<AWT Dev> Small fix for crasher in AWT

[Artem Ananiev]

Hi, Andrew,

JNU_GetEnv will crash, if "jvm" parameter is NULL. I don't know if this 
is a possible case, but I see (jvm != NULL) check, which makes be 
believe it's possible.

The rest of the fix looks fine.

Thanks,

Artem

On 11/30/2012 2:55 PM, Andrew Haley wrote:
> This one was reported by the LibreOffice folks.
>
> We don't check the return argument of JNU_GetEnv() in ToolkitErrorHandler:
>
>
> static int ToolkitErrorHandler(Display * dpy, XErrorEvent * event) {
>      if (jvm != NULL) {
>          JNIEnv * env = (JNIEnv *)JNU_GetEnv(jvm, JNI_VERSION_1_2);
>          return JNU_CallStaticMethodByName(env, NULL, "sun/awt/X11/XToolkit", "globalErrorHandler", "(JJ)I",
>                                            ptr_to_jlong(dpy), ptr_to_jlong(event)).i;
>      } else {
>          return 0;
>      }
> }
>
>
> JNU_GetEnv() will return NULL if this thread is not a Java thread, so
> we crash.  This will happen if SWT is loaded in an application that
> uses X itself in some threads.
>
> The patch is pretty trivial, we just have to check env before using it:
>
>
> --- jdk/src/solaris/native/sun/xawt/XlibWrapper.c~	2012-10-11 17:20:54.000000000 +0100
> +++ jdk/src/solaris/native/sun/xawt/XlibWrapper.c	2012-11-30 10:52:19.980613972 +0000
> @@ -1260,13 +1260,15 @@
>
>   JavaVM* jvm = NULL;
>   static int ToolkitErrorHandler(Display * dpy, XErrorEvent * event) {
> +    JNIEnv * env;
>       if (jvm != NULL) {
> -        JNIEnv * env = (JNIEnv *)JNU_GetEnv(jvm, JNI_VERSION_1_2);
> -        return JNU_CallStaticMethodByName(env, NULL, "sun/awt/X11/XToolkit", "globalErrorHandler", "(JJ)I",
> -                                          ptr_to_jlong(dpy), ptr_to_jlong(event)).i;
> -    } else {
> -        return 0;
> +	env = (JNIEnv *)JNU_GetEnv(jvm, JNI_VERSION_1_2);
> +	if (env) {
> +	    return JNU_CallStaticMethodByName(env, NULL, "sun/awt/X11/XToolkit", "globalErrorHandler", "(JJ)I",
> +					      ptr_to_jlong(dpy), ptr_to_jlong(event)).i;
> +	}
>       }
> +    return 0;
>   }
>
>   /*
>
>
> Andrew.
>