lib/cdefs.h

   1 /* Copyright (C) 1992-2019 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _SYS_CDEFS_H
  19 #define _SYS_CDEFS_H    1
  20
  21 /* We are almost always included from features.h. */
  22 #ifndef _FEATURES_H
  23 # include <features.h>
  24 #endif
  25
  26 /* The GNU libc does not support any K&R compilers or the traditional mode
  27    of ISO C compilers anymore.  Check for some of the combinations not
  28    anymore supported.  */
  29 #if defined __GNUC__ && !defined __STDC__
  30 # error "You need a ISO C conforming compiler to use the glibc headers"
  31 #endif
  32
  33 /* Some user header file might have defined this before.  */
  34 #undef  __P
  35 #undef  __PMT
  36
  37 #ifdef __GNUC__
  38
  39 /* All functions, except those with callbacks or those that
  40    synchronize memory, are leaf functions.  */
  41 # if __GNUC_PREREQ (4, 6) && !defined _LIBC
  42 #  define __LEAF , __leaf__
  43 #  define __LEAF_ATTR __attribute__ ((__leaf__))
  44 # else
  45 #  define __LEAF
  46 #  define __LEAF_ATTR
  47 # endif
  48
  49 /* GCC can always grok prototypes.  For C++ programs we add throw()
  50    to help it optimize the function calls.  But this works only with
  51    gcc 2.8.x and egcs.  For gcc 3.2 and up we even mark C functions
  52    as non-throwing using a function attribute since programs can use
  53    the -fexceptions options for C code as well.  */
  54 # if !defined __cplusplus && __GNUC_PREREQ (3, 3)
  55 #  define __THROW       __attribute__ ((__nothrow__ __LEAF))
  56 #  define __THROWNL     __attribute__ ((__nothrow__))
  57 #  define __NTH(fct)    __attribute__ ((__nothrow__ __LEAF)) fct
  58 #  define __NTHNL(fct)  __attribute__ ((__nothrow__)) fct
  59 # else
  60 #  if defined __cplusplus && __GNUC_PREREQ (2,8)
  61 #   define __THROW      throw ()
  62 #   define __THROWNL    throw ()
  63 #   define __NTH(fct)   __LEAF_ATTR fct throw ()
  64 #   define __NTHNL(fct) fct throw ()
  65 #  else
  66 #   define __THROW
  67 #   define __THROWNL
  68 #   define __NTH(fct)   fct
  69 #   define __NTHNL(fct) fct
  70 #  endif
  71 # endif
  72
  73 #else   /* Not GCC.  */
  74
  75 # if (defined __cplusplus                                               \
  76       || (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
  77 #  define __inline      inline
  78 # else
  79 #  define __inline              /* No inline functions.  */
  80 # endif
  81
  82 # define __THROW
  83 # define __THROWNL
  84 # define __NTH(fct)     fct
  85
  86 #endif  /* GCC.  */
  87
  88 /* Compilers that are not clang may object to
  89        #if defined __clang__ && __has_extension(...)
  90    even though they do not need to evaluate the right-hand side of the &&.  */
  91 #if defined __clang__ && defined __has_extension
  92 # define __glibc_clang_has_extension(ext) __has_extension (ext)
  93 #else
  94 # define __glibc_clang_has_extension(ext) 0
  95 #endif
  96
  97 /* These two macros are not used in glibc anymore.  They are kept here
  98    only because some other projects expect the macros to be defined.  */
  99 #define __P(args)       args
 100 #define __PMT(args)     args
 101
 102 /* For these things, GCC behaves the ANSI way normally,
 103    and the non-ANSI way under -traditional.  */
 104
 105 #define __CONCAT(x,y)   x ## y
 106 #define __STRING(x)     #x
 107
 108 /* This is not a typedef so `const __ptr_t' does the right thing.  */
 109 #define __ptr_t void *
 110
 111
 112 /* C++ needs to know that types and declarations are C, not C++.  */
 113 #ifdef  __cplusplus
 114 # define __BEGIN_DECLS  extern "C" {
 115 # define __END_DECLS    }
 116 #else
 117 # define __BEGIN_DECLS
 118 # define __END_DECLS
 119 #endif
 120
 121
 122 /* Fortify support.  */
 123 #define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
 124 #define __bos0(ptr) __builtin_object_size (ptr, 0)
 125
 126 #if __GNUC_PREREQ (4,3)
 127 # define __warndecl(name, msg) \
 128   extern void name (void) __attribute__((__warning__ (msg)))
 129 # define __warnattr(msg) __attribute__((__warning__ (msg)))
 130 # define __errordecl(name, msg) \
 131   extern void name (void) __attribute__((__error__ (msg)))
 132 #else
 133 # define __warndecl(name, msg) extern void name (void)
 134 # define __warnattr(msg)
 135 # define __errordecl(name, msg) extern void name (void)
 136 #endif
 137
 138 /* Support for flexible arrays.
