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>

3 files changed, 30 insertions, 40 deletions

diff --git a/include/linux/string.h b/include/linux/string.h
index 7f2eb6a477f9..ee5e9ccc4aae 100644
--- a/include/linux/string.h
+++ b/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
diff --git a/mm/util.c b/mm/util.c
index 78f3783bdcc8..bf340d806868 100644
--- a/mm/util.c
+++ b/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
  */
@@ -27,6 +26,30 @@ 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
  *
  * @src: memory region to duplicate
@@ -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.
  */
diff --git a/net/irda/irias_object.c b/net/irda/irias_object.c
index 4adaae242b9e..cf302457097b 100644
--- a/net/irda/irias_object.c
+++ b/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);