tcpdump/funcattrs.h
Guy Harris 45fc519a2a Don't test for __attribute__ in the configure script.
Instead, use compiler test macros to check whether *particular*
attributes are supported, and set various #defines appropriately, in
header files.

Rename the UNALIGNED structure attribute to ND_UNALIGNED, and ask
whether we still need it.
2018-01-21 17:57:20 -08:00

153 lines
5.3 KiB
C

/* -*- Mode: c; tab-width: 8; indent-tabs-mode: 1; c-basic-offset: 8; -*- */
/*
* Copyright (c) 1993, 1994, 1995, 1996, 1997
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the Computer Systems
* Engineering Group at Lawrence Berkeley Laboratory.
* 4. Neither the name of the University nor of the Laboratory may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lib_funcattrs_h
#define lib_funcattrs_h
#include "compiler-tests.h"
/*
* Attributes to apply to functions and their arguments, using various
* compiler-specific extensions.
*/
/*
* This was introduced by Clang:
*
* http://clang.llvm.org/docs/LanguageExtensions.html#has-attribute
*
* in some version (which version?); it has been picked up by GCC 5.0.
*/
#ifndef __has_attribute
/*
* It's a macro, so you can check whether it's defined to check
* whether it's supported.
*
* If it's not, define it to always return 0, so that we move on to
* the fallback checks.
*/
#define __has_attribute(x) 0
#endif
/*
* NORETURN, before a function declaration, means "this function
* never returns". (It must go before the function declaration, e.g.
* "extern NORETURN func(...)" rather than after the function
* declaration, as the MSVC version has to go before the declaration.)
*/
#if __has_attribute(noreturn) \
|| ND_IS_AT_LEAST_GNUC_VERSION(2,5) \
|| ND_IS_AT_LEAST_SUNC_VERSION(5,9) \
|| ND_IS_AT_LEAST_XL_C_VERSION(10,1) \
|| ND_IS_AT_LEAST_HP_C_VERSION(6,10)
/*
* Compiler with support for __attribute((noreturn)), or GCC 2.5 and
* later, or Solaris Studio 12 (Sun C 5.9) and later, or IBM XL C 10.1
* and later (do any earlier versions of XL C support this?), or
* HP aCC A.06.10 and later.
*/
#define NORETURN __attribute((noreturn))
/*
* However, GCC didn't support that for function *pointers* until GCC
* 4.1.0; see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3481.
*
* Sun C/Oracle Studio C doesn't seem to support it, either.
*/
#if (defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) < 401)) \
|| (defined(__SUNPRO_C))
#define NORETURN_FUNCPTR
#else
#define NORETURN_FUNCPTR __attribute((noreturn))
#endif
#elif defined(_MSC_VER)
/*
* MSVC.
* It doesn't allow __declspec(noreturn) to be applied to function
* pointers.
*/
#define NORETURN __declspec(noreturn)
#define NORETURN_FUNCPTR
#else
#define NORETURN
#define NORETURN_FUNCPTR
#endif
/*
* PRINTFLIKE(x,y), after a function declaration, means "this function
* does printf-style formatting, with the xth argument being the format
* string and the yth argument being the first argument for the format
* string".
*/
#if __has_attribute(__format__) \
|| ND_IS_AT_LEAST_GNUC_VERSION(2,3) \
|| ND_IS_AT_LEAST_XL_C_VERSION(10,1) \
|| ND_IS_AT_LEAST_HP_C_VERSION(6,10)
/*
* Compiler with support for it, or GCC 2.3 and later, or IBM XL C 10.1
* and later (do any earlier versions of XL C support this?),
* or HP aCC A.06.10 and later.
*/
#define PRINTFLIKE(x,y) __attribute__((__format__(__printf__,x,y)))
/*
* However, GCC didn't support that for function *pointers* until GCC
* 4.1.0; see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3481.
*/
#if (defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) < 401))
#define PRINTFLIKE_FUNCPTR(x,y)
#else
#define PRINTFLIKE_FUNCPTR(x,y) __attribute__((__format__(__printf__,x,y)))
#endif
#else
#define PRINTFLIKE(x,y)
#define PRINTFLIKE_FUNCPTR(x,y)
#endif
/*
* For flagging arguments as format strings in MSVC.
*/
#if _MSC_VER >= 1400
#include <sal.h>
#if _MSC_VER > 1400
#define FORMAT_STRING(p) _Printf_format_string_ p
#else
#define FORMAT_STRING(p) __format_string p
#endif
#else
#define FORMAT_STRING(p) p
#endif
#endif /* lib_funcattrs_h */