42 lines
1.3 KiB
Text
42 lines
1.3 KiB
Text
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sigchain API
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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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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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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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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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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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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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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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You can sigchain_push and sigchain_pop individual signals. For
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convenience, sigchain_push_common will push the handler onto the stack
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for many common signals.
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