misc/sys/cdefs.h

   1 /* Copyright (C) 1992-2017 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 _SYS_CDEFS_H
  19 #define _SYS_CDEFS_H    1
  20
  21 /* We are almost always included from features.h. */
  22 #ifndef _FEATURES_H
  23 # include <features.h>
  24 #endif
  25
  26 /* The GNU libc does not support any K&R compilers or the traditional mode
  27    of ISO C compilers anymore.  Check for some of the combinations not
  28    anymore supported.  */
  29 #if defined __GNUC__ && !defined __STDC__
  30 # error "You need a ISO C conforming compiler to use the glibc headers"
  31 #endif
  32
  33 /* Some user header file might have defined this before.  */
  34 #undef  __P
  35 #undef  __PMT
  36
  37 #ifdef __GNUC__
  38
  39 /* All functions, except those with callbacks or those that
  40    synchronize memory, are leaf functions.  */
  41 # if __GNUC_PREREQ (4, 6) && !defined _LIBC
  42 #  define __LEAF , __leaf__
  43 #  define __LEAF_ATTR __attribute__ ((__leaf__))
  44 # else
  45 #  define __LEAF
  46 #  define __LEAF_ATTR
  47 # endif
  48
  49 /* GCC can always grok prototypes.  For C++ programs we add throw()
  50    to help it optimize the function calls.  But this works only with
  51    gcc 2.8.x and egcs.  For gcc 3.2 and up we even mark C functions
  52    as non-throwing using a function attribute since programs can use
  53    the -fexceptions options for C code as well.  */
  54 # if !defined __cplusplus && __GNUC_PREREQ (3, 3)
  55 #  define __THROW       __attribute__ ((__nothrow__ __LEAF))
  56 #  define __THROWNL     __attribute__ ((__nothrow__))
  57 #  define __NTH(fct)    __attribute__ ((__nothrow__ __LEAF)) fct
  58 #  define __NTHNL(fct)  __attribute__ ((__nothrow__)) fct
  59 # else
  60 #  if defined __cplusplus && __GNUC_PREREQ (2,8)
  61 #   define __THROW      throw ()
  62 #   define __THROWNL    throw ()
  63 #   define __NTH(fct)   __LEAF_ATTR fct throw ()
  64 #   define __NTHNL(fct) fct throw ()
  65 #  else
  66 #   define __THROW
  67 #   define __THROWNL
  68 #   define __NTH(fct)   fct
  69 #   define __NTHNL(fct) fct
  70 #  endif
  71 # endif
  72
  73 #else   /* Not GCC.  */
  74
  75 # define __inline               /* No inline functions.  */
  76
  77 # define __THROW
  78 # define __THROWNL
  79 # define __NTH(fct)     fct
  80
  81 #endif  /* GCC.  */
  82
  83 /* Compilers that are not clang may object to
  84        #if defined __clang__ && __has_extension(...)
  85    even though they do not need to evaluate the right-hand side of the &&.  */
  86 #if defined __clang__ && defined __has_extension
  87 # define __glibc_clang_has_extension(ext) __has_extension (ext)
  88 #else
  89 # define __glibc_clang_has_extension(ext) 0
  90 #endif
  91
  92 /* These two macros are not used in glibc anymore.  They are kept here
  93    only because some other projects expect the macros to be defined.  */
  94 #define __P(args)       args
  95 #define __PMT(args)     args
  96
  97 /* For these things, GCC behaves the ANSI way normally,
  98    and the non-ANSI way under -traditional.  */
  99
 100 #define __CONCAT(x,y)   x ## y
 101 #define __STRING(x)     #x
 102
 103 /* This is not a typedef so `const __ptr_t' does the right thing.  */
 104 #define __ptr_t void *
 105
 106
 107 /* C++ needs to know that types and declarations are C, not C++.  */
 108 #ifdef  __cplusplus
 109 # define __BEGIN_DECLS  extern "C" {
 110 # define __END_DECLS    }
 111 #else
 112 # define __BEGIN_DECLS
 113 # define __END_DECLS
 114 #endif
 115
 116
 117 /* Fortify support.  */
 118 #define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
 119 #define __bos0(ptr) __builtin_object_size (ptr, 0)
 120
 121 #if __GNUC_PREREQ (4,3)
 122 # define __warndecl(name, msg) \
 123   extern void name (void) __attribute__((__warning__ (msg)))
 124 # define __warnattr(msg) __attribute__((__warning__ (msg)))
 125 # define __errordecl(name, msg) \
 126   extern void name (void) __attribute__((__error__ (msg)))
 127 #else
 128 # define __warndecl(name, msg) extern void name (void)
 129 # define __warnattr(msg)
 130 # define __errordecl(name, msg) extern void name (void)
 131 #endif
 132
 133 /* Support for flexible arrays.
