misc/sys/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__ && !defined __cplusplus
  31 # error "You need a ISO C or 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          || 3 < __clang_major__ + (5 <= __clang_minor__)))
  45 # define __glibc_has_attribute(attr) __has_attribute (attr)
  46 #else
  47 # define __glibc_has_attribute(attr) 0
  48 #endif
  49 #ifdef __has_builtin
  50 # define __glibc_has_builtin(name) __has_builtin (name)
  51 #else
  52 # define __glibc_has_builtin(name) 0
  53 #endif
  54 #ifdef __has_extension
  55 # define __glibc_has_extension(ext) __has_extension (ext)
  56 #else
  57 # define __glibc_has_extension(ext) 0
  58 #endif
  59
  60 #if defined __GNUC__ || defined __clang__
  61
  62 /* All functions, except those with callbacks or those that
  63    synchronize memory, are leaf functions.  */
  64 # if __GNUC_PREREQ (4, 6) && !defined _LIBC
  65 #  define __LEAF , __leaf__
  66 #  define __LEAF_ATTR __attribute__ ((__leaf__))
  67 # else
  68 #  define __LEAF
  69 #  define __LEAF_ATTR
  70 # endif
  71
  72 /* GCC can always grok prototypes.  For C++ programs we add throw()
  73    to help it optimize the function calls.  But this only works with
  74    gcc 2.8.x and egcs.  For gcc 3.4 and up we even mark C functions
  75    as non-throwing using a function attribute since programs can use
  76    the -fexceptions options for C code as well.  */
  77 # if !defined __cplusplus \
  78      && (__GNUC_PREREQ (3, 4) || __glibc_has_attribute (__nothrow__))
  79 #  define __THROW       __attribute__ ((__nothrow__ __LEAF))
  80 #  define __THROWNL     __attribute__ ((__nothrow__))
  81 #  define __NTH(fct)    __attribute__ ((__nothrow__ __LEAF)) fct
  82 #  define __NTHNL(fct)  __attribute__ ((__nothrow__)) fct
  83 # else
  84 #  if defined __cplusplus && (__GNUC_PREREQ (2,8) || __clang_major__ >= 4)
  85 #   if __cplusplus >= 201103L
  86 #    define __THROW     noexcept (true)
  87 #   else
  88 #    define __THROW     throw ()
  89 #   endif
  90 #   define __THROWNL    __THROW
  91 #   define __NTH(fct)   __LEAF_ATTR fct __THROW
  92 #   define __NTHNL(fct) fct __THROW
  93 #  else
  94 #   define __THROW
  95 #   define __THROWNL
  96 #   define __NTH(fct)   fct
  97 #   define __NTHNL(fct) fct
  98 #  endif
  99 # endif
 100
 101 # if __GNUC_PREREQ (4, 3) || __glibc_has_attribute (__cold__)
 102 #  define __COLD        __attribute__ ((__cold__))
 103 # else
 104 #  define __COLD
 105 # endif
 106
 107 #else   /* Not GCC or clang.  */
 108
 109 # if (defined __cplusplus                                               \
 110       || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
 111 #  define __inline      inline
 112 # else
 113 #  define __inline              /* No inline functions.  */
 114 # endif
 115
 116 # define __THROW
 117 # define __THROWNL
 118 # define __NTH(fct)     fct
 119 # define __COLD
 120
 121 #endif  /* GCC || clang.  */
 122
 123 /* These two macros are not used in glibc anymore.  They are kept here
 124    only because some other projects expect the macros to be defined.  */
 125 #define __P(args)       args
 126 #define __PMT(args)     args
 127
 128 /* For these things, GCC behaves the ANSI way normally,
 129    and the non-ANSI way under -traditional.  */
 130
 131 #define __CONCAT(x,y)   x ## y
 132 #define __STRING(x)     #x
 133
 134 /* This is not a typedef so `const __ptr_t' does the right thing.  */
 135 #define __ptr_t void *
 136
 137
 138 /* C++ needs to know that types and declarations are C, not C++.  */
 139 #ifdef  __cplusplus
 140 # define __BEGIN_DECLS  extern "C" {
 141 # define __END_DECLS    }
 142 #else
 143 # define __BEGIN_DECLS
 144 # define __END_DECLS
 145 #endif
 146
 147
 148 /* The overloadable attribute was added on clang 2.6. */
 149 #if defined __clang_major__ \
 150     && (__clang_major__ + (__clang_minor__ >= 6) > 2)
 151 # define __attribute_overloadable__ __attribute__((__overloadable__))
 152 #else
 153 # define __attribute_overloadable__
 154 #endif
 155
 156 /* Fortify support.  */
 157 #define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
 158 #define __bos0(ptr) __builtin_object_size (ptr, 0)
 159
 160 /* Use __builtin_dynamic_object_size at _FORTIFY_SOURCE=3 when available.  */
 161 #if __USE_FORTIFY_LEVEL == 3 && (__glibc_clang_prereq (9, 0)                  \
 162                                  || __GNUC_PREREQ (12, 0))
 163 # define __glibc_objsize0(__o) __builtin_dynamic_object_size (__o, 0)
