libc-top-half/musl/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         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);