1/* Copyright (C) 1991-2022 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 <https://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 _ISOC2X_SOURCE Extensions to ISO C99 from ISO C2X. 
28 __STDC_WANT_LIB_EXT2__ 
29 Extensions to ISO C99 from TR 27431-2:2010. 
30 __STDC_WANT_IEC_60559_BFP_EXT__ 
31 Extensions to ISO C11 from TS 18661-1:2014. 
32 __STDC_WANT_IEC_60559_FUNCS_EXT__ 
33 Extensions to ISO C11 from TS 18661-4:2015. 
34 __STDC_WANT_IEC_60559_TYPES_EXT__ 
35 Extensions to ISO C11 from TS 18661-3:2015. 
36 __STDC_WANT_IEC_60559_EXT__ 
37 ISO C2X interfaces defined only in Annex F. 
38 
39 _POSIX_SOURCE IEEE Std 1003.1. 
40 _POSIX_C_SOURCE If ==1, like _POSIX_SOURCE; if >=2 add IEEE Std 1003.2; 
41 if >=199309L, add IEEE Std 1003.1b-1993; 
42 if >=199506L, add IEEE Std 1003.1c-1995; 
43 if >=200112L, all of IEEE 1003.1-2004 
44 if >=200809L, all of IEEE 1003.1-2008 
45 _XOPEN_SOURCE Includes POSIX and XPG things. Set to 500 if 
46 Single Unix conformance is wanted, to 600 for the 
47 sixth revision, to 700 for the seventh revision. 
48 _XOPEN_SOURCE_EXTENDED XPG things and X/Open Unix extensions. 
49 _LARGEFILE_SOURCE Some more functions for correct standard I/O. 
50 _LARGEFILE64_SOURCE Additional functionality from LFS for large files. 
51 _FILE_OFFSET_BITS=N Select default filesystem interface. 
52 _ATFILE_SOURCE Additional *at interfaces. 
53 _DYNAMIC_STACK_SIZE_SOURCE Select correct (but non compile-time constant) 
54 MINSIGSTKSZ, SIGSTKSZ and PTHREAD_STACK_MIN. 
55 _GNU_SOURCE All of the above, plus GNU extensions. 
56 _DEFAULT_SOURCE The default set of features (taking precedence over 
57 __STRICT_ANSI__). 
58 
59 _FORTIFY_SOURCE Add security hardening to many library functions. 
60 Set to 1 or 2; 2 performs stricter checks than 1. 
61 
62 _REENTRANT, _THREAD_SAFE 
63 Obsolete; equivalent to _POSIX_C_SOURCE=199506L. 
64 
65 The `-ansi' switch to the GNU C compiler, and standards conformance 
66 options such as `-std=c99', define __STRICT_ANSI__. If none of 
67 these are defined, or if _DEFAULT_SOURCE is defined, the default is 
68 to have _POSIX_SOURCE set to one and _POSIX_C_SOURCE set to 
69 200809L, as well as enabling miscellaneous functions from BSD and 
70 SVID. If more than one of these are defined, they accumulate. For 
71 example __STRICT_ANSI__, _POSIX_SOURCE and _POSIX_C_SOURCE together 
72 give you ISO C, 1003.1, and 1003.2, but nothing else. 
73 
74 These are defined by this file and are used by the 
75 header files to decide what to declare or define: 
76 
77 __GLIBC_USE (F) Define things from feature set F. This is defined 
78 to 1 or 0; the subsequent macros are either defined 
79 or undefined, and those tests should be moved to 
80 __GLIBC_USE. 
81 __USE_ISOC11 Define ISO C11 things. 
82 __USE_ISOC99 Define ISO C99 things. 
83 __USE_ISOC95 Define ISO C90 AMD1 (C95) things. 
84 __USE_ISOCXX11 Define ISO C++11 things. 
85 __USE_POSIX Define IEEE Std 1003.1 things. 