 164 # define __glibc_objsize(__o) __builtin_dynamic_object_size (__o, 1)
 165 #else
 166 # define __glibc_objsize0(__o) __bos0 (__o)
 167 # define __glibc_objsize(__o) __bos (__o)
 168 #endif
 169
 170 #if __USE_FORTIFY_LEVEL > 0
 171 /* Compile time conditions to choose between the regular, _chk and _chk_warn
 172    variants.  These conditions should get evaluated to constant and optimized
 173    away.  */
 174
 175 #define __glibc_safe_len_cond(__l, __s, __osz) ((__l) <= (__osz) / (__s))
 176 #define __glibc_unsigned_or_positive(__l) \
 177   ((__typeof (__l)) 0 < (__typeof (__l)) -1                                   \
 178    || (__builtin_constant_p (__l) && (__l) > 0))
 179
 180 /* Length is known to be safe at compile time if the __L * __S <= __OBJSZ
 181    condition can be folded to a constant and if it is true, or unknown (-1) */
 182 #define __glibc_safe_or_unknown_len(__l, __s, __osz) \
 183   ((__builtin_constant_p (__osz) && (__osz) == (__SIZE_TYPE__) -1)            \
 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 /* Conversely, we know at compile time that the length is unsafe if the
 190    __L * __S <= __OBJSZ condition can be folded to a constant and if it is
 191    false.  */
 192 #define __glibc_unsafe_len(__l, __s, __osz) \
 193   (__glibc_unsigned_or_positive (__l)                                         \
 194    && __builtin_constant_p (__glibc_safe_len_cond ((__SIZE_TYPE__) (__l),     \
 195                                                    __s, __osz))               \
 196    && !__glibc_safe_len_cond ((__SIZE_TYPE__) (__l), __s, __osz))
 197
 198 /* To correctly instrument the fortify wrapper clang requires the
 199    pass_object_size attribute, and the attribute has the restriction that the
 200    argument needs to be 'const'.  Furthermore, to make it usable with C
 201    interfaces, clang provides the overload attribute, which provides a C++
 202    like function overload support.  The overloaded fortify wrapper with the
 203    pass_object_size attribute has precedence over the default symbol.
 204
 205    Also, clang does not support __va_arg_pack, so variadic functions are
 206    expanded to issue va_arg implementations. The error function must not have
 207    bodies (address takes are expanded to nonfortified calls), and with
 208    __fortify_function compiler might still create a body with the C++
 209    mangling name (due to the overload attribute).  In this case, the function
 210    is defined with __fortify_function_error_function macro instead.
 211
 212    The argument size check is also done with a clang-only attribute,
 213    __attribute__ ((__diagnose_if__ (...))), different than gcc which calls
 214    symbol_chk_warn alias with uses __warnattr attribute.
 215
 216    The pass_object_size was added on clang 4.0, __diagnose_if__ on 5.0,
 217    and pass_dynamic_object_size on 9.0.  */
 218 #if defined __clang_major__ && __clang_major__ >= 5
 219 # define __fortify_use_clang 1
 220
 221 # define __fortify_function_error_function static __attribute__((__unused__))
 222
 223 # define __fortify_clang_pass_object_size_n(n) \
 224   __attribute__ ((__pass_object_size__ (n)))
 225 # define __fortify_clang_pass_object_size0 \
 226   __fortify_clang_pass_object_size_n (0)
 227 # define __fortify_clang_pass_object_size \
 228   __fortify_clang_pass_object_size_n (__USE_FORTIFY_LEVEL > 1)
 229
 230 # if __clang_major__ >= 9
 231 #  define __fortify_clang_pass_dynamic_object_size_n(n) \
 232   __attribute__ ((__pass_dynamic_object_size__ (n)))
 233 #  define __fortify_clang_pass_dynamic_object_size0 \
 234   __fortify_clang_pass_dynamic_object_size_n (0)
 235 #  define __fortify_clang_pass_dynamic_object_size \
 236   __fortify_clang_pass_dynamic_object_size_n (1)
 237 # else
 238 #  define __fortify_clang_pass_dynamic_object_size_n(n)
 239 #  define __fortify_clang_pass_dynamic_object_size0
 240 #  define __fortify_clang_pass_dynamic_object_size
 241 # endif
 242
 243 # define __fortify_clang_bos_static_lt_impl(bos_val, n, s) \
 244   ((bos_val) != -1ULL && (n) > (bos_val) / (s))
 245 # define __fortify_clang_bos_static_lt2(__n, __e, __s) \
 246   __fortify_clang_bos_static_lt_impl (__bos (__e), __n, __s)
 247 # define __fortify_clang_bos_static_lt(__n, __e) \
 248   __fortify_clang_bos_static_lt2 (__n, __e, 1)
 249 # define __fortify_clang_bos0_static_lt2(__n, __e, __s) \
 250   __fortify_clang_bos_static_lt_impl (__bos0 (__e), __n, __s)
