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From: Albert ARIBAUD <albert.aribaud@free.fr>
To: Changli Gao <xiaosuo@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Amerigo Wang <xiyou.wangcong@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: PROPOSAL: extend pipe() to support NULL argument.
Date: Mon, 06 Jul 2009 08:30:16 +0200	[thread overview]
Message-ID: <4A5199F8.2010809@free.fr> (raw)
In-Reply-To: <412e6f7f0907052323g114ccbe0n2d17f3d870e42470@mail.gmail.com>

Changli Gao a écrit :
> On Mon, Jul 6, 2009 at 2:15 PM, Albert ARIBAUD<albert.aribaud@free.fr> wrote:
>>>
>>> pipe doesn't support llseek.
>> I wasn't thinking of actively seeking a file position, but simply that reads
>> and writes were independent (and both variable) in size, thus even without
>> (l)seeking, each endpoint has an independent read (resp. write) position to
>> track what's been read from (resp.written into) it at any time, and such a
>> position is, IIUC, single for a given fd, making a fd (a struct file)
>> insufficient for representing a pipe.
>>
>> Amicalement,
>> --
>> Albert.
>>
> pipe doesn't refer to pos when reading or writing. Please refer to
> pipe_read() and pipe_write() for more detail.

Hmm. Then how does pipe avoid overwriting what it's already written at the 
in endpoint, or reading twice the same data from the out endpoint?

Amicalement,
-- 
Albert.

  reply	other threads:[~2009-07-06  6:31 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-02  7:36 PROPOSAL: extend pipe() to support NULL argument Changli Gao
2009-07-02  9:13 ` Amerigo Wang
2009-07-02  9:18   ` Changli Gao
2009-07-02  9:46     ` Amerigo Wang
2009-07-02 10:04       ` Changli Gao
2009-07-02 10:21         ` Amerigo Wang
2009-07-03  0:43           ` Changli Gao
2009-07-03  1:55             ` Amerigo Wang
2009-07-03  2:10               ` Changli Gao
2009-07-03  3:00                 ` Amerigo Wang
2009-07-03  4:08                   ` Changli Gao
2009-07-03  5:19                     ` Amerigo Wang
2009-07-03  5:42                       ` Changli Gao
2009-07-03  7:15                         ` Amerigo Wang
2009-07-03  7:40                           ` Changli Gao
2009-07-03  8:16                             ` Amerigo Wang
2009-07-03  8:27                               ` Changli Gao
2009-07-03  9:42                                 ` Amerigo Wang
2009-07-03  9:59                                   ` Changli Gao
2009-07-03 10:23                                     ` Amerigo Wang
2009-07-03 10:28                                     ` Albert ARIBAUD
2009-07-06  1:12                                       ` Changli Gao
2009-07-06  6:15                                         ` Albert ARIBAUD
2009-07-06  6:23                                           ` Changli Gao
2009-07-06  6:30                                             ` Albert ARIBAUD [this message]
2009-07-07  4:43                                       ` Denys Vlasenko
2009-07-07  7:45                                         ` Changli Gao
2009-07-07 20:37                                           ` David Newall
2009-07-07 21:02                                             ` Zan Lynx
2009-07-08  4:41                                               ` Changli Gao
2009-07-08  4:43                                                 ` David Newall
2009-07-02 10:42     ` Alan Cox
2009-07-03  0:45       ` Changli Gao

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