lib/cdefs.h

   1 /* Copyright (C) 1992-2024 Free Software Foundation, Inc.
   2    Copyright The GNU Toolchain Authors.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _SYS_CDEFS_H
  20 #define _SYS_CDEFS_H    1
  21
  22 /* We are almost always included from features.h. */
  23 #ifndef _FEATURES_H
  24 # include <features.h>
  25 #endif
  26
  27 /* The GNU libc does not support any K&R compilers or the traditional mode
  28    of ISO C compilers anymore.  Check for some of the combinations not
  29    supported anymore.  */
  30 #if defined __GNUC__ && !defined __STDC__
  31 # error "You need a ISO C conforming compiler to use the glibc headers"
  32 #endif
  33
  34 /* Some user header file might have defined this before.  */
  35 #undef  __P
  36 #undef  __PMT
  37
  38 /* Compilers that lack __has_attribute may object to
  39        #if defined __has_attribute && __has_attribute (...)
  40    even though they do not need to evaluate the right-hand side of the &&.
  41    Similarly for __has_builtin, etc.  */
  42 #if (defined __has_attribute \
  43      && (!defined __clang_minor__ \
  44          || (defined __apple_build_version__ \
  45              ? 7000000 <= __apple_build_version__ \
  46              : 5 <= __clang_major__)))
  47 # define __glibc_has_attribute(attr) __has_attribute (attr)
  48 #else
  49 # define __glibc_has_attribute(attr) 0
  50 #endif
  51 #ifdef __has_builtin
  52 # define __glibc_has_builtin(name) __has_builtin (name)
  53 #else
  54 # define __glibc_has_builtin(name) 0
  55 #endif
  56 #ifdef __has_extension
  57 # define __glibc_has_extension(ext) __has_extension (ext)
  58 #else
  59 # define __glibc_has_extension(ext) 0
  60 #endif
  61
  62 #if defined __GNUC__ || defined __clang__
  63
  64 /* All functions, except those with callbacks or those that
  65    synchronize memory, are leaf functions.  */
  66 # if __GNUC_PREREQ (4, 6) && !defined _LIBC
  67 #  define __LEAF , __leaf__
  68 #  define __LEAF_ATTR __attribute__ ((__leaf__))
  69 # else
  70 #  define __LEAF
  71 #  define __LEAF_ATTR
  72 # endif
  73
  74 /* GCC can always grok prototypes.  For C++ programs we add throw()
  75    to help it optimize the function calls.  But this only works with
  76    gcc 2.8.x and egcs.  For gcc 3.4 and up we even mark C functions
  77    as non-throwing using a function attribute since programs can use
  78    the -fexceptions options for C code as well.  */
  79 # if !defined __cplusplus \
  80      && (__GNUC_PREREQ (3, 4) || __glibc_has_attribute (__nothrow__))
  81 #  define __THROW       __attribute__ ((__nothrow__ __LEAF))
  82 #  define __THROWNL     __attribute__ ((__nothrow__))
  83 #  define __NTH(fct)    __attribute__ ((__nothrow__ __LEAF)) fct
  84 #  define __NTHNL(fct)  __attribute__ ((__nothrow__)) fct
  85 # else
  86 #  if defined __cplusplus && (__GNUC_PREREQ (2,8) || __clang_major >= 4)
  87 #   if __cplusplus >= 201103L
  88 #    define __THROW     noexcept (true)
  89 #   else
  90 #    define __THROW     throw ()
  91 #   endif
  92 #   define __THROWNL    __THROW
  93 #   define __NTH(fct)   __LEAF_ATTR fct __THROW
  94 #   define __NTHNL(fct) fct __THROW
  95 #  else
  96 #   define __THROW
  97 #   define __THROWNL
  98 #   define __NTH(fct)   fct
  99 #   define __NTHNL(fct) fct
 100 #  endif
 101 # endif
 102
 103 #else   /* Not GCC or clang.  */
 104
 105 # if (defined __cplusplus                                               \
 106       || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
 107 #  define __inline      inline
 108 # else
 109 #  define __inline              /* No inline functions.  */
 110 # endif
 111
 112 # define __THROW
 113 # define __THROWNL
 114 # define __NTH(fct)     fct
 115
 116 #endif  /* GCC || clang.  */
 117
 118 /* These two macros are not used in glibc anymore.  They are kept here
 119    only because some other projects expect the macros to be defined.  */
 120 #define __P(args)       args
 121 #define __PMT(args)     args
 122
 123 /* For these things, GCC behaves the ANSI way normally,
 124    and the non-ANSI way under -traditional.  */
 125
 126 #define __CONCAT(x,y)   x ## y
 127 #define __STRING(x)     #x
 128
 129 /* This is not a typedef so `const __ptr_t' does the right thing.  */
 130 #define __ptr_t void *
 131
 132
 133 /* C++ needs to know that types and declarations are C, not C++.  */
 134 #ifdef  __cplusplus
 135 # define __BEGIN_DECLS  extern "C" {
 136 # define __END_DECLS    }
 137 #else
 138 # define __BEGIN_DECLS
 139 # define __END_DECLS
 140 #endif
 141
 142
 143 /* Gnulib avoids these definitions, as they don't work on non-glibc platforms.
