linux-kernel - Re: [PATCH] pipe: don't block after data has been written

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Message-ID: <20091105163603.GA4089@squirrel.roonstrasse.net>
Date:	Thu, 5 Nov 2009 17:36:03 +0100
From:	Max Kellermann <max@...mpel.org>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	linux-kernel@...r.kernel.org, mk@...all.com
Subject: Re: [PATCH] pipe: don't block after data has been written

On 2009/11/05 17:27, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Your patch breaks many programs, that dont use poll()/select()
> 
> char result[1000000];
> main()
> {
> 	computethings();
> 	write(1, buffer, 1000000);
> }

Your code does not check the return value of write().  This is a bug.

So how exactly does my patch break this program?

Let's read some more of the manual you cited: "If a write() requests
that more bytes be written than there is room for (for example, the
process' file size limit or the physical end of a medium), only as
many bytes as there is room for shall be written."
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