fusl/src/signal/sigaction.c

#include <signal.h>
#include <errno.h>
#include <string.h>
#include "syscall.h"
#include "pthread_impl.h"
#include "libc.h"
#include "ksigaction.h"

static int unmask_done;
static unsigned long handler_set[_NSIG / (8 * sizeof(long))];

void __get_handler_set(sigset_t* set) {
  memcpy(set, handler_set, sizeof handler_set);
}

int __libc_sigaction(int sig,
                     const struct sigaction* restrict sa,
                     struct sigaction* restrict old) {
  struct k_sigaction ksa, ksa_old;
  if (sa) {
    if ((uintptr_t)sa->sa_handler > 1UL) {
      a_or_l(handler_set + (sig - 1) / (8 * sizeof(long)),
             1UL << (sig - 1) % (8 * sizeof(long)));

      /* If pthread_create has not yet been called,
       * implementation-internal signals might not
       * yet have been unblocked. They must be
       * unblocked before any signal handler is
       * installed, so that an application cannot
       * receive an illegal sigset_t (with them
       * blocked) as part of the ucontext_t passed
       * to the signal handler. */
      if (!libc.threaded && !unmask_done) {
        __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG / 8);
        unmask_done = 1;
      }
    }
    ksa.handler = sa->sa_handler;
    ksa.flags = sa->sa_flags | SA_RESTORER;
    ksa.restorer = (sa->sa_flags & SA_SIGINFO) ? __restore_rt : __restore;
    memcpy(&ksa.mask, &sa->sa_mask, sizeof ksa.mask);
  }
  if (syscall(SYS_rt_sigaction, sig, sa ? &ksa : 0, old ? &ksa_old : 0,
              sizeof ksa.mask))
    return -1;
  if (old) {
    old->sa_handler = ksa_old.handler;
    old->sa_flags = ksa_old.flags;
    memcpy(&old->sa_mask, &ksa_old.mask, sizeof ksa_old.mask);
  }
  return 0;
}

int __sigaction(int sig,
                const struct sigaction* restrict sa,
                struct sigaction* restrict old) {
  if (sig - 32U < 3 || sig - 1U >= _NSIG - 1) {
    errno = EINVAL;
    return -1;
  }
  return __libc_sigaction(sig, sa, old);
}

weak_alias(__sigaction, sigaction);