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To: "Cygwin Mailing List" <cygwin AT cygwin DOT com>
Subject: Re: cygwin programs: realloc() segfault with library v1.3.1
References: <001001c0d192$1cb70240$0101a8c0 AT luckynet DOT adm>
From: Benjamin Riefenstahl <Benjamin DOT Riefenstahl AT ision DOT net>
Date: 02 May 2001 19:00:49 +0200
In-Reply-To: "Thunder from the hill"'s message of "Mon, 30 Apr 2001 09:21:33 -0700"
Message-ID: <ubspb1y9q.fsf@work1.work.maz.net>
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"Thunder from the hill" <thunder AT ngforever DOT de> writes:
> Again, this is the failing source code. Whenever realloc() is used
> in sendfile(), the MicroHTTPD segfaults.

As Chris says, you should limit examples.  Anyway I looked at your
code and your use of realloc().  You never do anything with the result
of your calls.  That won't work.  realloc() is designed to be used as

  void * some_buffer = NULL;
  ... 
  some_buffer = realloc( some_buffer, newlen );

or better, with minimal error handling:

  void * some_buffer = NULL;
  void * temp;
  ... 
  temp = realloc( some_buffer, newlen );
  if( NULL != temp )  some_buffer = temp;

In your code OTOH, all the allocated memory returned by realloc() is
just ignored so your code continues to read and write from the (now
probably invalid) previous pointer.

Note also that you will have to redesign the interface for your
clear() function to account for this usage.


so long, benny
-- 
ISION Internet AG
Benjamin Riefenstahl
mailto:benjamin DOT riefenstahl AT ision DOT net

Harburger Schlossstr. 1
D-21079 Hamburg
http://www.ision.net


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