 134    Headers that should use flexible arrays only if they're "real"
 135    (e.g. only if they won't affect sizeof()) should test
 136    #if __glibc_c99_flexarr_available.  */
 137 #if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 138 # define __flexarr      []
 139 # define __glibc_c99_flexarr_available 1
 140 #elif __GNUC_PREREQ (2,97)
 141 /* GCC 2.97 supports C99 flexible array members as an extension,
 142    even when in C89 mode or compiling C++ (any version).  */
 143 # define __flexarr      []
 144 # define __glibc_c99_flexarr_available 1
 145 #elif defined __GNUC__
 146 /* Pre-2.97 GCC did not support C99 flexible arrays but did have
 147    an equivalent extension with slightly different notation.  */
 148 # define __flexarr      [0]
 149 # define __glibc_c99_flexarr_available 1
 150 #else
 151 /* Some other non-C99 compiler.  Approximate with [1].  */
 152 # define __flexarr      [1]
 153 # define __glibc_c99_flexarr_available 0
 154 #endif
 155
 156
 157 /* __asm__ ("xyz") is used throughout the headers to rename functions
 158    at the assembly language level.  This is wrapped by the __REDIRECT
 159    macro, in order to support compilers that can do this some other
 160    way.  When compilers don't support asm-names at all, we have to do
 161    preprocessor tricks instead (which don't have exactly the right
 162    semantics, but it's the best we can do).
 163
 164    Example:
 165    int __REDIRECT(setpgrp, (__pid_t pid, __pid_t pgrp), setpgid); */
 166
 167 #if defined __GNUC__ && __GNUC__ >= 2
 168
 169 # define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
 170 # ifdef __cplusplus
 171 #  define __REDIRECT_NTH(name, proto, alias) \
 172      name proto __THROW __asm__ (__ASMNAME (#alias))
 173 #  define __REDIRECT_NTHNL(name, proto, alias) \
 174      name proto __THROWNL __asm__ (__ASMNAME (#alias))
 175 # else
 176 #  define __REDIRECT_NTH(name, proto, alias) \
 177      name proto __asm__ (__ASMNAME (#alias)) __THROW
 178 #  define __REDIRECT_NTHNL(name, proto, alias) \
 179      name proto __asm__ (__ASMNAME (#alias)) __THROWNL
 180 # endif
 181 # define __ASMNAME(cname)  __ASMNAME2 (__USER_LABEL_PREFIX__, cname)
 182 # define __ASMNAME2(prefix, cname) __STRING (prefix) cname
 183
 184 /*
 185 #elif __SOME_OTHER_COMPILER__
 186
 187 # define __REDIRECT(name, proto, alias) name proto; \
 188         _Pragma("let " #name " = " #alias)
 189 */
 190 #endif
 191
 192 /* GCC has various useful declarations that can be made with the
 193    `__attribute__' syntax.  All of the ways we use this do fine if
 194    they are omitted for compilers that don't understand it. */
 195 #if !defined __GNUC__ || __GNUC__ < 2
 196 # define __attribute__(xyz)     /* Ignore */
 197 #endif
 198
 199 /* At some point during the gcc 2.96 development the `malloc' attribute
 200    for functions was introduced.  We don't want to use it unconditionally
 201    (although this would be possible) since it generates warnings.  */
 202 #if __GNUC_PREREQ (2,96)
 203 # define __attribute_malloc__ __attribute__ ((__malloc__))
 204 #else
 205 # define __attribute_malloc__ /* Ignore */
 206 #endif
 207
 208 /* Tell the compiler which arguments to an allocation function
 209    indicate the size of the allocation.  */
 210 #if __GNUC_PREREQ (4, 3)
 211 # define __attribute_alloc_size__(params) \
 212   __attribute__ ((__alloc_size__ params))
 213 #else
 214 # define __attribute_alloc_size__(params) /* Ignore.  */
 215 #endif
 216
 217 /* At some point during the gcc 2.96 development the `pure' attribute
 218    for functions was introduced.  We don't want to use it unconditionally
 219    (although this would be possible) since it generates warnings.  */
 220 #if __GNUC_PREREQ (2,96)