 139    Headers that should use flexible arrays only if they're "real"
 140    (e.g. only if they won't affect sizeof()) should test
 141    #if __glibc_c99_flexarr_available.  */
 142 #if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L && !defined __HP_cc
 143 # define __flexarr      []
 144 # define __glibc_c99_flexarr_available 1
 145 #elif __GNUC_PREREQ (2,97)
 146 /* GCC 2.97 supports C99 flexible array members as an extension,
 147    even when in C89 mode or compiling C++ (any version).  */
 148 # define __flexarr      []
 149 # define __glibc_c99_flexarr_available 1
 150 #elif defined __GNUC__
 151 /* Pre-2.97 GCC did not support C99 flexible arrays but did have
 152    an equivalent extension with slightly different notation.  */
 153 # define __flexarr      [0]
 154 # define __glibc_c99_flexarr_available 1
 155 #else
 156 /* Some other non-C99 compiler.  Approximate with [1].  */
 157 # define __flexarr      [1]
 158 # define __glibc_c99_flexarr_available 0
 159 #endif
 160
 161
 162 /* __asm__ ("xyz") is used throughout the headers to rename functions
 163    at the assembly language level.  This is wrapped by the __REDIRECT
 164    macro, in order to support compilers that can do this some other
 165    way.  When compilers don't support asm-names at all, we have to do
 166    preprocessor tricks instead (which don't have exactly the right
 167    semantics, but it's the best we can do).
 168
 169    Example:
 170    int __REDIRECT(setpgrp, (__pid_t pid, __pid_t pgrp), setpgid); */
 171
 172 #if defined __GNUC__ && __GNUC__ >= 2
 173
 174 # define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
 175 # ifdef __cplusplus
 176 #  define __REDIRECT_NTH(name, proto, alias) \
 177      name proto __THROW __asm__ (__ASMNAME (#alias))
 178 #  define __REDIRECT_NTHNL(name, proto, alias) \
 179      name proto __THROWNL __asm__ (__ASMNAME (#alias))
 180 # else
 181 #  define __REDIRECT_NTH(name, proto, alias) \
 182      name proto __asm__ (__ASMNAME (#alias)) __THROW
 183 #  define __REDIRECT_NTHNL(name, proto, alias) \
 184      name proto __asm__ (__ASMNAME (#alias)) __THROWNL
 185 # endif
 186 # define __ASMNAME(cname)  __ASMNAME2 (__USER_LABEL_PREFIX__, cname)
 187 # define __ASMNAME2(prefix, cname) __STRING (prefix) cname
 188
 189 /*
 190 #elif __SOME_OTHER_COMPILER__
 191
 192 # define __REDIRECT(name, proto, alias) name proto; \
 193         _Pragma("let " #name " = " #alias)
 194 */
 195 #endif
 196
 197 /* GCC has various useful declarations that can be made with the
 198    `__attribute__' syntax.  All of the ways we use this do fine if
 199    they are omitted for compilers that don't understand it. */
 200 #if !defined __GNUC__ || __GNUC__ < 2
 201 # define __attribute__(xyz)     /* Ignore */
 202 #endif
 203
 204 /* At some point during the gcc 2.96 development the `malloc' attribute
 205    for functions was introduced.  We don't want to use it unconditionally
 206    (although this would be possible) since it generates warnings.  */
 207 #if __GNUC_PREREQ (2,96)
 208 # define __attribute_malloc__ __attribute__ ((__malloc__))
 209 #else
 210 # define __attribute_malloc__ /* Ignore */
 211 #endif
 212
 213 /* Tell the compiler which arguments to an allocation function
 214    indicate the size of the allocation.  */
 215 #if __GNUC_PREREQ (4, 3)
 216 # define __attribute_alloc_size__(params) \
 217   __attribute__ ((__alloc_size__ params))
 218 #else
 219 # define __attribute_alloc_size__(params) /* Ignore.  */
 220 #endif
 221
 222 /* At some point during the gcc 2.96 development the `pure' attribute
 223    for functions was introduced.  We don't want to use it unconditionally
 224    (although this would be possible) since it generates warnings.  */
 225 #if __GNUC_PREREQ (2,96)
 226 # define __attribute_pure__ __attribute__ ((__pure__))
 227 #else
 228 # define __attribute_pure__ /* Ignore */
 229 #endif
 230
 231 /* This declaration tells the compiler that the value is constant.  */
 232 #if __GNUC_PREREQ (2,5)
 233 # define __attribute_const__ __attribute__ ((__const__))
 234 #else
 235 # define __attribute_const__ /* Ignore */
 236 #endif
 237
 238 /* At some point during the gcc 3.1 development the `used' attribute
 239    for functions was introduced.  We don't want to use it unconditionally
