE11071@rei.suse.de> (raw)
In-Reply-To: <648997700.14823290.1418040193631.JavaMail.zimbra@redhat.com>

Hi!
> > >     ret = read(fd, buf, count);
> > >     if (ret >= 0 || errno != errnum) {
> > >         tst_resm(TFAIL, "read allows %s. returns %d: %s", msg, ret,
> > >         strerror(errno));
> > >         l_fail = TRUE;
> > 
> > As far as I can see this code tests that read() has returned negative
> > value and in this case errno must be set.
> > 
> > I.e.
> > 
> > if ret >= 0 -> read hasn't failed -> FAILURE
> > 
> > The errno != errnum is not evaluated unless the first condition has
> > failed (that means ret < 0) and in this case errno must be set.
> > 
> > The condition is equivalent to !(ret < 0 && errno == errnum)
> > 
> > Or am I missing something?
> 
> I think he refers to output of tst_resm being possibly misleading
> in case ret >= 0, that call is using strerror(errno).

Ah, now that makes sense.

Looks like a reasonable solution. Any other solution that I can think of
would add one more if statement...

-- 
Cyril Hrubis
chrubis@suse.cz

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  parent reply	other threads:[~2014-12-08 12:13 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-05 10:47 [LTP] [PATCH] diotest: set errno with zero before test with zero Zorro Lang
2014-12-08 11:53 ` Cyril Hrubis
     [not found]   ` <648997700.14823290.1418040193631.JavaMail.zimbra@redhat.com>
2014-12-08 12:13     ` Cyril Hrubis [this message]
2014-12-08 13:43 ` Cyril Hrubis

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