1/* Copyright (C) 1991-2017 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 Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the 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 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>. */
17
18#ifndef _FEATURES_H
19#define _FEATURES_H 1
20
21/* These are defined by the user (or the compiler)
22 to specify the desired environment:
23
24 __STRICT_ANSI__ ISO Standard C.
25 _ISOC99_SOURCE Extensions to ISO C89 from ISO C99.
26 _ISOC11_SOURCE Extensions to ISO C99 from ISO C11.
27 __STDC_WANT_LIB_EXT2__
28 Extensions to ISO C99 from TR 27431-2:2010.
29 __STDC_WANT_IEC_60559_BFP_EXT__
30 Extensions to ISO C11 from TS 18661-1:2014.
31 __STDC_WANT_IEC_60559_FUNCS_EXT__
32 Extensions to ISO C11 from TS 18661-4:2015.
33 __STDC_WANT_IEC_60559_TYPES_EXT__
34 Extensions to ISO C11 from TS 18661-3:2015.
35
36 _POSIX_SOURCE IEEE Std 1003.1.
37 _POSIX_C_SOURCE If ==1, like _POSIX_SOURCE; if >=2 add IEEE Std 1003.2;
38 if >=199309L, add IEEE Std 1003.1b-1993;
39 if >=199506L, add IEEE Std 1003.1c-1995;
40 if >=200112L, all of IEEE 1003.1-2004
41 if >=200809L, all of IEEE 1003.1-2008
42 _XOPEN_SOURCE Includes POSIX and XPG things. Set to 500 if
43 Single Unix conformance is wanted, to 600 for the
44 sixth revision, to 700 for the seventh revision.
45 _XOPEN_SOURCE_EXTENDED XPG things and X/Open Unix extensions.
46 _LARGEFILE_SOURCE Some more functions for correct standard I/O.
47 _LARGEFILE64_SOURCE Additional functionality from LFS for large files.
48 _FILE_OFFSET_BITS=N Select default filesystem interface.
49 _ATFILE_SOURCE Additional *at interfaces.
50 _GNU_SOURCE All of the above, plus GNU extensions.
51 _DEFAULT_SOURCE The default set of features (taking precedence over
52 __STRICT_ANSI__).
53
54 _FORTIFY_SOURCE Add security hardening to many library functions.
55 Set to 1 or 2; 2 performs stricter checks than 1.
56
57 _REENTRANT, _THREAD_SAFE
58 Obsolete; equivalent to _POSIX_C_SOURCE=199506L.
59
60 The `-ansi' switch to the GNU C compiler, and standards conformance
61 options such as `-std=c99', define __STRICT_ANSI__. If none of
62 these are defined, or if _DEFAULT_SOURCE is defined, the default is
63 to have _POSIX_SOURCE set to one and _POSIX_C_SOURCE set to
64 200809L, as well as enabling miscellaneous functions from BSD and
65 SVID. If more than one of these are defined, they accumulate. For
66 example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE together
67 give you ISO C, 1003.1, and 1003.2, but nothing else.
68
69 These are defined by this file and are used by the
70 header files to decide what to declare or define:
71
72 __GLIBC_USE (F) Define things from feature set F. This is defined
73 to 1 or 0; the subsequent macros are either defined
74 or undefined, and those tests should be moved to
75 __GLIBC_USE.
76 __USE_ISOC11 Define ISO C11 things.
77 __USE_ISOC99 Define ISO C99 things.
78 __USE_ISOC95 Define ISO C90 AMD1 (C95) things.
79 __USE_POSIX Define IEEE Std 1003.1 things.
80 __USE_POSIX2 Define IEEE Std 1003.2 things.
81 __USE_POSIX199309 Define IEEE Std 1003.1, and .1b things.
82 __USE_POSIX199506 Define IEEE Std 1003.1, .1b, .1c and .1i things.
83 __USE_XOPEN Define XPG things.
84 __USE_XOPEN_EXTENDED Define X/Open Unix things.
85 __USE_UNIX98 Define Single Unix V2 things.
86 __USE_XOPEN2K Define XPG6 things.
87 __USE_XOPEN2KXSI Define XPG6 XSI things.
88 __USE_XOPEN2K8 Define XPG7 things.
89 __USE_XOPEN2K8XSI Define XPG7 XSI things.
90 __USE_LARGEFILE Define correct standard I/O things.
91 __USE_LARGEFILE64 Define LFS things with separate names.
92 __USE_FILE_OFFSET64 Define 64bit interface as default.
93 __USE_MISC Define things from 4.3BSD or System V Unix.
94 __USE_ATFILE Define *at interfaces and AT_* constants for them.
