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