 144    In particular, __bos and __bos0 are defined differently in the Android libc.
 145  */
 146 #ifndef __GNULIB_CDEFS
 147
 148 /* Fortify support.  */
 149 # define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
 150 # define __bos0(ptr) __builtin_object_size (ptr, 0)
 151
 152 /* Use __builtin_dynamic_object_size at _FORTIFY_SOURCE=3 when available.  */
 153 # if __USE_FORTIFY_LEVEL == 3 && (__glibc_clang_prereq (9, 0)                 \
 154                                   || __GNUC_PREREQ (12, 0))
 155 #  define __glibc_objsize0(__o) __builtin_dynamic_object_size (__o, 0)
 156 #  define __glibc_objsize(__o) __builtin_dynamic_object_size (__o, 1)
 157 # else
 158 #  define __glibc_objsize0(__o) __bos0 (__o)
 159 #  define __glibc_objsize(__o) __bos (__o)
 160 # endif
 161
 162 /* Compile time conditions to choose between the regular, _chk and _chk_warn
 163    variants.  These conditions should get evaluated to constant and optimized
 164    away.  */
 165
 166 # define __glibc_safe_len_cond(__l, __s, __osz) ((__l) <= (__osz) / (__s))
 167 # define __glibc_unsigned_or_positive(__l) \
 168   ((__typeof (__l)) 0 < (__typeof (__l)) -1                                   \
 169    || (__builtin_constant_p (__l) && (__l) > 0))
 170
 171 /* Length is known to be safe at compile time if the __L * __S <= __OBJSZ
 172    condition can be folded to a constant and if it is true, or unknown (-1) */
 173 # define __glibc_safe_or_unknown_len(__l, __s, __osz) \
 174   ((__osz) == (__SIZE_TYPE__) -1                                              \
 175    || (__glibc_unsigned_or_positive (__l)                                     \
 176        && __builtin_constant_p (__glibc_safe_len_cond ((__SIZE_TYPE__) (__l), \
 177                                                        (__s), (__osz)))       \
 178        && __glibc_safe_len_cond ((__SIZE_TYPE__) (__l), (__s), (__osz))))
 179
 180 /* Conversely, we know at compile time that the length is unsafe if the
 181    __L * __S <= __OBJSZ condition can be folded to a constant and if it is
 182    false.  */
 183 # define __glibc_unsafe_len(__l, __s, __osz) \
 184   (__glibc_unsigned_or_positive (__l)                                         \
 185    && __builtin_constant_p (__glibc_safe_len_cond ((__SIZE_TYPE__) (__l),     \
 186                                                    __s, __osz))               \
 187    && !__glibc_safe_len_cond ((__SIZE_TYPE__) (__l), __s, __osz))
 188
 189 /* Fortify function f.  __f_alias, __f_chk and __f_chk_warn must be
 190    declared.  */
 191
 192 # define __glibc_fortify(f, __l, __s, __osz, ...) \
 193   (__glibc_safe_or_unknown_len (__l, __s, __osz)                              \
