root/lib/cdefs.h

INCLUDED FROM

     1 /* Copyright (C) 1992-2023 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              ? 6000000 <= __apple_build_version__ \
    46              : 3 < __clang_major__ + (5 <= __clang_minor__))))
    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 */