Version available on nuget fails with NullReferenceException (but not master)

[ancailliau]

The version available on nuget fails on OsX with 4.0.5 with the rule vul_drivecrypt.yar (among other) available on https://github.com/Neo23x0/signature-base/tree/master/yara. Compiling from source code leads to no error.

Unhandled exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
 ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Runtime.InteropServices.Marshal.PtrToStructureHelper(IntPtr ptr, Object structure, Boolean allowValueClasses)
   at System.Runtime.InteropServices.Marshal.PtrToStructureHelper(IntPtr ptr, Type structureType)
   at System.Runtime.InteropServices.Marshal.PtrToStructure(IntPtr ptr, Type structureType)
   at dnYara.Interop.ObjRefHelper.MarshalAndValidate[T](IntPtr struct_ptr, Func`2 validityChecker, T& destination_ptr)
   at dnYara.Interop.ObjRefHelper.EachStructOfTInObjRef[T](IntPtr ref_obj, Func`2 validityChecker)+MoveNext()
   at System.Linq.Enumerable.SelectEnumerableIterator`2.ToList()
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at dnYara.CompiledRules.ExtractRules()
   at dnYara.CompiledRules..ctor(IntPtr rulesPtr)
   at dnYara.Compiler.Compile()

[sbruyere]

Hello,

We just updated the NuGets to be compatible with Yara v4.0.0 to v4.1.1 (not yet latest version of Yara since there is some structure changes to be handled).

The latest NuGet version is 2.1.1.

For OSX compatibility you will need to find a way to compile libyara with cmake under OSX (and I would be interested to know how you compile the lib under OSX to update the readme instructions).

Thanks !