features.h

   1 /* Copyright (C) 1991, 92, 93, 95, 96, 97 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 Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    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    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #ifndef _FEATURES_H
  20
  21 #define _FEATURES_H     1
  22
  23 /* These are defined by the user (or the compiler)
  24    to specify the desired environment:
  25
  26    __STRICT_ANSI__      ISO Standard C.
  27    _ISOC9X_SOURCE       Extensions to ISO C 89 from ISO C 9x.
  28    _POSIX_SOURCE        IEEE Std 1003.1.
  29    _POSIX_C_SOURCE      If ==1, like _POSIX_SOURCE; if >=2 add IEEE Std 1003.2;
  30                         if >=199309L, add IEEE Std 1003.1b-1993
  31    _XOPEN_SOURCE        Includes POSIX and XPG things.
  32    _XOPEN_SOURCE_EXTENDED XPG things and X/Open Unix extensions.
  33    _BSD_SOURCE          ISO C, POSIX, and 4.3BSD things.
  34    _SVID_SOURCE         ISO C, POSIX, and SVID things.
  35    _GNU_SOURCE          All of the above, plus GNU extensions.
  36    _REENTRANT           Select additionally reentrant object.
  37    _THREAD_SAFE         Same as _REENTRANT, often used by other systems.
  38
  39    The `-ansi' switch to the GNU C compiler defines __STRICT_ANSI__.
  40    If none of these are defined, the default is all but _GNU_SOURCE.
  41    If more than one of these are defined, they accumulate.
  42    For example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE
  43    together give you ISO C, 1003.1, and 1003.2, but nothing else.
  44
  45    These are defined by this file and are used by the
  46    header files to decide what to declare or define:
  47
  48    __USE_ISOC9X         Define ISO C 9X things.
  49    __USE_POSIX          Define IEEE Std 1003.1 things.
  50    __USE_POSIX2         Define IEEE Std 1003.2 things.
  51    __USE_POSIX199309    Define IEEE Std 1003.1b things.
  52    __USE_XOPEN          Define XPG things.
  53    __USE_XOPEN_EXTENDED Define X/Open Unix things.
  54    __USE_BSD            Define 4.3BSD things.
  55    __USE_SVID           Define SVID things.
  56    __USE_MISC           Define things common to BSD and System V Unix.
  57    __USE_GNU            Define GNU extensions.
  58    __USE_REENTRANT      Define reentrant/thread-safe *_r functions.
  59    __FAVOR_BSD          Favor 4.3BSD things in cases of conflict.
  60
  61    The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
  62    defined by this file unconditionally.  `__GNU_LIBRARY__' is provided
  63    only for compatibility.  All new code should use the other symbols
  64    to test for features.
  65
  66    All macros listed above as possibly being defined by this file are
  67    explicitly undefined if they are not explicitly defined.
  68    Feature-test macros that are not defined by the user or compiler
  69    but are implied by the other feature-test macros defined (or by the
  70    lack of any definitions) are defined by the file.  */
  71
  72
  73 /* Undefine everything, so we get a clean slate.  */
  74 #undef  __USE_ISOC9X
  75 #undef  __USE_POSIX
  76 #undef  __USE_POSIX2
  77 #undef  __USE_POSIX199309
  78 #undef  __USE_XOPEN
  79 #undef  __USE_XOPEN_EXTENDED
  80 #undef  __USE_BSD
  81 #undef  __USE_SVID
  82 #undef  __USE_MISC
  83 #undef  __USE_GNU
  84 #undef  __USE_REENTRANT
  85 #undef  __FAVOR_BSD
  86 #undef  __KERNEL_STRICT_NAMES
  87
  88 /* Suppress kernel-name space pollution unless user expressedly asks
  89    for it.  */
  90 #ifndef _LOOSE_KERNEL_NAMES
  91 # define __KERNEL_STRICT_NAMES
  92 #endif
  93
  94 /* Always use ISO C things.  */
  95 #define __USE_ANSI      1
  96
  97
  98 /* If _BSD_SOURCE was defined by the user, favor BSD over POSIX.  */
  99 #if defined _BSD_SOURCE && \
 100     !(defined _POSIX_SOURCE || defined _POSIX_C_SOURCE || \
 101       defined _XOPEN_SOURCE || defined _XOPEN_SOURCE_EXTENDED || \
 102       defined _GNU_SOURCE || defined _SVID_SOURCE)
 103 # define __FAVOR_BSD    1
 104 #endif
 105
 106 /* If _GNU_SOURCE was defined by the user, turn on all the other features.  */
 107 #ifdef _GNU_SOURCE
 108 #undef  _ISOC9X_SOURCE
