sigaction.c raw

   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  	if (sa) {
  24  		if ((uintptr_t)sa->sa_handler > 1UL) {
  25  			a_or_l(handler_set+(sig-1)/(8*sizeof(long)),
  26  				1UL<<(sig-1)%(8*sizeof(long)));
  27  
  28  			/* If pthread_create has not yet been called,
  29  			 * implementation-internal signals might not
  30  			 * yet have been unblocked. They must be
  31  			 * unblocked before any signal handler is
  32  			 * installed, so that an application cannot
  33  			 * receive an illegal sigset_t (with them
  34  			 * blocked) as part of the ucontext_t passed
  35  			 * to the signal handler. */
  36  			if (!libc.threaded && !unmask_done) {
  37  				__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
  38  					SIGPT_SET, 0, _NSIG/8);
  39  				unmask_done = 1;
  40  			}
  41  
  42  			if (!(sa->sa_flags & SA_RESTART)) {
  43  				a_store(&__eintr_valid_flag, 1);
  44  			}
  45  		}
  46  		ksa.handler = sa->sa_handler;
  47  		ksa.flags = sa->sa_flags | SA_RESTORER;
  48  		ksa.restorer = (sa->sa_flags & SA_SIGINFO) ? __restore_rt : __restore;
  49  		memcpy(&ksa.mask, &sa->sa_mask, _NSIG/8);
  50  	}
  51  	int r = __syscall(SYS_rt_sigaction, sig, sa?&ksa:0, old?&ksa_old:0, _NSIG/8);
  52  	if (old && !r) {
  53  		old->sa_handler = ksa_old.handler;
  54  		old->sa_flags = ksa_old.flags;
  55  		memcpy(&old->sa_mask, &ksa_old.mask, _NSIG/8);
  56  	}
  57  	return __syscall_ret(r);
  58  }
  59  
  60  int __sigaction(int sig, const struct sigaction *restrict sa, struct sigaction *restrict old)
  61  {
  62  	unsigned long set[_NSIG/(8*sizeof(long))];
  63  
  64  	if (sig-32U < 3 || sig-1U >= _NSIG-1) {
  65  		errno = EINVAL;
  66  		return -1;
  67  	}
  68  
  69  	/* Doing anything with the disposition of SIGABRT requires a lock,
  70  	 * so that it cannot be changed while abort is terminating the
  71  	 * process and so any change made by abort can't be observed. */
  72  	if (sig == SIGABRT) {
  73  		__block_all_sigs(&set);
  74  		LOCK(__abort_lock);
  75  	}
  76  	int r = __libc_sigaction(sig, sa, old);
  77  	if (sig == SIGABRT) {
  78  		UNLOCK(__abort_lock);
  79  		__restore_sigs(&set);
  80  	}
  81  	return r;
  82  }
  83  
  84  weak_alias(__sigaction, sigaction);
  85