linux-kernel - bug reading /proc/sys/kernel/*: only first byte read.

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Message-ID: <4538C47B.9060808@tls.msk.ru>
Date:	Fri, 20 Oct 2006 16:43:39 +0400
From:	Michael Tokarev <mjt@....msk.ru>
To:	Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: bug reading /proc/sys/kernel/*: only first byte read.

I were debugging a weird problem with busybox, and come across
this chunk of strace output:

open("/proc/sys/kernel/osrelease", O_RDONLY) = 3
read(3, "2", 1)                         = 1
read(3, "", 1)                          = 0
close(3)                                = 0

As you can see, after reading one byte from /proc/sys/kernel/osrelease,
next read() returns 0, which is treated as end-of-file by an application.

Why busybox does this single-byte reads is another question (many
shells does that, in order to be able to stop reading at newline).

But this is definitely a bug in kernel, and should be fixed....

It exists in 2.6.17 and 2.6.18

Thanks.

/mjt
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