pythonplugin.cpp

/*******************************************************************************

Copyright The University of Auckland

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

*******************************************************************************/

//==============================================================================
// Python plugin
//==============================================================================

// This must be the first include file

#include "Python.h"

//==============================================================================

#include "coreguiutils.h"
#include "pythonplugin.h"

//==============================================================================

#include <QCoreApplication>
#include <QSettings>

//==============================================================================

#include <clocale>
#include <iostream>

#ifdef _WIN32
    #include <io.h>
#else
    #include <unistd.h>
#endif

#ifdef __FreeBSD__
    #include <fenv.h>
#endif

//==============================================================================

namespace OpenCOR {
namespace Python {

//==============================================================================

PLUGININFO_FUNC PythonPluginInfo()
{
    Descriptions descriptions;

    descriptions.insert("en", QString::fromUtf8("a plugin to provide the <a href=\"https://www.python.org/\">Python</a> language."));
    descriptions.insert("fr", QString::fromUtf8("une extension ..."));

    return new PluginInfo(PluginInfo::ThirdParty, false, true,
                          QStringList() << "zlib" << "OpenSSL",
                          descriptions);
}

//==============================================================================
// CLI interface
//==============================================================================

int PythonPlugin::executeCommand(const QString &pCommand,
                                 const QStringList &pArguments)
{
    // Pass the given CLI command to the Python interpreter

    if (!pCommand.compare("help")) {
        // Display the commands that we support

        runHelpCommand();

        return 0;
    } else if (pCommand.isEmpty() || !pCommand.compare("shell")) {
        // Run the Python interpreter

        return runPythonShell(pArguments);
    } else if (!pCommand.compare("pip")) {
        // Run the pip package installer

        return runPipInstaller(pArguments);
    } else {
        // Not a CLI command that we support

        runHelpCommand();

        return -1;
    }
}

//==============================================================================
// Plugin interface
//==============================================================================

bool PythonPlugin::definesPluginInterfaces()
{
    // We don't handle this interface...

    return false;
}

//==============================================================================

bool PythonPlugin::pluginInterfacesOk(const QString &pFileName,
                                      QObject *pInstance)
{
    Q_UNUSED(pFileName);
    Q_UNUSED(pInstance);

    // We don't handle this interface...

    return false;
}

//==============================================================================

void PythonPlugin::initializePlugin()
{
    // We must set PYTHONHOME to where Python is 'installed' **before** calling
    // any Python library code. Calling `Py_SetPythonHome()` doesn't work as
    // the `Py_Initialize()` code first checks the environment and, if PYTHONHOME
    // isn't set, uses the installation path compiled in at Python build time...

    auto applicationDirectories = QCoreApplication::applicationDirPath().split("/");
    applicationDirectories.removeLast();

    auto pythonHome = QString();
#if __APPLE__
    pythonHome = (applicationDirectories << "Frameworks" << "Python").join("/");
#elif _WIN32
    pythonHome = (applicationDirectories << "Python").join("/");
#else
    pythonHome = applicationDirectories.join("/");
#endif
    qputenv("PYTHONHOME", pythonHome.toUtf8());

    // Ensure the user's Python site directory (in ~/.local etc) isn't used

    Py_NoUserSiteDirectory = 1;
}

//==============================================================================

void PythonPlugin::finalizePlugin()
{
    // We don't handle this interface...
}

//==============================================================================

void PythonPlugin::pluginsInitialized(const Plugins &pLoadedPlugins)
{
    Q_UNUSED(pLoadedPlugins);

    // We don't handle this interface...
}

//==============================================================================

void PythonPlugin::loadSettings(QSettings *pSettings)
{
    Q_UNUSED(pSettings);

    // TODO: Retrieve our Python settings
}

//==============================================================================

void PythonPlugin::saveSettings(QSettings *pSettings) const
{
    Q_UNUSED(pSettings);

    // TODO: Keep track of our Python settings
}

//==============================================================================

void PythonPlugin::handleUrl(const QUrl &pUrl)
{
    Q_UNUSED(pUrl);

    // We don't handle this interface...
}

//==============================================================================
// Plugin specific
//==============================================================================

void PythonPlugin::runHelpCommand()
{
    // Output the commands we support

    std::cout << "Commands supported by the Python plugin:" << std::endl;
    std::cout << " * Display the commands supported by the Python plugin:" << std::endl;
    std::cout << "      help" << std::endl;
    std::cout << " * Run a Python interpreter:" << std::endl;
    std::cout << "      shell ..." << std::endl;
    std::cout << " * Install Python packages from PyPi:" << std::endl;
    std::cout << "      pip ..." << std::endl;
}

