1  /* Cancel a thread.
       2     Copyright (C) 2002-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library 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 GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library;  if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <pthread.h>
      20  
      21  #include <pt-internal.h>
      22  
      23  int
      24  pthread_cancel (pthread_t t)
      25  {
      26    int err = 0;
      27    struct __pthread *p;
      28  
      29    p = __pthread_getid (t);
      30    if (p == NULL)
      31      return ESRCH;
      32  
      33    __pthread_mutex_lock (&p->cancel_lock);
      34    if (p->cancel_pending)
      35      {
      36        __pthread_mutex_unlock (&p->cancel_lock);
      37        return 0;
      38      }
      39  
      40    p->cancel_pending = 1;
      41  
      42    if (p->cancel_state != PTHREAD_CANCEL_ENABLE)
      43      {
      44        __pthread_mutex_unlock (&p->cancel_lock);
      45        return 0;
      46      }
      47  
      48    if (p->cancel_type == PTHREAD_CANCEL_ASYNCHRONOUS)
      49      /* CANCEL_LOCK is unlocked by this call.  */
      50      err = __pthread_do_cancel (p);
      51    else
      52      {
      53        if (p->cancel_hook != NULL)
      54  	/* Thread blocking on a cancellation point.  Invoke hook to unblock.
      55  	   See __pthread_cond_timedwait_internal.  */
      56  	p->cancel_hook (p->cancel_hook_arg);
      57  
      58        __pthread_mutex_unlock (&p->cancel_lock);
      59      }
      60  
      61    return err;
      62  }