 240    (although this would be possible) since it generates warnings.  */
 241 #if __GNUC_PREREQ (3,1)
 242 # define __attribute_used__ __attribute__ ((__used__))
 243 # define __attribute_noinline__ __attribute__ ((__noinline__))
 244 #else
 245 # define __attribute_used__ __attribute__ ((__unused__))
 246 # define __attribute_noinline__ /* Ignore */
 247 #endif
 248
 249 /* Since version 3.2, gcc allows marking deprecated functions.  */
 250 #if __GNUC_PREREQ (3,2)
 251 # define __attribute_deprecated__ __attribute__ ((__deprecated__))
 252 #else
 253 # define __attribute_deprecated__ /* Ignore */
 254 #endif
 255
 256 /* Since version 4.5, gcc also allows one to specify the message printed
 257    when a deprecated function is used.  clang claims to be gcc 4.2, but
 258    may also support this feature.  */
 259 #if __GNUC_PREREQ (4,5) || \
 260     __glibc_clang_has_extension (__attribute_deprecated_with_message__)
 261 # define __attribute_deprecated_msg__(msg) \
 262          __attribute__ ((__deprecated__ (msg)))
 263 #else
 264 # define __attribute_deprecated_msg__(msg) __attribute_deprecated__
 265 #endif
 266
 267 /* At some point during the gcc 2.8 development the `format_arg' attribute
 268    for functions was introduced.  We don't want to use it unconditionally
 269    (although this would be possible) since it generates warnings.
 270    If several `format_arg' attributes are given for the same function, in
 271    gcc-3.0 and older, all but the last one are ignored.  In newer gccs,
 272    all designated arguments are considered.  */
 273 #if __GNUC_PREREQ (2,8)
 274 # define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
 275 #else
 276 # define __attribute_format_arg__(x) /* Ignore */
 277 #endif
 278
 279 /* At some point during the gcc 2.97 development the `strfmon' format
 280    attribute for functions was introduced.  We don't want to use it
 281    unconditionally (although this would be possible) since it
 282    generates warnings.  */
 283 #if __GNUC_PREREQ (2,97)
 284 # define __attribute_format_strfmon__(a,b) \
 285   __attribute__ ((__format__ (__strfmon__, a, b)))
 286 #else
 287 # define __attribute_format_strfmon__(a,b) /* Ignore */
 288 #endif
 289
 290 /* The nonnull function attribute marks pointer parameters that
 291    must not be NULL.  Do not define __nonnull if it is already defined,
 292    for portability when this file is used in Gnulib.  */
 293 #ifndef __nonnull
 294 # if __GNUC_PREREQ (3,3)
 295 #  define __nonnull(params) __attribute__ ((__nonnull__ params))
 296 # else
 297 #  define __nonnull(params)
 298 # endif
 299 #endif
 300
 301 /* If fortification mode, we warn about unused results of certain
 302    function calls which can lead to problems.  */
 303 #if __GNUC_PREREQ (3,4)
 304 # define __attribute_warn_unused_result__ \
 305    __attribute__ ((__warn_unused_result__))
 306 # if defined __USE_FORTIFY_LEVEL && __USE_FORTIFY_LEVEL > 0
 307 #  define __wur __attribute_warn_unused_result__
 308 # endif
 309 #else
 310 # define __attribute_warn_unused_result__ /* empty */
 311 #endif
 312 #ifndef __wur
 313 # define __wur /* Ignore */
 314 #endif
 315
 316 /* Forces a function to be always inlined.  */
 317 #if __GNUC_PREREQ (3,2)
 318 /* The Linux kernel defines __always_inline in stddef.h (283d7573), and
 319    it conflicts with this definition.  Therefore undefine it first to
 320    allow either header to be included first.  */
 321 # undef __always_inline
 322 # define __always_inline __inline __attribute__ ((__always_inline__))
 323 #else
 324 # undef __always_inline
 325 # define __always_inline __inline
 326 #endif
 327
 328 /* Associate error messages with the source location of the call site rather
 329    than with the source location inside the function.  */
 330 #if __GNUC_PREREQ (4,3)
 331 # define __attribute_artificial__ __attribute__ ((__artificial__))
 332 #else
 333 # define __attribute_artificial__ /* Ignore */
 334 #endif
 335
 336 /* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
 337    inline semantics, unless -fgnu89-inline is used.  Using __GNUC_STDC_INLINE__
 338    or __GNUC_GNU_INLINE is not a good enough check for gcc because gcc versions
 339    older than 4.3 may define these macros and still not guarantee GNU inlining
 340    semantics.
