signal.c

   1 #include <signal.h>
   2
   3 #define SIG_BLOCK       0
   4 #define SIG_UNBLOCK     1
   5 #define SIG_SETMASK     2
   6
   7 #define SA_NOCLDSTOP    1
   8 #define SA_NOCLDWAIT    2
   9 #define SA_SIGINFO      4
  10 #define SA_ONSTACK      0x08000000
  11 #define SA_RESTART      0x10000000
  12 #define SA_NODEFER      0x40000000
  13 #define SA_RESETHAND    0x80000000
  14 #define SA_RESTORER     0x04000000
  15
  16 struct sigset_t {
  17         unsigned long __bits[128 / sizeof(long)];
  18 };
  19 typedef struct sigset_t sigset_t;
  20
  21 struct sigaction {
  22         void (*sa_handler)(int);
  23         sigset_t sa_mask;
  24         int sa_flags;
  25         void (*sa_restorer)(void);
  26 };
  27
  28 int sigreturn(unsigned long n);
  29
  30 struct ksa {
  31         void *handler;
  32         unsigned long flags;
  33         int (*restorer)(unsigned long n);
  34         sigset_t mask;
  35 };
  36
  37 int __sigaction(int sig, const struct sigaction *sa, struct sigaction *old)
  38 {
  39         struct ksa ksa, _ksa;
  40         if (sa) {
  41                 ksa.handler = sa->sa_handler;
  42                 ksa.flags = sa->sa_flags | SA_RESTORER;
  43                 ksa.restorer = sigreturn;
  44                 ksa.mask = sa->sa_mask;
  45         }
  46         if (sigaction(sig, sa ? (long) &ksa : 0, old ? (long) &_ksa : 0, 8))
  47                 return -1;
  48         if (old) {
  49                 old->sa_handler = _ksa.handler;
  50                 old->sa_flags = _ksa.flags;
  51                 old->sa_mask = _ksa.mask;
  52         }
  53         return 0;
  54 }
  55
  56 int sigaction(int sig, struct sigaction *sa, struct sigaction *old_sa);
  57
  58 sighandler_t signal(int sig, sighandler_t func)
  59 {
  60         struct sigaction sa = {.sa_handler = func, .sa_flags = SA_RESTART};
  61         if (__sigaction(sig, &sa, &sa) < 0)
  62                 return SIG_ERR;
  63         return sa.sa_handler;
  64 }