native_client_sdk/src/libraries/third_party/pthreads-win32/signal.c

   1 /*
   2  * signal.c
   3  *
   4  * Description:
   5  * Thread-aware signal functions.
   6  *
   7  * --------------------------------------------------------------------------
   8  *
   9  *      Pthreads-win32 - POSIX Threads Library for Win32
  10  *      Copyright(C) 1998 John E. Bossom
  11  *      Copyright(C) 1999,2005 Pthreads-win32 contributors
  12  *
  13  *      Contact Email: rpj@callisto.canberra.edu.au
  14  *
  15  *      The current list of contributors is contained
  16  *      in the file CONTRIBUTORS included with the source
  17  *      code distribution. The list can also be seen at the
  18  *      following World Wide Web location:
  19  *      http://sources.redhat.com/pthreads-win32/contributors.html
  20  *
  21  *      This library is free software; you can redistribute it and/or
  22  *      modify it under the terms of the GNU Lesser General Public
  23  *      License as published by the Free Software Foundation; either
  24  *      version 2 of the License, or (at your option) any later version.
  25  *
  26  *      This library is distributed in the hope that it will be useful,
  27  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  29  *      Lesser General Public License for more details.
  30  *
  31  *      You should have received a copy of the GNU Lesser General Public
  32  *      License along with this library in the file COPYING.LIB;
  33  *      if not, write to the Free Software Foundation, Inc.,
  34  *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  35  */
  36
  37 /*
  38  * Possible future strategy for implementing pthread_kill()
  39  * ========================================================
  40  *
  41  * Win32 does not implement signals.
  42  * Signals are simply software interrupts.
  43  * pthread_kill() asks the system to deliver a specified
  44  * signal (interrupt) to a specified thread in the same
  45  * process.
  46  * Signals are always asynchronous (no deferred signals).
  47  * Pthread-win32 has an async cancelation mechanism.
  48  * A similar system can be written to deliver signals
  49  * within the same process (on ix86 processors at least).
  50  *
  51  * Each thread maintains information about which
  52  * signals it will respond to. Handler routines
  53  * are set on a per-process basis - not per-thread.
  54  * When signalled, a thread will check it's sigmask
  55  * and, if the signal is not being ignored, call the
  56  * handler routine associated with the signal. The
  57  * thread must then (except for some signals) return to
  58  * the point where it was interrupted.
  59  *
  60  * Ideally the system itself would check the target thread's
  61  * mask before possibly needlessly bothering the thread
  62  * itself. This could be done by pthread_kill(), that is,
  63  * in the signaling thread since it has access to
  64  * all pthread_t structures. It could also retrieve
  65  * the handler routine address to minimise the target
  66  * threads response overhead. This may also simplify
  67  * serialisation of the access to the per-thread signal
  68  * structures.
  69  *
  70  * pthread_kill() eventually calls a routine similar to
  71  * ptw32_cancel_thread() which manipulates the target
  72  * threads processor context to cause the thread to
  73  * run the handler launcher routine. pthread_kill() must
  74  * save the target threads current context so that the
  75  * handler launcher routine can restore the context after
  76  * the signal handler has returned. Some handlers will not
  77  * return, eg. the default SIGKILL handler may simply
  78  * call pthread_exit().
  79  *
  80  * The current context is saved in the target threads
  81  * pthread_t structure.
  82  */
  83
  84 #include "pthread.h"
  85 #include "implement.h"
  86
  87 #if defined(HAVE_SIGSET_T)
  88
  89 static void
  90 ptw32_signal_thread ()
  91 {
  92 }
  93
  94 static void
  95 ptw32_signal_callhandler ()
  96 {
  97 }
  98
  99 int
 100 pthread_sigmask (int how, sigset_t const *set, sigset_t * oset)
 101 {
 102   pthread_t thread = pthread_self ();
 103
 104   if (thread.p == NULL)
 105     {
 106       return ENOENT;
 107     }
 108
 109   /* Validate the `how' argument. */
 110   if (set != NULL)
 111     {
 112       switch (how)
 113         {
 114         case SIG_BLOCK:
 115           break;
 116         case SIG_UNBLOCK:
 117           break;
 118         case SIG_SETMASK:
 119           break;
 120         default:
 121           /* Invalid `how' argument. */
 122           return EINVAL;
 123         }
 124     }
 125
 126   /* Copy the old mask before modifying it. */
 127   if (oset != NULL)
 128     {
 129       memcpy (oset, &(thread.p->sigmask), sizeof (sigset_t));
 130     }
 131
 132   if (set != NULL)
 133     {
 134       unsigned int i;
 135
 136       /* FIXME: this code assumes that sigmask is an even multiple of
 137          the size of a long integer. */
 138
 139       unsigned long *src = (unsigned long const *) set;
 140       unsigned long *dest = (unsigned long *) &(thread.p->sigmask);
 141
 142       switch (how)
 143         {
 144         case SIG_BLOCK:
 145           for (i = 0; i < (sizeof (sigset_t) / sizeof (unsigned long)); i++)
 146             {
 147               /* OR the bit field longword-wise. */
 148               *dest++ |= *src++;
 149             }
 150           break;
 151         case SIG_UNBLOCK:
 152           for (i = 0; i < (sizeof (sigset_t) / sizeof (unsigned long)); i++)
 153             {
 154               /* XOR the bitfield longword-wise. */
 155               *dest++ ^= *src++;
 156             }
 157         case SIG_SETMASK:
 158           /* Replace the whole sigmask. */
 159           memcpy (&(thread.p->sigmask), set, sizeof (sigset_t));
 160           break;
 161         }
 162     }
 163
 164   return 0;
 165 }
 166
 167 int
 168 sigwait (const sigset_t * set, int *sig)
 169 {
 170   /* This routine is a cancellation point */
 171   pthread_test_cancel();
 172 }
 173
 174 int
 175 sigaction (int signum, const struct sigaction *act, struct sigaction *oldact)
 176 {
 177 }
 178
 179 #endif /* HAVE_SIGSET_T */