linux-kernel - [PATCH] lib: string: reduce unnecessary loop in strncpy

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Message-Id: <1572444859-3687-1-git-send-email-liuxiang_1999@126.com>
Date:   Wed, 30 Oct 2019 22:14:19 +0800
From:   Liu Xiang <liuxiang_1999@....com>
To:     linux-kernel@...r.kernel.org
Cc:     liuxiang_1999@....com
Subject: [PATCH] lib: string: reduce unnecessary loop in strncpy

Now in strncpy, even src[0] is 0, loop will execute count times until
count is 0. It is better to exit the loop immediately when *src is 0.

Signed-off-by: Liu Xiang <liuxiang_1999@....com>
---
 lib/string.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/lib/string.c b/lib/string.c
index 08ec58c..1065352 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -115,12 +115,8 @@ char *strncpy(char *dest, const char *src, size_t count)
 {
 	char *tmp = dest;
 
-	while (count) {
-		if ((*tmp = *src) != 0)
-			src++;
-		tmp++;
-		count--;
-	}
+	while (count-- && (*tmp++ = *src++) != '\0')
+		; /* nothing */
 	return dest;
 }
 EXPORT_SYMBOL(strncpy);
-- 
1.9.1