C callback with JNA makes JRE crash

[Nathan Barraille]

Hello,
I'm having more problems with JNA .

I'm trying to use a C API that uses callbacks to handle several session events (logged in, logged out, connection problem...).
The session object (called `sp_session` is an opaque struct). All the callbacks are registered in a `sp_session_callbacks` structure. According to the API, I am supposed to declare the callbacks object, and put it into a Config object that I will provide when creating the `sp_session` object. If I don't want to use certain callbacks, I am supposed to initialize them with `null`. The API is using the `__stdcall` calling convention.

Here is a snippet of the C header that's relevant to my problem:


#define SP_CALLCONV __stdcall typedef struct sp_session sp_session; ///< Representation of a session typedef enum sp_error { SP_ERROR_OK = 0, SP_ERROR_BAD_API_VERSION = 1, /* More errors */ } sp_error; typedef struct sp_session_callbacks { /** * Called when login has been processed and was successful */ void (SP_CALLCONV *logged_in)(sp_session *session, sp_error error); /** * Called when logout has been processed. Either called explicitly * if you initialize a logout operation, or implicitly if there * is a permanent connection error * * @param[in] session Session */ void (SP_CALLCONV *logged_out)(sp_session *session); /** * Called when there is a connection error, and the library has problems * reconnecting to the Spotify service. Could be called multiple times (as * long as the problem is present) */ void (SP_CALLCONV *connection_error)(sp_session *session, sp_error error); /* More callbacks */ } sp_session_callbacks; /** * Initialize a session. The session returned will be initialized, but you will need * to log in before you can perform any other operation */ SP_LIBEXPORT(sp_error) sp_session_create(const sp_session_config *config, sp_session **sess);


Here is my equivalent JNA code:

The sp_session object

 public class sp_session extends PointerType{
    	
    	public sp_session(Pointer address) {
    		super(address);
    	}
    	public sp_session() {
    		super();
    	}
    }

The sp_session_callbacks object, containing all the callbacks

public class sp_session_callbacks extends Structure{
    	public LoggedIn logged_in;
    	public LoggedOut logged_out;
    	public ConnectionError connection_error;
    }

The callbacks object (here is LoggedIn, but of course I have one for each callback)

public interface LoggedIn extends StdCallCallback {
    	public void logged_in(sp_session session, int error);
    }

The native library, with the declaration of all the methods

public interface JLibspotify extends StdCallLibrary{
            int sessionCreate(sp_session_config config, PointerByReference sess);
    	int sessionLogin(sp_session session, String username, String password);
            // All the other methods defined by the API
    }

**And my main class, binding it all together**

public class Test{
    	static{
    		System.loadLibrary("libspotify");
    	}
    	
    	public static void main(String[] args){
            JLibspotify lib = (JLibspotify)Native.loadLibrary("libspotify", JLibspotify.class);
    	    sp_session_config cfg = new sp_session_config();
            }
            sp_session_callbacks sessCallbacks = new sp_session_callbacks();
    		LoggedIn loggedInCallback = new LoggedIn(){
    			public void logged_in(sp_session session, int error) {
    				System.out.println("logged_in() called");
    			}
    			
    		};
            sessCallbacks.logged_in = loggedInCallback;
    
            cfg.session_callbacks = sessCallbacks;
    
            PointerByReference sessionPbr = new PointerByReference();
    
            int error_id = sessionCreate(cfg, sessionPbr); // CRASHES HERE
    
            sp_session mySession = new sp_session(sessionPbr.getValue());
        }
    }

So, the sessionCreate function call makes the JRE crash with the trace at the end of the post `EXCEPTION_ACCESS_VIOLATION (0xc0000005) problematic frame: C [jna3757192097716619498.tmp+0x8ce7]`.

It looks like the logged_in callback is causing this, because when I set it to `null` it runs ok. Plus, if I initialize the `connection_error` callback, that has the exact same signature, it doesn't crash either.

