From: Frederic Marmond <fmarmond@eprocess.fr>
To: Lawrence <law@cbf.chinese2000.net>
Cc: linux-assembly@vger.kernel.org
Subject: Re: A question on cat.asm from asmutils-0.17
Date: Tue, 18 Nov 2003 08:38:16 +0100 [thread overview]
Message-ID: <3FB9CC68.9090802@eprocess.fr> (raw)
In-Reply-To: <3FB9986D.60709@cbf.chinese2000.net>
Hi,
One of the goal of asmutils is to be as small as possible.
So, any 'non-very-necessary' things are commented out to save place.
In Linux, when you open file, a file descriptor is stored in the
process memory.
When you release the process, the system close all its opened files.
So, what is done in cat.asm is *not* a nice thing (every thing that is
opened must in theory be closed) but it is a good way to reduce code
size (from few bytes, but it is the power of assembly) without breaking
anything.
hope it helps
Fred
Lawrence wrote:
>Hi All,
>
>I'm trying to get acquintant with Linux assembly language by studying
>the asm code found in asmutils.
>
>While studying cat.asm, I discover that every time a file is opened
>using sys_open, there is no correspondent sys_close to it. (The codes
>were marked).
>
>I would like to ask if this is an legitimate way to open a file without
>closing it under Linux, or just a convenient way to let the
>shell/kernel(I'm not sure...) to close the file for us when cat is
>finished. For my experience on MS-DOS assembly, I must close an
>opened-file, or otherwise I'll encounter an out of file handle error.
>
>Thanks and Regards,
>Lawrence
>
>-
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>
prev parent reply other threads:[~2003-11-18 7:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-18 3:56 A question on cat.asm from asmutils-0.17 Lawrence
2003-11-18 7:38 ` Frederic Marmond [this message]
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