95 __USE_GNU Define GNU extensions.
96 __USE_FORTIFY_LEVEL Additional security measures used, according to level.
97
98 The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
99 defined by this file unconditionally. `__GNU_LIBRARY__' is provided
100 only for compatibility. All new code should use the other symbols
101 to test for features.
102
103 All macros listed above as possibly being defined by this file are
104 explicitly undefined if they are not explicitly defined.
105 Feature-test macros that are not defined by the user or compiler
106 but are implied by the other feature-test macros defined (or by the
107 lack of any definitions) are defined by the file.
108
109 ISO C feature test macros depend on the definition of the macro
110 when an affected header is included, not when the first system
111 header is included, and so they are handled in
112 <bits/libc-header-start.h>, which does not have a multiple include
113 guard. Feature test macros that can be handled from the first
114 system header included are handled here. */
115
116
117/* Undefine everything, so we get a clean slate. */
118#undef __USE_ISOC11
119#undef __USE_ISOC99
120#undef __USE_ISOC95
121#undef __USE_ISOCXX11
122#undef __USE_POSIX
123#undef __USE_POSIX2
124#undef __USE_POSIX199309
125#undef __USE_POSIX199506
126#undef __USE_XOPEN
127#undef __USE_XOPEN_EXTENDED
128#undef __USE_UNIX98
129#undef __USE_XOPEN2K
130#undef __USE_XOPEN2KXSI
131#undef __USE_XOPEN2K8
132#undef __USE_XOPEN2K8XSI
133#undef __USE_LARGEFILE
134#undef __USE_LARGEFILE64
135#undef __USE_FILE_OFFSET64
136#undef __USE_MISC
137#undef __USE_ATFILE
138#undef __USE_GNU
139#undef __USE_FORTIFY_LEVEL
140#undef __KERNEL_STRICT_NAMES
141#undef __GLIBC_USE_DEPRECATED_GETS
142
143/* Suppress kernel-name space pollution unless user expressedly asks
144 for it. */
145#ifndef _LOOSE_KERNEL_NAMES
146# define __KERNEL_STRICT_NAMES
147#endif
148
149/* Convenience macro to test the version of gcc.
150 Use like this:
151 #if __GNUC_PREREQ (2,8)
152 ... code requiring gcc 2.8 or later ...
153 #endif
154 Note: only works for GCC 2.0 and later, because __GNUC_MINOR__ was
155 added in 2.0. */
156#if defined __GNUC__ && defined __GNUC_MINOR__
157# define __GNUC_PREREQ(maj, min) \
158 ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
159#else
160# define __GNUC_PREREQ(maj, min) 0
161#endif
162
163/* Similarly for clang. Features added to GCC after version 4.2 may
164 or may not also be available in clang, and clang's definitions of
165 __GNUC(_MINOR)__ are fixed at 4 and 2 respectively. Not all such
166 features can be queried via __has_extension/__has_feature. */
167#if defined __clang_major__ && defined __clang_minor__
168# define __glibc_clang_prereq(maj, min) \
169 ((__clang_major__ << 16) + __clang_minor__ >= ((maj) << 16) + (min))
170#else
171# define __glibc_clang_prereq(maj, min) 0
172#endif
173
174/* Whether to use feature set F. */
175#define __GLIBC_USE(F) __GLIBC_USE_ ## F
176
177/* _BSD_SOURCE and _SVID_SOURCE are deprecated aliases for
178 _DEFAULT_SOURCE. If _DEFAULT_SOURCE is present we do not
179 issue a warning; the expectation is that the source is being
180 transitioned to use the new macro. */
181#if (defined _BSD_SOURCE || defined _SVID_SOURCE) \
182 && !defined _DEFAULT_SOURCE
183# warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"
184# undef _DEFAULT_SOURCE
185# define _DEFAULT_SOURCE 1
186#endif
187
188/* If _GNU_SOURCE was defined by the user, turn on all the other features. */
189#ifdef _GNU_SOURCE
190# undef _ISOC95_SOURCE
191# define _ISOC95_SOURCE 1
192# undef _ISOC99_SOURCE
193# define _ISOC99_SOURCE 1
194# undef _ISOC11_SOURCE
195# define _ISOC11_SOURCE 1
196# undef _POSIX_SOURCE
197# define _POSIX_SOURCE 1
198# undef _POSIX_C_SOURCE
199# define _POSIX_C_SOURCE 200809L
200# undef _XOPEN_SOURCE
201# define _XOPEN_SOURCE 700
202# undef _XOPEN_SOURCE_EXTENDED
203# define _XOPEN_SOURCE_EXTENDED 1
204# undef _LARGEFILE64_SOURCE
205# define _LARGEFILE64_SOURCE 1
206# undef _DEFAULT_SOURCE
207# define _DEFAULT_SOURCE 1
208# undef _ATFILE_SOURCE
209# define _ATFILE_SOURCE 1
210#endif
211
212/* If nothing (other than _GNU_SOURCE and _DEFAULT_SOURCE) is defined,
213 define _DEFAULT_SOURCE. */
214#if (defined _DEFAULT_SOURCE \
215 || (!defined __STRICT_ANSI__ \
216 && !defined _ISOC99_SOURCE \
217 && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE \
218 && !defined _XOPEN_SOURCE))
219# undef _DEFAULT_SOURCE
220# define _DEFAULT_SOURCE 1
221#endif
222
223/* This is to enable the ISO C11 extension. */
224#if (defined _ISOC11_SOURCE \
225 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112L))
226# define __USE_ISOC11 1
227#endif
228
229/* This is to enable the ISO C99 extension. */
230#if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \
231 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
232# define __USE_ISOC99 1
233#endif
234
235/* This is to enable the ISO C90 Amendment 1:1995 extension. */
236#if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \
237 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199409L))
238# define __USE_ISOC95 1
239#endif
240
241/* This is to enable compatibility for ISO C++11.