 194    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 195    : (__glibc_unsafe_len (__l, __s, __osz)                                    \
 196       ? __ ## f ## _chk_warn (__VA_ARGS__, __osz)                             \
 197       : __ ## f ## _chk (__VA_ARGS__, __osz)))                        \
 198
 199 /* Fortify function f, where object size argument passed to f is the number of
 200    elements and not total size.  */
 201
 202 # define __glibc_fortify_n(f, __l, __s, __osz, ...) \
 203   (__glibc_safe_or_unknown_len (__l, __s, __osz)                              \
 204    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 205    : (__glibc_unsafe_len (__l, __s, __osz)                                    \
 206       ? __ ## f ## _chk_warn (__VA_ARGS__, (__osz) / (__s))                   \
 207       : __ ## f ## _chk (__VA_ARGS__, (__osz) / (__s))))                      \
 208
 209 #endif
 210
 211
 212 #if __GNUC_PREREQ (4,3)
 213 # define __warnattr(msg) __attribute__((__warning__ (msg)))
 214 # define __errordecl(name, msg) \
 215   extern void name (void) __attribute__((__error__ (msg)))
 216 #else
 217 # define __warnattr(msg)
 218 # define __errordecl(name, msg) extern void name (void)
 219 #endif
 220
 221 /* Support for flexible arrays.
 222    Headers that should use flexible arrays only if they're "real"
 223    (e.g. only if they won't affect sizeof()) should test
 224    #if __glibc_c99_flexarr_available.  */
 225 #if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L && !defined __HP_cc
 226 # define __flexarr      []
 227 # define __glibc_c99_flexarr_available 1
 228 #elif __GNUC_PREREQ (2,97) || defined __clang__
 229 /* GCC 2.97 and clang support C99 flexible array members as an extension,
 230    even when in C89 mode or compiling C++ (any version).  */
 231 # define __flexarr      []
 232 # define __glibc_c99_flexarr_available 1
 233 #elif defined __GNUC__
 234 /* Pre-2.97 GCC did not support C99 flexible arrays but did have
 235    an equivalent extension with slightly different notation.  */
 236 # define __flexarr      [0]
 237 # define __glibc_c99_flexarr_available 1
 238 #else
 239 /* Some other non-C99 compiler.  Approximate with [1].  */
 240 # define __flexarr      [1]
 241 # define __glibc_c99_flexarr_available 0
 242 #endif
 243
 244
 245 /* __asm__ ("xyz") is used throughout the headers to rename functions
 246    at the assembly language level.  This is wrapped by the __REDIRECT
 247    macro, in order to support compilers that can do this some other
 248    way.  When compilers don't support asm-names at all, we have to do
 249    preprocessor tricks instead (which don't have exactly the right
 250    semantics, but it's the best we can do).