//==============================================================================

int PythonPlugin::runPipInstaller(const QStringList &pArguments)
{
// A helper macro
#define SET_AND_CHECK_PY_OBJECT(obj, value) \
    obj = (value);                          \
    if (obj == nullptr) {                   \
        PyErr_PrintEx(0);                   \
        break;                              \
    }

    // In case of failure

    int result = -1;

    // Python objects we create and use

    PyObject
        *argList = nullptr,
        *pipModule = nullptr,
        *pipMain = nullptr,
        *argTuple = nullptr,
        *pipMainResult = nullptr;

    // Initialise the Python interpreter

    Py_Initialize();

    do {
        const int argc = pArguments.size();

        // Create a Python list for the arguments

        SET_AND_CHECK_PY_OBJECT(argList, PyList_New(argc));

        // Copy arguments into the list

        for (int i = 0; i < argc; i++) {
            PyList_SET_ITEM(argList, i, PyUnicode_FromString(pArguments[i].toUtf8().constData()));
        }

        // import pip
        // pip.main(argList)

        SET_AND_CHECK_PY_OBJECT(argTuple, PyTuple_Pack(1, argList));
        SET_AND_CHECK_PY_OBJECT(pipModule, PyImport_ImportModule("pip"))
        SET_AND_CHECK_PY_OBJECT(pipMain, PyObject_GetAttrString(pipModule, "main"))
        SET_AND_CHECK_PY_OBJECT(pipMainResult, PyObject_CallObject(pipMain, argTuple));

        // All was well

        result = 0;
    } while (0);

    // Decrement the reference count of our Python objects

    Py_XDECREF(pipMain);
    Py_XDECREF(pipModule);
    Py_XDECREF(argTuple);
    Py_XDECREF(argList);

    // Finished with the interpreter

    Py_Finalize();

    return result;
}

//==============================================================================

int PythonPlugin::runPythonShell(const QStringList &pArguments)
{
    // The following has been adapted from `Programs/python.c` in the Python sources.

    const int argc = pArguments.size() + 1;
    wchar_t **argv_copy;
    /* We need a second copy, as Python might modify the first one. */
    wchar_t **argv_copy2;
    int i, res;
    char *oldloc;

    argv_copy = (wchar_t **)PyMem_RawMalloc(sizeof(wchar_t*) * (argc+1));
    argv_copy2 = (wchar_t **)PyMem_RawMalloc(sizeof(wchar_t*) * (argc+1));
    if (!argv_copy || !argv_copy2) {
        fprintf(stderr, "out of memory\n");
        return 1;
    }

    /* 754 requires that FP exceptions run in "no stop" mode by default,
     * and until C vendors implement C99's ways to control FP exceptions,
     * Python requires non-stop mode.  Alas, some platforms enable FP
     * exceptions by default.  Here we disable them.
     */
#ifdef __FreeBSD__
    fedisableexcept(FE_OVERFLOW);
#endif

    oldloc = _PyMem_RawStrdup(setlocale(LC_ALL, NULL));
    if (!oldloc) {
        fprintf(stderr, "out of memory\n");
        return 1;
    }

    setlocale(LC_ALL, "");
    argv_copy2[0] = argv_copy[0] = Py_DecodeLocale("python", NULL);
    for (i = 1; i < argc; i++) {
        argv_copy[i] = Py_DecodeLocale(pArguments[i-1].toUtf8().constData(), NULL);
        if (!argv_copy[i]) {
            PyMem_RawFree(oldloc);
            fprintf(stderr, "Fatal Python error: "
                            "unable to decode the command line argument #%i\n",
                            i + 1);
            return 1;
        }
        argv_copy2[i] = argv_copy[i];
    }
    argv_copy2[argc] = argv_copy[argc] = NULL;

    setlocale(LC_ALL, oldloc);
    PyMem_RawFree(oldloc);

    // N.B. PyMain() calls Py_Initialize() and Py_Finalize()

    res = Py_Main(argc, argv_copy);

    for (i = 0; i < argc; i++) {
        PyMem_RawFree(argv_copy2[i]);
    }
    PyMem_RawFree(argv_copy);
    PyMem_RawFree(argv_copy2);
    return res;
}

//==============================================================================

}   // namespace Python
}   // namespace OpenCOR

//==============================================================================
// End of file
//==============================================================================