 341
 342    clang++ identifies itself as gcc-4.2, but has support for GNU inlining
 343    semantics, that can be checked for by using the __GNUC_STDC_INLINE_ and
 344    __GNUC_GNU_INLINE__ macro definitions.  */
 345 #if (!defined __cplusplus || __GNUC_PREREQ (4,3) \
 346      || (defined __clang__ && (defined __GNUC_STDC_INLINE__ \
 347                                || defined __GNUC_GNU_INLINE__)))
 348 # if defined __GNUC_STDC_INLINE__ || defined __cplusplus
 349 #  define __extern_inline extern __inline __attribute__ ((__gnu_inline__))
 350 #  define __extern_always_inline \
 351   extern __always_inline __attribute__ ((__gnu_inline__))
 352 # else
 353 #  define __extern_inline extern __inline
 354 #  define __extern_always_inline extern __always_inline
 355 # endif
 356 #endif
 357
 358 #ifdef __extern_always_inline
 359 # define __fortify_function __extern_always_inline __attribute_artificial__
 360 #endif
 361
 362 /* GCC 4.3 and above allow passing all anonymous arguments of an
 363    __extern_always_inline function to some other vararg function.  */
 364 #if __GNUC_PREREQ (4,3)
 365 # define __va_arg_pack() __builtin_va_arg_pack ()
 366 # define __va_arg_pack_len() __builtin_va_arg_pack_len ()
 367 #endif
 368
 369 /* It is possible to compile containing GCC extensions even if GCC is
 370    run in pedantic mode if the uses are carefully marked using the
 371    `__extension__' keyword.  But this is not generally available before
 372    version 2.8.  */
 373 #if !__GNUC_PREREQ (2,8)
 374 # define __extension__          /* Ignore */
 375 #endif
 376
 377 /* __restrict is known in EGCS 1.2 and above. */
 378 #if !__GNUC_PREREQ (2,92)
 379 # if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 380 #  define __restrict    restrict
 381 # else
 382 #  define __restrict    /* Ignore */
 383 # endif
 384 #endif
 385
 386 /* ISO C99 also allows to declare arrays as non-overlapping.  The syntax is
 387      array_name[restrict]
 388    GCC 3.1 supports this.  */
 389 #if __GNUC_PREREQ (3,1) && !defined __GNUG__
 390 # define __restrict_arr __restrict
 391 #else
 392 # ifdef __GNUC__
 393 #  define __restrict_arr        /* Not supported in old GCC.  */
 394 # else
 395 #  if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
 396 #   define __restrict_arr       restrict
 397 #  else
 398 /* Some other non-C99 compiler.  */
 399 #   define __restrict_arr       /* Not supported.  */
 400 #  endif
 401 # endif
 402 #endif
 403
 404 #if __GNUC__ >= 3
 405 # define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
 406 # define __glibc_likely(cond)   __builtin_expect ((cond), 1)
 407 #else
 408 # define __glibc_unlikely(cond) (cond)
 409 # define __glibc_likely(cond)   (cond)
 410 #endif
 411
 412 #ifdef __has_attribute
 413 # define __glibc_has_attribute(attr)    __has_attribute (attr)
 414 #else
 415 # define __glibc_has_attribute(attr)    0
 416 #endif
 417
 418 #if (!defined _Noreturn \
 419      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 420      &&  !__GNUC_PREREQ (4,7))
 421 # if __GNUC_PREREQ (2,8)
 422 #  define _Noreturn __attribute__ ((__noreturn__))
 423 # else
 424 #  define _Noreturn
 425 # endif
 426 #endif
 427
 428 #if __GNUC_PREREQ (8, 0)
 429 /* Describes a char array whose address can safely be passed as the first
 430    argument to strncpy and strncat, as the char array is not necessarily
 431    a NUL-terminated string.  */
 432 # define __attribute_nonstring__ __attribute__ ((__nonstring__))
 433 #else
 434 # define __attribute_nonstring__
 435 #endif
