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<h5 class="subsubsection">3.2.3.3 Some more or less clever ideas</h5>

<p>You know the situation.  The program is prepared for debugging and in
all debugging sessions it runs well.  But once it is started without
debugging the error shows up.  A typical example is a memory leak that
becomes visible only when we turn off the debugging.  If you foresee
such situations you can still win.  Simply use something equivalent to
the following little program:

<pre class="example">     #include &lt;mcheck.h&gt;
     #include &lt;signal.h&gt;
     
     static void
     enable (int sig)
     {
       mtrace ();
       signal (SIGUSR1, enable);
     }
     
     static void
     disable (int sig)
     {
       muntrace ();
       signal (SIGUSR2, disable);
     }
     
     int
     main (int argc, char *argv[])
     {
       ...
     
       signal (SIGUSR1, enable);
       signal (SIGUSR2, disable);
     
       ...
     }
</pre>
   <p>I.e., the user can start the memory debugger any time s/he wants if the
program was started with <code>MALLOC_TRACE</code> set in the environment. 
The output will of course not show the allocations which happened before
the first signal but if there is a memory leak this will show up
nevertheless.

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