[alsa-devel] [PATCH v4 01/12] vsprintf: factorize "(null)" string

[André Goddard Rosa]

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 at gmail.com>
Acked-by: Frederic Weisbecker <fweisbec at gmail.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);
-- 
1.6.5.2.153.g6e31f.dirty