Thank you!

#
    # A fatal error has been detected by the Java Runtime Environment:
    #
    #  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x04dc8ce7, pid=3932, tid=6036
    #
    # JRE version: 7.0-b129
    # Java VM: Java HotSpot(TM) Client VM (21.0-b01 mixed mode, sharing windows-x86 )
    # Problematic frame:
    # C  [jna3757192097716619498.tmp+0x8ce7]
    #
    # If you would like to submit a bug report, please visit:
    #   http://java.sun.com/webapps/bugreport/crash.jsp
    # The crash happened outside the Java Virtual Machine in native code.
    # See problematic frame for where to report the bug.
    #
    
    ---------------  T H R E A D  ---------------
    
    Current thread (0x00a19400):  JavaThread "main" [_thread_in_native, id=6036, stack(0x00930000,0x00980000)]
    
    siginfo: ExceptionCode=0xc0000005, reading address 0xffff18a5
    
    Registers:
    EAX=0xffff18a5, EBX=0x04ea1610, ECX=0x04ea1610, EDX=0x1008d3e0
    ESP=0x0097f10c, EBP=0x0097f134, ESI=0x04ea1610, EDI=0x00000014
    EIP=0x04dc8ce7, EFLAGS=0x00210216
    
    Top of Stack: (sp=0x0097f10c)
    0x0097f10c:   04ea3da8 00000254 04ea12f0 0097f208
    0x0097f11c:   04ea1610 04ea12f0 04ea23ec 04ea23ac
    0x0097f12c:   0097f150 ffff18a5 0097f208 1008d3ea
    0x0097f13c:   04ea1610 10030d77 0097f7d4 100b79b0
    0x0097f14c:   ffffffff 1008d334 00000000 04ea1610
    0x0097f15c:   1008d3e0 04ea17f4 1008d9fd 00a19400
    0x0097f16c:   0097f310 00000008 00a10000 04cd10b0
    0x0097f17c:   00000000 00010001 00000000 00000000 
    
    Instructions: (pc=0x04dc8ce7)
    0x04dc8cc7:   08 89 04 24 e8 ff ef ff ff c9 c3 55 89 e5 83 ec
    0x04dc8cd7:   28 8b 45 14 8b 80 20 04 00 00 89 45 fc 8b 45 fc
    0x04dc8ce7:   8b 10 c7 44 24 08 04 00 01 00 8d 45 f8 89 44 24
    0x04dc8cf7:   04 8b 45 fc 89 04 24 8b 42 18 ff d0 83 ec 0c 85 
    
    
    Register to memory mapping:
    
    EAX=0xffff18a5 is an unknown value
    EBX=0x04ea1610 is an unknown value
    ECX=0x04ea1610 is an unknown value
    EDX=0x1008d3e0 is an unknown value
    ESP=0x0097f10c is pointing into the stack for thread: 0x00a19400
    EBP=0x0097f134 is pointing into the stack for thread: 0x00a19400
    ESI=0x04ea1610 is an unknown value
    EDI=0x00000014 is an unknown value
    
