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From: Chris Wolfe <cwolfe@globetrotter.qc.ca>
Newsgroups: comp.lang.ada,comp.lang.c++,comp.lang.c
Subject: Re: How Ada could have prevented the Red Code distributed denial of
 service attack.
Date: Tue, 07 Aug 2001 19:32:04 -0400
Organization: Queen's University, Kingston
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Xref: archiver1.google.com comp.lang.ada:11557 comp.lang.c++:80815
 comp.lang.c:72784
Date: 2001-08-07T19:32:04-04:00
List-Id: <comp.lang.ada>

Chris Wolfe wrote:
> 
> James Rogers wrote:
[snip]
> > The entry may only execute when the boundary condition is true, and
> > no other entry is concurrently accessing the protected object.
> 
> And when boundary condition is false? I'm assuming a runtime
> error of some sort, unless the wait is clearly documented.

Fixing the parameter, and adding a safe wait:

void Put(const Item &item)
{
  Access::Ptr ptr = Parts_Buf_Ptr.Enqueue();
  while (Size >= Buffer.Last) ptr.Wait();
  
  // etc...
}

void Get(Item &item)
{
  Access::Ptr ptr = Parts_Buf_Ptr.Enqueue();
  while (Size < 0) ptr.Wait();
  
  // etc...
}

Chris