mirror of
https://sourceware.org/git/glibc.git
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e27f41ba2b
Add <bits/indirect-return.h> and include it in <ucontext.h>. __INDIRECT_RETURN defined in <bits/indirect-return.h> indicates if swapcontext requires special compiler treatment. The default __INDIRECT_RETURN is empty. On x86, when shadow stack is enabled, __INDIRECT_RETURN is defined with indirect_return attribute, which has been added to GCC 9, to indicate that swapcontext returns via indirect branch. Otherwise __INDIRECT_RETURN is defined with returns_twice attribute. When shadow stack is enabled, remove always_inline attribute from prepare_test_buffer in string/tst-xbzero-opt.c to avoid: tst-xbzero-opt.c: In function ‘prepare_test_buffer’: tst-xbzero-opt.c:105:1: error: function ‘prepare_test_buffer’ can never be inlined because it uses setjmp prepare_test_buffer (unsigned char *buf) when indirect_return attribute isn't available. Reviewed-by: Carlos O'Donell <carlos@redhat.com> * bits/indirect-return.h: New file. * misc/sys/cdefs.h (__glibc_has_attribute): New. * sysdeps/x86/bits/indirect-return.h: Likewise. * stdlib/Makefile (headers): Add bits/indirect-return.h. * stdlib/ucontext.h: Include <bits/indirect-return.h>. (swapcontext): Add __INDIRECT_RETURN. * string/tst-xbzero-opt.c (ALWAYS_INLINE): New. (prepare_test_buffer): Use it.
508 lines
18 KiB
C
508 lines
18 KiB
C
/* Copyright (C) 1992-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _SYS_CDEFS_H
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#define _SYS_CDEFS_H 1
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/* We are almost always included from features.h. */
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#ifndef _FEATURES_H
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# include <features.h>
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#endif
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/* The GNU libc does not support any K&R compilers or the traditional mode
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of ISO C compilers anymore. Check for some of the combinations not
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anymore supported. */
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#if defined __GNUC__ && !defined __STDC__
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# error "You need a ISO C conforming compiler to use the glibc headers"
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#endif
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/* Some user header file might have defined this before. */
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#undef __P
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#undef __PMT
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#ifdef __GNUC__
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/* All functions, except those with callbacks or those that
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synchronize memory, are leaf functions. */
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# if __GNUC_PREREQ (4, 6) && !defined _LIBC
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# define __LEAF , __leaf__
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# define __LEAF_ATTR __attribute__ ((__leaf__))
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# else
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# define __LEAF
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# define __LEAF_ATTR
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# endif
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/* GCC can always grok prototypes. For C++ programs we add throw()
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to help it optimize the function calls. But this works only with
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gcc 2.8.x and egcs. For gcc 3.2 and up we even mark C functions
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as non-throwing using a function attribute since programs can use
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the -fexceptions options for C code as well. */
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# if !defined __cplusplus && __GNUC_PREREQ (3, 3)
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# define __THROW __attribute__ ((__nothrow__ __LEAF))
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# define __THROWNL __attribute__ ((__nothrow__))
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# define __NTH(fct) __attribute__ ((__nothrow__ __LEAF)) fct
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# define __NTHNL(fct) __attribute__ ((__nothrow__)) fct
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# else
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# if defined __cplusplus && __GNUC_PREREQ (2,8)
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# define __THROW throw ()
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# define __THROWNL throw ()
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# define __NTH(fct) __LEAF_ATTR fct throw ()
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# define __NTHNL(fct) fct throw ()
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# else
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# define __THROW
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# define __THROWNL
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# define __NTH(fct) fct
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# define __NTHNL(fct) fct
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# endif
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# endif
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#else /* Not GCC. */
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# if (defined __cplusplus \
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|| (defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L))
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# define __inline inline
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# else
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# define __inline /* No inline functions. */
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# endif
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# define __THROW
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# define __THROWNL
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# define __NTH(fct) fct
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#endif /* GCC. */
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/* Compilers that are not clang may object to
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#if defined __clang__ && __has_extension(...)
