1/* Copyright (C) 1991-2019 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_ISOCXX11 Define ISO C++11 things.
80 __USE_POSIX Define IEEE Std 1003.1 things.
81 __USE_POSIX2 Define IEEE Std 1003.2 things.
82 __USE_POSIX199309 Define IEEE Std 1003.1, and .1b things.
83 __USE_POSIX199506 Define IEEE Std 1003.1, .1b, .1c and .1i things.
84 __USE_XOPEN Define XPG things.
85 __USE_XOPEN_EXTENDED Define X/Open Unix things.
86 __USE_UNIX98 Define Single Unix V2 things.
87 __USE_XOPEN2K Define XPG6 things.
88 __USE_XOPEN2KXSI Define XPG6 XSI things.
89 __USE_XOPEN2K8 Define XPG7 things.
90 __USE_XOPEN2K8XSI Define XPG7 XSI things.
91 __USE_LARGEFILE Define correct standard I/O things.
92 __USE_LARGEFILE64 Define LFS things with separate names.
93 __USE_FILE_OFFSET64 Define 64bit interface as default.
94 __USE_MISC Define things from 4.3BSD or System V Unix.
95 __USE_ATFILE Define *at interfaces and AT_* constants for them.
96 __USE_GNU Define GNU extensions.
97 __USE_FORTIFY_LEVEL Additional security measures used, according to level.
98
99 The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
100 defined by this file unconditionally. `__GNU_LIBRARY__' is provided
101 only for compatibility. All new code should use the other symbols
102 to test for features.
103
104 All macros listed above as possibly being defined by this file are
105 explicitly undefined if they are not explicitly defined.
106 Feature-test macros that are not defined by the user or compiler
107 but are implied by the other feature-test macros defined (or by the
108 lack of any definitions) are defined by the file.
109
110 ISO C feature test macros depend on the definition of the macro
111 when an affected header is included, not when the first system
112 header is included, and so they are handled in
113 <bits/libc-header-start.h>, which does not have a multiple include
114 guard. Feature test macros that can be handled from the first
115 system header included are handled here. */
116
117
118/* Undefine everything, so we get a clean slate. */
119#undef __USE_ISOC11
120#undef __USE_ISOC99
121#undef __USE_ISOC95
122#undef __USE_ISOCXX11
123#undef __USE_POSIX
124#undef __USE_POSIX2
125#undef __USE_POSIX199309
126#undef __USE_POSIX199506
127#undef __USE_XOPEN
128#undef __USE_XOPEN_EXTENDED
129#undef __USE_UNIX98
130#undef __USE_XOPEN2K
131#undef __USE_XOPEN2KXSI
132#undef __USE_XOPEN2K8
133#undef __USE_XOPEN2K8XSI
134#undef __USE_LARGEFILE
135#undef __USE_LARGEFILE64
136#undef __USE_FILE_OFFSET64
137#undef __USE_MISC
138#undef __USE_ATFILE
139#undef __USE_GNU
140#undef __USE_FORTIFY_LEVEL
141#undef __KERNEL_STRICT_NAMES
142#undef __GLIBC_USE_DEPRECATED_GETS
143#undef __GLIBC_USE_DEPRECATED_SCANF
144
145/* Suppress kernel-name space pollution unless user expressedly asks
146 for it. */
147#ifndef _LOOSE_KERNEL_NAMES
148# define __KERNEL_STRICT_NAMES
149#endif
150
151/* Convenience macro to test the version of gcc.
152 Use like this:
153 #if __GNUC_PREREQ (2,8)
154 ... code requiring gcc 2.8 or later ...
