bits/libc-tsd.h

   1 /* libc-internal interface for thread-specific data.  Stub or TLS version.
   2    Copyright (C) 1998-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _GENERIC_BITS_LIBC_TSD_H
  20 #define _GENERIC_BITS_LIBC_TSD_H 1
  21
  22 /* This file defines the following macros for accessing a small fixed
  23    set of thread-specific `void *' data used only internally by libc.
  24
  25    __libc_tsd_define(CLASS, TYPE, KEY)  -- Define or declare a datum with TYPE
  26                                            for KEY.  CLASS can be `static' for
  27                                            keys used in only one source file,
  28                                            empty for global definitions, or
  29                                            `extern' for global declarations.
  30    __libc_tsd_address(TYPE, KEY)        -- Return the `TYPE *' pointing to
  31                                            the current thread's datum for KEY.
  32    __libc_tsd_get(TYPE, KEY)            -- Return the `TYPE' datum for KEY.
  33    __libc_tsd_set(TYPE, KEY, VALUE)     -- Set the datum for KEY to VALUE.
  34
  35    The set of available KEY's will usually be provided as an enum,
  36    and contains (at least):
  37                 _LIBC_TSD_KEY_MALLOC
  38                 _LIBC_TSD_KEY_DL_ERROR
  39                 _LIBC_TSD_KEY_RPC_VARS
  40    All uses must be the literal _LIBC_TSD_* name in the __libc_tsd_* macros.
  41    Some implementations may not provide any enum at all and instead
  42    using string pasting in the macros.  */
  43
  44 #include <tls.h>
  45
  46 /* When full support for __thread variables is available, this interface is
  47    just a trivial wrapper for it.  Without TLS, this is the generic/stub
  48    implementation for wholly single-threaded systems.
  49
  50    We don't define an enum for the possible key values, because the KEYs
  51    translate directly into variables by macro magic.  */
  52
  53 #define __libc_tsd_define(CLASS, TYPE, KEY)     \
  54   CLASS __thread TYPE __libc_tsd_##KEY attribute_tls_model_ie;
  55
  56 #define __libc_tsd_address(TYPE, KEY)           (&__libc_tsd_##KEY)
  57 #define __libc_tsd_get(TYPE, KEY)               (__libc_tsd_##KEY)
  58 #define __libc_tsd_set(TYPE, KEY, VALUE)        (__libc_tsd_##KEY = (VALUE))
  59
  60 #endif  /* bits/libc-tsd.h */