 251 # define __fortify_clang_bos0_static_lt(__n, __e) \
 252   __fortify_clang_bos0_static_lt2 (__n, __e, 1)
 253
 254 # define __fortify_clang_bosn_args(bos_fn, n, buf, div, complaint) \
 255   (__fortify_clang_bos_static_lt_impl (bos_fn (buf), n, div)), (complaint), \
 256   "warning"
 257
 258 # define __fortify_clang_warning(__c, __msg) \
 259   __attribute__ ((__diagnose_if__ ((__c), (__msg), "warning")))
 260 #  define __fortify_clang_error(__c, __msg) \
 261   __attribute__ ((__diagnose_if__ ((__c), (__msg), "error")))
 262 #  define __fortify_clang_warning_only_if_bos0_lt(n, buf, complaint) \
 263   __attribute__ ((__diagnose_if__ \
 264                   (__fortify_clang_bosn_args (__bos0, n, buf, 1, complaint))))
 265 # define __fortify_clang_warning_only_if_bos0_lt2(n, buf, div, complaint) \
 266   __attribute__ ((__diagnose_if__ \
 267                   (__fortify_clang_bosn_args (__bos0, n, buf, div, complaint))))
 268 # define __fortify_clang_warning_only_if_bos_lt(n, buf, complaint) \
 269   __attribute__ ((__diagnose_if__ \
 270                   (__fortify_clang_bosn_args (__bos, n, buf, 1, complaint))))
 271 # define __fortify_clang_warning_only_if_bos_lt2(n, buf, div, complaint) \
 272   __attribute__ ((__diagnose_if__ \
 273                   (__fortify_clang_bosn_args (__bos, n, buf, div, complaint))))
 274
 275 #  define __fortify_clang_prefer_this_overload \
 276   __attribute__ ((enable_if (1, "")))
 277 #  define __fortify_clang_unavailable(__msg) \
 278   __attribute__ ((unavailable(__msg)))
 279
 280 # if __USE_FORTIFY_LEVEL == 3
 281 #  define __fortify_clang_overload_arg(__type, __attr, __name) \
 282   __type __attr const __fortify_clang_pass_dynamic_object_size __name
 283 #  define __fortify_clang_overload_arg0(__type, __attr, __name) \
 284   __type __attr const __fortify_clang_pass_dynamic_object_size0 __name
 285 # else
 286 #  define __fortify_clang_overload_arg(__type, __attr, __name) \
 287   __type __attr const __fortify_clang_pass_object_size __name
 288 #  define __fortify_clang_overload_arg0(__type, __attr, __name) \
 289   __type __attr const __fortify_clang_pass_object_size0 __name
 290 # endif
 291
 292 # define __fortify_clang_mul_may_overflow(size, n) \
 293   ((size | n) >= (((size_t)1) << (8 * sizeof (size_t) / 2)))
 294
 295 # define __fortify_clang_size_too_small(__bos, __dest, __len) \
 296   (__bos (__dest) != (size_t) -1 && __bos (__dest) < __len)
 297 # define __fortify_clang_warn_if_src_too_large(__dest, __src) \
 298   __fortify_clang_warning (__fortify_clang_size_too_small (__glibc_objsize, \
 299                                                            __dest, \
 300                                                            __builtin_strlen (__src) + 1), \
 301                            "destination buffer will always be overflown by source")
 302 # define __fortify_clang_warn_if_dest_too_small(__dest, __len) \
 303   __fortify_clang_warning (__fortify_clang_size_too_small (__glibc_objsize, \
 304                                                            __dest, \
 305                                                            __len), \
 306                            "function called with bigger length than the destination buffer")
 307 # define __fortify_clang_warn_if_dest_too_small0(__dest, __len) \
 308   __fortify_clang_warning (__fortify_clang_size_too_small (__glibc_objsize0, \
 309                                                            __dest, \
 310                                                            __len), \
 311                            "function called with bigger length than the destination buffer")
 312 #else
 313 # define __fortify_use_clang 0
 314 # define __fortify_clang_warning(__c, __msg)
 315 # define __fortify_clang_warning_only_if_bos0_lt(__n, __buf, __complaint)
 316 # define __fortify_clang_warning_only_if_bos0_lt2(__n, __buf, __div, complaint)
 317 # define __fortify_clang_warning_only_if_bos_lt(__n, __buf, __complaint)
 318 # define __fortify_clang_warning_only_if_bos_lt2(__n, __buf, div, __complaint)
 319 # define __fortify_clang_overload_arg(__type, __attr, __name) \
 320  __type __attr __name
 321 # define __fortify_clang_overload_arg0(__type, __attr, __name) \
 322   __fortify_clang_overload_arg (__type, __attr, __name)
 323 # define __fortify_clang_warn_if_src_too_large(__dest, __src)
 324 # define __fortify_clang_warn_if_dest_too_small(__dest, __len)