    
    Stack: [0x00930000,0x00980000],  sp=0x0097f10c,  free space=316k
    Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
    C  [jna3757192097716619498.tmp+0x8ce7]  JNI_OnUnload+0x8d4
    C  [libspotify.dll+0x8d3ea]  sp_error_message+0x35a
    C  [jna3757192097716619498.tmp+0xdac7]  JNI_OnUnload+0x56b4
    C  [jna3757192097716619498.tmp+0x91b9]  JNI_OnUnload+0xda6
    C  [jna3757192097716619498.tmp+0x2161]
    C  [jna3757192097716619498.tmp+0x2849]  Java_com_sun_jna_Function_invokeInt+0x35
    j  com.sun.jna.Function.invokeInt(I[Ljava/lang/Object;)I+0
    j  com.sun.jna.Function.invoke([Ljava/lang/Object;Ljava/lang/Class;)Ljava/lang/Object;+309
    j  com.sun.jna.Function.invoke(Ljava/lang/Class;[Ljava/lang/Object;Ljava/util/Map;)Ljava/lang/Object;+194
    j  com.sun.jna.Library$Handler.invoke(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;+344
    j  $Proxy0.sessionCreate(Lcom/nbarraille/jspotify/model/sp_session_config;Lcom/sun/jna/ptr/PointerByReference;)I+20
    j  com.nbarraille.jspotify.main.Test.main([Ljava/lang/String;)V+272
    v  ~StubRoutines::call_stub
    V  [jvm.dll+0x115f6d]
    V  [jvm.dll+0x1b788e]
    V  [jvm.dll+0x115fed]
    V  [jvm.dll+0xa2507]
    V  [jvm.dll+0xac867]
    C  [javaw.exe+0x209e]
    C  [javaw.exe+0xa23b]
    C  [javaw.exe+0xa2c5]
    C  [kernel32.dll+0x51194]  BaseThreadInitThunk+0x12
    C  [ntdll.dll+0x5b429]  RtlInitializeExceptionChain+0x63
    C  [ntdll.dll+0x5b3fc]  RtlInitializeExceptionChain+0x36
    
    Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
    j  com.sun.jna.Function.invokeInt(I[Ljava/lang/Object;)I+0
    j  com.sun.jna.Function.invoke([Ljava/lang/Object;Ljava/lang/Class;)Ljava/lang/Object;+309
    j  com.sun.jna.Function.invoke(Ljava/lang/Class;[Ljava/lang/Object;Ljava/util/Map;)Ljava/lang/Object;+194
    j  com.sun.jna.Library$Handler.invoke(Ljava/lang/Object;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;+344
    j  $Proxy0.sessionCreate(Lcom/nbarraille/jspotify/model/sp_session_config;Lcom/sun/jna/ptr/PointerByReference;)I+20
    j  com.nbarraille.jspotify.main.Test.main([Ljava/lang/String;)V+272
    v  ~StubRoutines::call_stub
    
    ---------------  P R O C E S S  ---------------
    
    Java Threads: ( => current thread )
      0x00af0c00 JavaThread "Low Memory Detector" daemon [_thread_blocked, id=4516, stack(0x04080000,0x040d0000)]
      0x00ade800 JavaThread "C1 CompilerThread0" daemon [_thread_blocked, id=380, stack(0x03fb0000,0x04000000)]
      0x00ad9800 JavaThread "Attach Listener" daemon [_thread_blocked, id=4932, stack(0x03dc0000,0x03e10000)]
      0x00ad6400 JavaThread "Signal Dispatcher" daemon [_thread_blocked, id=112, stack(0x03f10000,0x03f60000)]
      0x00acd000 JavaThread "Finalizer" daemon [_thread_blocked, id=5012, stack(0x00990000,0x009e0000)]
      0x00ac7800 JavaThread "Reference Handler" daemon [_thread_blocked, id=3820, stack(0x03e20000,0x03e70000)]
    =>0x00a19400 JavaThread "main" [_thread_in_native, id=6036, stack(0x00930000,0x00980000)]
    
    Other Threads:
      0x00ac6400 VMThread [stack: 0x00be0000,0x00c30000] [id=1488]
      0x00b06400 WatcherThread [stack: 0x03d30000,0x03d80000] [id=4864]
    
    VM state:not at safepoint (normal execution)
    
