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Date:	Mon, 31 Jan 2005 21:59:38 -0800 (PST)
From:	Dan Ch <force296-cygwin AT yahoo DOT com>
Reply-To:	force296-cygwin AT yahoo DOT com
Subject:	Re: Why does cygwin1.dll use NtCreateFile() instead of CreateFile()
To:	Brian Ford <ford AT vss DOT fsi DOT com>
Cc:	cygwin AT cygwin DOT com
In-Reply-To:	<Pine.CYG.4.58.0501310901040.2732@fordpc.vss.fsi.com>
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On Mon, 31 Jan 2005, Brian Ford wrote:
> On Sun, 30 Jan 2005, Dan Ch wrote:
> > I noticed that cygwin-1.5.12-1/winsup/cygwin/fhandler.cc
> > uses NtCreateFile() instead of CreateFile() on Windows NT based
> > operating systems (NT, 2000, 2003, XP) for opening files.  Why?  I
> > checked the archives for this mailing list and noted some activity
> > that discuses some side affects caused by using NtCreateFile()
> > instead of CreateFile() such as being able to use file names that are
> > off limits to normal Windows applications.  But I could not find
> > anything that explains the benefits of using NtCreateFile() instead
> > of CreateFile().
>
> IIRC, NtCreateFile is significantly cheaper if you already have a file
> handle, especially on network drives where the name to handle
> translation and open are fairly expensive.  The original reason was
> purely performance (since I believe my company paid for some of this
> optimization).

Thank you for answering my question.  Now I understand why
CreateFile() instead of NtCreateFile() probably did not cause
any major bugs.

Dan Ch.


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