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

   1 /*
   2  * pthread_cancel.c
   3  *
   4  * Description:
   5  * POSIX thread functions related to thread cancellation.
   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 #include "pthread.h"
  38 #include "implement.h"
  39 #include "context.h"
  40
  41 static void
  42 ptw32_cancel_self (void)
  43 {
  44   ptw32_throw (PTW32_EPS_CANCEL);
  45
  46   /* Never reached */
  47 }
  48
  49 static void CALLBACK
  50 ptw32_cancel_callback (ULONG_PTR unused)
  51 {
  52   ptw32_throw (PTW32_EPS_CANCEL);
  53
  54   /* Never reached */
  55 }
  56
  57 /*
  58  * ptw32_RegisterCancelation() -
  59  * Must have args of same type as QueueUserAPCEx because this function
  60  * is a substitute for QueueUserAPCEx if it's not available.
  61  */
  62 DWORD
  63 ptw32_RegisterCancelation (PAPCFUNC unused1, HANDLE threadH, DWORD unused2)
  64 {
  65   CONTEXT context;
  66
  67   context.ContextFlags = CONTEXT_CONTROL;
  68   GetThreadContext (threadH, &context);
  69   PTW32_PROGCTR (context) = (DWORD_PTR) ptw32_cancel_self;
  70   SetThreadContext (threadH, &context);
  71   return 0;
  72 }
  73
  74 int
  75 pthread_cancel (pthread_t thread)
  76      /*
  77       * ------------------------------------------------------
  78       * DOCPUBLIC
  79       *      This function requests cancellation of 'thread'.
  80       *
  81       * PARAMETERS
  82       *      thread
  83       *              reference to an instance of pthread_t
  84       *
  85       *
  86       * DESCRIPTION
  87       *      This function requests cancellation of 'thread'.
  88       *      NOTE: cancellation is asynchronous; use pthread_join to
  89       *                wait for termination of 'thread' if necessary.
  90       *
  91       * RESULTS
  92       *              0               successfully requested cancellation,
  93       *              ESRCH           no thread found corresponding to 'thread',
  94       *              ENOMEM          implicit self thread create failed.
  95       * ------------------------------------------------------
  96       */
  97 {
  98   int result;
  99   int cancel_self;
 100   pthread_t self;
 101   ptw32_thread_t * tp;
 102   ptw32_mcs_local_node_t stateLock;
 103
 104   result = pthread_kill (thread, 0);
 105
 106   if (0 != result)
 107     {
 108       return result;
 109     }
 110
 111   if ((self = pthread_self ()).p == NULL)
 112     {
 113       return ENOMEM;
 114     };
 115
 116   /*
 117    * For self cancellation we need to ensure that a thread can't
 118    * deadlock itself trying to cancel itself asynchronously
 119    * (pthread_cancel is required to be an async-cancel
 120    * safe function).
 121    */
 122   cancel_self = pthread_equal (thread, self);
 123
 124   tp = (ptw32_thread_t *) thread.p;
 125
 126   /*
 127    * Lock for async-cancel safety.
 128    */
 129   ptw32_mcs_lock_acquire (&tp->stateLock, &stateLock);
 130
 131   if (tp->cancelType == PTHREAD_CANCEL_ASYNCHRONOUS
 132       && tp->cancelState == PTHREAD_CANCEL_ENABLE
 133       && tp->state < PThreadStateCanceling)
 134     {
 135       if (cancel_self)
 136         {
 137           tp->state = PThreadStateCanceling;
 138           tp->cancelState = PTHREAD_CANCEL_DISABLE;
 139
 140           ptw32_mcs_lock_release (&stateLock);
 141           ptw32_throw (PTW32_EPS_CANCEL);
 142
 143           /* Never reached */
 144         }
 145       else
 146         {
 147           HANDLE threadH = tp->threadH;
 148
 149           SuspendThread (threadH);
 150
 151           if (WaitForSingleObject (threadH, 0) == WAIT_TIMEOUT)
 152             {
 153               tp->state = PThreadStateCanceling;
 154               tp->cancelState = PTHREAD_CANCEL_DISABLE;
 155               /*
 156                * If alertdrv and QueueUserAPCEx is available then the following
 157                * will result in a call to QueueUserAPCEx with the args given, otherwise
 158                * this will result in a call to ptw32_RegisterCancelation and only
 159                * the threadH arg will be used.
 160                */
 161               ptw32_register_cancelation ((PAPCFUNC)ptw32_cancel_callback, threadH, 0);
 162               ptw32_mcs_lock_release (&stateLock);
 163               ResumeThread (threadH);
 164             }
 165         }
 166     }
 167   else
 168     {
 169       /*
 170        * Set for deferred cancellation.
 171        */
 172       if (tp->state < PThreadStateCancelPending)
 173         {
 174           tp->state = PThreadStateCancelPending;
 175           if (!SetEvent (tp->cancelEvent))
 176             {
 177               result = ESRCH;
 178             }
 179         }
 180       else if (tp->state >= PThreadStateCanceling)
 181         {
 182           result = ESRCH;
 183         }
 184
 185       ptw32_mcs_lock_release (&stateLock);
 186     }
 187
 188   return (result);
 189 }