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even though they do not need to evaluate the right-hand side of the &&. */
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#if defined __clang__ && defined __has_extension
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# define __glibc_clang_has_extension(ext) __has_extension (ext)
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#else
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# define __glibc_clang_has_extension(ext) 0
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#endif
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/* These two macros are not used in glibc anymore. They are kept here
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only because some other projects expect the macros to be defined. */
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#define __P(args) args
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#define __PMT(args) args
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/* For these things, GCC behaves the ANSI way normally,
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and the non-ANSI way under -traditional. */
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#define __CONCAT(x,y) x ## y
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#define __STRING(x) #x
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/* This is not a typedef so `const __ptr_t' does the right thing. */
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#define __ptr_t void *
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/* C++ needs to know that types and declarations are C, not C++. */
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#ifdef __cplusplus
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# define __BEGIN_DECLS extern "C" {
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# define __END_DECLS }
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#else
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# define __BEGIN_DECLS
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# define __END_DECLS
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#endif
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/* Fortify support. */
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#define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
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#define __bos0(ptr) __builtin_object_size (ptr, 0)
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#if __GNUC_PREREQ (4,3)
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# define __warndecl(name, msg) \
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extern void name (void) __attribute__((__warning__ (msg)))
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# define __warnattr(msg) __attribute__((__warning__ (msg)))
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# define __errordecl(name, msg) \
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extern void name (void) __attribute__((__error__ (msg)))
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#else
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# define __warndecl(name, msg) extern void name (void)
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# define __warnattr(msg)
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# define __errordecl(name, msg) extern void name (void)
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#endif
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/* Support for flexible arrays.
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Headers that should use flexible arrays only if they're "real"
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(e.g. only if they won't affect sizeof()) should test
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#if __glibc_c99_flexarr_available. */
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#if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
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# define __flexarr []
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# define __glibc_c99_flexarr_available 1
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#elif __GNUC_PREREQ (2,97)
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/* GCC 2.97 supports C99 flexible array members as an extension,
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even when in C89 mode or compiling C++ (any version). */
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# define __flexarr []
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# define __glibc_c99_flexarr_available 1
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#elif defined __GNUC__
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/* Pre-2.97 GCC did not support C99 flexible arrays but did have
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an equivalent extension with slightly different notation. */
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# define __flexarr [0]
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# define __glibc_c99_flexarr_available 1
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#else
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/* Some other non-C99 compiler. Approximate with [1]. */
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# define __flexarr [1]
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# define __glibc_c99_flexarr_available 0
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#endif
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/* __asm__ ("xyz") is used throughout the headers to rename functions
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at the assembly language level. This is wrapped by the __REDIRECT
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macro, in order to support compilers that can do this some other
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way. When compilers don't support asm-names at all, we have to do
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preprocessor tricks instead (which don't have exactly the right
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semantics, but it's the best we can do).
