[PATCH 1/3] lib/string: allow searching for NUL with strnchr

From: Peter Rosin <peda@axentia.se>
To: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Peter Rosin <peda@axentia.se>,
	Matthew Wilcox <mawilcox@microsoft.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 1/3] lib/string: allow searching for NUL with strnchr
Date: Mon, 6 May 2019 12:42:23 +0000	[thread overview]
Message-ID: <20190506124205.6565-2-peda@axentia.se> (raw)
In-Reply-To: <20190506124205.6565-1-peda@axentia.se>

strchr considers the terminating NUL to be part of the string, and NUL
can thus be searched for with that function. For consistency, do the
same with strnchr.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 lib/string.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/string.c b/lib/string.c
index 3ab861c1a857..9d64d7ab401a 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -367,6 +367,9 @@ EXPORT_SYMBOL(strncmp);
  * strchr - Find the first occurrence of a character in a string
  * @s: The string to be searched
  * @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
  */
 char *strchr(const char *s, int c)
 {
@@ -420,12 +423,18 @@ EXPORT_SYMBOL(strrchr);
  * @s: The string to be searched
  * @count: The number of characters to be searched
  * @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
  */
 char *strnchr(const char *s, size_t count, int c)
 {
-	for (; count-- && *s != '\0'; ++s)
+	while (count--) {
 		if (*s == (char)c)
 			return (char *)s;
+		if (*s++ == '\0')
+			break;
+	}
 	return NULL;
 }
 EXPORT_SYMBOL(strnchr);
-- 
2.11.0