86 __USE_POSIX2 Define IEEE Std 1003.2 things. 
87 __USE_POSIX199309 Define IEEE Std 1003.1, and .1b things. 
88 __USE_POSIX199506 Define IEEE Std 1003.1, .1b, .1c and .1i things. 
89 __USE_XOPEN Define XPG things. 
90 __USE_XOPEN_EXTENDED Define X/Open Unix things. 
91 __USE_UNIX98 Define Single Unix V2 things. 
92 __USE_XOPEN2K Define XPG6 things. 
93 __USE_XOPEN2KXSI Define XPG6 XSI things. 
94 __USE_XOPEN2K8 Define XPG7 things. 
95 __USE_XOPEN2K8XSI Define XPG7 XSI things. 
96 __USE_LARGEFILE Define correct standard I/O things. 
97 __USE_LARGEFILE64 Define LFS things with separate names. 
98 __USE_FILE_OFFSET64 Define 64bit interface as default. 
99 __USE_MISC Define things from 4.3BSD or System V Unix. 
100 __USE_ATFILE Define *at interfaces and AT_* constants for them. 
101 __USE_DYNAMIC_STACK_SIZE Define correct (but non compile-time constant) 
102 MINSIGSTKSZ, SIGSTKSZ and PTHREAD_STACK_MIN. 
103 __USE_GNU Define GNU extensions. 
104 __USE_FORTIFY_LEVEL Additional security measures used, according to level. 
105 
106 The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are 
107 defined by this file unconditionally. `__GNU_LIBRARY__' is provided 
108 only for compatibility. All new code should use the other symbols 
109 to test for features. 
110 
111 All macros listed above as possibly being defined by this file are 
112 explicitly undefined if they are not explicitly defined. 
113 Feature-test macros that are not defined by the user or compiler 
114 but are implied by the other feature-test macros defined (or by the 
115 lack of any definitions) are defined by the file. 
116 
117 ISO C feature test macros depend on the definition of the macro 
118 when an affected header is included, not when the first system 
119 header is included, and so they are handled in 
120 <bits/libc-header-start.h>, which does not have a multiple include 
121 guard. Feature test macros that can be handled from the first 
122 system header included are handled here. */ 
123 
124 
125/* Undefine everything, so we get a clean slate. */ 
126#undef __USE_ISOC11 
127#undef __USE_ISOC99 
128#undef __USE_ISOC95 
129#undef __USE_ISOCXX11 
130#undef __USE_POSIX 
131#undef __USE_POSIX2 
132#undef __USE_POSIX199309 
133#undef __USE_POSIX199506 
134#undef __USE_XOPEN 
135#undef __USE_XOPEN_EXTENDED 
136#undef __USE_UNIX98 
137#undef __USE_XOPEN2K 
138#undef __USE_XOPEN2KXSI 
139#undef __USE_XOPEN2K8 
140#undef __USE_XOPEN2K8XSI 
141#undef __USE_LARGEFILE 
142#undef __USE_LARGEFILE64 
143#undef __USE_FILE_OFFSET64 
144#undef __USE_MISC 
145#undef __USE_ATFILE 
146#undef __USE_DYNAMIC_STACK_SIZE 
147#undef __USE_GNU 
148#undef __USE_FORTIFY_LEVEL 
149#undef __KERNEL_STRICT_NAMES 
150#undef __GLIBC_USE_ISOC2X 
151#undef __GLIBC_USE_DEPRECATED_GETS 
152#undef __GLIBC_USE_DEPRECATED_SCANF 
153 
154/* Suppress kernel-name space pollution unless user expressedly asks 
155 for it. */ 
156#ifndef _LOOSE_KERNEL_NAMES 
157# define __KERNEL_STRICT_NAMES 
158#endif 
159 
160/* Convenience macro to test the version of gcc. 
161 Use like this: 
162 #if __GNUC_PREREQ (2,8) 
163 ... code requiring gcc 2.8 or later ... 