242
243 So far g++ does not provide a macro. Check the temporary macro for
244 now, too. */
245#if ((defined __cplusplus && __cplusplus >= 201103L) \
246 || defined __GXX_EXPERIMENTAL_CXX0X__)
247# define __USE_ISOCXX11 1
248#endif
249
250/* If none of the ANSI/POSIX macros are defined, or if _DEFAULT_SOURCE
251 is defined, use POSIX.1-2008 (or another version depending on
252 _XOPEN_SOURCE). */
253#ifdef _DEFAULT_SOURCE
254# if !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE
255# define __USE_POSIX_IMPLICITLY 1
256# endif
257# undef _POSIX_SOURCE
258# define _POSIX_SOURCE 1
259# undef _POSIX_C_SOURCE
260# define _POSIX_C_SOURCE 200809L
261#endif
262
263#if ((!defined __STRICT_ANSI__ \
264 || (defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) >= 500)) \
265 && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE)
266# define _POSIX_SOURCE 1
267# if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 500
268# define _POSIX_C_SOURCE 2
269# elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 600
270# define _POSIX_C_SOURCE 199506L
271# elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 700
272# define _POSIX_C_SOURCE 200112L
273# else
274# define _POSIX_C_SOURCE 200809L
275# endif
276# define __USE_POSIX_IMPLICITLY 1
277#endif
278
279/* Some C libraries once required _REENTRANT and/or _THREAD_SAFE to be
280 defined in all multithreaded code. GNU libc has not required this
281 for many years. We now treat them as compatibility synonyms for
282 _POSIX_C_SOURCE=199506L, which is the earliest level of POSIX with
283 comprehensive support for multithreaded code. Using them never
284 lowers the selected level of POSIX conformance, only raises it. */
285#if ((!defined _POSIX_C_SOURCE || (_POSIX_C_SOURCE - 0) < 199506L) \
286 && (defined _REENTRANT || defined _THREAD_SAFE))
287# define _POSIX_SOURCE 1
288# undef _POSIX_C_SOURCE
289# define _POSIX_C_SOURCE 199506L
290#endif
291
292#if (defined _POSIX_SOURCE \
293 || (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 1) \
294 || defined _XOPEN_SOURCE)
295# define __USE_POSIX 1
296#endif
297
298#if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE
299# define __USE_POSIX2 1
300#endif
301
302#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199309L
303# define __USE_POSIX199309 1
304#endif
305
306#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199506L
307# define __USE_POSIX199506 1
308#endif
309
310#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200112L
311# define __USE_XOPEN2K 1
312# undef __USE_ISOC95
313# define __USE_ISOC95 1
314# undef __USE_ISOC99
315# define __USE_ISOC99 1
316#endif
317
318#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200809L
319# define __USE_XOPEN2K8 1
320# undef _ATFILE_SOURCE
321# define _ATFILE_SOURCE 1
322#endif
323
324#ifdef _XOPEN_SOURCE
325# define __USE_XOPEN 1
326# if (_XOPEN_SOURCE - 0) >= 500
327# define __USE_XOPEN_EXTENDED 1
328# define __USE_UNIX98 1
329# undef _LARGEFILE_SOURCE
330# define _LARGEFILE_SOURCE 1
331# if (_XOPEN_SOURCE - 0) >= 600
332# if (_XOPEN_SOURCE - 0) >= 700
333# define __USE_XOPEN2K8 1
334# define __USE_XOPEN2K8XSI 1
335# endif
336# define __USE_XOPEN2K 1
337# define __USE_XOPEN2KXSI 1
338# undef __USE_ISOC95
339# define __USE_ISOC95 1
340# undef __USE_ISOC99
341# define __USE_ISOC99 1
342# endif
343# else
344# ifdef _XOPEN_SOURCE_EXTENDED
345# define __USE_XOPEN_EXTENDED 1
346# endif