    VM Mutex/Monitor currently owned by a thread: None
    
    Heap
     def new generation   total 4928K, used 3470K [0x23450000, 0x239a0000, 0x289a0000)
      eden space 4416K,  78% used [0x23450000, 0x237b3aa8, 0x238a0000)
      from space 512K,   0% used [0x238a0000, 0x238a0000, 0x23920000)
      to   space 512K,   0% used [0x23920000, 0x23920000, 0x239a0000)
     tenured generation   total 10944K, used 0K [0x289a0000, 0x29450000, 0x33450000)
       the space 10944K,   0% used [0x289a0000, 0x289a0000, 0x289a0200, 0x29450000)
     compacting perm gen  total 12288K, used 814K [0x33450000, 0x34050000, 0x37450000)
       the space 12288K,   6% used [0x33450000, 0x3351bad0, 0x3351bc00, 0x34050000)
        ro space 10240K,  43% used [0x37450000, 0x3789ce40, 0x3789d000, 0x37e50000)
        rw space 12288K,  53% used [0x37e50000, 0x384c2710, 0x384c2800, 0x38a50000)
    
    Code Cache  [0x01ca0000, 0x01d30000, 0x03ca0000)
     total_blobs=232 nmethods=82 adapters=86 free_code_cache=32973056 largest_free_block=0
    
    Dynamic libraries:
    0x00c70000 - 0x00ca0000 	C:\Program Files\Java\jdk1.7.0\bin\javaw.exe
    0x778f0000 - 0x77a2d000 	C:\Windows\SYSTEM32\ntdll.dll
    0x77070000 - 0x77144000 	C:\Windows\system32\kernel32.dll
    0x75cf0000 - 0x75d3a000 	C:\Windows\system32\KERNELBASE.dll
    0x75e10000 - 0x75eb0000 	C:\Windows\system32\ADVAPI32.dll
    0x775c0000 - 0x7766c000 	C:\Windows\system32\msvcrt.dll
    0x75d50000 - 0x75d69000 	C:\Windows\SYSTEM32\sechost.dll
    0x77670000 - 0x77711000 	C:\Windows\system32\RPCRT4.dll
    0x76f00000 - 0x76fc9000 	C:\Windows\system32\USER32.dll
    0x77a50000 - 0x77a9e000 	C:\Windows\system32\GDI32.dll
    0x77a30000 - 0x77a3a000 	C:\Windows\system32\LPK.dll
    0x75d70000 - 0x75e0d000 	C:\Windows\system32\USP10.dll
    0x74830000 - 0x749ce000 	C:\Windows\WinSxS\x86_microsoft.windows.common-controls_6595b64144ccf1df_6.0.7600.16661_none_420fe3fa2b8113bd\COMCTL32.dll
    0x772f0000 - 0x77347000 	C:\Windows\system32\SHLWAPI.dll
    0x775a0000 - 0x775bf000 	C:\Windows\system32\IMM32.DLL
    0x75eb0000 - 0x75f7c000 	C:\Windows\system32\MSCTF.dll
    0x72740000 - 0x727fe000 	C:\Program Files\Java\jdk1.7.0\jre\bin\msvcr100.dll
    0x67810000 - 0x67b19000 	C:\Program Files\Java\jdk1.7.0\jre\bin\client\jvm.dll
    0x746c0000 - 0x746f2000 	C:\Windows\system32\WINMM.dll
    0x73920000 - 0x7392c000 	C:\Program Files\Java\jdk1.7.0\jre\bin\verify.dll
    0x73330000 - 0x73350000 	C:\Program Files\Java\jdk1.7.0\jre\bin\java.dll
    0x75d40000 - 0x75d45000 	C:\Windows\system32\PSAPI.DLL
    0x733a0000 - 0x733b3000 	C:\Program Files\Java\jdk1.7.0\jre\bin\zip.dll
    0x10000000 - 0x10259000 	C:\Windows\System32\libspotify.dll
    0x77150000 - 0x77185000 	C:\Windows\system32\WS2_32.dll
    0x77a40000 - 0x77a46000 	C:\Windows\system32\NSI.dll
    0x75ba0000 - 0x75cbc000 	C:\Windows\system32\CRYPT32.dll
    0x75ab0000 - 0x75abc000 	C:\Windows\system32\MSASN1.dll
    0x74ee0000 - 0x74f38000 	C:\Windows\system32\WINHTTP.dll
    0x74e90000 - 0x74edf000 	C:\Windows\system32\webio.dll
    0x754c0000 - 0x754d6000 	C:\Windows\system32\CRYPTSP.dll
    0x75260000 - 0x7529b000 	C:\Windows\system32\rsaenh.dll
    0x750a0000 - 0x750b7000 	C:\Windows\system32\USERENV.dll
    0x75a40000 - 0x75a4b000 	C:\Windows\system32\profapi.dll
    0x75a30000 - 0x75a3c000 	C:\Windows\system32\CRYPTBASE.dll
    0x728a0000 - 0x728b6000 	C:\Program Files\Java\jdk1.7.0\jre\bin\net.dll
    0x75480000 - 0x754bc000 	C:\Windows\system32\mswsock.dll
    0x75470000 - 0x75476000 	C:\Windows\System32\wship6.dll
    0x73950000 - 0x73960000 	C:\Windows\system32\NLAapi.dll
    0x75340000 - 0x75384000 	C:\Windows\system32\DNSAPI.dll
    0x71030000 - 0x71038000 	C:\Windows\System32\winrnr.dll
    0x71020000 - 0x71030000 	C:\Windows\system32\napinsp.dll
    0x71000000 - 0x71012000 	C:\Windows\system32\pnrpnsp.dll
    0x74fd0000 - 0x74fd5000 	C:\Windows\System32\wshtcpip.dll
    0x74d30000 - 0x74d4c000 	C:\Windows\system32\IPHLPAPI.DLL
    0x74d20000 - 0x74d27000 	C:\Windows\system32\WINNSI.DLL
    0x70c60000 - 0x70c66000 	C:\Windows\system32\rasadhlp.dll
    0x71ba0000 - 0x71bd8000 	C:\Windows\System32\fwpuclnt.dll
    0x73930000 - 0x7393f000 	C:\Program Files\Java\jdk1.7.0\jre\bin\nio.dll
    0x04dc0000 - 0x04e12000 	C:\Users\nbarraille\AppData\Local\Temp\jna3757192097716619498.tmp
    