 251
 252    Example:
 253    int __REDIRECT(setpgrp, (__pid_t pid, __pid_t pgrp), setpgid); */
 254
 255 #if (defined __GNUC__ && __GNUC__ >= 2) || (__clang_major__ >= 4)
 256
 257 # define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
 258 # ifdef __cplusplus
 259 #  define __REDIRECT_NTH(name, proto, alias) \
 260      name proto __THROW __asm__ (__ASMNAME (#alias))
 261 #  define __REDIRECT_NTHNL(name, proto, alias) \
 262      name proto __THROWNL __asm__ (__ASMNAME (#alias))
 263 # else
 264 #  define __REDIRECT_NTH(name, proto, alias) \
 265      name proto __asm__ (__ASMNAME (#alias)) __THROW
 266 #  define __REDIRECT_NTHNL(name, proto, alias) \
 267      name proto __asm__ (__ASMNAME (#alias)) __THROWNL
 268 # endif
 269 # define __ASMNAME(cname)  __ASMNAME2 (__USER_LABEL_PREFIX__, cname)
 270 # define __ASMNAME2(prefix, cname) __STRING (prefix) cname
 271
 272 /*
 273 #elif __SOME_OTHER_COMPILER__
 274
 275 # define __REDIRECT(name, proto, alias) name proto; \
 276         _Pragma("let " #name " = " #alias)
 277 */
 278 #endif
 279
 280 /* GCC and clang have various useful declarations that can be made with
 281    the '__attribute__' syntax.  All of the ways we use this do fine if
 282    they are omitted for compilers that don't understand it.  */
 283 #if !(defined __GNUC__ || defined __clang__)
 284 # define __attribute__(xyz)     /* Ignore */
 285 #endif
 286
 287 /* At some point during the gcc 2.96 development the `malloc' attribute
 288    for functions was introduced.  We don't want to use it unconditionally
 289    (although this would be possible) since it generates warnings.  */
 290 #if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__malloc__)
 291 # define __attribute_malloc__ __attribute__ ((__malloc__))
 292 #else
 293 # define __attribute_malloc__ /* Ignore */
 294 #endif
 295
 296 /* Tell the compiler which arguments to an allocation function
 297    indicate the size of the allocation.  */
 298 #if __GNUC_PREREQ (4, 3)
 299 # define __attribute_alloc_size__(params) \
 300   __attribute__ ((__alloc_size__ params))
 301 #else
 302 # define __attribute_alloc_size__(params) /* Ignore.  */
 303 #endif
 304
 305 /* Tell the compiler which argument to an allocation function
 306    indicates the alignment of the allocation.  */
 307 #if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__alloc_align__)
 308 # define __attribute_alloc_align__(param) \
 309   __attribute__ ((__alloc_align__ param))
 310 #else
 311 # define __attribute_alloc_align__(param) /* Ignore.  */
 312 #endif
 313
 314 /* At some point during the gcc 2.96 development the `pure' attribute
 315    for functions was introduced.  We don't want to use it unconditionally
 316    (although this would be possible) since it generates warnings.  */
 317 #if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__pure__)
 318 # define __attribute_pure__ __attribute__ ((__pure__))
 319 #else
 320 # define __attribute_pure__ /* Ignore */
 321 #endif
 322
 323 /* This declaration tells the compiler that the value is constant.  */
 324 #if __GNUC_PREREQ (2,5) || __glibc_has_attribute (__const__)
 325 # define __attribute_const__ __attribute__ ((__const__))
 326 #else
 327 # define __attribute_const__ /* Ignore */
 328 #endif
 329
 330 #if __GNUC_PREREQ (2,7) || __glibc_has_attribute (__unused__)
 331 # define __attribute_maybe_unused__ __attribute__ ((__unused__))
 332 #else
 333 # define __attribute_maybe_unused__ /* Ignore */
 334 #endif
 335
 336 /* At some point during the gcc 3.1 development the `used' attribute
 337    for functions was introduced.  We don't want to use it unconditionally
 338    (although this would be possible) since it generates warnings.  */
 339 #if __GNUC_PREREQ (3,1) || __glibc_has_attribute (__used__)
 340 # define __attribute_used__ __attribute__ ((__used__))
 341 # define __attribute_noinline__ __attribute__ ((__noinline__))
 342 #else
 343 # define __attribute_used__ __attribute__ ((__unused__))
 344 # define __attribute_noinline__ /* Ignore */
 345 #endif
 346
 347 /* Since version 3.2, gcc allows marking deprecated functions.  */
 348 #if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__deprecated__)
 349 # define __attribute_deprecated__ __attribute__ ((__deprecated__))
 350 #else
 351 # define __attribute_deprecated__ /* Ignore */
 352 #endif
 353
 354 /* Since version 4.5, gcc also allows one to specify the message printed
 355    when a deprecated function is used.  clang claims to be gcc 4.2, but
 356    may also support this feature.  */
 357 #if __GNUC_PREREQ (4,5) \
 358     || __glibc_has_extension (__attribute_deprecated_with_message__)
 359 # define __attribute_deprecated_msg__(msg) \
 360          __attribute__ ((__deprecated__ (msg)))
 361 #else
 362 # define __attribute_deprecated_msg__(msg) __attribute_deprecated__
 363 #endif
 364
 365 /* At some point during the gcc 2.8 development the `format_arg' attribute
 366    for functions was introduced.  We don't want to use it unconditionally
 367    (although this would be possible) since it generates warnings.