 325 # define __fortify_clang_warn_if_dest_too_small0(__dest, __len)
 326 #endif
 327
 328
 329 /* Fortify function f.  __f_alias, __f_chk and __f_chk_warn must be
 330    declared.  */
 331
 332 #if !__fortify_use_clang
 333 # define __glibc_fortify(f, __l, __s, __osz, ...) \
 334   (__glibc_safe_or_unknown_len (__l, __s, __osz)                              \
 335    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 336    : (__glibc_unsafe_len (__l, __s, __osz)                                    \
 337       ? __ ## f ## _chk_warn (__VA_ARGS__, __osz)                             \
 338       : __ ## f ## _chk (__VA_ARGS__, __osz)))
 339 #else
 340 # define __glibc_fortify(f, __l, __s, __osz, ...) \
 341   (__osz == (__SIZE_TYPE__) -1)                                               \
 342    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 343    : __ ## f ## _chk (__VA_ARGS__, __osz)
 344 #endif
 345
 346 /* Fortify function f, where object size argument passed to f is the number of
 347    elements and not total size.  */
 348
 349 #if !__fortify_use_clang
 350 # define __glibc_fortify_n(f, __l, __s, __osz, ...) \
 351   (__glibc_safe_or_unknown_len (__l, __s, __osz)                              \
 352    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 353    : (__glibc_unsafe_len (__l, __s, __osz)                                    \
 354       ? __ ## f ## _chk_warn (__VA_ARGS__, (__osz) / (__s))                   \
 355       : __ ## f ## _chk (__VA_ARGS__, (__osz) / (__s))))
 356 # else
 357 # define __glibc_fortify_n(f, __l, __s, __osz, ...) \
 358   (__osz == (__SIZE_TYPE__) -1)                                               \
 359    ? __ ## f ## _alias (__VA_ARGS__)                                          \
 360    : __ ## f ## _chk (__VA_ARGS__, (__osz) / (__s))
 361 #endif
 362
 363 #endif /* __USE_FORTIFY_LEVEL > 0 */
 364
 365 #if __GNUC_PREREQ (4,3)
 366 # define __warnattr(msg) __attribute__((__warning__ (msg)))
 367 # define __errordecl(name, msg) \
 368   extern void name (void) __attribute__((__error__ (msg)))
 369 #else
 370 # define __warnattr(msg)
 371 # define __errordecl(name, msg) extern void name (void)
 372 #endif
 373
 374 /* Support for flexible arrays.
 375    Headers that should use flexible arrays only if they're "real"
 376    (e.g. only if they won't affect sizeof()) should test
 377    #if __glibc_c99_flexarr_available.  */
 378 #if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L && !defined __HP_cc
 379 # define __flexarr      []
 380 # define __glibc_c99_flexarr_available 1
 381 #elif __GNUC_PREREQ (2,97) || defined __clang__
 382 /* GCC 2.97 and clang support C99 flexible array members as an extension,
 383    even when in C89 mode or compiling C++ (any version).  */
 384 # define __flexarr      []
 385 # define __glibc_c99_flexarr_available 1
 386 #elif defined __GNUC__
 387 /* Pre-2.97 GCC did not support C99 flexible arrays but did have
 388    an equivalent extension with slightly different notation.  */
 389 # define __flexarr      [0]
 390 # define __glibc_c99_flexarr_available 1
 391 #else
 392 /* Some other non-C99 compiler.  Approximate with [1].  */
 393 # define __flexarr      [1]
 394 # define __glibc_c99_flexarr_available 0
 395 #endif
 396
 397
 398 /* __asm__ ("xyz") is used throughout the headers to rename functions
 399    at the assembly language level.  This is wrapped by the __REDIRECT
 400    macro, in order to support compilers that can do this some other
 401    way.  When compilers don't support asm-names at all, we have to do
 402    preprocessor tricks instead (which don't have exactly the right
 403    semantics, but it's the best we can do).
 404
 405    Example:
 406    int __REDIRECT(setpgrp, (__pid_t pid, __pid_t pgrp), setpgid); */
 407
 408 #if (defined __GNUC__ && __GNUC__ >= 2) || (__clang_major__ >= 4)
 409
 410 # define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
 411 # ifdef __cplusplus
 412 #  define __REDIRECT_NTH(name, proto, alias) \
 413      name proto __THROW __asm__ (__ASMNAME (#alias))
 414 #  define __REDIRECT_NTHNL(name, proto, alias) \
 415      name proto __THROWNL __asm__ (__ASMNAME (#alias))
 416 # else
 417 #  define __REDIRECT_NTH(name, proto, alias) \
 418      name proto __asm__ (__ASMNAME (#alias)) __THROW
 419 #  define __REDIRECT_NTHNL(name, proto, alias) \
 420      name proto __asm__ (__ASMNAME (#alias)) __THROWNL
 421 # endif
 422 # define __ASMNAME(cname)  __ASMNAME2 (__USER_LABEL_PREFIX__, cname)
