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JNA free memory created in the shared object dll

I tried libvirt java bindings and always get Access Violation error when the library try to use Native.free method to free memory allocated in the dll, so I write the following simple test.
public class HelloWorld {
public interface CLibrary extends Library {
CLibrary INSTANCE = (CLibrary) Native.loadLibrary("msvcrt", CLibrary.class);
Pointer _strdup(String src);
}
public static void main(String[] args) {
Pointer p = CLibrary.INSTANCE._strdup("HelloWorld");
Native.free(Pointer.nativeValue(p));
}
}
My environment is as following:
Windows 7 Ultimate SP1 64Bit, Jdk&Jvm is also 64bit(1.8.0_101), Eclipse Neon Release 64Bit, JNA version 4.2.2.
The program stop at Native.free line, and prompt App crash dialog, information is as following:
Problem signature:
Problem Event Name: APPCRASH
Application name: javaw.exe
Application version: 8.0.1010.13
Application timestamp: 576a4c7e
Fault module name: StackHash_c84f
Faulty module version: 6.1.7601.18247
Faulty module timestamp: 521eaf24
Exception code: c0000374
Exception offset: 00000000000c4102
OS version: 6.1.7601.2.1.0.256.1
Locale ID: 2052
Additional Information 1: c84f
Additional information 2: c84f3cec06e628f5bb4621d27c86f80d
Additional Information 3: 3b2e
Additional Information 4: 3b2e22e89759af30ea1b1d716fbf08f3
So I wondering if this way to free memory created in dll is wrong? Can you give me some advice, thanks!

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Pointer;
public class MemoryTest {
public interface CLibrary extends Library {
CLibrary INSTANCE = (CLibrary) Native.loadLibrary("c", CLibrary.class);
Pointer strdup(String src);
}
public static void main(String[] args) {
Pointer p = CLibrary.INSTANCE.strdup("HelloWorld");
Native.free(Pointer.nativeValue(p));
System.gc();
}
}
this test did run on Linux Ubuntu64 16.04 without any crash.

call Windows Color System from Java

I need to call Windows Color System functions from Java. Following this tutorial i tried to call DLL function using Java Native Access. All examples from this tutorial works fine. When i try to load and use Mscms.dll (one of the WCS libraries) that DLL seems to be loaded successfully, but i can not call any functions. List of functions is here.
I got a message:
Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function 'GetColorDirectory'
What's wrong with my code? Could you help me please?
import com.sun.jna.Library;
import com.sun.jna.Native;
public class WCS_test {
public interface Mscms extends Library {
// http://msdn.microsoft.com/en-us/library/dd316928%28v=vs.85%29.aspx
boolean GetColorDirectory(String pMachineName, String[] pBuffer, int pdwSize);
}
private static Mscms mscms = (Mscms) Native.loadLibrary("C:/Windows/system32/Mscms.dll", Mscms.class);
public static void main(String[] args) {
if (mscms != null)
System.out.println("Library loaded\n");
else
System.err.println("Library loading error\n");
String[] pBuffer = new String[1024];
mscms.GetColorDirectory(null, pBuffer, pBuffer.length);
}
}

When you get a java.lang.UnsatisfiedLinkError that means that it could not find the function 'GetColorDirectory' inside of the Mscms.dll. Looking at the link from your source code http://msdn.microsoft.com/en-us/library/dd316928%28v=vs.85%29.aspx you should try the Unicode name GetColorDirectoryW.

NuiGetSensorCount Java JNA

I am just learning how to use Java JNA, and I am trying to call a simple function from the Microsoft Kinect SDK. (NuiGetSensorCount) which just returns the number of connected kinects.
Here is my attempt:
import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.NativeLong;
import com.sun.jna.Pointer;
public class Driver {
public interface KinectLibrary extends Library {
KinectLibrary INSTANCE = (KinectLibrary)Native.loadLibrary(("Microsoft.Kinect"),KinectLibrary.class);
//_Check_return_ HRESULT NUIAPI NuiGetSensorCount( _In_ int * pCount );
NativeLong NuiGetSensorCount(Pointer pCount);
}
public static void main(String[] args) {
Pointer devCount = new Pointer(0);
KinectLibrary.INSTANCE.NuiGetSensorCount(devCount);
System.out.println("Devices:"+devCount.getInt(0));
}
}
But I get:
Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function 'NuiGetSensorCount': The specified procedure could not be found.
at com.sun.jna.Function.<init>(Function.java:208)
at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:536)
at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:513)
at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:499)
at com.sun.jna.Library$Handler.invoke(Library.java:199)
at $Proxy0.NuiGetSensorCount(Unknown Source)
at Driver.main(Driver.java:30)
Can anybody provide help of how to change my code so it finds the correct native function? And also provide some information/reference so that I could try to debug this myself (some way to see what function Java JNA is looking for, and compare it to what the .dll contains)

