Current CPython patch: https://github.com/tochilinak/cpython/pull/4/files.

All interaction between CPython and USVM is done through structure SymbolicAdapter.

Header: symbolicadapter.h.

Creation of symbolic adapter:

SymbolicAdapter *create_new_adapter(void *param);

param is a parameter that will be accessible in all symbolic handlers.

Run function with symbolic tracing:

PyObject *SymbolicAdapter_run(PyObject *self, PyObject *function, Py_ssize_t n, PyObject *const *args, runnable before_call, runnable after_call);

• self: pointer to SymbolicAdapter.
• function: function to run (only PyFunction is supported).
• n: number of arguments.
• args must be an array of tuples of size 2 (concrete and symbolic value for each argument).
• before_call: function to call right before execution.
• after_call: function to call right after execution.

Each of the following functions has a default implementation that does nothing, so any of them can be omitted.

All handlers accept param from create_new_adapter function as their first argument.

If return value of handler is int:

• 0 on success

• Anything else if an error has happened (exception must be set).

If return value of handler is PyObject *:

• Symbolic object on success (or Py_None if it is absent).

• 0 if an error has happened (exception must be set).

For descriptions of handlers see comments in symbolicadapter.h.