Re: [Boost-users] [BULK] Re: [BULK] [filesystem] function todetermineavailable space

From: Sohail Somani (s.somani_at_[hidden])
Date: 2005-09-12 19:15:37

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] 
> [mailto:boost-users-bounces_at_[hidden]] On Behalf Of me22
> Sent: Monday, September 12, 2005 4:36 PM
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] [BULK] Re: [BULK] [filesystem] 
> function todetermineavailable space
> 
> 
> On 12/09/05, Sohail Somani <s.somani_at_[hidden]> wrote:
> > What about using a type that guarantees a certain amount instead of 
> > just "max" (which may vary)? Or equivalently, are we 
> guaranteed that 
> > uintmax_t can hold, say one TB, on any platform that boost supports?
> > 
> 
> Even 1 TB isn't really safe.  I know a number of people with 
> more total storage than that.
> 
> How about a double?  The imprecision shouldn't be a worry -- 
> if you're beyond the range of a double's precision for free 
> space then being off by even a few MB it doesn't matter and 
> doubles are perfectly precise for small integral numbers.  ( 
> on x86 linux it seems my 64-bit doubles have 53 bits of 
> mantissa meaning they're perfectly precise for anything less 
> than 8192 TeraBytes.  I don't know what the standard specifes 
> though, and my 32-bit floats are only perfectly precise for 
> under 16 MB.  That being said, even the 32-bit float has a 
> max of over 3e26 TB, so just saying the precision of the 
> number returned is dependant on the precision of your 
> platform's double would get around that, assuming of course 
> we can assure that any rounding is done on the safe side. )
> 
> Also, the implementation could work internally in whatever it 
> wants to keep perfect precision and just feed out a double at the end.

Great idea. I'm ok with this. What about platforms like linux or
windows? What types do they use to report these stats?