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The C and C++ Include Header Files

cat -n /usr/include/x86_64-linux-gnu/bits/syslog.h

     1	/* Checking macros for syslog functions.
     2	   Copyright (C) 2005-2026 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_SYSLOG_H
    20	# error "Never include <bits/syslog.h> directly; use <sys/syslog.h> instead."
    21	#endif
    22	
    23	#include <bits/syslog-decl.h>
    24	
    25	#include <bits/floatn.h>
    26	#if defined __LDBL_COMPAT || __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
    27	# include <bits/syslog-ldbl.h>
    28	#endif
    29	
    30	/* The following functions must be used only after applying all asm
    31	   redirections, e.g. long double asm redirections.  */
    32	
    33	#ifdef __va_arg_pack
    34	__fortify_function void
    35	syslog (int __pri, const char *__fmt, ...)
    36	{
    37	  __syslog_chk (__pri, __USE_FORTIFY_LEVEL - 1, __fmt, __va_arg_pack ());
    38	}
    39	#elif __fortify_use_clang && defined __USE_MISC
    40	__fortify_function_error_function __attribute_overloadable__ void
    41	syslog (int __pri, __fortify_clang_overload_arg (const char *, , __fmt), ...)
    42	{
    43	  __gnuc_va_list __fortify_ap;
    44	  __builtin_va_start (__fortify_ap, __fmt);
    45	  __vsyslog_chk (__pri, __USE_FORTIFY_LEVEL - 1, __fmt, __fortify_ap);
    46	  __builtin_va_end (__fortify_ap);
    47	}
    48	#elif !defined __cplusplus
    49	# define syslog(pri, ...) \
    50	  __syslog_chk (pri, __USE_FORTIFY_LEVEL - 1, __VA_ARGS__)
    51	#endif
    52	
    53	
    54	#ifdef __USE_MISC
    55	__fortify_function __attribute_overloadable__ void
    56	vsyslog (int __pri, __fortify_clang_overload_arg (const char *, ,__fmt),
    57		 __gnuc_va_list __ap)
    58	{
    59	  __vsyslog_chk (__pri,  __USE_FORTIFY_LEVEL - 1, __fmt, __ap);
    60	}
    61	#endif