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Date: Wed, 6 Nov 2002 14:38:49 -0500
From: Adam Kropelin <akropel1@rochester.rr.com>
To: Clayton Weaver <cgweav@email.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [2.4.19] read(2) and page aligned buffers
Message-ID: <20021106193849.GA640@www.kroptech.com>
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On Wed, Nov 06, 2002 at 01:13:57PM -0500, Clayton Weaver wrote:
> a short count with errno == 0, the wrapper loops
> and tries to read the rest of the file to the
> offset into the buffer past what it already read,
> read() returns 0 with errno still == 0, and of
> course the wrapper decides that it must be at
> EOF (read() == 0 && errno == 0) and returns.

This isn't necessarily the cause of your problem, but your description
here smells an awful lot like classic errno abuse. errno is only valid
when read() returns -1. The check you cite in your last sentence is
illegal.

If read() returns 0, you're done. You're at EOF. If you're not actually
at EOF then *that* is a bug.

--Adam

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