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Date: Tue, 1 Feb 2005 16:00:58 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Fwd: Re: cp command - problem with sparse
Message-ID: <20050201150058.GB31305@cygbert.vinschen.de>
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References: <41FF88C8 DOT 5060604 AT byu DOT net>
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On Feb  1 06:48, Eric Blake wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
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> 
> This question came up on the coreutils list:
> 
> Does cygwin provide any support for sparse files on NTFS volumes that
> support it?  lseek() could be patched to use FSCTL_SET_ZERO_DATA when a
> seek jumps past the end of a file open for writing, but there is still the
> issue of when that file is given the FSCTL_SET_SPARSE attribute.

lseek already creates sparse files automatically in a write after lseek,
if the lseek seeked more than 128K beyond EOF.  128K is the value which
has been found to be the smallest sparse block size at which making
the file sparse makes a difference on XP.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          mailto:cygwin AT cygwin DOT com
Red Hat, Inc.

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