155 #endif
156 Note: only works for GCC 2.0 and later, because __GNUC_MINOR__ was
157 added in 2.0. */
158#if defined __GNUC__ && defined __GNUC_MINOR__
159# define __GNUC_PREREQ(maj, min) \
160 ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
161#else
162# define __GNUC_PREREQ(maj, min) 0
163#endif
164
165/* Similarly for clang. Features added to GCC after version 4.2 may
166 or may not also be available in clang, and clang's definitions of
167 __GNUC(_MINOR)__ are fixed at 4 and 2 respectively. Not all such
168 features can be queried via __has_extension/__has_feature. */
169#if defined __clang_major__ && defined __clang_minor__
170# define __glibc_clang_prereq(maj, min) \
171 ((__clang_major__ << 16) + __clang_minor__ >= ((maj) << 16) + (min))
172#else
173# define __glibc_clang_prereq(maj, min) 0
174#endif
175
176/* Whether to use feature set F. */
177#define __GLIBC_USE(F) __GLIBC_USE_ ## F
178
179/* _BSD_SOURCE and _SVID_SOURCE are deprecated aliases for
180 _DEFAULT_SOURCE. If _DEFAULT_SOURCE is present we do not
181 issue a warning; the expectation is that the source is being
182 transitioned to use the new macro. */
183#if (defined _BSD_SOURCE || defined _SVID_SOURCE) \
184 && !defined _DEFAULT_SOURCE
185# warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"
186# undef _DEFAULT_SOURCE
187# define _DEFAULT_SOURCE 1
188#endif
189
190/* If _GNU_SOURCE was defined by the user, turn on all the other features. */
191#ifdef _GNU_SOURCE
192# undef _ISOC95_SOURCE
193# define _ISOC95_SOURCE 1
194# undef _ISOC99_SOURCE
195# define _ISOC99_SOURCE 1
196# undef _ISOC11_SOURCE
197# define _ISOC11_SOURCE 1
198# undef _POSIX_SOURCE
199# define _POSIX_SOURCE 1
200# undef _POSIX_C_SOURCE
201# define _POSIX_C_SOURCE 200809L
202# undef _XOPEN_SOURCE
203# define _XOPEN_SOURCE 700
204# undef _XOPEN_SOURCE_EXTENDED
205# define _XOPEN_SOURCE_EXTENDED 1
206# undef _LARGEFILE64_SOURCE
207# define _LARGEFILE64_SOURCE 1
208# undef _DEFAULT_SOURCE
209# define _DEFAULT_SOURCE 1
210# undef _ATFILE_SOURCE
211# define _ATFILE_SOURCE 1
212#endif
213
214/* If nothing (other than _GNU_SOURCE and _DEFAULT_SOURCE) is defined,
215 define _DEFAULT_SOURCE. */
216#if (defined _DEFAULT_SOURCE \
217 || (!defined __STRICT_ANSI__ \
218 && !defined _ISOC99_SOURCE && !defined _ISOC11_SOURCE \
219 && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE \
220 && !defined _XOPEN_SOURCE))
221# undef _DEFAULT_SOURCE
222# define _DEFAULT_SOURCE 1
223#endif
224
225/* This is to enable the ISO C11 extension. */
226#if (defined _ISOC11_SOURCE \
227 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112L))
228# define __USE_ISOC11 1
229#endif
230
231/* This is to enable the ISO C99 extension. */
232#if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \
233 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
234# define __USE_ISOC99 1
235#endif
236
237/* This is to enable the ISO C90 Amendment 1:1995 extension. */
238#if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \
239 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199409L))
240# define __USE_ISOC95 1
241#endif
242
243#ifdef __cplusplus
244/* This is to enable compatibility for ISO C++17. */
245# if __cplusplus >= 201703L
246# define __USE_ISOC11 1
247# endif
248/* This is to enable compatibility for ISO C++11.