 109 #define _ISOC9X_SOURCE  1
 110 #undef  _POSIX_SOURCE
 111 #define _POSIX_SOURCE   1
 112 #undef  _POSIX_C_SOURCE
 113 #define _POSIX_C_SOURCE 199309L
 114 #undef  _XOPEN_SOURCE
 115 #define _XOPEN_SOURCE   1
 116 #undef  _XOPEN_SOURCE_EXTENDED
 117 #define _XOPEN_SOURCE_EXTENDED  1
 118 #undef  _BSD_SOURCE
 119 #define _BSD_SOURCE     1
 120 #undef  _SVID_SOURCE
 121 #define _SVID_SOURCE    1
 122 #endif
 123
 124 /* If nothing (other than _GNU_SOURCE) is defined,
 125    define _BSD_SOURCE and _SVID_SOURCE.  */
 126 #if (!defined __STRICT_ANSI__ && !defined _ISOC9X_SOURCE && \
 127      !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE && \
 128      !defined _XOPEN_SOURCE && !defined _XOPEN_SOURCE_EXTENDED && \
 129      !defined _BSD_SOURCE && !defined _SVID_SOURCE)
 130 #define _BSD_SOURCE     1
 131 #define _SVID_SOURCE    1
 132 #endif
 133
 134 /* This is to enable the ISO C 9x extension.  It will go away as soon
 135    as this standard is officially released.  */
 136 #ifdef _ISOC9X_SOURCE
 137 #define __USE_ISOC9X    1
 138 #endif
 139
 140 /* If none of the ANSI/POSIX macros are defined, use POSIX.1 and POSIX.2
 141    (and IEEE Std 1003.1b-1993 unless _XOPEN_SOURCE is defined).  */
 142 #if (!defined __STRICT_ANSI__ && !defined _POSIX_SOURCE && \
 143      !defined _POSIX_C_SOURCE)
 144 #define _POSIX_SOURCE   1
 145 #ifdef _XOPEN_SOURCE
 146 #define _POSIX_C_SOURCE 2
 147 #else
 148 #define _POSIX_C_SOURCE 199309L
 149 #endif
 150 #endif
 151
 152 #if defined _POSIX_SOURCE || _POSIX_C_SOURCE >= 1 || defined _XOPEN_SOURCE
 153 #define __USE_POSIX     1
 154 #endif
 155
 156 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE
 157 #define __USE_POSIX2    1
 158 #endif
 159
 160 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 199309L
 161 #define __USE_POSIX199309       1
 162 #endif
 163
 164 #ifdef  _XOPEN_SOURCE
 165 #define __USE_XOPEN     1
 166 #ifdef  _XOPEN_SOURCE_EXTENDED
 167 #define __USE_XOPEN_EXTENDED    1
 168 #endif
 169 #endif
 170
 171 #if defined _BSD_SOURCE || defined _SVID_SOURCE
 172 #define __USE_MISC      1
 173 #endif
 174
 175 #ifdef  _BSD_SOURCE
 176 #define __USE_BSD       1
 177 #endif
 178
 179 #ifdef  _SVID_SOURCE
 180 #define __USE_SVID      1
 181 #endif
 182
 183 #ifdef  _GNU_SOURCE
 184 #define __USE_GNU       1
 185 #endif
 186
 187 #if defined _REENTRANT || defined _THREAD_SAFE
 188 #define __USE_REENTRANT 1
 189 #endif
 190
 191
 192 /* This macro indicates that the installed library is the GNU C Library.
 193    For historic reasons the value now is 6 and this will stay from now
 194    on.  The use of this variable is deprecated.  Use __GLIBC__ and
 195    __GLIBC_MINOR__ now (see below) when you want to test for a specific
 196    GNU C library version and use the values in <gnu/lib-names.h> to get
 197    the sonames of the shared libraries.  */
 198 #undef  __GNU_LIBRARY__
 199 #define __GNU_LIBRARY__ 6
 200
 201 /* Major and minor version number of the GNU C library package.  Use
 202    these macros to test for features in specific releases.  */
 203 #define __GLIBC__       2
 204 #define __GLIBC_MINOR__ 1
 205
 206
 207 #if !defined __GNUC__ || __GNUC__ < 2
 208 /* In GCC version 2, (__extension__ EXPR) will not complain
 209    about GCC extensions used in EXPR under -ansi or -pedantic.  */
 210 #define __extension__
 211 #endif
 212
 213
 214 /* This is here only because every header file already includes this one.  */
 215 #ifndef __ASSEMBLER__
 216 #include <sys/cdefs.h>
 217 #endif
 218
 219 /* This is here only because every header file already includes this one.  */
 220 #ifndef _LIBC
 221 /* Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
 222    <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
 223    which will always return failure (and set errno to ENOSYS).
 224
 225    We avoid including <gnu/stubs.h> when compiling the C library itself to
 226    avoid a dependency loop.  stubs.h depends on every object file.  If
 227    this #include were done for the library source code, then every object
 228    file would depend on stubs.h.  */
 229
 230 #include <gnu/stubs.h>
 231 #endif
 232
 233 #endif  /* features.h  */