 368    If several `format_arg' attributes are given for the same function, in
 369    gcc-3.0 and older, all but the last one are ignored.  In newer gccs,
 370    all designated arguments are considered.  */
 371 #if __GNUC_PREREQ (2,8) || __glibc_has_attribute (__format_arg__)
 372 # define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
 373 #else
 374 # define __attribute_format_arg__(x) /* Ignore */
 375 #endif
 376
 377 /* At some point during the gcc 2.97 development the `strfmon' format
 378    attribute for functions was introduced.  We don't want to use it
 379    unconditionally (although this would be possible) since it
 380    generates warnings.  */
 381 #if __GNUC_PREREQ (2,97) || __glibc_has_attribute (__format__)
 382 # define __attribute_format_strfmon__(a,b) \
 383   __attribute__ ((__format__ (__strfmon__, a, b)))
 384 #else
 385 # define __attribute_format_strfmon__(a,b) /* Ignore */
 386 #endif
 387
 388 /* The nonnull function attribute marks pointer parameters that
 389    must not be NULL.  This has the name __nonnull in glibc,
 390    and __attribute_nonnull__ in files shared with Gnulib to avoid
 391    collision with a different __nonnull in DragonFlyBSD 5.9.  */
 392 #ifndef __attribute_nonnull__
 393 # if __GNUC_PREREQ (3,3) || __glibc_has_attribute (__nonnull__)
 394 #  define __attribute_nonnull__(params) __attribute__ ((__nonnull__ params))
 395 # else
 396 #  define __attribute_nonnull__(params)
 397 # endif
 398 #endif
 399 #ifndef __nonnull
 400 # define __nonnull(params) __attribute_nonnull__ (params)
 401 #endif
 402
 403 /* The returns_nonnull function attribute marks the return type of the function
 404    as always being non-null.  */
 405 #ifndef __returns_nonnull
 406 # if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__returns_nonnull__)
 407 # define __returns_nonnull __attribute__ ((__returns_nonnull__))
 408 # else
 409 # define __returns_nonnull
 410 # endif
 411 #endif
 412
 413 /* If fortification mode, we warn about unused results of certain
 414    function calls which can lead to problems.  */
 415 #if __GNUC_PREREQ (3,4) || __glibc_has_attribute (__warn_unused_result__)
 416 # define __attribute_warn_unused_result__ \
 417    __attribute__ ((__warn_unused_result__))
 418 # if defined __USE_FORTIFY_LEVEL && __USE_FORTIFY_LEVEL > 0
 419 #  define __wur __attribute_warn_unused_result__
 420 # endif
 421 #else
 422 # define __attribute_warn_unused_result__ /* empty */
 423 #endif
 424 #ifndef __wur
 425 # define __wur /* Ignore */
 426 #endif
 427
 428 /* Forces a function to be always inlined.  */
 429 #if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__always_inline__)
 430 /* The Linux kernel defines __always_inline in stddef.h (283d7573), and
 431    it conflicts with this definition.  Therefore undefine it first to
 432    allow either header to be included first.  */
 433 # undef __always_inline
 434 # define __always_inline __inline __attribute__ ((__always_inline__))
 435 #else
 436 # undef __always_inline
 437 # define __always_inline __inline
 438 #endif
 439
 440 /* Associate error messages with the source location of the call site rather
 441    than with the source location inside the function.  */
 442 #if __GNUC_PREREQ (4,3) || __glibc_has_attribute (__artificial__)
 443 # define __attribute_artificial__ __attribute__ ((__artificial__))
 444 #else
 445 # define __attribute_artificial__ /* Ignore */
 446 #endif
 447
 448 /* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
 449    inline semantics, unless -fgnu89-inline is used.  Using __GNUC_STDC_INLINE__
 450    or __GNUC_GNU_INLINE is not a good enough check for gcc because gcc versions
 451    older than 4.3 may define these macros and still not guarantee GNU inlining
 452    semantics.