249 Check the temporary macro for now, too. */
250# if __cplusplus >= 201103L || defined __GXX_EXPERIMENTAL_CXX0X__
251# define __USE_ISOCXX11 1
252# define __USE_ISOC99 1
253# endif
254#endif
255
256/* If none of the ANSI/POSIX macros are defined, or if _DEFAULT_SOURCE
257 is defined, use POSIX.1-2008 (or another version depending on
258 _XOPEN_SOURCE). */
259#ifdef _DEFAULT_SOURCE
260# if !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE
261# define __USE_POSIX_IMPLICITLY 1
262# endif
263# undef _POSIX_SOURCE
264# define _POSIX_SOURCE 1
265# undef _POSIX_C_SOURCE
266# define _POSIX_C_SOURCE 200809L
267#endif
268
269#if ((!defined __STRICT_ANSI__ \
270 || (defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) >= 500)) \
271 && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE)
272# define _POSIX_SOURCE 1
273# if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 500
274# define _POSIX_C_SOURCE 2
275# elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 600
276# define _POSIX_C_SOURCE 199506L
277# elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 700
278# define _POSIX_C_SOURCE 200112L
279# else
280# define _POSIX_C_SOURCE 200809L
281# endif
282# define __USE_POSIX_IMPLICITLY 1
283#endif
284
285/* Some C libraries once required _REENTRANT and/or _THREAD_SAFE to be
286 defined in all multithreaded code. GNU libc has not required this
287 for many years. We now treat them as compatibility synonyms for
288 _POSIX_C_SOURCE=199506L, which is the earliest level of POSIX with
289 comprehensive support for multithreaded code. Using them never
290 lowers the selected level of POSIX conformance, only raises it. */
291#if ((!defined _POSIX_C_SOURCE || (_POSIX_C_SOURCE - 0) < 199506L) \
292 && (defined _REENTRANT || defined _THREAD_SAFE))
293# define _POSIX_SOURCE 1
294# undef _POSIX_C_SOURCE
295# define _POSIX_C_SOURCE 199506L
296#endif
297
298#if (defined _POSIX_SOURCE \
299 || (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 1) \
300 || defined _XOPEN_SOURCE)
301# define __USE_POSIX 1
302#endif
303
304#if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE
305# define __USE_POSIX2 1
306#endif
307
308#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199309L
309# define __USE_POSIX199309 1
310#endif
311
312#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199506L
313# define __USE_POSIX199506 1
314#endif
315
316#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200112L
317# define __USE_XOPEN2K 1
318# undef __USE_ISOC95
319# define __USE_ISOC95 1
320# undef __USE_ISOC99
321# define __USE_ISOC99 1
322#endif
323
324#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200809L
325# define __USE_XOPEN2K8 1
326# undef _ATFILE_SOURCE
327# define _ATFILE_SOURCE 1
328#endif
329
330#ifdef _XOPEN_SOURCE
331# define __USE_XOPEN 1
332# if (_XOPEN_SOURCE - 0) >= 500
333# define __USE_XOPEN_EXTENDED 1
334# define __USE_UNIX98 1
335# undef _LARGEFILE_SOURCE
336# define _LARGEFILE_SOURCE 1
337# if (_XOPEN_SOURCE - 0) >= 600
338# if (_XOPEN_SOURCE - 0) >= 700
339# define __USE_XOPEN2K8 1
340# define __USE_XOPEN2K8XSI 1
341# endif
342# define __USE_XOPEN2K 1
343# define __USE_XOPEN2KXSI 1
344# undef __USE_ISOC95
345# define __USE_ISOC95 1
346# undef __USE_ISOC99
347# define __USE_ISOC99 1
348# endif
349# else
350# ifdef _XOPEN_SOURCE_EXTENDED
351# define __USE_XOPEN_EXTENDED 1
352# endif
353# endif
354#endif
355
356#ifdef _LARGEFILE_SOURCE
357# define __USE_LARGEFILE 1
358#endif
359
360#ifdef _LARGEFILE64_SOURCE
361# define __USE_LARGEFILE64 1
362#endif
363
364#if defined _FILE_OFFSET_BITS && _FILE_OFFSET_BITS == 64
365# define __USE_FILE_OFFSET64 1
366#endif
367
368#if defined _DEFAULT_SOURCE
369# define __USE_MISC 1
370#endif
371
372#ifdef _ATFILE_SOURCE
373# define __USE_ATFILE 1
374#endif
375
376#ifdef _GNU_SOURCE
377# define __USE_GNU 1
378#endif
379
380#if defined _FORTIFY_SOURCE && _FORTIFY_SOURCE > 0 \
381 && __GNUC_PREREQ (4, 1) && defined __OPTIMIZE__ && __OPTIMIZE__ > 0
382# if _FORTIFY_SOURCE > 1
383# define __USE_FORTIFY_LEVEL 2
384# else
385# define __USE_FORTIFY_LEVEL 1
386# endif
387#else
388# define __USE_FORTIFY_LEVEL 0
389#endif
390
391/* The function 'gets' existed in C89, but is impossible to use
392 safely. It has been removed from ISO C11 and ISO C++14. Note: for
393 compatibility with various implementations of <cstdio>, this test
394 must consider only the value of __cplusplus when compiling C++. */
395#if defined __cplusplus ? __cplusplus >= 201402L : defined __USE_ISOC11
396# define __GLIBC_USE_DEPRECATED_GETS 0
397#else
398# define __GLIBC_USE_DEPRECATED_GETS 1
399#endif
400
401/* GNU formerly extended the scanf functions with modified format
402 specifiers %as, %aS, and %a[...] that allocate a buffer for the
403 input using malloc. This extension conflicts with ISO C99, which
404 defines %a as a standalone format specifier that reads a floating-
405 point number; moreover, POSIX.1-2008 provides the same feature
406 using the modifier letter 'm' instead (%ms, %mS, %m[...]).
