Panama unresolved error when instantiating wayland struct...

Fri Feb 15 00:06:46 UTC 2019

I previously allocated a wl_list in my code. I'm still new to the 
foreign interfaces, so I'm not aware if there's a way to allocate the 
wl_listener using a pre-allocated wl_list.

Mark

On 2/15/19 12:49 AM, Maurizio Cimadamore wrote:
>
> On 14/02/2019 23:38, Mark Hammons wrote:
>> Hi Maurizio,
>>
>> No, wl_list is defined in wayland_utils.h while wl_listener is in 
>> wayland_server_core.h. I am currently looking through the issues on 
>> the openjdk tracker and seeing if there's a mitigation for this.
>
> Right - you beat me to this:
>
> https://people.freedesktop.org/~whot/wayland-doxygen/wayland/Server/structwl__listener.html 
>
>
> and
>
> https://people.freedesktop.org/~whot/wayland-doxygen/wayland/Server/structwl__list.html 
>
>
> Unfortunately this issue is not easy to workaround. I'll make sure to 
> create a JBS entry for it (we do have one, but it's probably not 
> visible outside).
>
> I'll also try to play with this a bit to see what can be done - with 
> this issue sometimes it helps to allocate the inner struct first (e.g. 
> wl_list), and then the one that depends on it (e.g. wl_listener).
>
> Maurizio
>
>>
>> ~Mark
>>
>> On 2/15/19 12:30 AM, Maurizio Cimadamore wrote:
>>> Hi Mark,
>>> thanks for the report - from the looks of it, it seems an issue with 
>>> cross-header layout resolution, which is listed in the 'known 
>>> issues' in the EA page:
>>>
>>> "Dynamic layout resolution doesn't work across multiple headers."
>>>
>>> I will check in more details tomorrow, and confirm, one way or another.
>>>
>>> Quick check: are wl_list and wl_listener defined in the same header 
>>> file? If not that's likely the issue here.
>>>
>>> I think Pointer<?> is the correct type - jextract tries to insert as 
>>> more general types as possible when inserting Pointer in argument 
>>> position; if it generated Pointer<Void>, and that was an ordinary 
>>> function call, you could only call it with another Pointer<Void> - 
>>> if the argument type is Pointer<?> you can pass _any_ pointer - e.g. 
>>> Pointer<Byte>, Pointer<Integer> which is kind of close to what you 
>>> can do in C.
>>>
>>> Maurizio
>>>
>>> On 14/02/2019 22:23, Mark Hammons wrote:
>>>> Hi all,
>>>>
>>>> I decided to try to take the dive on project panama, starting with 
>>>> making a binding to linux's wayland server. I used the following 
>>>> command: ~/bin/jdk-13/bin/jextract 
>>>> /usr/include/wayland/wayland-server-core.h 
>>>> /usr/include/wayland/wayland-server.h 
>>>> /usr/include/wayland/wayland-util.h 
>>>> /usr/include/wayland/wayland-version.h 
>>>> /usr/include/wayland/wayland-server-protocol.h -I 
>>>> /usr/include/wayland -L /usr/lib64/ --record-library-path -l 
>>>> wayland-server -t wayland -o wayland_server.jar
>>>>
>>>>
>>>> When I try to allocate a wl_listener struct, I get the following 
>>>> error:
>>>>
>>>> [error] Exception in thread "main" 
>>>> java.lang.UnsupportedOperationException: bitsSize on Unresolved
>>>> [error]     at 
>>>> java.base/java.foreign.layout.Unresolved.bitsSize(Unresolved.java:76)
>>>> [error]     at 
>>>> java.base/java.util.stream.ReferencePipeline$5$1.accept(ReferencePipeline.java:229)
>>>> [error]     at 
>>>> java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948)
>>>> [error]     at 
>>>> java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
>>>> [error]     at 
>>>> java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
>>>> [error]     at 
>>>> java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
>>>> [error]     at 
>>>> java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
>>>> [error]     at 
>>>> java.base/java.util.stream.LongPipeline.reduce(LongPipeline.java:474)
>>>> [error]     at 
>>>> java.base/java.util.stream.LongPipeline.sum(LongPipeline.java:432)
>>>> [error]     at 
>>>> java.base/java.foreign.layout.Group.bitsSize(Group.java:119)
>>>> [error]     at 
>>>> java.base/java.foreign.memory.LayoutType.bytesSize(LayoutType.java:49)
>>>> [error]     at 
>>>> java.base/jdk.internal.foreign.ScopeImpl.allocateInternal(ScopeImpl.java:66)
>>>> [error]     at 
>>>> java.base/jdk.internal.foreign.ScopeImpl.allocate(ScopeImpl.java:92)
>>>> [error]     at 
>>>> java.base/jdk.internal.foreign.ScopeImpl.allocateStruct(ScopeImpl.java:98)
>>>> [error]     at TestApp$.delayedEndpoint$TestApp$1(TestApp.scala:22)
>>>> [error]     at TestApp$delayedInit$body.apply(TestApp.scala:13)
>>>> [error]     at scala.Function0.apply$mcV$sp(Function0.scala:39)
>>>> [error]     at scala.Function0.apply$mcV$sp$(Function0.scala:39)
>>>> [error]     at 
>>>> scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:17) 
>>>>
>>>> [error]     at scala.App.$anonfun$main$1$adapted(App.scala:80)
>>>> [error]     at scala.collection.immutable.List.foreach(List.scala:392)
>>>> [error]     at scala.App.main(App.scala:80)
>>>> [error]     at scala.App.main$(App.scala:78)
>>>> [error]     at TestApp$.main(TestApp.scala:13)
>>>> [error]     at TestApp.main(TestApp.scala)
>>>>
>>>> Looking at other bugs involving this kind of error message, it 
>>>> appears that unresolved is a type for when there's not enough 
>>>> layout information? In any case, here's the struct in question:
>>>>
>>>> struct wl_listener {
>>>>         struct wl_list link;
>>>>         wl_notify_func_t notify;
>>>> };
>>>>
>>>> and the definition of the elements:
>>>>
>>>> typedef void (*wl_notify_func_t)(struct wl_listener *listener, void 
>>>> *data);
>>>>
>>>> struct wl_list {
>>>>         /** Previous list element */
>>>>         struct wl_list *prev;
>>>>         /** Next list element */
>>>>         struct wl_list *next;
>>>> };
>>>>
>>>> I'm fairly certain the issue lies with the function pointer notify. 
>>>> When I looked at the decompiled source, wl_notify_func_t is defined 
>>>> as:
>>>>
>>>>     @FunctionalInterface
>>>>     @NativeCallback("(u64:${wl_listener}u64:v)v")
>>>>     public interface FI5 {
>>>>         void fn(Pointer<wayland_server_core.wl_listener> var1, 
>>>> Pointer<?> var2);
>>>>     }
>>>>
>>>>
>>>> which seems suspicious to me. var2 should be a Pointer<Void> I 
>>>> would think. It's a type I see elsewhere in the source for this 
>>>> file, so it seems suspect that var2 is a Pointer<?>.
>>>>
>>>>
>>>> Is this a bug? Am I just using jextract wrong?
>>>>
>>>> Thanks for your help,
>>>>
>>>> Mark Hammons
>>>>