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| <h4 class="subsection">24.4.2 Handlers That Terminate the Process</h4> |
| |
| <p>Handler functions that terminate the program are typically used to cause |
| orderly cleanup or recovery from program error signals and interactive |
| interrupts. |
| |
| <p>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: |
| |
| <pre class="smallexample"> volatile sig_atomic_t fatal_error_in_progress = 0; |
| |
| void |
| fatal_error_signal (int sig) |
| { |
| /* <span class="roman">Since this handler is established for more than one kind of signal, </span> |
| <span class="roman">it might still get invoked recursively by delivery of some other kind</span> |
| <span class="roman">of signal. Use a static variable to keep track of that.</span> */ |
| if (fatal_error_in_progress) |
| raise (sig); |
| fatal_error_in_progress = 1; |
| |
| /* <span class="roman">Now do the clean up actions:</span> |
| <span class="roman">- reset terminal modes</span> |
| <span class="roman">- kill child processes</span> |
| <span class="roman">- remove lock files</span> */ |
| ... |
| |
| /* <span class="roman">Now reraise the signal. We reactivate the signal's</span> |
| <span class="roman">default handling, which is to terminate the process.</span> |
| <span class="roman">We could just call </span><code>exit</code><span class="roman"> or </span><code>abort</code><span class="roman">,</span> |
| <span class="roman">but reraising the signal sets the return status</span> |
| <span class="roman">from the process correctly.</span> */ |
| signal (sig, SIG_DFL); |
| raise (sig); |
| } |
| </pre> |
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