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Date:	Tue, 1 Feb 2005 09:59:50 -0500
From:	Christopher Faylor <cgf-no-personal-reply-please AT cygwin DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: Fwd: Re: cp command - problem with sparse
Message-ID:	<20050201145950.GC4186@trixie.casa.cgf.cx>
Reply-To:	cygwin AT cygwin DOT com
References:	<41FF88C8 DOT 5060604 AT byu DOT net>
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On Tue, Feb 01, 2005 at 06:48:56AM -0700, Eric Blake wrote:
>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.

Yes.

  % fgrep FSCTL_SET_SPARSE *.cc
  fhandler.cc:          BOOL r = DeviceIoControl (h, FSCTL_SET_SPARSE, NULL, 0, NULL,
  fhandler.cc:          syscall_printf ("%d = DeviceIoControl(%p, FSCTL_SET_SPARSE, "

There are limitations on when a file is considered sparse, however.  The archives
probably have more details.

cgf

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