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[glibc.git] / include / features.h
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1 /* Copyright (C) 1991,92,93,95,96,97,98,99, 2000 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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.
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.
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. */
19 #ifndef _FEATURES_H
20 #define _FEATURES_H 1
22 /* These are defined by the user (or the compiler)
23 to specify the desired environment:
25 __STRICT_ANSI__ ISO Standard C.
26 _ISOC99_SOURCE Extensions to ISO C89 from ISO C99.
27 _POSIX_SOURCE IEEE Std 1003.1.
28 _POSIX_C_SOURCE If ==1, like _POSIX_SOURCE; if >=2 add IEEE Std 1003.2;
29 if >=199309L, add IEEE Std 1003.1b-1993;
30 if >=199506L, add IEEE Std 1003.1c-1995
31 _XOPEN_SOURCE Includes POSIX and XPG things. Set to 500 if
32 Single Unix conformance is wanted, to 600 for the
33 upcoming sixth revision.
34 _XOPEN_SOURCE_EXTENDED XPG things and X/Open Unix extensions.
35 _LARGEFILE_SOURCE Some more functions for correct standard I/O.
36 _LARGEFILE64_SOURCE Additional functionality from LFS for large files.
37 _FILE_OFFSET_BITS=N Select default filesystem interface.
38 _BSD_SOURCE ISO C, POSIX, and 4.3BSD things.
39 _SVID_SOURCE ISO C, POSIX, and SVID things.
40 _GNU_SOURCE All of the above, plus GNU extensions.
41 _REENTRANT Select additionally reentrant object.
42 _THREAD_SAFE Same as _REENTRANT, often used by other systems.
44 The `-ansi' switch to the GNU C compiler defines __STRICT_ANSI__.
45 If none of these are defined, the default is all but _GNU_SOURCE.
46 If more than one of these are defined, they accumulate.
47 For example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE
48 together give you ISO C, 1003.1, and 1003.2, but nothing else.
50 These are defined by this file and are used by the
51 header files to decide what to declare or define:
53 __USE_ISOC99 Define ISO C99 things.
54 __USE_POSIX Define IEEE Std 1003.1 things.
55 __USE_POSIX2 Define IEEE Std 1003.2 things.
56 __USE_POSIX199309 Define IEEE Std 1003.1, and .1b things.
57 __USE_POSIX199506 Define IEEE Std 1003.1, .1b, .1c and .1i things.
58 __USE_XOPEN Define XPG things.
59 __USE_XOPEN_EXTENDED Define X/Open Unix things.
60 __USE_UNIX98 Define Single Unix V2 things.
61 __USE_XOPEN2K Define XPG6 things.
62 __USE_LARGEFILE Define correct standard I/O things.
63 __USE_LARGEFILE64 Define LFS things with separate names.
64 __USE_FILE_OFFSET64 Define 64bit interface as default.
65 __USE_BSD Define 4.3BSD things.
66 __USE_SVID Define SVID things.
67 __USE_MISC Define things common to BSD and System V Unix.
68 __USE_GNU Define GNU extensions.
69 __USE_REENTRANT Define reentrant/thread-safe *_r functions.
70 __FAVOR_BSD Favor 4.3BSD things in cases of conflict.
72 The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
73 defined by this file unconditionally. `__GNU_LIBRARY__' is provided
74 only for compatibility. All new code should use the other symbols
75 to test for features.
77 All macros listed above as possibly being defined by this file are
78 explicitly undefined if they are not explicitly defined.
