nptl/pthread_getspecific.c

   1 /* Copyright (C) 2002, 2003 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <stdlib.h>
  21 #include "pthreadP.h"
  22
  23
  24 void *
  25 __pthread_getspecific (key)
  26      pthread_key_t key;
  27 {
  28   struct pthread_key_data *data;
  29
  30   /* Special case access to the first 2nd-level block.  This is the
  31      usual case.  */
  32   if (__builtin_expect (key < PTHREAD_KEY_2NDLEVEL_SIZE, 1))
  33     data = &THREAD_SELF->specific_1stblock[key];
  34   else
  35     {
  36       /* Verify the key is sane.  */
  37       if (key >= PTHREAD_KEYS_MAX)
  38         /* Not valid.  */
  39         return NULL;
  40
  41       unsigned int idx1st = key / PTHREAD_KEY_2NDLEVEL_SIZE;
  42       unsigned int idx2nd = key % PTHREAD_KEY_2NDLEVEL_SIZE;
  43
  44       /* If the sequence number doesn't match or the key cannot be defined
  45          for this thread since the second level array is not allocated
  46          return NULL, too.  */
  47       struct pthread_key_data *level2 = THREAD_GETMEM_NC (THREAD_SELF,
  48                                                           specific, idx1st);
  49       if (level2 == NULL)
  50         /* Not allocated, therefore no data.  */
  51         return NULL;
  52
  53       /* There is data.  */
  54       data = &level2[idx2nd];
  55     }
  56
  57   void *result = data->data;
  58   if (result != NULL)
  59     {
  60       uintptr_t seq = data->seq;
  61
  62       if (__builtin_expect (seq != __pthread_keys[key].seq, 0))
  63         result = data->data = NULL;
  64     }
  65
  66   return result;
  67 }
  68 strong_alias (__pthread_getspecific, pthread_getspecific)
  69 strong_alias (__pthread_getspecific, __pthread_getspecific_internal)