 453
 454    clang++ identifies itself as gcc-4.2, but has support for GNU inlining
 455    semantics, that can be checked for by using the __GNUC_STDC_INLINE_ and
 456    __GNUC_GNU_INLINE__ macro definitions.  */
 457 #if (!defined __cplusplus || __GNUC_PREREQ (4,3) \
 458      || (defined __clang__ && (defined __GNUC_STDC_INLINE__ \
 459                                || defined __GNUC_GNU_INLINE__)))
 460 # if defined __GNUC_STDC_INLINE__ || defined __cplusplus
 461 #  define __extern_inline extern __inline __attribute__ ((__gnu_inline__))
 462 #  define __extern_always_inline \
 463   extern __always_inline __attribute__ ((__gnu_inline__))
 464 # else
 465 #  define __extern_inline extern __inline
 466 #  define __extern_always_inline extern __always_inline
 467 # endif
 468 #endif
 469
 470 #ifdef __extern_always_inline
 471 # define __fortify_function __extern_always_inline __attribute_artificial__
 472 #endif
 473
 474 /* GCC 4.3 and above allow passing all anonymous arguments of an
 475    __extern_always_inline function to some other vararg function.  */
 476 #if __GNUC_PREREQ (4,3)
 477 # define __va_arg_pack() __builtin_va_arg_pack ()
 478 # define __va_arg_pack_len() __builtin_va_arg_pack_len ()
 479 #endif
 480
 481 /* It is possible to compile containing GCC extensions even if GCC is
 482    run in pedantic mode if the uses are carefully marked using the
 483    `__extension__' keyword.  But this is not generally available before
 484    version 2.8.  */
 485 #if !(__GNUC_PREREQ (2,8) || defined __clang__)
 486 # define __extension__          /* Ignore */
 487 #endif
 488
 489 /* __restrict is known in EGCS 1.2 and above, and in clang.
 490    It works also in C++ mode (outside of arrays), but only when spelled
 491    as '__restrict', not 'restrict'.  */
 492 #if !(__GNUC_PREREQ (2,92) || __clang_major__ >= 3)
 493 # if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 494 #  define __restrict    restrict
 495 # else
 496 #  define __restrict    /* Ignore */
 497 # endif
 498 #endif
 499
 500 /* ISO C99 also allows to declare arrays as non-overlapping.  The syntax is
 501      array_name[restrict]
 502    GCC 3.1 and clang support this.
 503    This syntax is not usable in C++ mode.  */
 504 #if (__GNUC_PREREQ (3,1) || __clang_major__ >= 3) && !defined __cplusplus
 505 # define __restrict_arr __restrict
 506 #else
 507 # ifdef __GNUC__
 508 #  define __restrict_arr        /* Not supported in old GCC.  */
 509 # else
 510 #  if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 511 #   define __restrict_arr       restrict
 512 #  else
 513 /* Some other non-C99 compiler.  */
 514 #   define __restrict_arr       /* Not supported.  */
 515 #  endif
 516 # endif
 517 #endif
 518
 519 #if (__GNUC__ >= 3) || __glibc_has_builtin (__builtin_expect)
 520 # define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
 521 # define __glibc_likely(cond)   __builtin_expect ((cond), 1)
 522 #else
 523 # define __glibc_unlikely(cond) (cond)
 524 # define __glibc_likely(cond)   (cond)
 525 #endif
 526
 527 #if (!defined _Noreturn \
 528      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 529      &&  !(__GNUC_PREREQ (4,7) \
 530            || (3 < __clang_major__ + (5 <= __clang_minor__))))
 531 # if __GNUC_PREREQ (2,8)
 532 #  define _Noreturn __attribute__ ((__noreturn__))
 533 # else
 534 #  define _Noreturn
 535 # endif
 536 #endif
 537
 538 #if __GNUC_PREREQ (8, 0)
 539 /* Describes a char array whose address can safely be passed as the first
 540    argument to strncpy and strncat, as the char array is not necessarily
 541    a NUL-terminated string.  */
 542 # define __attribute_nonstring__ __attribute__ ((__nonstring__))
 543 #else
 544 # define __attribute_nonstring__
 545 #endif
 546
 547 /* Undefine (also defined in libc-symbols.h).  */
 548 #undef __attribute_copy__
 549 #if __GNUC_PREREQ (9, 0)
 550 /* Copies attributes from the declaration or type referenced by