79 Feature-test macros that are not defined by the user or compiler
80 but are implied by the other feature-test macros defined (or by the
81 lack of any definitions) are defined by the file. */
84 /* Undefine everything, so we get a clean slate. */
85 #undef __USE_ISOC99
86 #undef __USE_POSIX
87 #undef __USE_POSIX2
88 #undef __USE_POSIX199309
89 #undef __USE_POSIX199506
90 #undef __USE_XOPEN
91 #undef __USE_XOPEN_EXTENDED
92 #undef __USE_UNIX98
93 #undef __USE_XOPEN2K
94 #undef __USE_LARGEFILE
95 #undef __USE_LARGEFILE64
96 #undef __USE_FILE_OFFSET64
97 #undef __USE_BSD
98 #undef __USE_SVID
99 #undef __USE_MISC
100 #undef __USE_GNU
101 #undef __USE_REENTRANT
102 #undef __FAVOR_BSD
103 #undef __KERNEL_STRICT_NAMES
105 /* Suppress kernel-name space pollution unless user expressedly asks
106 for it. */
107 #ifndef _LOOSE_KERNEL_NAMES
108 # define __KERNEL_STRICT_NAMES
109 #endif
111 /* Always use ISO C things. */
112 #define __USE_ANSI 1
115 /* If _BSD_SOURCE was defined by the user, favor BSD over POSIX. */
116 #if defined _BSD_SOURCE && \
117 !(defined _POSIX_SOURCE || defined _POSIX_C_SOURCE || \
118 defined _XOPEN_SOURCE || defined _XOPEN_SOURCE_EXTENDED || \
119 defined _GNU_SOURCE || defined _SVID_SOURCE)
120 # define __FAVOR_BSD 1
121 #endif
123 /* If _GNU_SOURCE was defined by the user, turn on all the other features. */
124 #ifdef _GNU_SOURCE
125 # undef _ISOC99_SOURCE
126 # define _ISOC99_SOURCE 1
127 # undef _POSIX_SOURCE
128 # define _POSIX_SOURCE 1
129 # undef _POSIX_C_SOURCE
130 # define _POSIX_C_SOURCE 199506L
131 # undef _XOPEN_SOURCE
132 # define _XOPEN_SOURCE 600
133 # undef _XOPEN_SOURCE_EXTENDED
134 # define _XOPEN_SOURCE_EXTENDED 1
135 # undef _LARGEFILE64_SOURCE
136 # define _LARGEFILE64_SOURCE 1
137 # undef _BSD_SOURCE
138 # define _BSD_SOURCE 1
139 # undef _SVID_SOURCE
140 # define _SVID_SOURCE 1
141 #endif
143 /* If nothing (other than _GNU_SOURCE) is defined,
144 define _BSD_SOURCE and _SVID_SOURCE. */
145 #if (!defined __STRICT_ANSI__ && !defined _ISOC99_SOURCE && \
146 !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE && \
147 !defined _XOPEN_SOURCE && !defined _XOPEN_SOURCE_EXTENDED && \
148 !defined _BSD_SOURCE && !defined _SVID_SOURCE)
149 # define _BSD_SOURCE 1
150 # define _SVID_SOURCE 1
151 #endif
153 /* This is to enable the ISO C99 extension. Also recognize the old macro
154 which was used prior to the standard acceptance. This macro will
155 eventually go away and the features enabled by default once the ISO C99
156 standard is widely adopted. */
157 #if (defined _ISOC99_SOURCE || defined _ISOC9X_SOURCE \
158 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
159 # define __USE_ISOC99 1
160 #endif
162 /* If none of the ANSI/POSIX macros are defined, use POSIX.1 and POSIX.2
163 (and IEEE Std 1003.1b-1993 unless _XOPEN_SOURCE is defined). */
164 #if (!defined __STRICT_ANSI__ && !defined _POSIX_SOURCE && \
165 !defined _POSIX_C_SOURCE)
166 # define _POSIX_SOURCE 1
167 # if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 500
168 # define _POSIX_C_SOURCE 2
169 # else
170 # define _POSIX_C_SOURCE 199506L
171 # endif
172 #endif
174 #if defined _POSIX_SOURCE || _POSIX_C_SOURCE >= 1 || defined _XOPEN_SOURCE
175 # define __USE_POSIX 1
176 #endif
178 #if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE
179 # define __USE_POSIX2 1
180 #endif
182 #if (_POSIX_C_SOURCE - 0) >= 199309L
183 # define __USE_POSIX199309 1
184 #endif
186 #if (_POSIX_C_SOURCE - 0) >= 199506L
187 # define __USE_POSIX199506 1
188 #endif
190 #ifdef _XOPEN_SOURCE
191 # define __USE_XOPEN 1
192 # if (_XOPEN_SOURCE - 0) >= 500
