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| | #include <signal.h>
void (*sigset(int sig, void (*handler)(int)))(int)
{
struct sigaction sa, sa_old;
sigset_t mask, mask_old;
sigemptyset(&mask);
if (sigaddset(&mask, sig) < 0)
return SIG_ERR;
if (handler == SIG_HOLD) {
if (sigaction(sig, 0, &sa_old) < 0)
return SIG_ERR;
if (sigprocmask(SIG_BLOCK, &mask, &mask_old) < 0)
return SIG_ERR;
} else {
sa.sa_handler = handler;
sa.sa_flags = 0;
sigemptyset(&sa.sa_mask);
if (sigaction(sig, &sa, &sa_old) < 0)
return SIG_ERR;
if (sigprocmask(SIG_UNBLOCK, &mask, &mask_old) < 0)
return SIG_ERR;
}
return sigismember(&mask_old, sig) ? SIG_HOLD : sa_old.sa_handler;
}
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