nptl/pthread_rwlock_init.c

   1 /* Copyright (C) 2002-2020 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   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 "pthreadP.h"
  20 #include <string.h>
  21 #include <pthread-offsets.h>
  22
  23
  24 static const struct pthread_rwlockattr default_rwlockattr =
  25   {
  26     .lockkind = PTHREAD_RWLOCK_DEFAULT_NP,
  27     .pshared = PTHREAD_PROCESS_PRIVATE
  28   };
  29
  30
  31 /* See pthread_rwlock_common.c.  */
  32 int
  33 __pthread_rwlock_init (pthread_rwlock_t *rwlock,
  34                        const pthread_rwlockattr_t *attr)
  35 {
  36   ASSERT_TYPE_SIZE (pthread_rwlock_t, __SIZEOF_PTHREAD_RWLOCK_T);
  37
  38   /* The __flags is the only field where its offset should be checked to
  39      avoid ABI breakage with static initializers.  */
  40   ASSERT_PTHREAD_INTERNAL_OFFSET (pthread_rwlock_t, __data.__flags,
  41                                   __PTHREAD_RWLOCK_FLAGS_OFFSET);
  42   ASSERT_PTHREAD_INTERNAL_MEMBER_SIZE (pthread_rwlock_t, __data.__flags,
  43                                        int);
  44
  45   const struct pthread_rwlockattr *iattr;
  46
  47   iattr = ((const struct pthread_rwlockattr *) attr) ?: &default_rwlockattr;
  48
  49   memset (rwlock, '\0', sizeof (*rwlock));
  50
  51   rwlock->__data.__flags = iattr->lockkind;
  52
  53   /* The value of __SHARED in a private rwlock must be zero.  */
  54   rwlock->__data.__shared = (iattr->pshared != PTHREAD_PROCESS_PRIVATE);
  55
  56   return 0;
  57 }
  58 strong_alias (__pthread_rwlock_init, pthread_rwlock_init)