[PATCH v2 1/2] string: implement strchrnul

[Ahmad Fatoum]

We have at least two places opencoding strchrnul, one of them needlessly
iterating twice instead of once over the string. Replace both by calling
a common single pass implementation.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
v1 -> v2:
  no change
---
 commands/hwclock.c     |  8 --------
 drivers/of/base.c      |  5 +----
 include/linux/string.h |  4 ++++
 lib/string.c           | 18 ++++++++++++++++++
 4 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/commands/hwclock.c b/commands/hwclock.c
index 1b5c2cd100ca..7a5600c456c9 100644
--- a/commands/hwclock.c
+++ b/commands/hwclock.c
@@ -9,14 +9,6 @@
 #include <string.h>
 #include <environment.h>
 
-static char *strchrnul(const char *s, int c)
-{
-	while (*s != '\0' && *s != c)
-		s++;
-
-	return (char *)s;
-}
-
 static int sscanf_two_digits(char *s, int *res)
 {
 	char buf[3];
diff --git a/drivers/of/base.c b/drivers/of/base.c
index f962159597df..1a1265bdd689 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2497,10 +2497,7 @@ struct device_node *of_get_stdoutpath(void)
 	if (!name)
 		return 0;
 
-	/* This could make use of strchrnul if it were available */
-	p = strchr(name, ':');
-	if (!p)
-		p = name + strlen(name);
+	p = strchrnul(name, ':');
 
 	q = xstrndup(name, p - name);
 
diff --git a/include/linux/string.h b/include/linux/string.h
index 55bc905c0e6b..47a27a391f0b 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -25,6 +25,10 @@ extern __kernel_size_t strspn(const char *,const char *);
 	(typeof(&(s1)[0]))(_strstr((s1), (s2))); \
 	})
 
+#ifndef __HAVE_ARCH_STRCHRNUL
+extern char * strchrnul(const char *,int);
+#endif
+
 /*
  * Include machine specific inline routines
  */
diff --git a/lib/string.c b/lib/string.c
index bad186586fac..9aeb1d883022 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -274,6 +274,24 @@ char * _strchr(const char * s, int c)
 #endif
 EXPORT_SYMBOL(_strchr);
 
+#ifndef __HAVE_ARCH_STRCHRNUL
+/**
+ * strchrnul - Find and return a character in a string, or end of string
+ * @s: The string to be searched
+ * @c: The character to search for
+ *
+ * Returns pointer to first occurrence of 'c' in s. If c is not found, then
+ * return a pointer to the null byte at the end of s.
+ */
+char *strchrnul(const char *s, int c)
+{
+	while (*s && *s != (char)c)
+		s++;
+	return (char *)s;
+}
+EXPORT_SYMBOL(strchrnul);
+#endif
+
 #ifndef __HAVE_ARCH_STRRCHR
 /**
  * strrchr - Find the last occurrence of a character in a string
-- 
2.30.2