 221 # define __attribute_pure__ __attribute__ ((__pure__))
 222 #else
 223 # define __attribute_pure__ /* Ignore */
 224 #endif
 225
 226 /* This declaration tells the compiler that the value is constant.  */
 227 #if __GNUC_PREREQ (2,5)
 228 # define __attribute_const__ __attribute__ ((__const__))
 229 #else
 230 # define __attribute_const__ /* Ignore */
 231 #endif
 232
 233 /* At some point during the gcc 3.1 development the `used' attribute
 234    for functions was introduced.  We don't want to use it unconditionally
 235    (although this would be possible) since it generates warnings.  */
 236 #if __GNUC_PREREQ (3,1)
 237 # define __attribute_used__ __attribute__ ((__used__))
 238 # define __attribute_noinline__ __attribute__ ((__noinline__))
 239 #else
 240 # define __attribute_used__ __attribute__ ((__unused__))
 241 # define __attribute_noinline__ /* Ignore */
 242 #endif
 243
 244 /* Since version 3.2, gcc allows marking deprecated functions.  */
 245 #if __GNUC_PREREQ (3,2)
 246 # define __attribute_deprecated__ __attribute__ ((__deprecated__))
 247 #else
 248 # define __attribute_deprecated__ /* Ignore */
 249 #endif
 250
 251 /* Since version 4.5, gcc also allows one to specify the message printed
 252    when a deprecated function is used.  clang claims to be gcc 4.2, but
 253    may also support this feature.  */
 254 #if __GNUC_PREREQ (4,5) || \
 255     __glibc_clang_has_extension (__attribute_deprecated_with_message__)
 256 # define __attribute_deprecated_msg__(msg) \
 257          __attribute__ ((__deprecated__ (msg)))
 258 #else
 259 # define __attribute_deprecated_msg__(msg) __attribute_deprecated__
 260 #endif
 261
 262 /* At some point during the gcc 2.8 development the `format_arg' attribute
 263    for functions was introduced.  We don't want to use it unconditionally
 264    (although this would be possible) since it generates warnings.
 265    If several `format_arg' attributes are given for the same function, in
 266    gcc-3.0 and older, all but the last one are ignored.  In newer gccs,
 267    all designated arguments are considered.  */
 268 #if __GNUC_PREREQ (2,8)
 269 # define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
 270 #else
 271 # define __attribute_format_arg__(x) /* Ignore */
 272 #endif
 273
 274 /* At some point during the gcc 2.97 development the `strfmon' format
 275    attribute for functions was introduced.  We don't want to use it
 276    unconditionally (although this would be possible) since it
 277    generates warnings.  */
 278 #if __GNUC_PREREQ (2,97)
 279 # define __attribute_format_strfmon__(a,b) \
 280   __attribute__ ((__format__ (__strfmon__, a, b)))
 281 #else
 282 # define __attribute_format_strfmon__(a,b) /* Ignore */
 283 #endif
 284
 285 /* The nonull function attribute allows to mark pointer parameters which
 286    must not be NULL.  */
 287 #if __GNUC_PREREQ (3,3)
 288 # define __nonnull(params) __attribute__ ((__nonnull__ params))
 289 #else
 290 # define __nonnull(params)
 291 #endif
 292
 293 /* If fortification mode, we warn about unused results of certain
 294    function calls which can lead to problems.  */
 295 #if __GNUC_PREREQ (3,4)
 296 # define __attribute_warn_unused_result__ \
 297    __attribute__ ((__warn_unused_result__))
 298 # if __USE_FORTIFY_LEVEL > 0
 299 #  define __wur __attribute_warn_unused_result__
 300 # endif
 301 #else
 302 # define __attribute_warn_unused_result__ /* empty */
 303 #endif
 304 #ifndef __wur
 305 # define __wur /* Ignore */
 306 #endif
 307
 308 /* Forces a function to be always inlined.  */
 309 #if __GNUC_PREREQ (3,2)
 310 /* The Linux kernel defines __always_inline in stddef.h (283d7573), and
 311    it conflicts with this definition.  Therefore undefine it first to
