57 lines
1.7 KiB
C
57 lines
1.7 KiB
C
#ifndef SIGCHAIN_H
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#define SIGCHAIN_H
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/**
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* Code often wants to set a signal handler to clean up temporary files or
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* other work-in-progress when we die unexpectedly. For multiple pieces of
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* code to do this without conflicting, each piece of code must remember
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* the old value of the handler and restore it either when:
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*
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* 1. The work-in-progress is finished, and the handler is no longer
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* necessary. The handler should revert to the original behavior
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* (either another handler, SIG_DFL, or SIG_IGN).
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*
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* 2. The signal is received. We should then do our cleanup, then chain
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* to the next handler (or die if it is SIG_DFL).
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*
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* Sigchain is a tiny library for keeping a stack of handlers. Your handler
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* and installation code should look something like:
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*
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* ------------------------------------------
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* void clean_foo_on_signal(int sig)
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* {
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* clean_foo();
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* sigchain_pop(sig);
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* raise(sig);
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* }
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*
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* void other_func()
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* {
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* sigchain_push_common(clean_foo_on_signal);
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* mess_up_foo();
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* clean_foo();
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* }
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* ------------------------------------------
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*
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*/
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/**
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* Handlers are given the typedef of sigchain_fun. This is the same type
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* that is given to signal() or sigaction(). It is perfectly reasonable to
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* push SIG_DFL or SIG_IGN onto the stack.
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*/
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typedef void (*sigchain_fun)(int);
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/* You can sigchain_push and sigchain_pop individual signals. */
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int sigchain_push(int sig, sigchain_fun f);
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int sigchain_pop(int sig);
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/**
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* push the handler onto the stack for the common signals:
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* SIGINT, SIGHUP, SIGTERM, SIGQUIT and SIGPIPE.
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*/
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void sigchain_push_common(sigchain_fun f);
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void sigchain_pop_common(void);
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#endif /* SIGCHAIN_H */
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