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