XorTroll / libjavm

Small, header-only, zero-dependency C++17 Java VM library

libjavm

Simple, compact, zero-dependency C++17 Java Virtual Machine library

The only "dependencies" it does require are standard C/C++17 libraries, plus the offial Java standard library (rt.jar file) since virtually all compiled Java uses it.

Note that, for threading and synchronization items (mutexes, condvars...) you must provide your own implementation. Nevertheless, libjavm provides a default implementation with pthread for threading and standard C++ for sync stuff (pthread_t, std::recursive_mutex, std::condition_variable_any...)

It provides everything necessary to run Java (8 or lower...?) code in any kind of system.

Credits

• python-jvm-interpreter, as the original base for the project.

• andyzip library, since it's used for JAR loading as an easy-to-use and header-only ZIP file reading library.

• KiVM, since it's code was checked for a lot of aspects of the VM.

• Official Oracle VM specs (although these are for Java 11)

Usage

Check the examples directory for some example programs using this library.

TODO: proper documentation...

Comparison with JRE

The tests used to test the VM (slightly modified KiVM tests) are located at javm-test-suite. Currently 26 out of 28 tests are successfully passed (comparing their output with JRE):

• ArgumentTest: pass!

• ArithmeticTest: pass!

• ArrayTest: pass!

• ArrayTest1: pass!

• ArrayTest2: pass!

• AssertTest: pass!

• ChineseTest: pass!

• ClassCastTest: pass!

• ClassNameTest: pass!

• CovScriptJNITest: pass!

• ExceptionTest: pass!

• ExceptionTest1: pass!

• ExceptionTest2: pass!

• ExceptionTest3: pass!

• FileTest: fail (filesystem-related native methods aren't implemented)

• GCTest: pass!

• HashTest: pass!

• HelloWorld: pass!

• LambdaTest: fail (dynamic stuff not implemented yet)

• Main: pass!

• PackagePrivateTest: pass!

• Polymorphism: pass!

• StaticFieldTest: pass!

• StaticResolution: pass!

• StringBuilderTest1: pass!

• ThreadExceptionTest: pass!

• ThreadTest: pass!

TO-DO list

• Implement invokedynamic, wide, tableswitch opcodes

• Implement not implemented standard native methods (only implemented basic ones to get past initialization, for now)

• Dynamic invoking stuff, related to invokedynamic opcode (method handle support, constant pool items related to this...)

• Support or take into account other annotations (currently only CallerSensitive is checked)

• The many TODO comments spread in code

• (...)