Re: Quick close of all the open files.

[Måns Rullgård <mru@inprovide.com>]

Valdis.Kletnieks@vt.edu writes:

> On Wed, 07 Jun 2006 03:15:43 +0530, vamsi krishna said:
>> Hello,
>> 
>> I found that the following code is closing all the open files by the
>> program, do you think its a bug in kernel code?
>> 
>> ------------
>> fp = tmpfile();
>> fp->_chain = stderr;
>> fpclose(fp);
>> fp = NULL;
>
> strace that, and see how many times close() gets called.  If it gets
> called once, it's a kernel bug.  If it gets called once for each open
> file, it's a userspace bug.

Actually, it's not a bug at all.

> For bonus points, how did you verify that all the open files were closed?
>
> (Hint - what does that fp->_chain = stderr *really* do? ;)

As it touches the innards of the FILE type, it invokes undefined
behavior.  Nothing that follows can be considered a bug.

-- 
Måns Rullgård
mru@inprovide.com

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