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Date: Thu, 22 Jun 2006 17:01:27 -0500
From: Dan Nelson <dnelson@allantgroup.com>
To: Mike Meyer <mwm-keyword-freebsdhackers2.e313df@mired.org>
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Cc: freebsd-hackers@freebsd.org, Andrew <andrew.chace@gmail.com>
Subject: Re: Coding question: finding the size of a block device
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In the last episode (Jun 22), Mike Meyer said:
> In <1151008839.2360.30.camel@LatitudeFC5.network>, Andrew <andrew.chace@gmail.com> typed:
> > So I guess my question is: is there a POSIX compatible function that
> > will allow me to check the size of a given block device?
> 
> I'd be surprised - POSIX doesn't seem to deal with block devices at all.
> 
> Checking the sources to df, it uses statfs to get the
> information. Linux appears to have it as well, so it may be portable.

statfs only works on mounted filesystems, not arbitrary block devices.

/usr/sbin/diskinfo uses ioctl(fd, DIOCGMEDIASIZE, &mediasize), where
mediasize is an off_t.  

-- 
	Dan Nelson
	dnelson@allantgroup.com