 423 # define __ASMNAME2(prefix, cname) __STRING (prefix) cname
 424
 425 #ifndef __REDIRECT_FORTIFY
 426 #define __REDIRECT_FORTIFY __REDIRECT
 427 #endif
 428
 429 #ifndef __REDIRECT_FORTIFY_NTH
 430 #define __REDIRECT_FORTIFY_NTH __REDIRECT_NTH
 431 #endif
 432
 433 /*
 434 #elif __SOME_OTHER_COMPILER__
 435
 436 # define __REDIRECT(name, proto, alias) name proto; \
 437         _Pragma("let " #name " = " #alias)
 438 */
 439 #endif
 440
 441 /* GCC and clang have various useful declarations that can be made with
 442    the '__attribute__' syntax.  All of the ways we use this do fine if
 443    they are omitted for compilers that don't understand it.  */
 444 #if !(defined __GNUC__ || defined __clang__)
 445 # define __attribute__(xyz)     /* Ignore */
 446 #endif
 447
 448 /* At some point during the gcc 2.96 development the `malloc' attribute
 449    for functions was introduced.  We don't want to use it unconditionally
 450    (although this would be possible) since it generates warnings.  */
 451 #if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__malloc__)
 452 # define __attribute_malloc__ __attribute__ ((__malloc__))
 453 #else
 454 # define __attribute_malloc__ /* Ignore */
 455 #endif
 456
 457 /* Tell the compiler which arguments to an allocation function
 458    indicate the size of the allocation.  */
 459 #if __GNUC_PREREQ (4, 3)
 460 # define __attribute_alloc_size__(params) \
 461   __attribute__ ((__alloc_size__ params))
 462 #else
 463 # define __attribute_alloc_size__(params) /* Ignore.  */
 464 #endif
 465
 466 /* Tell the compiler which argument to an allocation function
 467    indicates the alignment of the allocation.  */
 468 #if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__alloc_align__)
 469 # define __attribute_alloc_align__(param) \
 470   __attribute__ ((__alloc_align__ param))
 471 #else
 472 # define __attribute_alloc_align__(param) /* Ignore.  */
 473 #endif
 474
 475 /* At some point during the gcc 2.96 development the `pure' attribute
 476    for functions was introduced.  We don't want to use it unconditionally
 477    (although this would be possible) since it generates warnings.  */
 478 #if __GNUC_PREREQ (2,96) || __glibc_has_attribute (__pure__)
 479 # define __attribute_pure__ __attribute__ ((__pure__))
 480 #else
 481 # define __attribute_pure__ /* Ignore */
 482 #endif
 483
 484 /* This declaration tells the compiler that the value is constant.  */
 485 #if __GNUC_PREREQ (2,5) || __glibc_has_attribute (__const__)
 486 # define __attribute_const__ __attribute__ ((__const__))
 487 #else
 488 # define __attribute_const__ /* Ignore */
 489 #endif
 490
 491 #if __GNUC_PREREQ (2,7) || __glibc_has_attribute (__unused__)
 492 # define __attribute_maybe_unused__ __attribute__ ((__unused__))
 493 #else
 494 # define __attribute_maybe_unused__ /* Ignore */
 495 #endif
 496
 497 /* At some point during the gcc 3.1 development the `used' attribute
 498    for functions was introduced.  We don't want to use it unconditionally
 499    (although this would be possible) since it generates warnings.  */
 500 #if __GNUC_PREREQ (3,1) || __glibc_has_attribute (__used__)
 501 # define __attribute_used__ __attribute__ ((__used__))
 502 # define __attribute_noinline__ __attribute__ ((__noinline__))
 503 #else
 504 # define __attribute_used__ __attribute__ ((__unused__))
 505 # define __attribute_noinline__ /* Ignore */
 506 #endif
 507
 508 /* Since version 3.2, gcc allows marking deprecated functions.  */
 509 #if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__deprecated__)
 510 # define __attribute_deprecated__ __attribute__ ((__deprecated__))
 511 #else
 512 # define __attribute_deprecated__ /* Ignore */
 513 #endif
 514
 515 /* Since version 4.5, gcc also allows one to specify the message printed
 516    when a deprecated function is used.  clang claims to be gcc 4.2, but
 517    may also support this feature.  */
 518 #if __GNUC_PREREQ (4,5) \
 519     || __glibc_has_extension (__attribute_deprecated_with_message__)
 520 # define __attribute_deprecated_msg__(msg) \
 521          __attribute__ ((__deprecated__ (msg)))
 522 #else
 523 # define __attribute_deprecated_msg__(msg) __attribute_deprecated__
 524 #endif
 525
 526 /* At some point during the gcc 2.8 development the `format_arg' attribute
 527    for functions was introduced.  We don't want to use it unconditionally
 528    (although this would be possible) since it generates warnings.