    VM Arguments:
    jvm_args: -Djava.library.path=C:\Windows\System32 -Dfile.encoding=Cp1252 
    java_command: com.nbarraille.jspotify.main.Test
    Launcher Type: SUN_STANDARD
    
    Environment Variables:
    PATH=C:/Program Files/Java/jdk1.7.0/bin/../jre/bin/client;C:/Program Files/Java/jdk1.7.0/bin/../jre/bin;C:/Program Files/Java/jdk1.7.0/bin/../jre/lib/i386;C:\Windows\System32
    USERNAME=nbarraille
    OS=Windows_NT
    PROCESSOR_IDENTIFIER=x86 Family 6 Model 23 Stepping 10, GenuineIntel
    
    
    
    ---------------  S Y S T E M  ---------------
    
    OS: Windows 7 Build 7600 
    
    CPU:total 2 (2 cores per cpu, 1 threads per core) family 6 model 23 stepping 10, cmov, cx8, fxsr, mmx, sse, sse2, sse3, ssse3, sse4.1
    
    Memory: 4k page, physical 3624108k(1667672k free), swap 7246452k(4953532k free)
    
    vm_info: Java HotSpot(TM) Client VM (21.0-b01) for windows-x86 JRE (1.7.0-ea-b129), built on Feb 10 2011 07:43:39 by "java_re" with unknown MS VC++:1600
    
    time: Sat Mar 05 12:49:35 2011
    elapsed time: 0 seconds

[Rob Spoor]

Shouldn't sp_session extend Structure? After all, that's how you declare it.

[Nathan Barraille]

I think in order to extend structure, I need to know the different fields of a C struct, don't I?
I happen to read that opaque struct should be converted to PointerType in JNA.
Also, if it was the problem, wouldn't it also crash when I set up the logged_in callback as null?
But I can try.

Thanks