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