I figured out my problem. First, I used a program called dependency walker http://dependencywalker.com/ to view all the symbols in the DLL and I determined that the DLL I was using (Microsoft.Kinect.dll) did not actually contain the function I was trying to call. I found out that Kinect10.dll was the one I needed. After changing that, I had to make a small change to my pointer and it works perfectly!
Here is the fixed code.
import com.sun.jna.Native;
import com.sun.jna.NativeLong;
import com.sun.jna.ptr.IntByReference;
import com.sun.jna.win32.StdCallLibrary;
public class Driver{
public interface KinectLibrary extends StdCallLibrary {
KinectLibrary INSTANCE = (KinectLibrary)Native.loadLibrary(("Kinect10"),KinectLibrary.class);
//_Check_return_ HRESULT NUIAPI NuiGetSensorCount( _In_ int * pCount );
NativeLong NuiGetSensorCount(IntByReference pCount);
}
public static void main(String[] args) {
IntByReference a = new IntByReference();
KinectLibrary.INSTANCE.NuiGetSensorCount(a);
System.out.println("Devices:"+a.getValue());
}
}

Using DLL in java through JNA

I am using dll in java using JNA, but i am getting below error
Exception in thread "main" java.lang.UnsatisfiedLinkError: Error looking up function 'GetStatus': The specified procedure could not be found.
Not getting how to resolve this issue?
Please help.
Here is java code
import com.sun.jna.Library;
import com.sun.jna.Native;
/** Simple example of native library declaration and usage. */
public class First {
public interface TEST extends Library {
public String GetStatus();
}
public static void main(String[] args) {
TEST obj = (TEST ) Native.loadLibrary("TEST ", TEST .class);
System.out.println( obj.GetStatus());
}
}

This Nugget is super easy to use and works perfectly. https://www.nuget.org/packages/UnmanagedExports
You need Visual Studio 2012 (express).
Once installed, just add [RGiesecke.DllExport.DllExport] before any static function you want to export. That's it!
Example:
C#
[RGiesecke.DllExport.DllExport]
public static int YourFunction(string data)
{
/*Your code here*/
return 1;
}
Java
Add the import at the top:
import com.sun.jna.Native;
Add the interface in your class. Its your C# function name preceded by the letter "I":
public interface IYourFunction extends com.sun.jna.Library
{
public int YourFunction(String tStr);
};
Call your DLL where you need it in your class:
IYourFunction iYourFunction = (IYourFunction )Native.loadLibrary("full or relative path to DLL withouth the .dll extention", IYourFunction.class);//call JNA
System.out.println("Returned: " + IYourFunction.YourFunction("some parameter"));
EDIT:
If the DLL is 32bit, the JDK/JRE has to be 32bit as well. Add the following check to your code:
if(!System.getProperty("os.arch").equals("x86")) {
throw new Exception(".NET DLL " + "32bits JRE/JDK is required. Currently using " + System.getProperty("os.arch") + ".\r\nTry changing your PATH environement variable.");
}

JNA access to 64-bit DLL (Windows7 64-bit)

Could you please advice. I have simple DLL (under Windows 7 64-bit) and simple Java code with JNA access to this DLL.
The problem is when I use 64-bit version of this DLL looks like I can't get parameter from Java in my DLL test function giveIntGetInt, and I have no problem when I use 32-bit DLL.
Where I was wrong?
Thank you!
import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.Platform;
import com.sun.jna.Pointer;
/** Simple example of native library declaration and usage. */
public class HelloWorld {
public interface simpleDLL extends Library {
simpleDLL INSTANCE = (simpleDLL) Native.loadLibrary(
(Platform.isWindows() ? "simpleDLL" : "simpleDLLLinuxPort"), simpleDLL.class);
int giveIntGetInt(int a); // int giveIntGetInt(int a);
}
public static void main(String[] args) {
int b = simpleDLL.INSTANCE.giveIntGetInt(2);
System.out.println("Hello, World\n");
System.out.println(String.format("Argument %d", b));
}
}
this is C dll method:
int simpleDLL::giveIntGetInt(int a)
{
return 2*a;
}
For example, this is I've got with 64-bit dll:
Hello, World
Argument 181140
32-bit dll:
Hello, World
Argument 4