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Example:
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int __REDIRECT(setpgrp, (__pid_t pid, __pid_t pgrp), setpgid); */
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#if defined __GNUC__ && __GNUC__ >= 2
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# define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
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# ifdef __cplusplus
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# define __REDIRECT_NTH(name, proto, alias) \
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name proto __THROW __asm__ (__ASMNAME (#alias))
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# define __REDIRECT_NTHNL(name, proto, alias) \
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name proto __THROWNL __asm__ (__ASMNAME (#alias))
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# else
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# define __REDIRECT_NTH(name, proto, alias) \
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name proto __asm__ (__ASMNAME (#alias)) __THROW
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# define __REDIRECT_NTHNL(name, proto, alias) \
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name proto __asm__ (__ASMNAME (#alias)) __THROWNL
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# endif
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# define __ASMNAME(cname) __ASMNAME2 (__USER_LABEL_PREFIX__, cname)
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# define __ASMNAME2(prefix, cname) __STRING (prefix) cname
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/*
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#elif __SOME_OTHER_COMPILER__
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# define __REDIRECT(name, proto, alias) name proto; \
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_Pragma("let " #name " = " #alias)
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*/
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#endif
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/* GCC has various useful declarations that can be made with the
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`__attribute__' syntax. All of the ways we use this do fine if
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they are omitted for compilers that don't understand it. */
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#if !defined __GNUC__ || __GNUC__ < 2
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# define __attribute__(xyz) /* Ignore */
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#endif
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/* At some point during the gcc 2.96 development the `malloc' attribute
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for functions was introduced. We don't want to use it unconditionally
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(although this would be possible) since it generates warnings. */
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#if __GNUC_PREREQ (2,96)
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# define __attribute_malloc__ __attribute__ ((__malloc__))
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#else
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# define __attribute_malloc__ /* Ignore */
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#endif
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/* Tell the compiler which arguments to an allocation function
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indicate the size of the allocation. */
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#if __GNUC_PREREQ (4, 3)
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# define __attribute_alloc_size__(params) \
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__attribute__ ((__alloc_size__ params))
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#else
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# define __attribute_alloc_size__(params) /* Ignore. */
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#endif
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/* At some point during the gcc 2.96 development the `pure' attribute
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for functions was introduced. We don't want to use it unconditionally
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(although this would be possible) since it generates warnings. */
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#if __GNUC_PREREQ (2,96)
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# define __attribute_pure__ __attribute__ ((__pure__))
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#else
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# define __attribute_pure__ /* Ignore */
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#endif
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/* This declaration tells the compiler that the value is constant. */
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#if __GNUC_PREREQ (2,5)
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# define __attribute_const__ __attribute__ ((__const__))
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#else
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# define __attribute_const__ /* Ignore */
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#endif
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/* At some point during the gcc 3.1 development the `used' attribute
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for functions was introduced. We don't want to use it unconditionally
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(although this would be possible) since it generates warnings. */
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#if __GNUC_PREREQ (3,1)
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# define __attribute_used__ __attribute__ ((__used__))
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# define __attribute_noinline__ __attribute__ ((__noinline__))
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#else
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# define __attribute_used__ __attribute__ ((__unused__))
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# define __attribute_noinline__ /* Ignore */
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#endif
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/* Since version 3.2, gcc allows marking deprecated functions. */
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#if __GNUC_PREREQ (3,2)
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# define __attribute_deprecated__ __attribute__ ((__deprecated__))
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#else
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# define __attribute_deprecated__ /* Ignore */
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#endif
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/* Since version 4.5, gcc also allows one to specify the message printed
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when a deprecated function is used. clang claims to be gcc 4.2, but
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may also support this feature. */
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#if __GNUC_PREREQ (4,5) || \
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__glibc_clang_has_extension (__attribute_deprecated_with_message__)
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# define __attribute_deprecated_msg__(msg) \
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__attribute__ ((__deprecated__ (msg)))
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#else
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# define __attribute_deprecated_msg__(msg) __attribute_deprecated__
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#endif
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/* At some point during the gcc 2.8 development the `format_arg' attribute
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for functions was introduced. We don't want to use it unconditionally
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(although this would be possible) since it generates warnings.
