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.  Since the signal is blocked,
     it will receive its 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. */
  raise (sig);
}

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