nptl/pthread_key_create.c

   1  /* Copyright (C) 2002-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include "pthreadP.h"
  20 #include <atomic.h>
  21 #include <shlib-compat.h>
  22
  23 int
  24 ___pthread_key_create (pthread_key_t *key, void (*destr) (void *))
  25 {
  26   /* Find a slot in __pthread_keys which is unused.  */
  27   for (size_t cnt = 0; cnt < PTHREAD_KEYS_MAX; ++cnt)
  28     {
  29       uintptr_t seq = __pthread_keys[cnt].seq;
  30
  31       if (KEY_UNUSED (seq) && KEY_USABLE (seq)
  32           /* We found an unused slot.  Try to allocate it.  */
  33           && ! atomic_compare_and_exchange_bool_acq (&__pthread_keys[cnt].seq,
  34                                                      seq + 1, seq))
  35         {
  36           /* Remember the destructor.  */
  37           __pthread_keys[cnt].destr = destr;
  38
  39           /* Return the key to the caller.  */
  40           *key = cnt;
  41
  42           /* The call succeeded.  */
  43           return 0;
  44         }
  45     }
  46
  47   return EAGAIN;
  48 }
  49 versioned_symbol (libc, ___pthread_key_create, __pthread_key_create,
  50                   GLIBC_2_34);
  51 libc_hidden_ver (___pthread_key_create, __pthread_key_create)
  52
  53 versioned_symbol (libc, ___pthread_key_create, pthread_key_create,
  54                   GLIBC_2_34);
  55 #if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_34)
  56 compat_symbol (libpthread, ___pthread_key_create, __pthread_key_create,
  57                GLIBC_2_0);
  58 compat_symbol (libpthread, ___pthread_key_create, pthread_key_create,
  59                GLIBC_2_0);
  60 #endif