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If several `format_arg' attributes are given for the same function, in
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gcc-3.0 and older, all but the last one are ignored. In newer gccs,
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all designated arguments are considered. */
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#if __GNUC_PREREQ (2,8)
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# define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
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#else
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# define __attribute_format_arg__(x) /* Ignore */
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#endif
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/* At some point during the gcc 2.97 development the `strfmon' format
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attribute for functions was introduced. We don't want to use it
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unconditionally (although this would be possible) since it
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generates warnings. */
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#if __GNUC_PREREQ (2,97)
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# define __attribute_format_strfmon__(a,b) \
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__attribute__ ((__format__ (__strfmon__, a, b)))
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#else
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# define __attribute_format_strfmon__(a,b) /* Ignore */
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#endif
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/* The nonull function attribute allows to mark pointer parameters which
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must not be NULL. */
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#if __GNUC_PREREQ (3,3)
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# define __nonnull(params) __attribute__ ((__nonnull__ params))
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#else
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# define __nonnull(params)
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#endif
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/* If fortification mode, we warn about unused results of certain
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function calls which can lead to problems. */
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#if __GNUC_PREREQ (3,4)
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# define __attribute_warn_unused_result__ \
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__attribute__ ((__warn_unused_result__))
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# if __USE_FORTIFY_LEVEL > 0
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# define __wur __attribute_warn_unused_result__
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# endif
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#else
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# define __attribute_warn_unused_result__ /* empty */
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#endif
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#ifndef __wur
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# define __wur /* Ignore */
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#endif
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/* Forces a function to be always inlined. */
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#if __GNUC_PREREQ (3,2)
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/* The Linux kernel defines __always_inline in stddef.h (283d7573), and
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it conflicts with this definition. Therefore undefine it first to
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allow either header to be included first. */
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# undef __always_inline
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# define __always_inline __inline __attribute__ ((__always_inline__))
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#else
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# undef __always_inline
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# define __always_inline __inline
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#endif
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/* Associate error messages with the source location of the call site rather
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than with the source location inside the function. */
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#if __GNUC_PREREQ (4,3)
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# define __attribute_artificial__ __attribute__ ((__artificial__))
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#else
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# define __attribute_artificial__ /* Ignore */
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#endif
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/* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
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inline semantics, unless -fgnu89-inline is used. Using __GNUC_STDC_INLINE__
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or __GNUC_GNU_INLINE is not a good enough check for gcc because gcc versions
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older than 4.3 may define these macros and still not guarantee GNU inlining
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semantics.
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clang++ identifies itself as gcc-4.2, but has support for GNU inlining
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semantics, that can be checked fot by using the __GNUC_STDC_INLINE_ and
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__GNUC_GNU_INLINE__ macro definitions. */
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#if (!defined __cplusplus || __GNUC_PREREQ (4,3) \
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|| (defined __clang__ && (defined __GNUC_STDC_INLINE__ \
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|| defined __GNUC_GNU_INLINE__)))
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# if defined __GNUC_STDC_INLINE__ || defined __cplusplus
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# define __extern_inline extern __inline __attribute__ ((__gnu_inline__))
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# define __extern_always_inline \
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extern __always_inline __attribute__ ((__gnu_inline__))
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# else
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# define __extern_inline extern __inline
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# define __extern_always_inline extern __always_inline
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# endif
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#endif
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#ifdef __extern_always_inline
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# define __fortify_function __extern_always_inline __attribute_artificial__
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#endif
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/* GCC 4.3 and above allow passing all anonymous arguments of an
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__extern_always_inline function to some other vararg function. */
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#if __GNUC_PREREQ (4,3)
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# define __va_arg_pack() __builtin_va_arg_pack ()
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# define __va_arg_pack_len() __builtin_va_arg_pack_len ()
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#endif
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/* It is possible to compile containing GCC extensions even if GCC is
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run in pedantic mode if the uses are carefully marked using the
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`__extension__' keyword. But this is not generally available before
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version 2.8. */
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#if !__GNUC_PREREQ (2,8)
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# define __extension__ /* Ignore */
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#endif
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/* __restrict is known in EGCS 1.2 and above. */
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#if !__GNUC_PREREQ (2,92)
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# if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
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# define __restrict restrict
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# else
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# define __restrict /* Ignore */
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# endif
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#endif
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/* ISO C99 also allows to declare arrays as non-overlapping. The syntax is
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array_name[restrict]
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GCC 3.1 supports this. */
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#if __GNUC_PREREQ (3,1) && !defined __GNUG__
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# define __restrict_arr __restrict
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#else
