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glibc/misc/sys/cdefs.h
Martin Sebor 7532837d7b The -Wstringop-truncation option new in GCC 8 detects common misuses 
of the strncat and strncpy function that may result in truncating
the copied string before the terminating NUL.  To avoid false positive
warnings for correct code that intentionally creates sequences of
characters that aren't guaranteed to be NUL-terminated, arrays that
are intended to store such sequences should be decorated with a new
nonstring attribute.  This change add this attribute to Glibc and
uses it to suppress such false positives.

ChangeLog:
	* misc/sys/cdefs.h (__attribute_nonstring__): New macro.
	* sysdeps/gnu/bits/utmp.h (struct utmp): Use it.
	* sysdeps/unix/sysv/linux/s390/bits/utmp.h (struct utmp): Same.
2017-11-15 17:39:59 -07:00

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/* Copyright (C) 1992-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef _SYS_CDEFS_H
#define _SYS_CDEFS_H 1
/* We are almost always included from features.h. */
#ifndef _FEATURES_H
# include <features.h>
#endif
/* The GNU libc does not support any K&R compilers or the traditional mode
of ISO C compilers anymore. Check for some of the combinations not
anymore supported. */
#if defined __GNUC__ && !defined __STDC__
# error "You need a ISO C conforming compiler to use the glibc headers"
#endif
/* Some user header file might have defined this before. */
#undef __P
#undef __PMT
#ifdef __GNUC__
/* All functions, except those with callbacks or those that
synchronize memory, are leaf functions. */
# if __GNUC_PREREQ (4, 6) && !defined _LIBC
# define __LEAF , __leaf__
# define __LEAF_ATTR __attribute__ ((__leaf__))
# else
# define __LEAF
# define __LEAF_ATTR
# endif
/* GCC can always grok prototypes. For C++ programs we add throw()
to help it optimize the function calls. But this works only with
gcc 2.8.x and egcs. For gcc 3.2 and up we even mark C functions
as non-throwing using a function attribute since programs can use
the -fexceptions options for C code as well. */
# if !defined __cplusplus && __GNUC_PREREQ (3, 3)
# define __THROW __attribute__ ((__nothrow__ __LEAF))
# define __THROWNL __attribute__ ((__nothrow__))
# define __NTH(fct) __attribute__ ((__nothrow__ __LEAF)) fct
# define __NTHNL(fct) __attribute__ ((__nothrow__)) fct
# else
# if defined __cplusplus && __GNUC_PREREQ (2,8)
# define __THROW throw ()
# define __THROWNL throw ()
# define __NTH(fct) __LEAF_ATTR fct throw ()
# define __NTHNL(fct) fct throw ()
# else
# define __THROW
# define __THROWNL
# define __NTH(fct) fct
# define __NTHNL(fct) fct
# endif
# endif
#else /* Not GCC. */
# define __inline /* No inline functions. */
# define __THROW
# define __THROWNL
# define __NTH(fct) fct
#endif /* GCC. */
/* Compilers that are not clang may object to
#if defined __clang__ && __has_extension(...)
even though they do not need to evaluate the right-hand side of the &&. */
#if defined __clang__ && defined __has_extension
# define __glibc_clang_has_extension(ext) __has_extension (ext)
#else
# define __glibc_clang_has_extension(ext) 0
#endif
/* These two macros are not used in glibc anymore. They are kept here
only because some other projects expect the macros to be defined. */
#define __P(args) args
#define __PMT(args) args
/* For these things, GCC behaves the ANSI way normally,
and the non-ANSI way under -traditional. */
#define __CONCAT(x,y) x ## y
#define __STRING(x) #x
/* This is not a typedef so `const __ptr_t' does the right thing. */
#define __ptr_t void *
/* C++ needs to know that types and declarations are C, not C++. */
#ifdef __cplusplus
# define __BEGIN_DECLS extern "C" {
# define __END_DECLS }
#else
# define __BEGIN_DECLS
# define __END_DECLS
#endif
/* Fortify support. */
#define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
#define __bos0(ptr) __builtin_object_size (ptr, 0)
#if __GNUC_PREREQ (4,3)
# define __warndecl(name, msg) \
extern void name (void) __attribute__((__warning__ (msg)))
# define __warnattr(msg) __attribute__((__warning__ (msg)))
# define __errordecl(name, msg) \
extern void name (void) __attribute__((__error__ (msg)))
#else
# define __warndecl(name, msg) extern void name (void)
# define __warnattr(msg)
# define __errordecl(name, msg) extern void name (void)
#endif
/* Support for flexible arrays.
