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From: Peter Chubb <peter@chubb.wattle.id.au>
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Date: Wed, 15 Jan 2003 09:55:39 +1100
To: root@chaos.analogic.com
Cc: DervishD <raul@pleyades.net>, Linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Changing argv[0] under Linux.
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>>>>> "Richard" == Richard B Johnson <root@chaos.analogic.com> writes:

Richard> On Tue, 14 Jan 2003, DervishD wrote:
>> Hi Richard :)
>> 
>>>> Any header where I can see the length for argv[0] or is this SOME
>>>> kind of unoficial standard? Just doing strcpy seems dangerous to
>>>> me  (you can read 'paranoid'...).  

>> They need to have space for _POSIX_PATH_MAX (512 bytes), to claim POSIX
>> compatibility so any POSIX system will have at  least 512 bytes
>> available because the pathname of the executable normally goes
>> there.

No, because argv[0] is followed immediately  by a NUL then argv[1],
then argv[2], etc.  They're not fixed length strings -- the kernel
allocates just enough for the actual arguments, rounded up to
PAGESIZE.

So if you copy more than strlen(argv[0]), you'll start overwriting
argv[1].

--
Dr Peter Chubb				    peterc@gelato.unsw.edu.au
You are lost in a maze of BitKeeper repositories, all almost the same.
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