 529    If several `format_arg' attributes are given for the same function, in
 530    gcc-3.0 and older, all but the last one are ignored.  In newer gccs,
 531    all designated arguments are considered.  */
 532 #if __GNUC_PREREQ (2,8) || __glibc_has_attribute (__format_arg__)
 533 # define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
 534 #else
 535 # define __attribute_format_arg__(x) /* Ignore */
 536 #endif
 537
 538 /* At some point during the gcc 2.97 development the `strfmon' format
 539    attribute for functions was introduced.  We don't want to use it
 540    unconditionally (although this would be possible) since it
 541    generates warnings.  */
 542 #if __GNUC_PREREQ (2,97) || __glibc_has_attribute (__format__)
 543 # define __attribute_format_strfmon__(a,b) \
 544   __attribute__ ((__format__ (__strfmon__, a, b)))
 545 #else
 546 # define __attribute_format_strfmon__(a,b) /* Ignore */
 547 #endif
 548
 549 /* The nonnull function attribute marks pointer parameters that
 550    must not be NULL.  This has the name __nonnull in glibc,
 551    and __attribute_nonnull__ in files shared with Gnulib to avoid
 552    collision with a different __nonnull in DragonFlyBSD 5.9.  */
 553 #ifndef __attribute_nonnull__
 554 # if __GNUC_PREREQ (3,3) || __glibc_has_attribute (__nonnull__)
 555 #  define __attribute_nonnull__(params) __attribute__ ((__nonnull__ params))
 556 # else
 557 #  define __attribute_nonnull__(params)
 558 # endif
 559 #endif
 560 #ifndef __nonnull
 561 # define __nonnull(params) __attribute_nonnull__ (params)
 562 #endif
 563
 564 /* The returns_nonnull function attribute marks the return type of the function
 565    as always being non-null.  */
 566 #ifndef __returns_nonnull
 567 # if __GNUC_PREREQ (4, 9) || __glibc_has_attribute (__returns_nonnull__)
 568 # define __returns_nonnull __attribute__ ((__returns_nonnull__))
 569 # else
 570 # define __returns_nonnull
 571 # endif
 572 #endif
 573
 574 /* If fortification mode, we warn about unused results of certain
 575    function calls which can lead to problems.  */
 576 #if __GNUC_PREREQ (3,4) || __glibc_has_attribute (__warn_unused_result__)
 577 # define __attribute_warn_unused_result__ \
 578    __attribute__ ((__warn_unused_result__))
 579 # if defined __USE_FORTIFY_LEVEL && __USE_FORTIFY_LEVEL > 0
 580 #  define __wur __attribute_warn_unused_result__
 581 # endif
 582 #else
 583 # define __attribute_warn_unused_result__ /* empty */
 584 #endif
 585 #ifndef __wur
 586 # define __wur /* Ignore */
 587 #endif
 588
 589 /* Forces a function to be always inlined.  */
 590 #if __GNUC_PREREQ (3,2) || __glibc_has_attribute (__always_inline__)
 591 /* The Linux kernel defines __always_inline in stddef.h (283d7573), and
 592    it conflicts with this definition.  Therefore undefine it first to
 593    allow either header to be included first.  */
 594 # undef __always_inline
 595 # define __always_inline __inline __attribute__ ((__always_inline__))
 596 #else
 597 # undef __always_inline
 598 # define __always_inline __inline
 599 #endif
 600
 601 /* Associate error messages with the source location of the call site rather
 602    than with the source location inside the function.  */
 603 #if __GNUC_PREREQ (4,3) || __glibc_has_attribute (__artificial__)
 604 # define __attribute_artificial__ __attribute__ ((__artificial__))
 605 #else
 606 # define __attribute_artificial__ /* Ignore */
 607 #endif
 608
 609 /* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
 610    inline semantics, unless -fgnu89-inline is used.  Using __GNUC_STDC_INLINE__
 611    or __GNUC_GNU_INLINE is not a good enough check for gcc because gcc versions
 612    older than 4.3 may define these macros and still not guarantee GNU inlining
 613    semantics.
 614
 615    clang++ identifies itself as gcc-4.2, but has support for GNU inlining
 616    semantics, that can be checked for by using the __GNUC_STDC_INLINE_ and
 617    __GNUC_GNU_INLINE__ macro definitions.  */
 618 #if (!defined __cplusplus || __GNUC_PREREQ (4,3) \
 619      || (defined __clang__ && (defined __GNUC_STDC_INLINE__ \
 620                                || defined __GNUC_GNU_INLINE__)))
 621 # if defined __GNUC_STDC_INLINE__ || defined __cplusplus
 622 #  define __extern_inline extern __inline __attribute__ ((__gnu_inline__))
 623 #  define __extern_always_inline \
 624   extern __always_inline __attribute__ ((__gnu_inline__))
 625 # else
 626 #  define __extern_inline extern __inline
 627 #  define __extern_always_inline extern __always_inline
 628 # endif
 629 #endif
 630
 631 #ifdef __extern_always_inline
 632 # define __fortify_function __extern_always_inline __attribute_artificial__
 633 #endif
 634
 635 /* GCC 4.3 and above allow passing all anonymous arguments of an
 636    __extern_always_inline function to some other vararg function.  */
 637 #if __GNUC_PREREQ (4,3)
 638 # define __va_arg_pack() __builtin_va_arg_pack ()
 639 # define __va_arg_pack_len() __builtin_va_arg_pack_len ()
 640 #endif
 641
 642 /* It is possible to compile containing GCC extensions even if GCC is
 643    run in pedantic mode if the uses are carefully marked using the
 644    `__extension__' keyword.  But this is not generally available before
 645    version 2.8.  */
 646 #if !(__GNUC_PREREQ (2,8) || defined __clang__)
 647 # define __extension__          /* Ignore */
 648 #endif
 649
 650 /* __restrict is known in EGCS 1.2 and above, and in clang.
