src/signal/sigset.c

   1 #include <signal.h>
   2
   3 void (*sigset(int sig, void (*handler)(int)))(int)
   4 {
   5         struct sigaction sa, sa_old;
   6         sigset_t mask, mask_old;
   7
   8         sigemptyset(&mask);
   9         if (sigaddset(&mask, sig) < 0)
  10                 return SIG_ERR;
  11
  12         if (handler == SIG_HOLD) {
  13                 if (sigaction(sig, 0, &sa_old) < 0)
  14                         return SIG_ERR;
  15                 if (sigprocmask(SIG_BLOCK, &mask, &mask_old) < 0)
  16                         return SIG_ERR;
  17         } else {
  18                 sa.sa_handler = handler;
  19                 sa.sa_flags = 0;
  20                 sigemptyset(&sa.sa_mask);
  21                 if (sigaction(sig, &sa, &sa_old) < 0)
  22                         return SIG_ERR;
  23                 if (sigprocmask(SIG_UNBLOCK, &mask, &mask_old) < 0)
  24                         return SIG_ERR;
  25         }
  26         return sigismember(&mask_old, sig) ? SIG_HOLD : sa_old.sa_handler;
  27 }