linuxthreads/signals.c

   1 /* Linuxthreads - a simple clone()-based implementation of Posix        */
   2 /* threads for Linux.                                                   */
   3 /* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr)              */
   4 /*                                                                      */
   5 /* This program is free software; you can redistribute it and/or        */
   6 /* modify it under the terms of the GNU Library General Public License  */
   7 /* as published by the Free Software Foundation; either version 2       */
   8 /* of the License, or (at your option) any later version.               */
   9 /*                                                                      */
  10 /* This program is distributed in the hope that it will be useful,      */
  11 /* but WITHOUT ANY WARRANTY; without even the implied warranty of       */
  12 /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        */
  13 /* GNU Library General Public License for more details.                 */
  14
  15 /* Handling of signals */
  16
  17 #include <errno.h>
  18 #include <signal.h>
  19 #include "pthread.h"
  20 #include "internals.h"
  21 #include "spinlock.h"
  22 #include <ucontext.h>
  23
  24
  25 int pthread_sigmask(int how, const sigset_t * newmask, sigset_t * oldmask)
  26 {
  27   sigset_t mask;
  28
  29   if (newmask != NULL) {
  30     mask = *newmask;
  31     /* Don't allow __pthread_sig_restart to be unmasked.
  32        Don't allow __pthread_sig_cancel to be masked. */
  33     switch(how) {
  34     case SIG_SETMASK:
  35       sigaddset(&mask, __pthread_sig_restart);
  36       sigdelset(&mask, __pthread_sig_cancel);
  37       if (__pthread_sig_debug > 0)
  38         sigdelset(&mask, __pthread_sig_debug);
  39       break;
  40     case SIG_BLOCK:
  41       sigdelset(&mask, __pthread_sig_cancel);
  42       if (__pthread_sig_debug > 0)
  43         sigdelset(&mask, __pthread_sig_debug);
  44       break;
  45     case SIG_UNBLOCK:
  46       sigdelset(&mask, __pthread_sig_restart);
  47       break;
  48     }
  49     newmask = &mask;
  50   }
  51   if (sigprocmask(how, newmask, oldmask) == -1)
  52     return errno;
  53   else
  54     return 0;
  55 }
  56
  57 int pthread_kill(pthread_t thread, int signo)
  58 {
  59   pthread_handle handle = thread_handle(thread);
  60   int pid;
  61
  62   __pthread_lock(&handle->h_lock, NULL);
  63   if (invalid_handle(handle, thread)) {
  64     __pthread_unlock(&handle->h_lock);
  65     return ESRCH;
  66   }
  67   pid = handle->h_descr->p_pid;
  68   __pthread_unlock(&handle->h_lock);
  69   if (kill(pid, signo) == -1)
  70     return errno;
  71   else
  72     return 0;
  73 }
  74
  75 union sighandler __sighandler[NSIG] =
  76   { [1 ... NSIG - 1] = { (arch_sighandler_t) SIG_ERR } };
  77
  78 /* The wrapper around sigaction.  Install our own signal handler
  79    around the signal. */
  80 int __pthread_sigaction(int sig, const struct sigaction * act,
  81                         struct sigaction * oact)
  82 {
  83   struct sigaction newact;
  84   struct sigaction *newactp;
  85   __sighandler_t old = SIG_DFL;
  86
  87   if (sig == __pthread_sig_restart ||
  88       sig == __pthread_sig_cancel ||
  89       (sig == __pthread_sig_debug && __pthread_sig_debug > 0))
  90     {
  91       __set_errno (EINVAL);
  92       return -1;
  93     }
  94   if (sig > 0 && sig < NSIG)
  95     old = (__sighandler_t) __sighandler[sig].old;
  96   if (act)
  97     {
  98       newact = *act;
  99       if (act->sa_handler != SIG_IGN && act->sa_handler != SIG_DFL
 100           && sig > 0 && sig < NSIG)
 101         {
 102           if (act->sa_flags & SA_SIGINFO)
 103             newact.sa_handler = (__sighandler_t) __pthread_sighandler_rt;
 104           else
 105             newact.sa_handler = (__sighandler_t) __pthread_sighandler;
