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From: Paul Jackson <pj@sgi.com>
To: Roland Dreier <roland@topspin.com>
Cc: greg@kroah.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][1/2] [RESEND] kobject: add HOTPLUG_ENV_VAR
Date: Tue, 28 Sep 2004 09:00:32 -0700	[thread overview]
Message-ID: <20040928090032.292d12e8.pj@sgi.com> (raw)
In-Reply-To: <52mzzacsyk.fsf@topspin.com>

> So the next env var is going to be concatenated with this one.

Right you are - unlike most times where one is trying to concatenate
strings, this time you want the nul char separator.

> It's precisely this sort of easy-to-make off-by-one bug that convinces
> me the hotplug environment variable handling needs to be wrapped up in
> a helper macro or function.

Perhaps - but perhaps also I've shown you ways to use a function with
fewer non-const variables.

And perhaps the placing of the nul chars should be explicit:

	if (length < buffer_size)
		buffer[length++] = '\0';

so that someone else doesn't either miss the intentional inclusion of
the nul as I just did, or does see it and thinks it's an off-by-one
error and "fixes" it.

That macro was ugly.

Adding to my previous rules of:
  * minimum number variables
  * simplest invariants on variables
  * functions beat macros
now include:
  * explicit coding of anything out of the ordinary.

-- 
                          I won't rest till it's the best ...
                          Programmer, Linux Scalability
                          Paul Jackson <pj@sgi.com> 1.650.933.1373

  reply	other threads:[~2004-09-28 16:02 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-09-27 16:31 [PATCH][0/2] [RESEND] Hotplug variable patches Roland Dreier
2004-09-27 16:31 ` [PATCH][1/2] [RESEND] kobject: add HOTPLUG_ENV_VAR Roland Dreier
2004-09-27 16:31   ` [PATCH][2/2] [RESEND] USB: use HOTPLUG_ENV_VAR in core/usb.c Roland Dreier
2004-09-27 20:10   ` [PATCH][1/2] [RESEND] kobject: add HOTPLUG_ENV_VAR Paul Jackson
2004-09-27 22:10     ` Roland Dreier
2004-09-28  6:43       ` Paul Jackson
2004-09-28 15:29         ` Roland Dreier
2004-09-28 16:00           ` Paul Jackson [this message]
2004-09-28 16:13             ` Roland Dreier
2004-09-28 21:56               ` Greg KH
  -- strict thread matches above, loose matches on Subject: below --
2004-09-27 16:59 [PATCH][0/2] [RESEND] Hotplug variable patches Roland Dreier
2004-09-27 16:59 ` [PATCH][1/2] [RESEND] kobject: add HOTPLUG_ENV_VAR Roland Dreier

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