linux-kernel - Re: RTC wakealarm write-only, still has 644 permissions

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Message-ID: <20071002093641.GA11039@atrey.karlin.mff.cuni.cz>
Date:	Tue, 2 Oct 2007 11:36:41 +0200
From:	Pavel Machek <pavel@....cz>
To:	David Brownell <david-b@...bell.net>
Cc:	rtc-linux@...glegroups.com,
	kernel list <linux-kernel@...r.kernel.org>,
	Alessandro Zummo <alessandro.zummo@...ertech.it>
Subject: Re: RTC wakealarm write-only, still has 644 permissions

Hi!

> > > ...should they be changed to 200? Or perhaps file should be readable?
> 
> No, mode 644 is fine.  No reason to prevent "other" people from
> reading the alarm time (is there?) and if you write a legal value,
> that will work.  So $SUBJECT is no problem at all.

Yep, agreed. I was confused by fact that it does not give invalid
values back. 

> > > root@amd:/sys/class/rtc/rtc0# cat wakealarm 
> > > root@amd:/sys/class/rtc/rtc0# echo 132719 > wakealarm 
> 
> At which point I'd expect
> 
> # echo $?
> 
> would indicate the write failed.  That's a LONG time in the
> past (January 2, 1970), so that setting would be rejected.

echo $? says 0 here :-(.

> > > root@amd:/sys/class/rtc/rtc0# 
> > > 
> > > ...standard PC with reasonably recent kernel...
> 
> Yeah, well a "standard PC" is chock full of fairly bizarrely
> glitchey hardware.  Clocks and timers have more than their
> fair share, or x86_64 NOHZ support would be merged by now!

:-). Ok. Thinkpad x60.
								Pavel


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