 651    It works also in C++ mode (outside of arrays), but only when spelled
 652    as '__restrict', not 'restrict'.  */
 653 #if !(__GNUC_PREREQ (2,92) || __clang_major__ >= 3)
 654 # if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 655 #  define __restrict    restrict
 656 # else
 657 #  define __restrict    /* Ignore */
 658 # endif
 659 #endif
 660
 661 /* ISO C99 also allows to declare arrays as non-overlapping.  The syntax is
 662      array_name[restrict]
 663    GCC 3.1 and clang support this.
 664    This syntax is not usable in C++ mode.  */
 665 #if (__GNUC_PREREQ (3,1) || __clang_major__ >= 3) && !defined __cplusplus
 666 # define __restrict_arr __restrict
 667 #else
 668 # ifdef __GNUC__
 669 #  define __restrict_arr        /* Not supported in old GCC.  */
 670 # else
 671 #  if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 672 #   define __restrict_arr       restrict
 673 #  else
 674 /* Some other non-C99 compiler.  */
 675 #   define __restrict_arr       /* Not supported.  */
 676 #  endif
 677 # endif
 678 #endif
 679
 680 #if (__GNUC__ >= 3) || __glibc_has_builtin (__builtin_expect)
 681 # define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
 682 # define __glibc_likely(cond)   __builtin_expect ((cond), 1)
 683 #else
 684 # define __glibc_unlikely(cond) (cond)
 685 # define __glibc_likely(cond)   (cond)
 686 #endif
 687
 688 #if (!defined _Noreturn \
 689      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 690      &&  !(__GNUC_PREREQ (4,7) \
 691            || (3 < __clang_major__ + (5 <= __clang_minor__))))
 692 # if __GNUC_PREREQ (2,8)
 693 #  define _Noreturn __attribute__ ((__noreturn__))
 694 # else
 695 #  define _Noreturn
 696 # endif
 697 #endif
 698
 699 #if __GNUC_PREREQ (8, 0)
 700 /* Describes a char array whose address can safely be passed as the first
 701    argument to strncpy and strncat, as the char array is not necessarily
 702    a NUL-terminated string.  */
 703 # define __attribute_nonstring__ __attribute__ ((__nonstring__))
 704 #else
 705 # define __attribute_nonstring__
 706 #endif
 707
 708 /* Undefine (also defined in libc-symbols.h).  */
 709 #undef __attribute_copy__
 710 #if __GNUC_PREREQ (9, 0)
 711 /* Copies attributes from the declaration or type referenced by
 712    the argument.  */
 713 # define __attribute_copy__(arg) __attribute__ ((__copy__ (arg)))
 714 #else
 715 # define __attribute_copy__(arg)
 716 #endif
 717
 718 #if (!defined _Static_assert && !defined __cplusplus \
 719      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 720      && (!(__GNUC_PREREQ (4, 6) || __clang_major__ >= 4) \
 721          || defined __STRICT_ANSI__))
 722 # define _Static_assert(expr, diagnostic) \
 723     extern int (*__Static_assert_function (void)) \
 724       [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
 725 #endif
 726
 727 /* Gnulib avoids including these, as they don't work on non-glibc or
 728    older glibc platforms.  */
 729 #ifndef __GNULIB_CDEFS
 730 # include <bits/wordsize.h>
 731 # include <bits/long-double.h>
 732 #endif
 733
 734 #if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
 735 # ifdef __REDIRECT
 736
 737 /* Alias name defined automatically.  */
 738 #  define __LDBL_REDIR(name, proto) ... unused__ldbl_redir
 739 #  define __LDBL_REDIR_DECL(name) \
 740   extern __typeof (name) name __asm (__ASMNAME ("__" #name "ieee128"));
 741 #  define __REDIRECT_LDBL(name, proto, alias) \
 742   name proto __asm (__ASMNAME ("__" #alias "ieee128"))
 743
 744 /* Alias name defined automatically, with leading underscores.  */
 745 #  define __LDBL_REDIR2_DECL(name) \
 746   extern __typeof (__##name) __##name \
 747     __asm (__ASMNAME ("__" #name "ieee128"));
 748
 749 /* Alias name defined manually.  */
 750 #  define __LDBL_REDIR1(name, proto, alias) ... unused__ldbl_redir1
 751 #  define __LDBL_REDIR1_DECL(name, alias) \
 752   extern __typeof (name) name __asm (__ASMNAME (#alias));
 753
 754 #  define __LDBL_REDIR1_NTH(name, proto, alias) \
 755   __REDIRECT_NTH (name, proto, alias)
 756 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 757   __LDBL_REDIR1_NTH (name, proto, __##alias##ieee128)
 758
 759 /* Unused.  */
 760 #  define __LDBL_REDIR_NTH(name, proto) ... unused__ldbl_redir_nth
 761
 762 # else
 763 _Static_assert (0, "IEEE 128-bits long double requires redirection on this platform");
 764 # endif
 765 #elif defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
 766 # define __LDBL_COMPAT 1
 767 # ifdef __REDIRECT
 768 #  define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
 769 #  define __LDBL_REDIR(name, proto) \
 770   __LDBL_REDIR1 (name, proto, __nldbl_##name)
 771 #  define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
