Return-Path: 
 <stdcxx-dev-return-1228-apmail-incubator-stdcxx-dev-archive=incubator.apache.org@incubator.apache.org>
Delivered-To: apmail-incubator-stdcxx-dev-archive@www.apache.org
Received: (qmail 67805 invoked from network); 26 Apr 2006 01:05:18 -0000
Received: from hermes.apache.org (HELO mail.apache.org) (209.237.227.199)
  by minotaur.apache.org with SMTP; 26 Apr 2006 01:05:18 -0000
Received: (qmail 93705 invoked by uid 500); 26 Apr 2006 01:05:18 -0000
Delivered-To: apmail-incubator-stdcxx-dev-archive@incubator.apache.org
Received: (qmail 93690 invoked by uid 500); 26 Apr 2006 01:05:17 -0000
Mailing-List: contact stdcxx-dev-help@incubator.apache.org; run by ezmlm
Precedence: bulk
List-Help: <mailto:stdcxx-dev-help@incubator.apache.org>
List-Unsubscribe: <mailto:stdcxx-dev-unsubscribe@incubator.apache.org>
List-Post: <mailto:stdcxx-dev@incubator.apache.org>
List-Id: <stdcxx-dev.incubator.apache.org>
Reply-To: stdcxx-dev@incubator.apache.org
Delivered-To: mailing list stdcxx-dev@incubator.apache.org
Received: (qmail 93669 invoked by uid 99); 26 Apr 2006 01:05:17 -0000
Received: from asf.osuosl.org (HELO asf.osuosl.org) (140.211.166.49)
    by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 25 Apr 2006 18:05:17 -0700
X-ASF-Spam-Status: No, hits=0.0 required=10.0
	tests=
X-Spam-Check-By: apache.org
Received-SPF: neutral (asf.osuosl.org: local policy)
Received: from [208.30.140.160] (HELO moroha.quovadx.com) (208.30.140.160)
    by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 25 Apr 2006 18:05:17 -0700
Received: from bco-exchange.bco.roguewave.com (bco-exchange.bco.roguewave.com
 [172.19.31.48])
	by moroha.quovadx.com (8.13.4/8.13.4) with ESMTP id k3Q14Wkk031162
	for <stdcxx-dev@incubator.apache.org>; Wed, 26 Apr 2006 01:04:33 GMT
Received: from [10.70.3.113] (10.70.3.113 [10.70.3.113]) by
 bco-exchange.bco.roguewave.com with SMTP (Microsoft Exchange Internet Mail
 Service Version 5.5.2657.72)
	id 2YG6D6DR; Tue, 25 Apr 2006 19:01:48 -0600
Message-ID: <444EC747.1090200@roguewave.com>
Date: Tue, 25 Apr 2006 19:05:11 -0600
From: Martin Sebor <sebor@roguewave.com>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20050920
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: stdcxx-dev@incubator.apache.org
Subject: Re: 21.string.replace length_error (win32, msvc-7.1)
References: <4D6A8407B7AC6F4D95B0E55C4E7C4C6204171AA3@exmsk.moscow.vdiweb.com>
In-Reply-To: 
 <4D6A8407B7AC6F4D95B0E55C4E7C4C6204171AA3@exmsk.moscow.vdiweb.com>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
X-Virus-Checked: Checked by ClamAV on apache.org
X-Spam-Rating: minotaur.apache.org 1.6.2 0/1000/N

Anton Pevtsov wrote:
> The following code fails with access violation (segmentation fault on
> Linux) error on Win32, MSVC-7.1 (Suse Linux, gcc 4.0.2)

Strictly speaking, the behavior of this program is undefined
since this overload of replace is specified to return

     s.replace (0, 1, string ("a", s.max_size() + 1))

and the expression string ("a", s.max_size() + 1) has undefined
semantics due to the array "a" having fewer than the number of
elements specified by the second argument.

But from a QoI standpoint, since we don't actually invoke the
ctor to create the temporary string from the array, we could
detect and avoid the (potential) undefined behavior and throw
the appropriate exception instead.

Could you open a Jira issue and reference this thread in the
archive in it?

Thanks
Martin

> 
> #include <iostream>
> #include <string>
> #include <stdexcept>
> 
> static char long_string [4096] = {'a'};
> 
> int main (void)
> {
>     try 
>     {
>         std::string s (long_string, 4095);
>         s.replace (0, 1, "a", s.max_size () + 1);
> 
>         std::cout << "Expect length error, got nothing" << '\n';
>     }
>     catch (std::length_error& e)
>     {
>         std::cout << "Got expected length error" << '\n';
>     }
> 
>     return 0;
> }
> 
> 
> I suspect a bug in replace implementation, string.cc line 327:
> The check 
> 
> __size0 - __xlen <= max_size () - __n2
> 
> is not enough in this case.
> 
> 
> Could you take a look when you have a chance, please?
> 
> 
> Thanks,
> Anton Pevtsov