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4a16d072 JK |
1 | #ifndef SIGCHAIN_H |
2 | #define SIGCHAIN_H | |
3 | ||
c0be43f8 HW |
4 | /** |
5 | * Code often wants to set a signal handler to clean up temporary files or | |
6 | * other work-in-progress when we die unexpectedly. For multiple pieces of | |
7 | * code to do this without conflicting, each piece of code must remember | |
8 | * the old value of the handler and restore it either when: | |
9 | * | |
10 | * 1. The work-in-progress is finished, and the handler is no longer | |
11 | * necessary. The handler should revert to the original behavior | |
12 | * (either another handler, SIG_DFL, or SIG_IGN). | |
13 | * | |
14 | * 2. The signal is received. We should then do our cleanup, then chain | |
15 | * to the next handler (or die if it is SIG_DFL). | |
16 | * | |
17 | * Sigchain is a tiny library for keeping a stack of handlers. Your handler | |
18 | * and installation code should look something like: | |
19 | * | |
20 | * ------------------------------------------ | |
21 | * void clean_foo_on_signal(int sig) | |
22 | * { | |
23 | * clean_foo(); | |
24 | * sigchain_pop(sig); | |
25 | * raise(sig); | |
26 | * } | |
27 | * | |
28 | * void other_func() | |
29 | * { | |
30 | * sigchain_push_common(clean_foo_on_signal); | |
31 | * mess_up_foo(); | |
32 | * clean_foo(); | |
33 | * } | |
34 | * ------------------------------------------ | |
35 | * | |
36 | */ | |
37 | ||
38 | /** | |
39 | * Handlers are given the typedef of sigchain_fun. This is the same type | |
40 | * that is given to signal() or sigaction(). It is perfectly reasonable to | |
41 | * push SIG_DFL or SIG_IGN onto the stack. | |
42 | */ | |
4a16d072 JK |
43 | typedef void (*sigchain_fun)(int); |
44 | ||
c0be43f8 | 45 | /* You can sigchain_push and sigchain_pop individual signals. */ |
4a16d072 JK |
46 | int sigchain_push(int sig, sigchain_fun f); |
47 | int sigchain_pop(int sig); | |
48 | ||
c0be43f8 HW |
49 | /** |
50 | * push the handler onto the stack for the common signals: | |
51 | * SIGINT, SIGHUP, SIGTERM, SIGQUIT and SIGPIPE. | |
52 | */ | |
57b235a4 | 53 | void sigchain_push_common(sigchain_fun f); |
c0be43f8 | 54 | |
bfb6b53c | 55 | void sigchain_pop_common(void); |
57b235a4 | 56 | |
4a16d072 | 57 | #endif /* SIGCHAIN_H */ |