[PATCH 1/4] makedumpfile: redefine numerical limitaction macros.

From: Wang Nan <wangnan0@huawei.com>
To: kumagai-atsushi@mxc.nes.nec.co.jp
Cc: Wang Nan <wangnan0@huawei.com>, Liu Hua <sdu.liu@huawei.com>,
	kexec@lists.infradead.org, Wang Nan <pi3orama@gmail.com>,
	Petr Tesarik <ptesarik@suse.cz>, Geng Hui <hui.geng@huawei.com>
Subject: [PATCH 1/4] makedumpfile: redefine numerical limitaction macros.
Date: Sat, 26 Apr 2014 12:07:06 +0800	[thread overview]
Message-ID: <1398485229-43295-2-git-send-email-wangnan0@huawei.com> (raw)
In-Reply-To: <1398485229-43295-1-git-send-email-wangnan0@huawei.com>

From: Wang Nan <pi3orama@gmail.com>

According to C standard, numerical limitations macros such as ULONG_MAX
should be defined in <limits.h>, and must be defined as "constant
expressions suitable for use in #if preprocessing directives." (see
"Numerical limits" section in the standard).

Original definition in common.h breaks this rule:

 #define LONG_MAX ((long)(~0UL>>1))

which causes macros like following failure:

 #if LONG_MAX == 2147483647
 # define LONG_BIT	32
 #else
 # define LONG_BIT	64
 #endif

Unfortunately, the above code piece is taken from real glibc header
(/usr/include/bits/xopen_lim.h), which is happen to be included by
<limits.h> if _GNU_SOURCE is defined.

This patch include <limits.h> in common.h to use C standard numerical
macros. For system without such macros defined by C, this patch also
defines L(L)ONG_MAX in a standard compatible way. By checking wich

gcc -dM -E - <<<''

we know that __LONG_MAX__ and __LLONG_MAX__ macros should be defined by
gcc by default. Definition of ULONG_MAX and ULLONG_MAX are taken from
gcc standard include file (include-fixed/limits.h).

In addition, macro ULONGLONG_MAX is nonstandard, the standard way for
defining max ulonglong is ULLONG_MAX.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Cc: Petr Tesarik <ptesarik@suse.cz>
Cc: kexec@lists.infradead.org
Cc: Geng Hui <hui.geng@huawei.com>
Cc: Liu Hua <sdu.liu@huawei.com>

---
 common.h | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/common.h b/common.h
index 6ad3ca7..124f107 100644
--- a/common.h
+++ b/common.h
@@ -16,17 +16,29 @@
 #ifndef _COMMON_H
 #define _COMMON_H
 
+#include <limits.h>
+
 #define TRUE		(1)
 #define FALSE		(0)
 #define ERROR		(-1)
 
 #ifndef LONG_MAX
-#define LONG_MAX	((long)(~0UL>>1))
+# warning LONG_MAX should have been defined in <limits.h>
+# define LONG_MAX	__LONG_MAX__
 #endif
 #ifndef ULONG_MAX
-#define ULONG_MAX	(~0UL)
+# warning ULONG_MAX should have been defined in <limits.h>
+# define ULONG_MAX	(LONG_MAX * 2UL + 1UL)
+#endif
+#ifndef LLONG_MAX
+# warning LLONG_MAX should have been defined in <limits.h>
+# define LLONG_MAX __LONG_LONG_MAX__
+#endif
+#ifndef ULLONG_MAX
+# warning ULLONG_MAX should have been defined in <limits.h>
+# define ULLONG_MAX (LLONG_MAX * 2ULL + 1ULL)
 #endif
-#define ULONGLONG_MAX	(~0ULL)
+#define ULONGLONG_MAX	ULLONG_MAX
 
 #define MAX(a,b)	((a) > (b) ? (a) : (b))
 #define MIN(a,b)	((a) < (b) ? (a) : (b))
-- 
1.8.4


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