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# ifdef __GNUC__
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# define __restrict_arr /* Not supported in old GCC. */
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# else
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# if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
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# define __restrict_arr restrict
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# else
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/* Some other non-C99 compiler. */
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# define __restrict_arr /* Not supported. */
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# endif
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# endif
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#endif
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#if __GNUC__ >= 3
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# define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
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# define __glibc_likely(cond) __builtin_expect ((cond), 1)
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#else
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# define __glibc_unlikely(cond) (cond)
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# define __glibc_likely(cond) (cond)
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#endif
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#ifdef __has_attribute
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# define __glibc_has_attribute(attr) __has_attribute (attr)
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#else
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# define __glibc_has_attribute(attr) 0
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#endif
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#if (!defined _Noreturn \
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&& (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
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&& !__GNUC_PREREQ (4,7))
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# if __GNUC_PREREQ (2,8)
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# define _Noreturn __attribute__ ((__noreturn__))
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# else
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# define _Noreturn
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# endif
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#endif
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#if __GNUC_PREREQ (8, 0)
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/* Describes a char array whose address can safely be passed as the first
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argument to strncpy and strncat, as the char array is not necessarily
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a NUL-terminated string. */
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# define __attribute_nonstring__ __attribute__ ((__nonstring__))
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#else
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# define __attribute_nonstring__
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#endif
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#if (!defined _Static_assert && !defined __cplusplus \
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&& (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
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&& (!__GNUC_PREREQ (4, 6) || defined __STRICT_ANSI__))
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# define _Static_assert(expr, diagnostic) \
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extern int (*__Static_assert_function (void)) \
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[!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
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#endif
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#include <bits/wordsize.h>
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#include <bits/long-double.h>
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#if defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
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# define __LDBL_COMPAT 1
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# ifdef __REDIRECT
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# define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
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# define __LDBL_REDIR(name, proto) \
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__LDBL_REDIR1 (name, proto, __nldbl_##name)
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# define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
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# define __LDBL_REDIR_NTH(name, proto) \
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__LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
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# define __LDBL_REDIR1_DECL(name, alias) \
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extern __typeof (name) name __asm (__ASMNAME (#alias));
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# define __LDBL_REDIR_DECL(name) \
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extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
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# define __REDIRECT_LDBL(name, proto, alias) \
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__LDBL_REDIR1 (name, proto, __nldbl_##alias)
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# define __REDIRECT_NTH_LDBL(name, proto, alias) \
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__LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
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# endif
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#endif
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#if !defined __LDBL_COMPAT || !defined __REDIRECT
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# define __LDBL_REDIR1(name, proto, alias) name proto
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# define __LDBL_REDIR(name, proto) name proto
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# define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
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# define __LDBL_REDIR_NTH(name, proto) name proto __THROW
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# define __LDBL_REDIR_DECL(name)
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# ifdef __REDIRECT
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# define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
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# define __REDIRECT_NTH_LDBL(name, proto, alias) \
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__REDIRECT_NTH (name, proto, alias)
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# endif
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#endif
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/* __glibc_macro_warning (MESSAGE) issues warning MESSAGE. This is
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intended for use in preprocessor macros.
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Note: MESSAGE must be a _single_ string; concatenation of string
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literals is not supported. */
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#if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
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# define __glibc_macro_warning1(message) _Pragma (#message)
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# define __glibc_macro_warning(message) \
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__glibc_macro_warning1 (GCC warning message)
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#else
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# define __glibc_macro_warning(msg)
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#endif
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/* Generic selection (ISO C11) is a C-only feature, available in GCC
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since version 4.9. Previous versions do not provide generic
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selection, even though they might set __STDC_VERSION__ to 201112L,
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when in -std=c11 mode. Thus, we must check for !defined __GNUC__
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when testing __STDC_VERSION__ for generic selection support.
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On the other hand, Clang also defines __GNUC__, so a clang-specific
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check is required to enable the use of generic selection. */
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#if !defined __cplusplus \
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&& (__GNUC_PREREQ (4, 9) \
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|| __glibc_clang_has_extension (c_generic_selections) \
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|| (!defined __GNUC__ && defined __STDC_VERSION__ \
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&& __STDC_VERSION__ >= 201112L))
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# define __HAVE_GENERIC_SELECTION 1
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#else
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# define __HAVE_GENERIC_SELECTION 0
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#endif
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#endif /* sys/cdefs.h */
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