164 #endif 
165 Note: only works for GCC 2.0 and later, because __GNUC_MINOR__ was 
166 added in 2.0. */ 
167#if defined __GNUC__ && defined __GNUC_MINOR__ 
168# define __GNUC_PREREQ(maj, min) \ 
169 ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min)) 
170#else 
171# define __GNUC_PREREQ(maj, min) 0 
172#endif 
173 
174/* Similarly for clang. Features added to GCC after version 4.2 may 
175 or may not also be available in clang, and clang's definitions of 
176 __GNUC(_MINOR)__ are fixed at 4 and 2 respectively. Not all such 
177 features can be queried via __has_extension/__has_feature. */ 
178#if defined __clang_major__ && defined __clang_minor__ 
179# define __glibc_clang_prereq(maj, min) \ 
180 ((__clang_major__ << 16) + __clang_minor__ >= ((maj) << 16) + (min)) 
181#else 
182# define __glibc_clang_prereq(maj, min) 0 
183#endif 
184 
185/* Whether to use feature set F. */ 
186#define __GLIBC_USE(F) __GLIBC_USE_ ## F 
187 
188/* _BSD_SOURCE and _SVID_SOURCE are deprecated aliases for 
189 _DEFAULT_SOURCE. If _DEFAULT_SOURCE is present we do not 
190 issue a warning; the expectation is that the source is being 
191 transitioned to use the new macro. */ 
192#if (defined _BSD_SOURCE || defined _SVID_SOURCE) \ 
193 && !defined _DEFAULT_SOURCE 
194# warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE" 
195# undef _DEFAULT_SOURCE 
196# define _DEFAULT_SOURCE 1 
197#endif 
198 
199/* If _GNU_SOURCE was defined by the user, turn on all the other features. */ 
200#ifdef _GNU_SOURCE 
201# undef _ISOC95_SOURCE 
202# define _ISOC95_SOURCE 1 
203# undef _ISOC99_SOURCE 
204# define _ISOC99_SOURCE 1 
205# undef _ISOC11_SOURCE 
206# define _ISOC11_SOURCE 1 
207# undef _ISOC2X_SOURCE 
208# define _ISOC2X_SOURCE 1 
209# undef _POSIX_SOURCE 
210# define _POSIX_SOURCE 1 
211# undef _POSIX_C_SOURCE 
212# define _POSIX_C_SOURCE 200809L 
213# undef _XOPEN_SOURCE 
214# define _XOPEN_SOURCE 700 
215# undef _XOPEN_SOURCE_EXTENDED 
216# define _XOPEN_SOURCE_EXTENDED 1 
217# undef _LARGEFILE64_SOURCE 
218# define _LARGEFILE64_SOURCE 1 
219# undef _DEFAULT_SOURCE 
220# define _DEFAULT_SOURCE 1 
221# undef _ATFILE_SOURCE 
222# define _ATFILE_SOURCE 1 
223# undef _DYNAMIC_STACK_SIZE_SOURCE 
224# define _DYNAMIC_STACK_SIZE_SOURCE 1 
225#endif 
226 
227/* If nothing (other than _GNU_SOURCE and _DEFAULT_SOURCE) is defined, 
228 define _DEFAULT_SOURCE. */ 
229#if (defined _DEFAULT_SOURCE \ 
230 || (!defined __STRICT_ANSI__ \ 
231 && !defined _ISOC99_SOURCE && !defined _ISOC11_SOURCE \ 
232 && !defined _ISOC2X_SOURCE \ 
233 && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE \ 
234 && !defined _XOPEN_SOURCE)) 
235# undef _DEFAULT_SOURCE 
236# define _DEFAULT_SOURCE 1 
237#endif 
238 
239/* This is to enable the ISO C2X extension. */ 
240#if (defined _ISOC2X_SOURCE \ 
241 || (defined __STDC_VERSION__ && __STDC_VERSION__ > 201710L)) 
242# define __GLIBC_USE_ISOC2X 1 
243#else 
244# define __GLIBC_USE_ISOC2X 0 
245#endif 
246 
247/* This is to enable the ISO C11 extension. */ 
248#if (defined _ISOC11_SOURCE || defined _ISOC2X_SOURCE \ 
249 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112L)) 
250# define __USE_ISOC11 1 
251#endif 
252 
253/* This is to enable the ISO C99 extension. */ 
254#if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \ 
255 || defined _ISOC2X_SOURCE \ 
256 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L)) 
257# define __USE_ISOC99 1 
258#endif 
259 
260/* This is to enable the ISO C90 Amendment 1:1995 extension. */ 
261#if (defined _ISOC99_SOURCE || defined _ISOC11_SOURCE \ 
262 || defined _ISOC2X_SOURCE \ 
263 || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199409L)) 
264# define __USE_ISOC95 1 
265#endif 
266 
267#ifdef __cplusplus 
268/* This is to enable compatibility for ISO C++17. */ 
269# if __cplusplus >= 201703L 
270# define __USE_ISOC11 1 
271# endif 
272/* This is to enable compatibility for ISO C++11. 