193 # define __USE_XOPEN_EXTENDED 1
194 # define __USE_UNIX98 1
195 # undef _LARGEFILE_SOURCE
196 # define _LARGEFILE_SOURCE 1
197 # if (_XOPEN_SOURCE - 0) >= 600
198 # define __USE_XOPEN2K 1
199 # endif
200 # else
201 # ifdef _XOPEN_SOURCE_EXTENDED
202 # define __USE_XOPEN_EXTENDED 1
203 # endif
204 # endif
205 #endif
207 #ifdef _LARGEFILE_SOURCE
208 # define __USE_LARGEFILE 1
209 #endif
211 #ifdef _LARGEFILE64_SOURCE
212 # define __USE_LARGEFILE64 1
213 #endif
215 #if defined _FILE_OFFSET_BITS && _FILE_OFFSET_BITS == 64
216 # define __USE_FILE_OFFSET64 1
217 #endif
219 #if defined _BSD_SOURCE || defined _SVID_SOURCE
220 # define __USE_MISC 1
221 #endif
223 #ifdef _BSD_SOURCE
224 # define __USE_BSD 1
225 #endif
227 #ifdef _SVID_SOURCE
228 # define __USE_SVID 1
229 #endif
231 #ifdef _GNU_SOURCE
232 # define __USE_GNU 1
233 #endif
235 #if defined _REENTRANT || defined _THREAD_SAFE
236 # define __USE_REENTRANT 1
237 #endif
239 /* We do support the IEC 559 math functionality, real and complex. */
240 #define __STDC_IEC_559__ 1
241 #define __STDC_IEC_559_COMPLEX__ 1
243 /* This macro indicates that the installed library is the GNU C Library.
244 For historic reasons the value now is 6 and this will stay from now
245 on. The use of this variable is deprecated. Use __GLIBC__ and
246 __GLIBC_MINOR__ now (see below) when you want to test for a specific
247 GNU C library version and use the values in <gnu/lib-names.h> to get
248 the sonames of the shared libraries. */
249 #undef __GNU_LIBRARY__
250 #define __GNU_LIBRARY__ 6
252 /* Major and minor version number of the GNU C library package. Use
253 these macros to test for features in specific releases. */
254 #define __GLIBC__ 2
255 #define __GLIBC_MINOR__ 2
257 /* Convenience macros to test the versions of glibc and gcc.
258 Use them like this:
259 #if __GNUC_PREREQ (2,8)
260 ... code requiring gcc 2.8 or later ...
261 #endif
262 Note - they won't work for gcc1 or glibc1, since the _MINOR macros
263 were not defined then. */
264 #if defined __GNUC__ && defined __GNUC_MINOR__
265 # define __GNUC_PREREQ(maj, min) \
266 ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
267 #else
268 # define __GNUC_PREREQ(maj, min) 0
269 #endif
271 #define __GLIBC_PREREQ(maj, min) \
272 ((__GLIBC__ << 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min))
274 /* This is here only because every header file already includes this one. */
275 #ifndef __ASSEMBLER__
276 #ifndef _SYS_CDEFS_H
277 # include <sys/cdefs.h>
278 #endif
280 /* If we don't have __REDIRECT, prototypes will be missing if
281 __USE_FILE_OFFSET64 but not __USE_LARGEFILE[64]. */
282 # if defined __USE_FILE_OFFSET64 && !defined __REDIRECT
283 # define __USE_LARGEFILE
284 # define __USE_LARGEFILE64
285 # endif
287 #endif /* !ASSEMBLER */
289 /* Decide whether we can define 'extern inline' functions in headers. */
290 #if __GNUC_PREREQ (2, 7) && defined __OPTIMIZE__ && !defined __OPTIMIZE_SIZE__
291 # define __USE_EXTERN_INLINES 1
292 #endif
294 /* This is here only because every header file already includes this one. */
295 #ifndef _LIBC
296 /* Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
297 <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
298 which will always return failure (and set errno to ENOSYS).
300 We avoid including <gnu/stubs.h> when compiling the C library itself to
301 avoid a dependency loop. stubs.h depends on every object file. If
302 this #include were done for the library source code, then every object
303 file would depend on stubs.h. */
305 # include <gnu/stubs.h>
306 #endif
308 #endif /* features.h */