Headers that should use flexible arrays only if they're "real"
(e.g. only if they won't affect sizeof()) should test
#if __glibc_c99_flexarr_available. */
#if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
# define __flexarr []
# define __glibc_c99_flexarr_available 1
#elif __GNUC_PREREQ (2,97)
/* GCC 2.97 supports C99 flexible array members as an extension,
even when in C89 mode or compiling C++ (any version). */
# define __flexarr []
# define __glibc_c99_flexarr_available 1
#elif defined __GNUC__
/* Pre-2.97 GCC did not support C99 flexible arrays but did have
an equivalent extension with slightly different notation. */
# define __flexarr [0]
# define __glibc_c99_flexarr_available 1
#else
/* Some other non-C99 compiler. Approximate with [1]. */
# define __flexarr [1]
# define __glibc_c99_flexarr_available 0
#endif
/* __asm__ ("xyz") is used throughout the headers to rename functions
at the assembly language level. This is wrapped by the __REDIRECT
macro, in order to support compilers that can do this some other
way. When compilers don't support asm-names at all, we have to do
preprocessor tricks instead (which don't have exactly the right
semantics, but it's the best we can do).
Example:
int __REDIRECT(setpgrp, (__pid_t pid, __pid_t pgrp), setpgid); */
#if defined __GNUC__ && __GNUC__ >= 2
# define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
# ifdef __cplusplus
# define __REDIRECT_NTH(name, proto, alias) \
name proto __THROW __asm__ (__ASMNAME (#alias))
# define __REDIRECT_NTHNL(name, proto, alias) \
name proto __THROWNL __asm__ (__ASMNAME (#alias))
# else
# define __REDIRECT_NTH(name, proto, alias) \
name proto __asm__ (__ASMNAME (#alias)) __THROW
# define __REDIRECT_NTHNL(name, proto, alias) \
name proto __asm__ (__ASMNAME (#alias)) __THROWNL
# endif
# define __ASMNAME(cname) __ASMNAME2 (__USER_LABEL_PREFIX__, cname)
# define __ASMNAME2(prefix, cname) __STRING (prefix) cname
/*
#elif __SOME_OTHER_COMPILER__
# define __REDIRECT(name, proto, alias) name proto; \
_Pragma("let " #name " = " #alias)
*/
#endif
/* GCC has various useful declarations that can be made with the
`__attribute__' syntax. All of the ways we use this do fine if
they are omitted for compilers that don't understand it. */
#if !defined __GNUC__ || __GNUC__ < 2
# define __attribute__(xyz) /* Ignore */
#endif
/* At some point during the gcc 2.96 development the `malloc' attribute
for functions was introduced. We don't want to use it unconditionally
(although this would be possible) since it generates warnings. */
#if __GNUC_PREREQ (2,96)
# define __attribute_malloc__ __attribute__ ((__malloc__))
#else
# define __attribute_malloc__ /* Ignore */
#endif
/* Tell the compiler which arguments to an allocation function
indicate the size of the allocation. */
#if __GNUC_PREREQ (4, 3)
# define __attribute_alloc_size__(params) \
__attribute__ ((__alloc_size__ params))
#else
# define __attribute_alloc_size__(params) /* Ignore. */
#endif
/* At some point during the gcc 2.96 development the `pure' attribute
for functions was introduced. We don't want to use it unconditionally
(although this would be possible) since it generates warnings. */
#if __GNUC_PREREQ (2,96)
# define __attribute_pure__ __attribute__ ((__pure__))
#else
# define __attribute_pure__ /* Ignore */
#endif
/* This declaration tells the compiler that the value is constant. */
#if __GNUC_PREREQ (2,5)
# define __attribute_const__ __attribute__ ((__const__))
#else
# define __attribute_const__ /* Ignore */
#endif
/* At some point during the gcc 3.1 development the `used' attribute
for functions was introduced. We don't want to use it unconditionally
(although this would be possible) since it generates warnings. */
#if __GNUC_PREREQ (3,1)
# define __attribute_used__ __attribute__ ((__used__))
# define __attribute_noinline__ __attribute__ ((__noinline__))
#else
# define __attribute_used__ __attribute__ ((__unused__))
# define __attribute_noinline__ /* Ignore */
#endif
/* Since version 3.2, gcc allows marking deprecated functions. */
#if __GNUC_PREREQ (3,2)
# define __attribute_deprecated__ __attribute__ ((__deprecated__))
#else
# define __attribute_deprecated__ /* Ignore */
#endif
/* Since version 4.5, gcc also allows one to specify the message printed
when a deprecated function is used. clang claims to be gcc 4.2, but
may also support this feature. */
#if __GNUC_PREREQ (4,5) || \
__glibc_clang_has_extension (__attribute_deprecated_with_message__)
# define __attribute_deprecated_msg__(msg) \
__attribute__ ((__deprecated__ (msg)))
#else
# define __attribute_deprecated_msg__(msg) __attribute_deprecated__
#endif
/* At some point during the gcc 2.8 development the `format_arg' attribute
for functions was introduced. We don't want to use it unconditionally
(although this would be possible) since it generates warnings.