 312    allow either header to be included first.  */
 313 # undef __always_inline
 314 # define __always_inline __inline __attribute__ ((__always_inline__))
 315 #else
 316 # undef __always_inline
 317 # define __always_inline __inline
 318 #endif
 319
 320 /* Associate error messages with the source location of the call site rather
 321    than with the source location inside the function.  */
 322 #if __GNUC_PREREQ (4,3)
 323 # define __attribute_artificial__ __attribute__ ((__artificial__))
 324 #else
 325 # define __attribute_artificial__ /* Ignore */
 326 #endif
 327
 328 /* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
 329    inline semantics, unless -fgnu89-inline is used.  Using __GNUC_STDC_INLINE__
 330    or __GNUC_GNU_INLINE is not a good enough check for gcc because gcc versions
 331    older than 4.3 may define these macros and still not guarantee GNU inlining
 332    semantics.
 333
 334    clang++ identifies itself as gcc-4.2, but has support for GNU inlining
 335    semantics, that can be checked fot by using the __GNUC_STDC_INLINE_ and
 336    __GNUC_GNU_INLINE__ macro definitions.  */
 337 #if (!defined __cplusplus || __GNUC_PREREQ (4,3) \
 338      || (defined __clang__ && (defined __GNUC_STDC_INLINE__ \
 339                                || defined __GNUC_GNU_INLINE__)))
 340 # if defined __GNUC_STDC_INLINE__ || defined __cplusplus
 341 #  define __extern_inline extern __inline __attribute__ ((__gnu_inline__))
 342 #  define __extern_always_inline \
 343   extern __always_inline __attribute__ ((__gnu_inline__))
 344 # else
 345 #  define __extern_inline extern __inline
 346 #  define __extern_always_inline extern __always_inline
 347 # endif
 348 #endif
 349
 350 #ifdef __extern_always_inline
 351 # define __fortify_function __extern_always_inline __attribute_artificial__
 352 #endif
 353
 354 /* GCC 4.3 and above allow passing all anonymous arguments of an
 355    __extern_always_inline function to some other vararg function.  */
 356 #if __GNUC_PREREQ (4,3)
 357 # define __va_arg_pack() __builtin_va_arg_pack ()
 358 # define __va_arg_pack_len() __builtin_va_arg_pack_len ()
 359 #endif
 360
 361 /* It is possible to compile containing GCC extensions even if GCC is
 362    run in pedantic mode if the uses are carefully marked using the
 363    `__extension__' keyword.  But this is not generally available before
 364    version 2.8.  */
 365 #if !__GNUC_PREREQ (2,8)
 366 # define __extension__          /* Ignore */
 367 #endif
 368
 369 /* __restrict is known in EGCS 1.2 and above. */
 370 #if !__GNUC_PREREQ (2,92)
 371 # define __restrict     /* Ignore */
 372 #endif
 373
 374 /* ISO C99 also allows to declare arrays as non-overlapping.  The syntax is
 375      array_name[restrict]
 376    GCC 3.1 supports this.  */
 377 #if __GNUC_PREREQ (3,1) && !defined __GNUG__
 378 # define __restrict_arr __restrict
 379 #else
 380 # ifdef __GNUC__
 381 #  define __restrict_arr        /* Not supported in old GCC.  */
 382 # else
 383 #  if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 384 #   define __restrict_arr       restrict
 385 #  else
 386 /* Some other non-C99 compiler.  */
 387 #   define __restrict_arr       /* Not supported.  */
 388 #  endif
 389 # endif
 390 #endif
 391
 392 #if __GNUC__ >= 3
 393 # define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
 394 # define __glibc_likely(cond)   __builtin_expect ((cond), 1)
 395 #else
 396 # define __glibc_unlikely(cond) (cond)
 397 # define __glibc_likely(cond)   (cond)
 398 #endif
 399
 400 #if (!defined _Noreturn \
 401      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 402      &&  !__GNUC_PREREQ (4,7))
 403 # if __GNUC_PREREQ (2,8)
 404 #  define _Noreturn __attribute__ ((__noreturn__))
 405 # else
 406 #  define _Noreturn
