nsz Git - musl/blob - src/signal/sigaction.c

   1 #include <signal.h>
   2 #include <errno.h>
   3 #include <string.h>
   4 #include "syscall.h"
   5 #include "pthread_impl.h"
   6 #include "libc.h"
   7 #include "lock.h"
   8 #include "ksigaction.h"
   9
  10 static int unmask_done;
  11 static unsigned long handler_set[_NSIG/(8*sizeof(long))];
  12
  13 void __get_handler_set(sigset_t *set)
  14 {
  15         memcpy(set, handler_set, sizeof handler_set);
  16 }
  17
  18 volatile int __eintr_valid_flag;
  19
  20 int __libc_sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old)
  21 {
  22         struct k_sigaction ksa, ksa_old;
  23         unsigned long set[_NSIG/(8*sizeof(long))];
  24         /* Doing anything with the disposition of SIGABRT requires a lock,
  25          * so that it cannot be changed while abort is terminating the
  26          * process and so any change made by abort can't be observed. */
  27         if (sig == SIGABRT) {
  28                 __block_all_sigs(&set);
  29                 LOCK(__abort_lock);
  30         }
  31         if (sa) {
  32                 if ((uintptr_t)sa->sa_handler > 1UL) {
  33                         a_or_l(handler_set+(sig-1)/(8*sizeof(long)),
  34                                 1UL<<(sig-1)%(8*sizeof(long)));
  35
  36                         /* If pthread_create has not yet been called,
  37                          * implementation-internal signals might not
  38                          * yet have been unblocked. They must be
  39                          * unblocked before any signal handler is
  40                          * installed, so that an application cannot
  41                          * receive an illegal sigset_t (with them
  42                          * blocked) as part of the ucontext_t passed
  43                          * to the signal handler. */
  44                         if (!libc.threaded && !unmask_done) {
  45                                 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
  46                                         SIGPT_SET, 0, _NSIG/8);
  47                                 unmask_done = 1;
  48                         }
  49
  50                         if (!(sa->sa_flags & SA_RESTART)) {
  51                                 a_store(&__eintr_valid_flag, 1);
  52                         }
  53                 }
  54                 ksa.handler = sa->sa_handler;
  55                 ksa.flags = sa->sa_flags | SA_RESTORER;
  56                 ksa.restorer = (sa->sa_flags & SA_SIGINFO) ? __restore_rt : __restore;
  57                 memcpy(&ksa.mask, &sa->sa_mask, _NSIG/8);
  58         }
  59         int r = __syscall(SYS_rt_sigaction, sig, sa?&ksa:0, old?&ksa_old:0, _NSIG/8);
  60         if (sig == SIGABRT) {
  61                 UNLOCK(__abort_lock);
  62                 __restore_sigs(&set);
  63         }
  64         if (old && !r) {
  65                 old->sa_handler = ksa_old.handler;
  66                 old->sa_flags = ksa_old.flags;
  67                 memcpy(&old->sa_mask, &ksa_old.mask, _NSIG/8);
  68         }
  69         return __syscall_ret(r);
  70 }
  71
  72 int __sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old)
  73 {
  74         if (sig-32U < 3 || sig-1U >= _NSIG-1) {
  75                 errno = EINVAL;
  76                 return -1;
  77         }
  78         return __libc_sigaction(sig, sa, old);
  79 }
  80
  81 weak_alias(__sigaction, sigaction);