python_importer.c

#include "python_importer.h"

PyObject *py_handler = NULL;
bool always_import = false;

void debug(int level, const char *text)
{
    DEBUG(level, ("vfs_python: %s\n", text));
}

static PyObject* py_debug(PyObject* self, PyObject* args) {
    int level = 5;
    const char* text;

    if (!PyArg_ParseTuple(args, "|is", &level, &text)) {
        // If parsing with an integer fails, try parsing just the string
        PyErr_Clear();
        if (!PyArg_ParseTuple(args, "s", &text)) {
            return NULL;
        }
    }

    debug(level, text);

    Py_RETURN_NONE;
}

static PyMethodDef debug_method = {
    "debug", (PyCFunction)py_debug, METH_VARARGS, "Log debug message"
};

void add_debug_function_to_globals() {
    PyObject *module_dict = PyImport_GetModuleDict();
    PyObject *builtins = PyDict_GetItemString(module_dict, "builtins");

    if (builtins != NULL) {
        PyObject *py_func = PyCFunction_NewEx(&debug_method, NULL, NULL);
        PyDict_SetItemString(PyModule_GetDict(builtins), "debug", py_func);
        Py_DECREF(py_func);
    }
}

const char *get_conf(vfs_handle_struct *handle, const char *name)
{
    return lp_parm_const_string(SNUM(handle->conn), "python", name, NULL);
}

PyObject *get_py_mod(const char *script_path)
{
    PyObject *py_mod;
    PyObject *py_imp_str, *py_imp_handle, *py_imp_dict;
    PyObject *py_imp_load_source, *py_args_tuple;

    Py_Initialize();
    add_debug_function_to_globals();

    py_imp_str = PyUnicode_FromString("imp");
    py_imp_handle = PyImport_Import(py_imp_str);
    py_imp_dict = PyModule_GetDict(py_imp_handle);
    py_imp_load_source = PyDict_GetItemString(py_imp_dict, "load_source");

    py_args_tuple = PyTuple_New(2);
    PyTuple_SetItem(py_args_tuple, 0, PyUnicode_FromString("handler"));
    PyTuple_SetItem(py_args_tuple, 1, PyUnicode_FromString(script_path));

    py_mod = PyObject_CallObject(py_imp_load_source, py_args_tuple);

    Py_DECREF(py_args_tuple);
    Py_DECREF(py_imp_str);
    Py_DECREF(py_imp_handle);
    Py_DECREF(py_imp_dict);
    Py_DECREF(py_imp_load_source);

    return py_mod;
}

PyObject *get_py_func(PyObject *py_mod, const char *func_name)
{
    PyObject *py_func_name = PyUnicode_FromString(func_name);
    PyObject *py_func = PyObject_GetAttr(py_mod, py_func_name);
    Py_DECREF(py_func_name);

    if (py_func != NULL)
    {
        if (PyCallable_Check(py_func) == 1)
        {
            return py_func;
        }
    }
    debug(5, "something went wrong get_py_func.");
    return NULL;
}

PyObject *get_func(vfs_handle_struct *handle, const char *func_name)
{
    debug(5, "get_func");
    if ((py_handler == NULL) || (always_import == true))
    {
        debug(5, "importing module.");
        const char *script_path = get_conf(handle, "script");
        py_handler = get_py_mod(script_path);
    }

    return get_py_func(py_handler, func_name);
}