From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <ecos-devel-return-1929-listarch-ecos-devel=sources.redhat.com@ecos.sourceware.org>
Received: (qmail 26486 invoked by alias); 7 Oct 2011 15:06:19 -0000
Received: (qmail 26401 invoked by uid 22791); 7 Oct 2011 15:06:18 -0000
X-SWARE-Spam-Status: No, hits=-2.5 required=5.0	tests=AWL,BAYES_00
X-Spam-Check-By: sourceware.org
Received: from relay01.alfahosting-server.de (HELO relay01.alfahosting-server.de) (80.86.191.88)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 07 Oct 2011 15:05:57 +0000
Received: by relay01.alfahosting-server.de (Postfix, from userid 1001)	id C08A132C017D; Fri,  7 Oct 2011 17:05:55 +0200 (CEST)
X-Spam-DCC: :
Received: from alfa3018.alfahosting-server.de (alfa3018.alfahosting-server.de [82.197.146.36])	by relay01.alfahosting-server.de (Postfix) with ESMTP id 69DEB32C019D	for <ecos-devel@ecos.sourceware.org>; Fri,  7 Oct 2011 17:05:51 +0200 (CEST)
Received: from laabs.hf.ifn.et.tu-dresden.de (unknown [141.30.128.185])	by alfa3018.alfahosting-server.de (Postfix) with ESMTPSA id 62129515D62B	for <ecos-devel@ecos.sourceware.org>; Fri,  7 Oct 2011 17:05:51 +0200 (CEST)
Message-ID: <4E8F15B5.6060909@mailbox.tu-dresden.de>
Date: Fri, 07 Oct 2011 15:06:00 -0000
From: Martin Laabs <martin.laabs@mailbox.tu-dresden.de>
Reply-To: uni@martinlaabs.de
User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:7.0.1) Gecko/20111004 Thunderbird/7.0.1
MIME-Version: 1.0
To: eCos Developer List <ecos-devel@ecos.sourceware.org>
Subject: Re: Configtool segfaults
References: <4E8C5768.8090804@mailbox.tu-dresden.de>
In-Reply-To: <4E8C5768.8090804@mailbox.tu-dresden.de>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-Virus-Checker-Version: clamassassin 1.2.4 with ClamAV 0.97.2/13760/Fri Oct  7 02:58:24 2011
X-IsSubscribed: yes
Mailing-List: contact ecos-devel-help@ecos.sourceware.org; run by ezmlm
Precedence: bulk
List-Id: <ecos-devel.ecos.sourceware.org>
List-Subscribe: <mailto:ecos-devel-subscribe@ecos.sourceware.org>
List-Post: <mailto:ecos-devel@ecos.sourceware.org>
List-Help: <mailto:ecos-devel-help@ecos.sourceware.org>, <http://ecos.sourceware.org/lists.html#faqs>
Sender: ecos-devel-owner@ecos.sourceware.org
X-SW-Source: 2011-10/txt/msg00001.txt.bz2

Hello,

  I compiled the configtool on my amd64 system (freebsd). After changing some
  int* casts to intptr_t compiling the configtool worked. (Any interests in
  the diff?)
  However - starting the configtool out of a long directory lead to a
  segfault. I traced down the problem to the String::vFormat function

void String::vFormat(LPCTSTR  pszFormat, va_list marker)
{
   for(int nLength=100;nLength;) {
     TCHAR *buf=new TCHAR[1+nLength];
     int n=_vsntprintf(buf, nLength, pszFormat, marker );
     if(-1==n){
       nLength*=2;  // NT behavior
     } else if (n<nLength){
       string::operator=(buf);
       nLength=0;   // trigger exit from loop
     } else {
       nLength=n+1; // UNIX behavior generally, or NT behavior when buffer 
size exactly matches required length
     }
     delete [] buf;
   }
}

When the for-loop runs the second time (which occurs when the output string 
is longer that 100 chars) the _vsntprintf function is called a second time. 
This is not allowed because the va_list argument marker has  already 
consumed during the first call.

Anyway - the coding style of this function seems to be somewhat strange. 
Why using the "nLength=0;   // trigger exit from loop" instead of calling 
exit? However - I'm not very familiar with c++ so it might be the better 
way to exit that loop.

Greetings,
  Martin Laabs