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(libc.info)Termination in Handler

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Handlers That Terminate the Process
-----------------------------------

   Handler functions that terminate the program are typically used to
cause orderly cleanup or recovery from program error signals and
interactive interrupts.

   The cleanest way for a handler to terminate the process is to raise
the same signal that ran the handler in the first place.  Here is how
to do this:

     volatile sig_atomic_t fatal_error_in_progress = 0;
     
     void
     fatal_error_signal (int sig)
     {
       /* Since this handler is established for more than one kind of signal, 
          it might still get invoked recursively by delivery of some other kind
          of signal.  Use a static variable to keep track of that. */
       if (fatal_error_in_progress)
         raise (sig);
       fatal_error_in_progress = 1;
     
       /* Now do the clean up actions:
          - reset terminal modes
          - kill child processes
          - remove lock files */
       ...
     
       /* Now reraise the signal.  We reactivate the signal's
          default handling, which is to terminate the process.
          We could just call `exit' or `abort',
          but reraising the signal sets the return status
          from the process correctly. */
       signal (sig, SIG_DFL);
       raise (sig);
     }