 436
 437 #if (!defined _Static_assert && !defined __cplusplus \
 438      && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
 439      && (!__GNUC_PREREQ (4, 6) || defined __STRICT_ANSI__))
 440 # define _Static_assert(expr, diagnostic) \
 441     extern int (*__Static_assert_function (void)) \
 442       [!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
 443 #endif
 444
 445 /* The #ifndef lets Gnulib avoid including these on non-glibc
 446    platforms, where the includes typically do not exist.  */
 447 #ifndef __WORDSIZE
 448 # include <bits/wordsize.h>
 449 # include <bits/long-double.h>
 450 #endif
 451
 452 #if defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
 453 # define __LDBL_COMPAT 1
 454 # ifdef __REDIRECT
 455 #  define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
 456 #  define __LDBL_REDIR(name, proto) \
 457   __LDBL_REDIR1 (name, proto, __nldbl_##name)
 458 #  define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
 459 #  define __LDBL_REDIR_NTH(name, proto) \
 460   __LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
 461 #  define __LDBL_REDIR1_DECL(name, alias) \
 462   extern __typeof (name) name __asm (__ASMNAME (#alias));
 463 #  define __LDBL_REDIR_DECL(name) \
 464   extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
 465 #  define __REDIRECT_LDBL(name, proto, alias) \
 466   __LDBL_REDIR1 (name, proto, __nldbl_##alias)
 467 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 468   __LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
 469 # endif
 470 #endif
 471 #if !defined __LDBL_COMPAT || !defined __REDIRECT
 472 # define __LDBL_REDIR1(name, proto, alias) name proto
 473 # define __LDBL_REDIR(name, proto) name proto
 474 # define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
 475 # define __LDBL_REDIR_NTH(name, proto) name proto __THROW
 476 # define __LDBL_REDIR_DECL(name)
 477 # ifdef __REDIRECT
 478 #  define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
 479 #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
 480   __REDIRECT_NTH (name, proto, alias)
 481 # endif
 482 #endif
 483
 484 /* __glibc_macro_warning (MESSAGE) issues warning MESSAGE.  This is
 485    intended for use in preprocessor macros.
 486
 487    Note: MESSAGE must be a _single_ string; concatenation of string
 488    literals is not supported.  */
 489 #if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
 490 # define __glibc_macro_warning1(message) _Pragma (#message)
 491 # define __glibc_macro_warning(message) \
 492   __glibc_macro_warning1 (GCC warning message)
 493 #else
 494 # define __glibc_macro_warning(msg)
 495 #endif
 496
 497 /* Generic selection (ISO C11) is a C-only feature, available in GCC
 498    since version 4.9.  Previous versions do not provide generic
 499    selection, even though they might set __STDC_VERSION__ to 201112L,
 500    when in -std=c11 mode.  Thus, we must check for !defined __GNUC__
 501    when testing __STDC_VERSION__ for generic selection support.
 502    On the other hand, Clang also defines __GNUC__, so a clang-specific
 503    check is required to enable the use of generic selection.  */
 504 #if !defined __cplusplus \
 505     && (__GNUC_PREREQ (4, 9) \
 506         || __glibc_clang_has_extension (c_generic_selections) \
 507         || (!defined __GNUC__ && defined __STDC_VERSION__ \
 508             && __STDC_VERSION__ >= 201112L))
 509 # define __HAVE_GENERIC_SELECTION 1
 510 #else
 511 # define __HAVE_GENERIC_SELECTION 0
 512 #endif
 513
 514 #endif   /* sys/cdefs.h */