linux-kernel - [PATCH v2 1/7] vsprintf: factorize "(null)" string

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Message-ID: <b8bf37780911020926n6a7eda42w94a6dd38bdaf57b5@mail.gmail.com>
Date:	Mon, 2 Nov 2009 15:26:13 -0200
From:	André Goddard Rosa <andre.goddard@...il.com>
To:	Frederic Weisbecker <fweisbec@...il.com>, laijs@...fujitsu.com,
	mingo@...e.hu, davem@...emloft.net, akpm@...ux-foundation.org,
	harvey.harrison@...il.com,
	linux list <linux-kernel@...r.kernel.org>
Cc:	me <andre.goddard@...il.com>
Subject: [PATCH v2 1/7] vsprintf: factorize "(null)" string

>From eb05d349fdae1e495eafccb6f4a639f4dc248098 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Goddard=20Rosa?= <andre.goddard@...il.com>
Date: Sun, 1 Nov 2009 12:15:59 -0200
Subject: [PATCH v2 1/7] vsprintf: factorize "(null)" string
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Change "<NULL>" to "(null)" and make it a static const char[] hoping that
the compiler will make null_str a label to a read-only area containing it.

See:
http://people.redhat.com/drepper/dsohowto.pdf part 2.4.2
http://udrepper.livejournal.com/13851.html
http://udrepper.livejournal.com/15119.html

Signed-off-by: André Goddard Rosa <andre.goddard@...il.com>
---
 lib/vsprintf.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 33bed5e..002f462 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -34,6 +34,8 @@
 /* Works only for digits and letters, but small and fast */
 #define TOLOWER(x) ((x) | 0x20)

+static const char null_str[] = "(null)";
+
 static unsigned int simple_guess_base(const char *cp)
 {
 	if (cp[0] == '0') {
@@ -546,12 +548,12 @@ static char *number(char *buf, char *end,
unsigned long long num,
 	return buf;
 }

-static char *string(char *buf, char *end, char *s, struct printf_spec spec)
+static char *string(char *buf, char *end, const char *s, struct
printf_spec spec)
 {
 	int len, i;

 	if ((unsigned long)s < PAGE_SIZE)
-		s = "<NULL>";
+		s = null_str;

 	len = strnlen(s, spec.precision);

@@ -822,7 +824,7 @@ static char *pointer(const char *fmt, char *buf,
char *end, void *ptr,
 			struct printf_spec spec)
 {
 	if (!ptr)
-		return string(buf, end, "(null)", spec);
+		return string(buf, end, null_str, spec);

 	switch (*fmt) {
 	case 'F':
@@ -1445,7 +1447,7 @@ do {									\
 			size_t len;
 			if ((unsigned long)save_str > (unsigned long)-PAGE_SIZE
 					|| (unsigned long)save_str < PAGE_SIZE)
-				save_str = "<NULL>";
+				save_str = null_str;
 			len = strlen(save_str);
 			if (str + len + 1 < end)
 				memcpy(str, save_str, len + 1);
-- 
1.6.5.2.140.g5f809
--
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