 551    the argument.  */
 552 # define __attribute_copy__(arg) __attribute__ ((__copy__ (arg)))
 553 #else
 554 # define __attribute_copy__(arg)
 555 #endif
 556
 557 #if (!defined _Static_assert && !defined __cplusplus \
 558      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 559      && (!(__GNUC_PREREQ (4, 6) || __clang_major__ >= 4) \
 560          || defined __STRICT_ANSI__))
 561 # define _Static_assert(expr, diagnostic) \
 562     extern int (*__Static_assert_function (void)) \
 563       [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
 564 #endif
 565
 566 /* Gnulib avoids including these, as they don't work on non-glibc or
 567    older glibc platforms.  */
 568 #ifndef __GNULIB_CDEFS
 569 # include <bits/wordsize.h>
 570 # include <bits/long-double.h>
 571 #endif
 572
 573 #if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
 574 # ifdef __REDIRECT
 575
 576 /* Alias name defined automatically.  */
 577 #  define __LDBL_REDIR(name, proto) ... unused__ldbl_redir
 578 #  define __LDBL_REDIR_DECL(name) \
 579   extern __typeof (name) name __asm (__ASMNAME ("__" #name "ieee128"));
 580
 581 /* Alias name defined automatically, with leading underscores.  */
 582 #  define __LDBL_REDIR2_DECL(name) \
 583   extern __typeof (__##name) __##name \
 584     __asm (__ASMNAME ("__" #name "ieee128"));
 585
 586 /* Alias name defined manually.  */
 587 #  define __LDBL_REDIR1(name, proto, alias) ... unused__ldbl_redir1
 588 #  define __LDBL_REDIR1_DECL(name, alias) \
 589   extern __typeof (name) name __asm (__ASMNAME (#alias));
 590
 591 #  define __LDBL_REDIR1_NTH(name, proto, alias) \
 592   __REDIRECT_NTH (name, proto, alias)
 593 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 594   __LDBL_REDIR1_NTH (name, proto, __##alias##ieee128)
 595
 596 /* Unused.  */
 597 #  define __REDIRECT_LDBL(name, proto, alias) ... unused__redirect_ldbl
 598 #  define __LDBL_REDIR_NTH(name, proto) ... unused__ldbl_redir_nth
 599
 600 # else
 601 _Static_assert (0, "IEEE 128-bits long double requires redirection on this platform");
 602 # endif
 603 #elif defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
 604 # define __LDBL_COMPAT 1
 605 # ifdef __REDIRECT
 606 #  define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
 607 #  define __LDBL_REDIR(name, proto) \
 608   __LDBL_REDIR1 (name, proto, __nldbl_##name)
 609 #  define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
 610 #  define __LDBL_REDIR_NTH(name, proto) \
 611   __LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
 612 #  define __LDBL_REDIR2_DECL(name) \
 613   extern __typeof (__##name) __##name __asm (__ASMNAME ("__nldbl___" #name));
 614 #  define __LDBL_REDIR1_DECL(name, alias) \
 615   extern __typeof (name) name __asm (__ASMNAME (#alias));
 616 #  define __LDBL_REDIR_DECL(name) \
 617   extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
 618 #  define __REDIRECT_LDBL(name, proto, alias) \
 619   __LDBL_REDIR1 (name, proto, __nldbl_##alias)
 620 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 621   __LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
 622 # endif
 623 #endif
 624 #if (!defined __LDBL_COMPAT && __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 0) \
 625     || !defined __REDIRECT
 626 # define __LDBL_REDIR1(name, proto, alias) name proto
 627 # define __LDBL_REDIR(name, proto) name proto
 628 # define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
 629 # define __LDBL_REDIR_NTH(name, proto) name proto __THROW
 630 # define __LDBL_REDIR2_DECL(name)
 631 # define __LDBL_REDIR_DECL(name)
 632 # ifdef __REDIRECT
 633 #  define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
 634 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 635   __REDIRECT_NTH (name, proto, alias)
 636 # endif
 637 #endif
 638
 639 /* __glibc_macro_warning (MESSAGE) issues warning MESSAGE.  This is
 640    intended for use in preprocessor macros.
