add kstrndup

Add a kstrndup function, modelled on strndup.  Like strndup this
returns a string copied into its own allocated memory, but it copies
no more than the specified number of bytes from the source.

Remove private strndup() from irda code.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@mandriva.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Panagiotis Issaris <takis@issaris.org>
Cc: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>

include/linux/string.h

@@ -105,6 +105,7 @@ extern void * memchr(const void *,int,__kernel_size_t);
 #endif
 
 extern char *kstrdup(const char *s, gfp_t gfp);
+extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
 extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
 
 #ifdef __cplusplus

mm/util.c

@@ -6,7 +6,6 @@
 
 /**
  * kstrdup - allocate space for and copy an existing string
- *
  * @s: the string to duplicate
  * @gfp: the GFP mask used in the kmalloc() call when allocating memory
  */
@@ -26,6 +25,30 @@ char *kstrdup(const char *s, gfp_t gfp)
 }
 EXPORT_SYMBOL(kstrdup);
 
+/**
+ * kstrndup - allocate space for and copy an existing string
+ * @s: the string to duplicate
+ * @max: read at most @max chars from @s
+ * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ */
+char *kstrndup(const char *s, size_t max, gfp_t gfp)
+{
+	size_t len;
+	char *buf;
+
+	if (!s)
+		return NULL;
+
+	len = strnlen(s, max);
+	buf = kmalloc_track_caller(len+1, gfp);
+	if (buf) {
+		memcpy(buf, s, len);
+		buf[len] = '\0';
+	}
+	return buf;
+}
+EXPORT_SYMBOL(kstrndup);
+
 /**
  * kmemdup - duplicate region of memory
  *
@@ -80,7 +103,6 @@ EXPORT_SYMBOL(krealloc);
 
 /*
  * strndup_user - duplicate an existing string from user space
- *
  * @s: The string to duplicate
  * @n: Maximum number of bytes to copy, including the trailing NUL.
  */

net/irda/irias_object.c

@@ -36,39 +36,6 @@ hashbin_t *irias_objects;
  */
 struct ias_value irias_missing = { IAS_MISSING, 0, 0, 0, {0}};
 
-/*
- * Function strndup (str, max)
- *
- *    My own kernel version of strndup!
- *
- * Faster, check boundary... Jean II
- */
-static char *strndup(char *str, size_t max)
-{
-	char *new_str;
-	int len;
-
-	/* Check string */
-	if (str == NULL)
-		return NULL;
-	/* Check length, truncate */
-	len = strlen(str);
-	if(len > max)
-		len = max;
-
-	/* Allocate new string */
-	new_str = kmalloc(len + 1, GFP_ATOMIC);
-	if (new_str == NULL) {
-		IRDA_WARNING("%s: Unable to kmalloc!\n", __FUNCTION__);
-		return NULL;
-	}
-
-	/* Copy and truncate */
-	memcpy(new_str, str, len);
-	new_str[len] = '\0';
-
-	return new_str;
-}
 
 /*
  * Function ias_new_object (name, id)
@@ -90,7 +57,7 @@ struct ias_object *irias_new_object( char *name, int id)
 	}
 
 	obj->magic = IAS_OBJECT_MAGIC;
-	obj->name = strndup(name, IAS_MAX_CLASSNAME);
+	obj->name = kstrndup(name, IAS_MAX_CLASSNAME, GFP_ATOMIC);
 	if (!obj->name) {
 		IRDA_WARNING("%s(), Unable to allocate name!\n",
 			     __FUNCTION__);
@@ -360,7 +327,7 @@ void irias_add_integer_attrib(struct ias_object *obj, char *name, int value,
 	}
 
 	attrib->magic = IAS_ATTRIB_MAGIC;
-	attrib->name = strndup(name, IAS_MAX_ATTRIBNAME);
+	attrib->name = kstrndup(name, IAS_MAX_ATTRIBNAME, GFP_ATOMIC);
 
 	/* Insert value */
 	attrib->value = irias_new_integer_value(value);
@@ -404,7 +371,7 @@ void irias_add_octseq_attrib(struct ias_object *obj, char *name, __u8 *octets,
 	}
 
 	attrib->magic = IAS_ATTRIB_MAGIC;
-	attrib->name = strndup(name, IAS_MAX_ATTRIBNAME);
+	attrib->name = kstrndup(name, IAS_MAX_ATTRIBNAME, GFP_ATOMIC);
 
 	attrib->value = irias_new_octseq_value( octets, len);
 	if (!attrib->name || !attrib->value) {
@@ -446,7 +413,7 @@ void irias_add_string_attrib(struct ias_object *obj, char *name, char *value,
 	}
 
 	attrib->magic = IAS_ATTRIB_MAGIC;
-	attrib->name = strndup(name, IAS_MAX_ATTRIBNAME);
+	attrib->name = kstrndup(name, IAS_MAX_ATTRIBNAME, GFP_ATOMIC);
 
 	attrib->value = irias_new_string_value(value);
 	if (!attrib->name || !attrib->value) {
@@ -506,7 +473,7 @@ struct ias_value *irias_new_string_value(char *string)
 
 	value->type = IAS_STRING;
 	value->charset = CS_ASCII;
-	value->t.string = strndup(string, IAS_MAX_STRING);
+	value->t.string = kstrndup(string, IAS_MAX_STRING, GFP_ATOMIC);
 	if (!value->t.string) {
 		IRDA_WARNING("%s: Unable to kmalloc!\n", __FUNCTION__);
 		kfree(value);