If several `format_arg' attributes are given for the same function, in
gcc-3.0 and older, all but the last one are ignored. In newer gccs,
all designated arguments are considered. */
#if __GNUC_PREREQ (2,8)
# define __attribute_format_arg__(x) __attribute__ ((__format_arg__ (x)))
#else
# define __attribute_format_arg__(x) /* Ignore */
#endif
/* At some point during the gcc 2.97 development the `strfmon' format
attribute for functions was introduced. We don't want to use it
unconditionally (although this would be possible) since it
generates warnings. */
#if __GNUC_PREREQ (2,97)
# define __attribute_format_strfmon__(a,b) \
__attribute__ ((__format__ (__strfmon__, a, b)))
#else
# define __attribute_format_strfmon__(a,b) /* Ignore */
#endif
/* The nonull function attribute allows to mark pointer parameters which
must not be NULL. */
#if __GNUC_PREREQ (3,3)
# define __nonnull(params) __attribute__ ((__nonnull__ params))
#else
# define __nonnull(params)
#endif
/* If fortification mode, we warn about unused results of certain
function calls which can lead to problems. */
#if __GNUC_PREREQ (3,4)
# define __attribute_warn_unused_result__ \
__attribute__ ((__warn_unused_result__))
# if __USE_FORTIFY_LEVEL > 0
# define __wur __attribute_warn_unused_result__
# endif
#else
# define __attribute_warn_unused_result__ /* empty */
#endif
#ifndef __wur
# define __wur /* Ignore */
#endif
/* Forces a function to be always inlined. */
#if __GNUC_PREREQ (3,2)
/* The Linux kernel defines __always_inline in stddef.h (283d7573), and
it conflicts with this definition. Therefore undefine it first to
allow either header to be included first. */
# undef __always_inline
# define __always_inline __inline __attribute__ ((__always_inline__))
#else
# undef __always_inline
# define __always_inline __inline
#endif
/* Associate error messages with the source location of the call site rather
than with the source location inside the function. */
#if __GNUC_PREREQ (4,3)
# define __attribute_artificial__ __attribute__ ((__artificial__))
#else
# define __attribute_artificial__ /* Ignore */
#endif
/* GCC 4.3 and above with -std=c99 or -std=gnu99 implements ISO C99
inline semantics, unless -fgnu89-inline is used. Using __GNUC_STDC_INLINE__
or __GNUC_GNU_INLINE is not a good enough check for gcc because gcc versions
older than 4.3 may define these macros and still not guarantee GNU inlining
semantics.
clang++ identifies itself as gcc-4.2, but has support for GNU inlining
semantics, that can be checked fot by using the __GNUC_STDC_INLINE_ and
__GNUC_GNU_INLINE__ macro definitions. */
#if (!defined __cplusplus || __GNUC_PREREQ (4,3) \
|| (defined __clang__ && (defined __GNUC_STDC_INLINE__ \
|| defined __GNUC_GNU_INLINE__)))
# if defined __GNUC_STDC_INLINE__ || defined __cplusplus
# define __extern_inline extern __inline __attribute__ ((__gnu_inline__))
# define __extern_always_inline \
extern __always_inline __attribute__ ((__gnu_inline__))
# else
# define __extern_inline extern __inline
# define __extern_always_inline extern __always_inline
# endif
#endif
#ifdef __extern_always_inline
# define __fortify_function __extern_always_inline __attribute_artificial__
#endif
/* GCC 4.3 and above allow passing all anonymous arguments of an
__extern_always_inline function to some other vararg function. */
#if __GNUC_PREREQ (4,3)
# define __va_arg_pack() __builtin_va_arg_pack ()
# define __va_arg_pack_len() __builtin_va_arg_pack_len ()
#endif
/* It is possible to compile containing GCC extensions even if GCC is
run in pedantic mode if the uses are carefully marked using the
`__extension__' keyword. But this is not generally available before
version 2.8. */
#if !__GNUC_PREREQ (2,8)
# define __extension__ /* Ignore */
#endif
/* __restrict is known in EGCS 1.2 and above. */
#if !__GNUC_PREREQ (2,92)
# define __restrict /* Ignore */
#endif
/* ISO C99 also allows to declare arrays as non-overlapping. The syntax is
array_name[restrict]
GCC 3.1 supports this. */
#if __GNUC_PREREQ (3,1) && !defined __GNUG__
