X-Recipient: archive-cygwin AT delorie DOT com
DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:reply-to:from:to:references:in-reply-to
	:subject:date:message-id:mime-version:content-type
	:content-transfer-encoding; q=dns; s=default; b=o08ibwXLPMnKgI1q
	qVkJbm+vBM/y4X72M0UEeFyLYLM9cFOLUas9ZCOQxjfUrAGG956YfxeQLRlaMM72
	gzku4Z53Sbvfdmu/Yx/dytZtK3TvR2kk+hwQMEOCXzJBwgFISIKIE9TDJrUQnXcf
	3GhR8rjWa9ywgVyfVDEe6FLrfLg=
DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:reply-to:from:to:references:in-reply-to
	:subject:date:message-id:mime-version:content-type
	:content-transfer-encoding; s=default; bh=J/jSu+ZYon6fCwnqMkYr9F
	blrtM=; b=MGRmTB/WKaCFbgwR3K9MOgaZdCWzc1sRRqvnx2vIjIF5Mx1lSAGKhD
	MuG/Y/YkD4/lVoOV/tlagFAUGKrzqRIDoM6ACWQWmK7nu8bkCFeaLoxhBnMm/8cm
	7QFx8jaaUfhO4KEgPPyyxWTQQ60+rVOrO4CQ4c9AUNDQegISPKwyM=
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id: <cygwin.cygwin.com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
Authentication-Results: sourceware.org; auth=none
X-Virus-Found: No
X-Spam-SWARE-Status: No, score=0.2 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.2
X-HELO: p3plsmtpa06-07.prod.phx3.secureserver.net
Reply-To: <sbardwell AT lbmsys DOT com>
From: "Steven Bardwell" <SBardwell AT lbmsys DOT com>
To: <cygwin AT cygwin DOT com>
References: <01a801cf1cfa$77957900$66c06b00$@lbmsys.com> <20140129181250 DOT GW2821 AT calimero DOT vinschen DOT de> <52E95786 DOT 8050606 AT gmail DOT com> <20140130095822 DOT GY2821 AT calimero DOT vinschen DOT de> <001801cf1db6$66c47c40$344d74c0$@lbmsys.com> <20140130124558 DOT GA2821 AT calimero DOT vinschen DOT de>
In-Reply-To: <20140130124558.GA2821@calimero.vinschen.de>
Subject: RE: second call to mmap() results in error
Date: Thu, 30 Jan 2014 08:19:54 -0500
Message-ID: <003801cf1dbd$fc3ffc70$f4bff550$@lbmsys.com>
MIME-Version: 1.0
Content-Type: text/plain;	charset="utf-8"
X-IsSubscribed: yes
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from quoted-printable to 8bit by delorie.com id s0UDKE4P031776

> On Jan 30 07:25, Steven Bardwell wrote:
> > > > On 29/01/2014 19:12, Corinna Vinschen wrote:
> > > > >On Jan 29 09:00, Steven Bardwell wrote:
> > > > >>My application needs several areas of shared memory, and I am
> getting
> > > an
> > > > >>error ("No such device") on the second call to mmap(). The first call
> > > works
> > > > >>fine.
> > >
> > > Sorry guys, but it still works fine for me.  I tried your testcase on W7
> > > 32, W7 64 in 32 and 64 bit, and on Windows 8.1 64 in 32 and 64 bit.  I
> > > tried it with Cygwin 1.7.27 and with the latest snapshot.  I'm always
> > > getting the output "Shared memory initialized" and no error at all.
> > >
> > >
> > > Any chance one of you guys could debug this further, by stepping
> through
> > > the Cygwin mmap64 function, preferredly using the latest snapshot or,
> > > a self-built Cygwin DLL from?
> > >
> > >
> > > Corinna
> >
> > I reinstalled Cygwin, rebooted and the error persisted. Running 'gdb' and
> > stepping through the program showed that the call to mmap() fails for
> /block1
> > also -- it is returning an invalid address. This simplification of the program
> > shows that error on my machine ('Bus error (core dumped)' ) occurs
> > when it tries to do the memcpy() to the mapped address.
> The reason is that ftruncate is defined with the second argument being
> off_t, which is 8 byte.  524304 is an int (4 byte) only, though.  Since
> ftruncate is declared in unistd.h, but you didn't include unistd.h, the
> 2nd parameter to ftruncate is auto-propagated to int, which results in
> an invalid new file length, and which makes ftruncate fail.  Since you
> missed to check ftruncate's return value... you get the idea.
> 
> 
> Corinna

Thanks so much for wasting your time debugging my program. 

Adding the <unistd.h> fixes the problem in all its iterations -- the original mmap() 
test works (without the call to ftruncate()), as well as the second one. 

You all run a great technical support operation.

Steve


--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple