Prevent out-of-bounds read if strings are not \0 terminated

The documentation does not state whether the strings in DEVMODE are
\0 terminated so assume they might be not

Author: matthiasblaesing

contrib/platform/src/com/sun/jna/platform/win32/WinGDI.java

@@ -23,16 +23,16 @@
  */
 package com.sun.jna.platform.win32;
 
+import com.sun.jna.Native;
 import com.sun.jna.NativeLong;
 import com.sun.jna.Pointer;
 import com.sun.jna.Structure;
 import com.sun.jna.Structure.FieldOrder;
 import com.sun.jna.platform.win32.WinNT.HANDLE;
 import com.sun.jna.Union;
 
-import java.text.ParseException;
-
 import static com.sun.jna.platform.win32.WinDef.*;
+import java.nio.charset.StandardCharsets;
 
 /**
  * Ported from WinGDI.h.
@@ -276,19 +276,24 @@ public static class ByReference extends DEVMODE implements Structure.ByReference
          * Converts dmDeviceName from raw byte[] to String
          */
         public String getDmDeviceName() {
-            int offset = fieldOffset("dmDeviceName");
-            return CHAR_WIDTH == 1 ? getPointer().getString(offset) : getPointer().getWideString(offset);
+            if(CHAR_WIDTH == 1) {
+                return Native.toString(dmFormName);
+            } else {
+                return new String(dmDeviceName, StandardCharsets.UTF_16LE);
+            }
         }
 
         /**
          * Converts dmFormName from raw byte[] to String
          */
         public String getDmFormName() {
-            int offset = fieldOffset("dmFormName");
-            return CHAR_WIDTH == 1 ? getPointer().getString(offset) : getPointer().getWideString(offset);
+            if(CHAR_WIDTH == 1) {
+                return Native.toString(dmFormName);
+            } else {
+                return new String(dmFormName, StandardCharsets.UTF_16LE);
+            }
         }
 
-
         public static class DUMMYUNIONNAME extends Union {
             public DUMMYSTRUCTNAME dummystructname;