Added compare_string().

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@4184 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/disk_device_manager/KDiskDeviceUtils.h

@@ -55,6 +55,30 @@ set_string(char *&location, const char *newValue)
 	return error;
 }
 
+// compare_string
+/*!	\brief \c NULL aware strcmp().
+
+	\c NULL is considered the least of all strings. \c NULL equals \c NULL.
+
+	\param str1 First string.
+	\param str2 Second string.
+	\return A value less than 0, if \a str1 is less than \a str2,
+			0, if they are equal, or a value greater than 0, if
+			\a str1 is greater \a str2.
+*/
+static inline
+int
+compare_string(const char *str1, const char *str2)
+{
+	if (str1 == NULL) {
+		if (str2 == NULL)
+			return 0;
+		return 1;
+	} else if (str2 == NULL)
+		return -1;
+	return strcmp(str1, str2);
+}
+
 
 // locking