 772 #  define __LDBL_REDIR_NTH(name, proto) \
 773   __LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
 774 #  define __LDBL_REDIR2_DECL(name) \
 775   extern __typeof (__##name) __##name __asm (__ASMNAME ("__nldbl___" #name));
 776 #  define __LDBL_REDIR1_DECL(name, alias) \
 777   extern __typeof (name) name __asm (__ASMNAME (#alias));
 778 #  define __LDBL_REDIR_DECL(name) \
 779   extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
 780 #  define __REDIRECT_LDBL(name, proto, alias) \
 781   __LDBL_REDIR1 (name, proto, __nldbl_##alias)
 782 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 783   __LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
 784 # endif
 785 #endif
 786 #if (!defined __LDBL_COMPAT && __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 0) \
 787     || !defined __REDIRECT
 788 # define __LDBL_REDIR1(name, proto, alias) name proto
 789 # define __LDBL_REDIR(name, proto) name proto
 790 # define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
 791 # define __LDBL_REDIR_NTH(name, proto) name proto __THROW
 792 # define __LDBL_REDIR2_DECL(name)
 793 # define __LDBL_REDIR_DECL(name)
 794 # ifdef __REDIRECT
 795 #  define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
 796 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 797   __REDIRECT_NTH (name, proto, alias)
 798 # endif
 799 #endif
 800
 801 /* __glibc_macro_warning (MESSAGE) issues warning MESSAGE.  This is
 802    intended for use in preprocessor macros.
 803
 804    Note: MESSAGE must be a _single_ string; concatenation of string
 805    literals is not supported.  */
 806 #if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
 807 # define __glibc_macro_warning1(message) _Pragma (#message)
 808 # define __glibc_macro_warning(message) \
 809   __glibc_macro_warning1 (GCC warning message)
 810 #else
 811 # define __glibc_macro_warning(msg)
 812 #endif
 813
 814 /* Generic selection (ISO C11) is a C-only feature, available in GCC
 815    since version 4.9.  Previous versions do not provide generic
 816    selection, even though they might set __STDC_VERSION__ to 201112L,
 817    when in -std=c11 mode.  Thus, we must check for !defined __GNUC__
 818    when testing __STDC_VERSION__ for generic selection support.
 819    On the other hand, Clang also defines __GNUC__, so a clang-specific
 820    check is required to enable the use of generic selection.  */
 821 #if !defined __cplusplus \
 822     && (__GNUC_PREREQ (4, 9) \
 823         || __glibc_has_extension (c_generic_selections) \
 824         || (!defined __GNUC__ && defined __STDC_VERSION__ \
 825             && __STDC_VERSION__ >= 201112L))
 826 # define __HAVE_GENERIC_SELECTION 1
 827 #else
 828 # define __HAVE_GENERIC_SELECTION 0
 829 #endif
 830
 831 #if __GNUC_PREREQ (10, 0)
 832 /* Designates a 1-based positional argument ref-index of pointer type
 833    that can be used to access size-index elements of the pointed-to
 834    array according to access mode, or at least one element when
 835    size-index is not provided:
 836      access (access-mode, <ref-index> [, <size-index>])  */
 837 #  define __attr_access(x) __attribute__ ((__access__ x))
 838 /* For _FORTIFY_SOURCE == 3 we use __builtin_dynamic_object_size, which may
 839    use the access attribute to get object sizes from function definition
 840    arguments, so we can't use them on functions we fortify.  Drop the access
 841    attribute for such functions.  */
 842 #  if __USE_FORTIFY_LEVEL == 3
 843 #    define __fortified_attr_access(a, o, s)
 844 #  else
 845 #    define __fortified_attr_access(a, o, s) __attr_access ((a, o, s))
 846 #  endif
 847 #  if __GNUC_PREREQ (11, 0)
 848 #    define __attr_access_none(argno) __attribute__ ((__access__ (__none__, argno)))
 849 #  else
 850 #    define __attr_access_none(argno)
 851 #  endif
 852 #else
 853 #  define __fortified_attr_access(a, o, s)
 854 #  define __attr_access(x)
 855 #  define __attr_access_none(argno)
 856 #endif
 857
 858 #if __GNUC_PREREQ (11, 0)
 859 /* Designates dealloc as a function to call to deallocate objects
 860    allocated by the declared function.  */
 861 # define __attr_dealloc(dealloc, argno) \
 862     __attribute__ ((__malloc__ (dealloc, argno)))
 863 # define __attr_dealloc_free __attr_dealloc (__builtin_free, 1)
 864 #else
 865 # define __attr_dealloc(dealloc, argno)
 866 # define __attr_dealloc_free
 867 #endif
 868
 869 /* Specify that a function such as setjmp or vfork may return
 870    twice.  */
 871 #if __GNUC_PREREQ (4, 1)
 872 # define __attribute_returns_twice__ __attribute__ ((__returns_twice__))
 873 #else
 874 # define __attribute_returns_twice__ /* Ignore.  */
 875 #endif
 876
 877 #endif   /* sys/cdefs.h */