273 Check the temporary macro for now, too. */ 
274# if __cplusplus >= 201103L || defined __GXX_EXPERIMENTAL_CXX0X__ 
275# define __USE_ISOCXX11 1 
276# define __USE_ISOC99 1 
277# endif 
278#endif 
279 
280/* If none of the ANSI/POSIX macros are defined, or if _DEFAULT_SOURCE 
281 is defined, use POSIX.1-2008 (or another version depending on 
282 _XOPEN_SOURCE). */ 
283#ifdef _DEFAULT_SOURCE 
284# if !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE 
285# define __USE_POSIX_IMPLICITLY 1 
286# endif 
287# undef _POSIX_SOURCE 
288# define _POSIX_SOURCE 1 
289# undef _POSIX_C_SOURCE 
290# define _POSIX_C_SOURCE 200809L 
291#endif 
292 
293#if ((!defined __STRICT_ANSI__ \ 
294 || (defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) >= 500)) \ 
295 && !defined _POSIX_SOURCE && !defined _POSIX_C_SOURCE) 
296# define _POSIX_SOURCE 1 
297# if defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 500 
298# define _POSIX_C_SOURCE 2 
299# elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 600 
300# define _POSIX_C_SOURCE 199506L 
301# elif defined _XOPEN_SOURCE && (_XOPEN_SOURCE - 0) < 700 
302# define _POSIX_C_SOURCE 200112L 
303# else 
304# define _POSIX_C_SOURCE 200809L 
305# endif 
306# define __USE_POSIX_IMPLICITLY 1 
307#endif 
308 
309/* Some C libraries once required _REENTRANT and/or _THREAD_SAFE to be 
310 defined in all multithreaded code. GNU libc has not required this 
311 for many years. We now treat them as compatibility synonyms for 
312 _POSIX_C_SOURCE=199506L, which is the earliest level of POSIX with 
313 comprehensive support for multithreaded code. Using them never 
314 lowers the selected level of POSIX conformance, only raises it. */ 
315#if ((!defined _POSIX_C_SOURCE || (_POSIX_C_SOURCE - 0) < 199506L) \ 
316 && (defined _REENTRANT || defined _THREAD_SAFE)) 
317# define _POSIX_SOURCE 1 
318# undef _POSIX_C_SOURCE 
319# define _POSIX_C_SOURCE 199506L 
320#endif 
321 
322#if (defined _POSIX_SOURCE \ 
323 || (defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 1) \ 
324 || defined _XOPEN_SOURCE) 
325# define __USE_POSIX 1 
326#endif 
327 
328#if defined _POSIX_C_SOURCE && _POSIX_C_SOURCE >= 2 || defined _XOPEN_SOURCE 
329# define __USE_POSIX2 1 
330#endif 
331 
332#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199309L 
333# define __USE_POSIX199309 1 
334#endif 
335 
336#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 199506L 
337# define __USE_POSIX199506 1 
338#endif 
339 
340#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200112L 
341# define __USE_XOPEN2K 1 
342# undef __USE_ISOC95 
343# define __USE_ISOC95 1 
344# undef __USE_ISOC99 
345# define __USE_ISOC99 1 
346#endif 
347 
348#if defined _POSIX_C_SOURCE && (_POSIX_C_SOURCE - 0) >= 200809L 
349# define __USE_XOPEN2K8 1 
