libpthread/linuxthreads_db/td_thr_tls_get_addr.c

   1 /* Get address of thread local variable.
   2    Copyright (C) 2002,2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 2002.
   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    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <link.h>
  21 #include "thread_dbP.h"
  22
  23 /* Value used for dtv entries for which the allocation is delayed.  */
  24 # define TLS_DTV_UNALLOCATED    ((void *) -1l)
  25
  26
  27 td_err_e
  28 td_thr_tls_get_addr (const td_thrhandle_t *th __attribute__ ((unused)),
  29                      void *map_address __attribute__ ((unused)),
  30                      size_t offset __attribute__ ((unused)),
  31                      void **address __attribute__ ((unused)))
  32 {
  33 #if defined(USE_TLS) && USE_TLS
  34   size_t modid;
  35   union dtv pdtv, *dtvp;
  36
  37   LOG ("td_thr_tls_get_addr");
  38
  39   /* Get the DTV pointer from the thread descriptor.  */
  40   if (ps_pdread (th->th_ta_p->ph,
  41                  &((struct _pthread_descr_struct *) th->th_unique)->p_header.data.dtvp,
  42                  &dtvp, sizeof dtvp) != PS_OK)
  43     return TD_ERR;      /* XXX Other error value?  */
  44
  45   /* Read the module ID from the link_map.  */
  46   if (ps_pdread (th->th_ta_p->ph,
  47                  &((struct link_map *) map_address)->l_tls_modid,
  48                  &modid, sizeof modid) != PS_OK)
  49     return TD_ERR;      /* XXX Other error value?  */
  50
  51   /* Get the corresponding entry in the DTV.  */
  52   if (ps_pdread (th->th_ta_p->ph, dtvp + modid,
  53                  &pdtv, sizeof (union dtv)) != PS_OK)
  54     return TD_ERR;      /* XXX Other error value?  */
  55
  56   /* It could be that the memory for this module is not allocated for
  57      the given thread.  */
  58   if (pdtv.pointer == TLS_DTV_UNALLOCATED)
  59     /* There is not much we can do.  */
  60     return TD_NOTALLOC;
  61
  62   *address = (char *) pdtv.pointer + offset;
  63
  64   return TD_OK;
  65 #else
  66   return TD_ERR;
  67 #endif
  68 }