 641
 642    Note: MESSAGE must be a _single_ string; concatenation of string
 643    literals is not supported.  */
 644 #if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
 645 # define __glibc_macro_warning1(message) _Pragma (#message)
 646 # define __glibc_macro_warning(message) \
 647   __glibc_macro_warning1 (GCC warning message)
 648 #else
 649 # define __glibc_macro_warning(msg)
 650 #endif
 651
 652 /* Generic selection (ISO C11) is a C-only feature, available in GCC
 653    since version 4.9.  Previous versions do not provide generic
 654    selection, even though they might set __STDC_VERSION__ to 201112L,
 655    when in -std=c11 mode.  Thus, we must check for !defined __GNUC__
 656    when testing __STDC_VERSION__ for generic selection support.
 657    On the other hand, Clang also defines __GNUC__, so a clang-specific
 658    check is required to enable the use of generic selection.  */
 659 #if !defined __cplusplus \
 660     && (__GNUC_PREREQ (4, 9) \
 661         || __glibc_has_extension (c_generic_selections) \
 662         || (!defined __GNUC__ && defined __STDC_VERSION__ \
 663             && __STDC_VERSION__ >= 201112L))
 664 # define __HAVE_GENERIC_SELECTION 1
 665 #else
 666 # define __HAVE_GENERIC_SELECTION 0
 667 #endif
 668
 669 #if __GNUC_PREREQ (10, 0)
 670 /* Designates a 1-based positional argument ref-index of pointer type
 671    that can be used to access size-index elements of the pointed-to
 672    array according to access mode, or at least one element when
 673    size-index is not provided:
 674      access (access-mode, <ref-index> [, <size-index>])  */
 675 #  define __attr_access(x) __attribute__ ((__access__ x))
 676 /* For _FORTIFY_SOURCE == 3 we use __builtin_dynamic_object_size, which may
 677    use the access attribute to get object sizes from function definition
 678    arguments, so we can't use them on functions we fortify.  Drop the object
 679    size hints for such functions.  */
 680 #  if __USE_FORTIFY_LEVEL == 3
 681 #    define __fortified_attr_access(a, o, s) __attribute__ ((__access__ (a, o)))
 682 #  else
 683 #    define __fortified_attr_access(a, o, s) __attr_access ((a, o, s))
 684 #  endif
 685 #  if __GNUC_PREREQ (11, 0)
 686 #    define __attr_access_none(argno) __attribute__ ((__access__ (__none__, argno)))
 687 #  else
 688 #    define __attr_access_none(argno)
 689 #  endif
 690 #else
 691 #  define __fortified_attr_access(a, o, s)
 692 #  define __attr_access(x)
 693 #  define __attr_access_none(argno)
 694 #endif
 695
 696 #if __GNUC_PREREQ (11, 0)
 697 /* Designates dealloc as a function to call to deallocate objects
 698    allocated by the declared function.  */
 699 # define __attr_dealloc(dealloc, argno) \
 700     __attribute__ ((__malloc__ (dealloc, argno)))
 701 # define __attr_dealloc_free __attr_dealloc (__builtin_free, 1)
 702 #else
 703 # define __attr_dealloc(dealloc, argno)
 704 # define __attr_dealloc_free
 705 #endif
 706
 707 /* Specify that a function such as setjmp or vfork may return
 708    twice.  */
 709 #if __GNUC_PREREQ (4, 1)
 710 # define __attribute_returns_twice__ __attribute__ ((__returns_twice__))
 711 #else
 712 # define __attribute_returns_twice__ /* Ignore.  */
 713 #endif
 714
 715 #endif   /* sys/cdefs.h */