The C and C++ Include Header Files

/usr/include/x86_64-linux-gnu/bits/indirect-return.h


$ cat -n /usr/include/x86_64-linux-gnu/bits/indirect-return.h

     1	/* Definition of __INDIRECT_RETURN.  x86 version.
     2	   Copyright (C) 2018-2024 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 _UCONTEXT_H
    20	# error "Never include <bits/indirect-return.h> directly; use <ucontext.h> instead."
    21	#endif
    22	
    23	/* On x86, swapcontext returns via indirect branch when the shadow stack
    24	   is enabled.  Define __INDIRECT_RETURN to indicate whether swapcontext
    25	   returns via indirect branch.  */
    26	#if defined __CET__ && (__CET__ & 2) != 0
    27	# if __glibc_has_attribute (__indirect_return__)
    28	#  define __INDIRECT_RETURN __attribute__ ((__indirect_return__))
    29	# else
    30	/* Newer compilers provide the indirect_return attribute, but without
    31	   it we can use returns_twice to affect the optimizer in the same
    32	   way and avoid unsafe optimizations.  */
    33	#  define __INDIRECT_RETURN __attribute__ ((__returns_twice__))
    34	# endif
    35	#else
    36	# define __INDIRECT_RETURN
    37	#endif