diff options
Diffstat (limited to 'sigchain.h')
| -rw-r--r-- | sigchain.h | 45 |
1 files changed, 45 insertions, 0 deletions
@@ -1,12 +1,57 @@ #ifndef SIGCHAIN_H #define SIGCHAIN_H +/** + * Code often wants to set a signal handler to clean up temporary files or + * other work-in-progress when we die unexpectedly. 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: + * + * 1. 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). + * + * 2. The signal is received. We should then do our cleanup, then chain + * to the next handler (or die if it is SIG_DFL). + * + * Sigchain is a tiny library for keeping a stack of handlers. Your handler + * and installation code should look something like: + * + * ------------------------------------------ + * 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(); + * } + * ------------------------------------------ + * + */ + +/** + * 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. + */ typedef void (*sigchain_fun)(int); +/* You can sigchain_push and sigchain_pop individual signals. */ int sigchain_push(int sig, sigchain_fun f); int sigchain_pop(int sig); +/** + * push the handler onto the stack for the common signals: + * SIGINT, SIGHUP, SIGTERM, SIGQUIT and SIGPIPE. + */ void sigchain_push_common(sigchain_fun f); + void sigchain_pop_common(void); #endif /* SIGCHAIN_H */ |