1  /* Support for single-thread optimizations.
       2     Copyright (C) 2020-2023 Free Software Foundation, Inc.
       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_SINGLE_THREADED_H
      20  #define _SYS_SINGLE_THREADED_H
      21  
      22  #include <features.h>
      23  
      24  __BEGIN_DECLS
      25  
      26  /* If this variable is non-zero, then the current thread is the only
      27     thread in the process image.  If it is zero, the process might be
      28     multi-threaded.  */
      29  extern char __libc_single_threaded;
      30  
      31  __END_DECLS
      32  
      33  #endif /* _SYS_SINGLE_THREADED_H */