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Date: Thu, 27 Aug 2015 08:17:29 +0800
Message-ID: <CAGk-QBtv5a4+x=XAi5TE+icUjuiZwnZNkfMvcAAOOOCt=uRzGw@mail.gmail.com>
Subject: Re: [PATCH] kernel/sysctl.c: If "count" including the terminating
 byte '\0' the write system call should retrun success.
From: Sean Fu <fxinrong@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Austin S Hemmelgarn <ahferroin7@gmail.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Ulrich Obergfell <uobergfe@redhat.com>,
        Prarit Bhargava <prarit@redhat.com>,
        Eric B Munson <emunson@akamai.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>, Don Zickus <dzickus@redhat.com>,
        Heinrich Schuchardt <xypron.glpk@gmx.de>,
        David Rientjes <rientjes@google.com>, linux-kernel@vger.kernel.org
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On Thu, Aug 27, 2015 at 4:36 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> On Wed, 26 Aug 2015 23:48:01 +0800
> Sean Fu <fxinrong@gmail.com> wrote:
>
>
>> > Defending the patch, I can't imagine any user space code expecting the
>> > current behavior. The current behavior is that if you write "1\0" it
>> > will error out instead of accepting the "1". I can't come up with a
>> > scenario that would require userspace to expect "1\0" to fail. Can you?
>> Thanks
>
> Although, with the current patch, would "1\02" fail? It should.
Yes, "1\02" is equal to "1\2"(count=2) or "1\2\0"(count=3), So it should fail.

code
len = write(fd, "1\0\2", 3);

strace execute result:
write(3, "1\2\0", 3)                    = -1 EINVAL (Invalid argument)

>
> -- Steve
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