347# endif
348#endif
349
350#ifdef _LARGEFILE_SOURCE
351# define __USE_LARGEFILE 1
352#endif
353
354#ifdef _LARGEFILE64_SOURCE
355# define __USE_LARGEFILE64 1
356#endif
357
358#if defined _FILE_OFFSET_BITS && _FILE_OFFSET_BITS == 64
359# define __USE_FILE_OFFSET64 1
360#endif
361
362#if defined _DEFAULT_SOURCE
363# define __USE_MISC 1
364#endif
365
366#ifdef _ATFILE_SOURCE
367# define __USE_ATFILE 1
368#endif
369
370#ifdef _GNU_SOURCE
371# define __USE_GNU 1
372#endif
373
374#if defined _FORTIFY_SOURCE && _FORTIFY_SOURCE > 0
375# if !defined __OPTIMIZE__ || __OPTIMIZE__ <= 0
376# warning _FORTIFY_SOURCE requires compiling with optimization (-O)
377# elif !__GNUC_PREREQ (4, 1)
378# warning _FORTIFY_SOURCE requires GCC 4.1 or later
379# elif _FORTIFY_SOURCE > 1
380# define __USE_FORTIFY_LEVEL 2
381# else
382# define __USE_FORTIFY_LEVEL 1
383# endif
384#endif
385#ifndef __USE_FORTIFY_LEVEL
386# define __USE_FORTIFY_LEVEL 0
387#endif
388
389/* The function 'gets' existed in C89, but is impossible to use
390 safely. It has been removed from ISO C11 and ISO C++14. Note: for
391 compatibility with various implementations of <cstdio>, this test
392 must consider only the value of __cplusplus when compiling C++. */
393#if defined __cplusplus ? __cplusplus >= 201402L : defined __USE_ISOC11
394# define __GLIBC_USE_DEPRECATED_GETS 0
395#else
396# define __GLIBC_USE_DEPRECATED_GETS 1
397#endif
398
399/* Get definitions of __STDC_* predefined macros, if the compiler has
400 not preincluded this header automatically. */
401#include <stdc-predef.h>
402
403/* This macro indicates that the installed library is the GNU C Library.
404 For historic reasons the value now is 6 and this will stay from now
405 on. The use of this variable is deprecated. Use __GLIBC__ and
406 __GLIBC_MINOR__ now (see below) when you want to test for a specific
407 GNU C library version and use the values in <gnu/lib-names.h> to get
408 the sonames of the shared libraries. */
409#undef __GNU_LIBRARY__
410#define __GNU_LIBRARY__ 6
411
412/* Major and minor version number of the GNU C library package. Use
413 these macros to test for features in specific releases. */
414#define __GLIBC__ 2
415#define __GLIBC_MINOR__ 26
416
417#define __GLIBC_PREREQ(maj, min) \
418 ((__GLIBC__ << 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min))
419
420/* This is here only because every header file already includes this one. */
421#ifndef __ASSEMBLER__
422# ifndef _SYS_CDEFS_H
423# include <sys/cdefs.h>
424# endif
425
426/* If we don't have __REDIRECT, prototypes will be missing if
427 __USE_FILE_OFFSET64 but not __USE_LARGEFILE[64]. */
428# if defined __USE_FILE_OFFSET64 && !defined __REDIRECT
429# define __USE_LARGEFILE 1
430# define __USE_LARGEFILE64 1
431# endif
432
433#endif /* !ASSEMBLER */
434
435/* Decide whether we can define 'extern inline' functions in headers. */
436#if __GNUC_PREREQ (2, 7) && defined __OPTIMIZE__ \
437 && !defined __OPTIMIZE_SIZE__ && !defined __NO_INLINE__ \
438 && defined __extern_inline
439# define __USE_EXTERN_INLINES 1
440#endif
441
442
443/* This is here only because every header file already includes this one.
444 Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
445 <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
446 that will always return failure (and set errno to ENOSYS). */
447#include <gnu/stubs.h>
448
449
450#endif /* features.h */
451