Re: [cp-patches] Bug in java_nio_VMDirectByteBuffer.c

[Archie Cobbs]

Archie Cobbs wrote:
> In gnu_java_awt_peer_gtk_GdkPixbufDecoder.c, in the function
> query_formats(), there is a loop where (*env)->NewStringUTF()
> is invoked over and over again. There are two bugs actually:
>
> 1- The function exhausts the pool of local native references.
>    It should use DeleteLocalRef() to free them as it goes along.
> 2- It doesn't check for exceptions from any of the JNI functions
>    it invokes.
>
> In my case, (*env)->NewStringUTF() threw an exception because of #1,
> but the exception was not checked for because of #2, causing an
> assertion failure. So just fixing #1 would fix the crash in practice.
>
> For #2 it probably suffices for now to use assert() like is done earlier
> in the function after the FindClass() call.

OK, I'm fixing this one too (see attached patch).

-Archie

__________________________________________________________________________
Archie Cobbs      *        CTO, Awarix        *      http://www.awarix.com

--- 
/home/archie/classpath/cvs/native/jni/gtk-peer/gnu_java_awt_peer_gtk_GdkPixbufDecoder.c
     Fri Jan 21 09:16:23 2005
+++ native/jni/gtk-peer/gnu_java_awt_peer_gtk_GdkPixbufDecoder.c        Wed Mar 
16 09:18:18 2005
@@ -206,6 +206,7 @@
   jclass formatClass;
   jmethodID addExtensionID;
   jmethodID addMimeTypeID;
+  jobject string;
 
   formatClass = (*env)->FindClass
     (env, "gnu/java/awt/peer/gtk/GdkPixbufDecoder$ImageFormatSpec");
@@ -227,26 +228,33 @@
       format = (GdkPixbufFormat *) f->data;
       name = gdk_pixbuf_format_get_name(format);
 
+      string = (*env)->NewStringUTF(env, name);
+      g_assert(string != NULL);
+
       jformat = (*env)->CallStaticObjectMethod 
-       (env, clazz, registerFormatID,                              
-        (*env)->NewStringUTF(env, name),
+       (env, clazz, registerFormatID, string,
         (jboolean) gdk_pixbuf_format_is_writable(format));
+      (*env)->DeleteLocalRef(env, string);
 
       g_assert(jformat != NULL);
       
       ch = gdk_pixbuf_format_get_extensions(format);
       while (*ch)
        {
-         (*env)->CallVoidMethod (env, jformat, addExtensionID, 
-                                 (*env)->NewStringUTF(env, *ch)); 
+         string = (*env)->NewStringUTF(env, *ch);
+         g_assert(string != NULL);
+         (*env)->CallVoidMethod (env, jformat, addExtensionID, string);
+         (*env)->DeleteLocalRef(env, string);
          ++ch;
        }
       
       ch = gdk_pixbuf_format_get_mime_types(format);
       while (*ch)
        {
-         (*env)->CallVoidMethod (env, jformat, addMimeTypeID, 
-                                 (*env)->NewStringUTF(env, *ch)); 
+         string = (*env)->NewStringUTF(env, *ch);
+         g_assert(string != NULL);
+         (*env)->CallVoidMethod (env, jformat, addMimeTypeID, string);
+         (*env)->DeleteLocalRef(env, string);
          ++ch;
        }
     }