407
408 We now follow C99 unless GNU extensions are active and the compiler
409 is specifically in C89 or C++98 mode (strict or not). For
410 instance, with GCC, -std=gnu11 will have C99-compliant scanf with
411 or without -D_GNU_SOURCE, but -std=c89 -D_GNU_SOURCE will have the
412 old extension. */
413#if defined __USE_GNU && \
414 (defined __cplusplus \
415 ? (__cplusplus < 201103L && !defined __GXX_EXPERIMENTAL_CXX0X__) \
416 : (!defined __STDC_VERSION__ || __STDC_VERSION__ < 199901L))
417# define __GLIBC_USE_DEPRECATED_SCANF 1
418#else
419# define __GLIBC_USE_DEPRECATED_SCANF 0
420#endif
421
422/* Get definitions of __STDC_* predefined macros, if the compiler has
423 not preincluded this header automatically. */
424#include <stdc-predef.h>
425
426/* This macro indicates that the installed library is the GNU C Library.
427 For historic reasons the value now is 6 and this will stay from now
428 on. The use of this variable is deprecated. Use __GLIBC__ and
429 __GLIBC_MINOR__ now (see below) when you want to test for a specific
430 GNU C library version and use the values in <gnu/lib-names.h> to get
431 the sonames of the shared libraries. */
432#undef __GNU_LIBRARY__
433#define __GNU_LIBRARY__ 6
434
435/* Major and minor version number of the GNU C library package. Use
436 these macros to test for features in specific releases. */
437#define __GLIBC__ 2
438#define __GLIBC_MINOR__ 29
439
440#define __GLIBC_PREREQ(maj, min) \
441 ((__GLIBC__ << 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min))
442
443/* This is here only because every header file already includes this one. */
444#ifndef __ASSEMBLER__
445# ifndef _SYS_CDEFS_H
446# include <sys/cdefs.h>
447# endif
448
449/* If we don't have __REDIRECT, prototypes will be missing if
450 __USE_FILE_OFFSET64 but not __USE_LARGEFILE[64]. */
451# if defined __USE_FILE_OFFSET64 && !defined __REDIRECT
452# define __USE_LARGEFILE 1
453# define __USE_LARGEFILE64 1
454# endif
455
456#endif /* !ASSEMBLER */
457
458/* Decide whether we can define 'extern inline' functions in headers. */
459#if __GNUC_PREREQ (2, 7) && defined __OPTIMIZE__ \
460 && !defined __OPTIMIZE_SIZE__ && !defined __NO_INLINE__ \
461 && defined __extern_inline
462# define __USE_EXTERN_INLINES 1
463#endif
464
465
466/* This is here only because every header file already includes this one.
467 Get the definitions of all the appropriate `__stub_FUNCTION' symbols.
468 <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub
469 that will always return failure (and set errno to ENOSYS). */
470#include <gnu/stubs.h>
471
472
473#endif /* features.h */
474