 106           if (old == SIG_IGN || old == SIG_DFL || old == SIG_ERR)
 107             __sighandler[sig].old = (arch_sighandler_t) act->sa_handler;
 108         }
 109       newactp = &newact;
 110     }
 111   else
 112     newactp = NULL;
 113   if (__libc_sigaction(sig, newactp, oact) == -1)
 114     {
 115       if (act)
 116         __sighandler[sig].old = (arch_sighandler_t) old;
 117       return -1;
 118     }
 119   if (sig > 0 && sig < NSIG)
 120     {
 121       if (oact != NULL
 122           /* We may have inherited SIG_IGN from the parent, so return the
 123              kernel's idea of the signal handler the first time
 124              through.  */
 125           && old != SIG_ERR)
 126         oact->sa_handler = old;
 127       if (act)
 128         /* For the assignment it does not matter whether it's a normal
 129            or real-time signal.  */
 130         __sighandler[sig].old = (arch_sighandler_t) act->sa_handler;
 131     }
 132   return 0;
 133 }
 134 #ifdef SHARED
 135 strong_alias(__pthread_sigaction, __sigaction)
 136 strong_alias(__pthread_sigaction, sigaction)
 137 #endif
 138
 139 /* sigwait -- synchronously wait for a signal */
 140 int __pthread_sigwait(const sigset_t * set, int * sig)
 141 {
 142   volatile pthread_descr self = thread_self();
 143   sigset_t mask;
 144   int s;
 145   sigjmp_buf jmpbuf;
 146   struct sigaction sa;
 147
 148   /* Get ready to block all signals except those in set
 149      and the cancellation signal.
 150      Also check that handlers are installed on all signals in set,
 151      and if not, install our dummy handler.  This is conformant to
 152      POSIX: "The effect of sigwait() on the signal actions for the
 153      signals in set is unspecified." */
 154   sigfillset(&mask);
 155   sigdelset(&mask, __pthread_sig_cancel);
 156   for (s = 1; s < NSIG; s++) {
 157     if (sigismember(set, s) &&
 158         s != __pthread_sig_restart &&
 159         s != __pthread_sig_cancel &&
 160         s != __pthread_sig_debug) {
 161       sigdelset(&mask, s);
 162       if (__sighandler[s].old == (arch_sighandler_t) SIG_ERR ||
 163           __sighandler[s].old == (arch_sighandler_t) SIG_DFL ||
 164           __sighandler[s].old == (arch_sighandler_t) SIG_IGN) {
 165         sa.sa_handler = __pthread_null_sighandler;
 166         sigfillset(&sa.sa_mask);
 167         sa.sa_flags = 0;
 168         sigaction(s, &sa, NULL);
 169       }
 170     }
 171   }
 172   /* Test for cancellation */
 173   if (sigsetjmp(jmpbuf, 1) == 0) {
 174     THREAD_SETMEM(self, p_cancel_jmp, &jmpbuf);
 175     if (! (THREAD_GETMEM(self, p_canceled)
 176            && THREAD_GETMEM(self, p_cancelstate) == PTHREAD_CANCEL_ENABLE)) {
 177       /* Reset the signal count */
 178       THREAD_SETMEM(self, p_signal, 0);
 179       /* Say we're in sigwait */
 180       THREAD_SETMEM(self, p_sigwaiting, 1);
 181       /* Unblock the signals and wait for them */
 182       sigsuspend(&mask);
 183     }
 184   }
 185   THREAD_SETMEM(self, p_cancel_jmp, NULL);
 186   /* The signals are now reblocked.  Check for cancellation */
 187   pthread_testcancel();
 188   /* We should have self->p_signal != 0 and equal to the signal received */
 189   *sig = THREAD_GETMEM(self, p_signal);
 190   return 0;
 191 }
 192 #ifdef SHARED
 193 strong_alias (__pthread_sigwait, sigwait)
 194 #endif
 195
 196 /* Redefine raise() to send signal to calling thread only,
 197    as per POSIX 1003.1c */
 198 int __pthread_raise (int sig)
 199 {
 200   int retcode = pthread_kill(pthread_self(), sig);
 201   if (retcode == 0)
 202     return 0;
 203   else {
 204     errno = retcode;
 205     return -1;
 206   }
 207 }
 208 #ifdef SHARED
 209 strong_alias (__pthread_raise, raise)
 210 #endif
 211
 212 /* This files handles cancellation internally.  */
 213 LIBC_CANCEL_HANDLED ();