sysdeps/mach/hurd/htl/pt-mutex-transfer-np.c

   1 /* pthread_mutex_transfer_np.  Transfer mutex ownership to another thread.
   2    Hurd version.
   3    Copyright (C) 2016-2023 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library;  if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <pthread.h>
  21 #include <stdlib.h>
  22 #include <assert.h>
  23 #include <pt-internal.h>
  24 #include "pt-mutex.h"
  25 #include <hurdlock.h>
  26
  27 int
  28 __pthread_mutex_transfer_np (pthread_mutex_t *mtxp, pthread_t th)
  29 {
  30   struct __pthread *self = _pthread_self ();
  31   struct __pthread *pt = __pthread_getid (th);
  32
  33   if (pt == NULL)
  34     return ESRCH;
  35   else if (pt == self)
  36     return 0;
  37
  38   int ret = 0;
  39   int flags = mtxp->__flags & GSYNC_SHARED;
  40
  41   switch (MTX_TYPE (mtxp))
  42     {
  43     case PT_MTX_NORMAL:
  44       break;
  45
  46     case PT_MTX_RECURSIVE:
  47     case PT_MTX_ERRORCHECK:
  48       if (!mtx_owned_p (mtxp, self, flags))
  49         ret = EPERM;
  50       else
  51         mtx_set_owner (mtxp, pt, flags);
  52
  53       break;
  54
  55     case PT_MTX_NORMAL | PTHREAD_MUTEX_ROBUST:
  56     case PT_MTX_RECURSIVE | PTHREAD_MUTEX_ROBUST:
  57     case PT_MTX_ERRORCHECK | PTHREAD_MUTEX_ROBUST:
  58       /* Note that this can be used to transfer an inconsistent
  59        * mutex as well. The new owner will still have the same
  60        * flags as the original. */
  61       if (mtxp->__owner_id != self->thread
  62           || (int) (mtxp->__lock & LLL_OWNER_MASK) != __getpid ())
  63         ret = EPERM;
  64       else
  65         mtxp->__owner_id = pt->thread;
  66
  67       break;
  68
  69     default:
  70       ret = EINVAL;
  71     }
  72
  73   return ret;
  74 }
  75
  76 weak_alias (__pthread_mutex_transfer_np, pthread_mutex_transfer_np)