From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cyril Hrubis <chrubis@suse.cz>
Date: Tue, 17 May 2016 16:19:06 +0200
Subject: [LTP] [PATCH] creat05: count opened fds
In-Reply-To: <04943ef887b09df79204f36b924dcf753a7b3037.1463488840.git.jstancek@redhat.com>
References: <04943ef887b09df79204f36b924dcf753a7b3037.1463488840.git.jstancek@redhat.com>
Message-ID: <20160517141906.GG12051@rei.lan>
List-Id: <ltp.lists.linux.it>
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To: ltp@lists.linux.it

Hi!
> This testcase estimates number of opened fds by opening
> a new one and assuming there are no gaps. This doesn't always
> hold true. There can be gaps if test harness that runs it
> opens couple fds with O_CLOEXEC prior to starting creat05.
> As result, testcase unexpectedly fails in setup.

As far as I understand it the O_CLOEXEC is not the problem here. It may
be reproduced even without it when the test harness leaves an open fd
after some open one, right?

Something as:

fd0 = open("foo", ...);
fd1 = open("bar", ...);
close(fd0);
fork();
if (!pid)
	exec("creat05");


And in that case the testcase can do even without listing the
/proc/self/fd. Since POSIX specifies that we get the smallest unused fd
for each creat() we can just call it in a loop until the resulting
fd == max_fd - 1. We would have to allocate the array to store the fds
so that we can close them in cleanup though.

-- 
Cyril Hrubis
chrubis@suse.cz