350# undef _ATFILE_SOURCE 
351# define _ATFILE_SOURCE 1 
352#endif 
353 
354#ifdef _XOPEN_SOURCE 
355# define __USE_XOPEN 1 
356# if (_XOPEN_SOURCE - 0) >= 500 
357# define __USE_XOPEN_EXTENDED 1 
358# define __USE_UNIX98 1 
359# undef _LARGEFILE_SOURCE 
360# define _LARGEFILE_SOURCE 1 
361# if (_XOPEN_SOURCE - 0) >= 600 
362# if (_XOPEN_SOURCE - 0) >= 700 
363# define __USE_XOPEN2K8 1 
364# define __USE_XOPEN2K8XSI 1 
365# endif 
366# define __USE_XOPEN2K 1 
367# define __USE_XOPEN2KXSI 1 
368# undef __USE_ISOC95 
369# define __USE_ISOC95 1 
370# undef __USE_ISOC99 
371# define __USE_ISOC99 1 
372# endif 
373# else 
374# ifdef _XOPEN_SOURCE_EXTENDED 
375# define __USE_XOPEN_EXTENDED 1 
376# endif 
377# endif 
378#endif 
379 
380#ifdef _LARGEFILE_SOURCE 
381# define __USE_LARGEFILE 1 
382#endif 
383 
384#ifdef _LARGEFILE64_SOURCE 
385# define __USE_LARGEFILE64 1 
386#endif 
387 
388#if defined _FILE_OFFSET_BITS && _FILE_OFFSET_BITS == 64 
389# define __USE_FILE_OFFSET64 1 
390#endif 
391 
392#include <features-time64.h> 
393 
394#if defined _DEFAULT_SOURCE 
395# define __USE_MISC 1 
396#endif 
397 
398#ifdef _ATFILE_SOURCE 
399# define __USE_ATFILE 1 
400#endif 
401 
402#ifdef _DYNAMIC_STACK_SIZE_SOURCE 
403# define __USE_DYNAMIC_STACK_SIZE 1 
404#endif 
405 
406#ifdef _GNU_SOURCE 
407# define __USE_GNU 1 
408#endif 
409 
410#if defined _FORTIFY_SOURCE && _FORTIFY_SOURCE > 0 
411# if !defined __OPTIMIZE__ || __OPTIMIZE__ <= 0 
412# elif !__GNUC_PREREQ (4, 1) 
413# elif _FORTIFY_SOURCE > 2 && (__glibc_clang_prereq (9, 0) \ 
414 || __GNUC_PREREQ (12, 0)) 
415 
416# if _FORTIFY_SOURCE > 3 
417# endif 
418# define __USE_FORTIFY_LEVEL 3 
419# elif _FORTIFY_SOURCE > 1 
420# if _FORTIFY_SOURCE > 2 
421# endif 
422# define __USE_FORTIFY_LEVEL 2 
423# else 
424# define __USE_FORTIFY_LEVEL 1 
425# endif 
426#endif 
427#ifndef __USE_FORTIFY_LEVEL 
428# define __USE_FORTIFY_LEVEL 0 
429#endif 
430 
431/* The function 'gets' existed in C89, but is impossible to use 
432 safely. It has been removed from ISO C11 and ISO C++14. Note: for 
433 compatibility with various implementations of <cstdio>, this test 
434 must consider only the value of __cplusplus when compiling C++. */ 
435#if defined __cplusplus ? __cplusplus >= 201402L : defined __USE_ISOC11 
436# define __GLIBC_USE_DEPRECATED_GETS 0 
437#else 
438# define __GLIBC_USE_DEPRECATED_GETS 1 
439#endif 
440 
441/* GNU formerly extended the scanf functions with modified format 
442 specifiers %as, %aS, and %a[...] that allocate a buffer for the 
443 input using malloc. This extension conflicts with ISO C99, which 
444 defines %a as a standalone format specifier that reads a floating- 
445 point number; moreover, POSIX.1-2008 provides the same feature 
446 using the modifier letter 'm' instead (%ms, %mS, %m[...]). 
