linux-kernel - [PATCH] lib: string.c: Added a funktion function strzcpy

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Message-Id: <1411510416-16655-2-git-send-email-rickard_strandqvist@spectrumdigital.se>
Date:	Wed, 24 Sep 2014 00:13:36 +0200
From:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>,
	Grant Likely <grant.likely@...aro.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@...ux.intel.com>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] lib: string.c:  Added a funktion function strzcpy

Added a function strzcpy which works the same as strncpy,
but guaranteed to produce the trailing null character.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
---
 include/linux/string.h |    1 +
 lib/string.c           |   31 +++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h
index d36977e..d789ee5e 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -22,6 +22,7 @@ extern char * strcpy(char *,const char *);
 #ifndef __HAVE_ARCH_STRNCPY
 extern char * strncpy(char *,const char *, __kernel_size_t);
 #endif
+extern char *strzcpy(char *, const char *, __kernel_size_t);
 #ifndef __HAVE_ARCH_STRLCPY
 size_t strlcpy(char *, const char *, size_t);
 #endif
diff --git a/lib/string.c b/lib/string.c
index f3c6ff5..582a832 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -134,6 +134,37 @@ char *strncpy(char *dest, const char *src, size_t count)
 EXPORT_SYMBOL(strncpy);
 #endif
 
+/**
+ * strzcpy - Copy a length-limited, C-string
+ * @dest: Where to copy the string to
+ * @src: Where to copy the string from
+ * @count: The maximum number of bytes to copy
+ *
+ * The result is %NUL-terminated,
+ * as long as count is greater than zero.
+ *
+ * In the case where the length of @src is less than  that  of
+ * count, the remainder of @dest will be padded with %NUL.
+ *
+ */
+char *strzcpy(char *dest, const char *src, size_t count)
+{
+	char *tmp = dest;
+
+	while (count) {
+		if ((*tmp = *src) != 0)
+			src++;
+		tmp++;
+		count--;
+	}
+
+	if (dest != tmp)
+		*--tmp = '\0';
+
+	return dest;
+}
+EXPORT_SYMBOL(strzcpy);
+
 #ifndef __HAVE_ARCH_STRLCPY
 /**
  * strlcpy - Copy a C-string into a sized buffer
-- 
1.7.10.4

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