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For multiple pieces of code to do this without conflicting, each piece of code must remember the old value of the handler and restore it either when:</p></div> <div class="olist arabic"><ol class="arabic"> <li> <p> The work-in-progress is finished, and the handler is no longer necessary. The handler should revert to the original behavior (either another handler, SIG_DFL, or SIG_IGN). </p> </li> <li> <p> The signal is received. We should then do our cleanup, then chain to the next handler (or die if it is SIG_DFL). </p> </li> </ol></div> <div class="paragraph"><p>Sigchain is a tiny library for keeping a stack of handlers. Your handler and installation code should look something like:</p></div> <div class="listingblock"> <div class="content"> <pre><tt> void clean_foo_on_signal(int sig) { clean_foo(); sigchain_pop(sig); raise(sig); } void other_func() { sigchain_push_common(clean_foo_on_signal); mess_up_foo(); clean_foo(); }</tt></pre> </div></div> <div class="paragraph"><p>Handlers are given the typedef of sigchain_fun. This is the same type that is given to signal() or sigaction(). It is perfectly reasonable to push SIG_DFL or SIG_IGN onto the stack.</p></div> <div class="paragraph"><p>You can sigchain_push and sigchain_pop individual signals. For convenience, sigchain_push_common will push the handler onto the stack for many common signals.</p></div> </div> </div> <div id="footer"> <div id="footer-text"> Last updated 2011-01-06 00:29:02 UTC </div> </div> </body> </html>