447 
448 We now follow C99 unless GNU extensions are active and the compiler 
449 is specifically in C89 or C++98 mode (strict or not). For 
450 instance, with GCC, -std=gnu11 will have C99-compliant scanf with 
451 or without -D_GNU_SOURCE, but -std=c89 -D_GNU_SOURCE will have the 
452 old extension. */ 
453#if (defined __USE_GNU \ 
454 && (defined __cplusplus \ 
455 ? (__cplusplus < 201103L && !defined __GXX_EXPERIMENTAL_CXX0X__) \ 
456 : (!defined __STDC_VERSION__ || __STDC_VERSION__ < 199901L))) 
457# define __GLIBC_USE_DEPRECATED_SCANF 1 
458#else 
459# define __GLIBC_USE_DEPRECATED_SCANF 0 
460#endif 
461 
462/* Get definitions of __STDC_* predefined macros, if the compiler has 
463 not preincluded this header automatically. */ 
464#include <stdc-predef.h> 
465 
466/* This macro indicates that the installed library is the GNU C Library. 
467 For historic reasons the value now is 6 and this will stay from now 
468 on. The use of this variable is deprecated. Use __GLIBC__ and 
469 __GLIBC_MINOR__ now (see below) when you want to test for a specific 
470 GNU C library version and use the values in <gnu/lib-names.h> to get 
471 the sonames of the shared libraries. */ 
472#undef __GNU_LIBRARY__ 
473#define __GNU_LIBRARY__ 6 
474 
475/* Major and minor version number of the GNU C library package. Use 
476 these macros to test for features in specific releases. */ 
477#define __GLIBC__ 2 
478#define __GLIBC_MINOR__ 35 
479 
480#define __GLIBC_PREREQ(maj, min) \ 
481 ((__GLIBC__ << 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min)) 
482 
483/* This is here only because every header file already includes this one. */ 
484#ifndef __ASSEMBLER__ 
485# ifndef _SYS_CDEFS_H 
486# include <sys/cdefs.h> 
487# endif 
488 
489/* If we don't have __REDIRECT, prototypes will be missing if 
490 __USE_FILE_OFFSET64 but not __USE_LARGEFILE[64]. */ 
491# if defined __USE_FILE_OFFSET64 && !defined __REDIRECT 
492# define __USE_LARGEFILE 1 
493# define __USE_LARGEFILE64 1 
494# endif 
495 
496#endif /* !ASSEMBLER */ 
497 
498/* Decide whether we can define 'extern inline' functions in headers. */ 
499#if __GNUC_PREREQ (2, 7) && defined __OPTIMIZE__ \ 
500 && !defined __OPTIMIZE_SIZE__ && !defined __NO_INLINE__ \ 
501 && defined __extern_inline 
502# define __USE_EXTERN_INLINES 1 
503#endif 
504 
505 
506/* This is here only because every header file already includes this one. 
507 Get the definitions of all the appropriate `__stub_FUNCTION' symbols. 
508 <gnu/stubs.h> contains `#define __stub_FUNCTION' when FUNCTION is a stub 
509 that will always return failure (and set errno to ENOSYS). */ 
510#include <gnu/stubs.h> 
511 
512 
513#endif /* features.h */ 
514