1  // Specific definitions for GNU/Linux  -*- C++ -*-
       2  
       3  // Copyright (C) 2000-2023 Free Software Foundation, Inc.
       4  //
       5  // This file is part of the GNU ISO C++ Library.  This library is free
       6  // software; you can redistribute it and/or modify it under the
       7  // terms of the GNU General Public License as published by the
       8  // Free Software Foundation; either version 3, or (at your option)
       9  // any later version.
      10  
      11  // This library is distributed in the hope that it will be useful,
      12  // but WITHOUT ANY WARRANTY; without even the implied warranty of
      13  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      14  // GNU General Public License for more details.
      15  
      16  // Under Section 7 of GPL version 3, you are granted additional
      17  // permissions described in the GCC Runtime Library Exception, version
      18  // 3.1, as published by the Free Software Foundation.
      19  
      20  // You should have received a copy of the GNU General Public License and
      21  // a copy of the GCC Runtime Library Exception along with this program;
      22  // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      23  // <http://www.gnu.org/licenses/>.
      24  
      25  /** @file bits/os_defines.h
      26   *  This is an internal header file, included by other library headers.
      27   *  Do not attempt to use it directly. @headername{iosfwd}
      28   */
      29  
      30  #ifndef _GLIBCXX_OS_DEFINES
      31  #define _GLIBCXX_OS_DEFINES 1
      32  
      33  // System-specific #define, typedefs, corrections, etc, go here.  This
      34  // file will come before all others.
      35  
      36  // This keeps isalnum, et al from being propagated as macros.
      37  #define __NO_CTYPE 1
      38  
      39  #include <features.h>
      40  
      41  // Provide a declaration for the possibly deprecated gets function, as
      42  // glibc 2.15 and later does not declare gets for ISO C11 when
      43  // __GNU_SOURCE is defined.
      44  #if __GLIBC_PREREQ(2,15) && defined(_GNU_SOURCE)
      45  # undef _GLIBCXX_HAVE_GETS
      46  #endif
      47  
      48  // Glibc 2.23 removed the obsolete isinf and isnan declarations. Check the
      49  // version dynamically in case it has changed since libstdc++ was configured.
      50  #define _GLIBCXX_NO_OBSOLETE_ISINF_ISNAN_DYNAMIC __GLIBC_PREREQ(2,23)
      51  
      52  // Glibc 2.26 on i?86/x86-64/ia64/ppc64le added *f128 support.
      53  // Glibc 2.27 added it also on many other arches but those have IEEE quad
      54  // long double.
      55  #if __GLIBC_PREREQ(2, 26) \
      56      && (defined(__i386__) || defined(__x86_64__) || defined (__ia64__) \
      57  	|| (defined(__powerpc__) && defined(_ARCH_PWR8) \
      58  	    && defined(__LITTLE_ENDIAN__) && (_CALL_ELF == 2) \
      59  	    && defined(__FLOAT128__)))
      60  # define _GLIBCXX_HAVE_FLOAT128_MATH 1
      61  #endif
      62  
      63  #ifdef __linux__
      64  // The following libpthread properties only apply to Linux, not GNU/Hurd.
      65  
      66  # if __GLIBC_PREREQ(2, 27)
      67  // Since glibc 2.27 pthread_self() is usable without linking to libpthread.
      68  #  define _GLIBCXX_NATIVE_THREAD_ID pthread_self()
      69  # else
      70  // Before then it was in libc.so.6 but not libc.a, and always returns 0,
      71  // which breaks the invariant this_thread::get_id() != thread::id{}.
      72  // So only use it if we know the libpthread version is available.
      73  // Otherwise use (__gthread_t)1 as the ID of the main (and only) thread.
      74  #  define _GLIBCXX_NATIVE_THREAD_ID \
      75     (__gthread_active_p() ? __gthread_self() : (__gthread_t)1)
      76  # endif
      77  
      78  # if __GLIBC_PREREQ(2, 34)
      79  // Since glibc 2.34 all pthreads functions are usable without linking to
      80  // libpthread.
      81  #  define _GLIBCXX_GTHREAD_USE_WEAK 0
      82  # endif
      83  #endif // __linux__
      84  
      85  #endif