# define __restrict_arr __restrict
#else
# ifdef __GNUC__
# define __restrict_arr /* Not supported in old GCC. */
# else
# if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
# define __restrict_arr restrict
# else
/* Some other non-C99 compiler. */
# define __restrict_arr /* Not supported. */
# endif
# endif
#endif
#if __GNUC__ >= 3
# define __glibc_unlikely(cond) __builtin_expect ((cond), 0)
# define __glibc_likely(cond) __builtin_expect ((cond), 1)
#else
# define __glibc_unlikely(cond) (cond)
# define __glibc_likely(cond) (cond)
#endif
#if (!defined _Noreturn \
&& (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
&& !__GNUC_PREREQ (4,7))
# if __GNUC_PREREQ (2,8)
# define _Noreturn __attribute__ ((__noreturn__))
# else
# define _Noreturn
# endif
#endif
#if __GNUC_PREREQ (8, 0)
/* Describes a char array whose address can safely be passed as the first
argument to strncpy and strncat, as the char array is not necessarily
a NUL-terminated string. */
# define __attribute_nonstring__ __attribute__ ((__nonstring__))
#else
# define __attribute_nonstring__
#endif
#if (!defined _Static_assert && !defined __cplusplus \
&& (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
&& (!__GNUC_PREREQ (4, 6) || defined __STRICT_ANSI__))
# define _Static_assert(expr, diagnostic) \
extern int (*__Static_assert_function (void)) \
[!!sizeof (struct { int __error_if_negative: (expr) ? 2 : -1; })]
#endif
#include <bits/wordsize.h>
#include <bits/long-double.h>
#if defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
# define __LDBL_COMPAT 1
# ifdef __REDIRECT
# define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
# define __LDBL_REDIR(name, proto) \
__LDBL_REDIR1 (name, proto, __nldbl_##name)
# define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
# define __LDBL_REDIR_NTH(name, proto) \
__LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
# define __LDBL_REDIR1_DECL(name, alias) \
extern __typeof (name) name __asm (__ASMNAME (#alias));
# define __LDBL_REDIR_DECL(name) \
extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
# define __REDIRECT_LDBL(name, proto, alias) \
__LDBL_REDIR1 (name, proto, __nldbl_##alias)
# define __REDIRECT_NTH_LDBL(name, proto, alias) \
__LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
# endif
#endif
#if !defined __LDBL_COMPAT || !defined __REDIRECT
# define __LDBL_REDIR1(name, proto, alias) name proto
# define __LDBL_REDIR(name, proto) name proto
# define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
# define __LDBL_REDIR_NTH(name, proto) name proto __THROW
# define __LDBL_REDIR_DECL(name)
# ifdef __REDIRECT
# define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
# define __REDIRECT_NTH_LDBL(name, proto, alias) \
__REDIRECT_NTH (name, proto, alias)
# endif
#endif
/* __glibc_macro_warning (MESSAGE) issues warning MESSAGE. This is
intended for use in preprocessor macros.
Note: MESSAGE must be a _single_ string; concatenation of string
literals is not supported. */
#if __GNUC_PREREQ (4,8) || __glibc_clang_prereq (3,5)
# define __glibc_macro_warning1(message) _Pragma (#message)
# define __glibc_macro_warning(message) \
__glibc_macro_warning1 (GCC warning message)
#else
# define __glibc_macro_warning(msg)
#endif
/* Generic selection (ISO C11) is a C-only feature, available in GCC
since version 4.9. Previous versions do not provide generic
selection, even though they might set __STDC_VERSION__ to 201112L,
when in -std=c11 mode. Thus, we must check for !defined __GNUC__
when testing __STDC_VERSION__ for generic selection support.
On the other hand, Clang also defines __GNUC__, so a clang-specific
check is required to enable the use of generic selection. */
#if !defined __cplusplus \
&& (__GNUC_PREREQ (4, 9) \
|| __glibc_clang_has_extension (c_generic_selections) \
|| (!defined __GNUC__ && defined __STDC_VERSION__ \
&& __STDC_VERSION__ >= 201112L))
# define __HAVE_GENERIC_SELECTION 1
#else
# define __HAVE_GENERIC_SELECTION 0
#endif
#endif /* sys/cdefs.h */
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