 407 # endif
 408 #endif
 409
 410 #if __GNUC_PREREQ (8, 0)
 411 /* Describes a char array whose address can safely be passed as the first
 412    argument to strncpy and strncat, as the char array is not necessarily
 413    a NUL-terminated string.  */
 414 # define __attribute_nonstring__ __attribute__ ((__nonstring__))
 415 #else
 416 # define __attribute_nonstring__
 417 #endif
 418
 419 #if (!defined _Static_assert && !defined __cplusplus \
 420      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 421      && (!__GNUC_PREREQ (4, 6) || defined __STRICT_ANSI__))
 422 # define _Static_assert(expr, diagnostic) \
 423     extern int (*__Static_assert_function (void)) \
 424       [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
 425 #endif
 426
 427 #include <bits/wordsize.h>
 428 #include <bits/long-double.h>
 429
 430 #if defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
 431 # define __LDBL_COMPAT 1
 432 # ifdef __REDIRECT
 433 #  define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
 434 #  define __LDBL_REDIR(name, proto) \
 435   __LDBL_REDIR1 (name, proto, __nldbl_##name)
 436 #  define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
 437 #  define __LDBL_REDIR_NTH(name, proto) \
 438   __LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
 439 #  define __LDBL_REDIR1_DECL(name, alias) \
 440   extern __typeof (name) name __asm (__ASMNAME (#alias));
 441 #  define __LDBL_REDIR_DECL(name) \
 442   extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
 443 #  define __REDIRECT_LDBL(name, proto, alias) \
 444   __LDBL_REDIR1 (name, proto, __nldbl_##alias)
 445 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 446   __LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
 447 # endif
 448 #endif
 449 #if !defined __LDBL_COMPAT || !defined __REDIRECT
 450 # define __LDBL_REDIR1(name, proto, alias) name proto
 451 # define __LDBL_REDIR(name, proto) name proto
 452 # define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
 453 # define __LDBL_REDIR_NTH(name, proto) name proto __THROW
 454 # define __LDBL_REDIR_DECL(name)
 455 # ifdef __REDIRECT
 456 #  define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
 457 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 458   __REDIRECT_NTH (name, proto, alias)
 459 # endif
 460 #endif
 461
 462 /* __glibc_macro_warning (MESSAGE) issues warning MESSAGE.  This is
 463    intended for use in preprocessor macros.
 464
 465    Note: MESSAGE must be a _single_ string; concatenation of string
 466    literals is not supported.  */
 467 #if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
 468 # define __glibc_macro_warning1(message) _Pragma (#message)
 469 # define __glibc_macro_warning(message) \
 470   __glibc_macro_warning1 (GCC warning message)
 471 #else
 472 # define __glibc_macro_warning(msg)
 473 #endif
 474
 475 /* Generic selection (ISO C11) is a C-only feature, available in GCC
 476    since version 4.9.  Previous versions do not provide generic
 477    selection, even though they might set __STDC_VERSION__ to 201112L,
 478    when in -std=c11 mode.  Thus, we must check for !defined __GNUC__
 479    when testing __STDC_VERSION__ for generic selection support.
 480    On the other hand, Clang also defines __GNUC__, so a clang-specific
 481    check is required to enable the use of generic selection.  */
 482 #if !defined __cplusplus \
 483     && (__GNUC_PREREQ (4, 9) \
 484         || __glibc_clang_has_extension (c_generic_selections) \
 485         || (!defined __GNUC__ && defined __STDC_VERSION__ \
 486             && __STDC_VERSION__ >= 201112L))
 487 # define __HAVE_GENERIC_SELECTION 1
 488 #else
 489 # define __HAVE_GENERIC_SELECTION 0
 490 #endif
 491
 492 #endif   /* sys/cdefs.h */