Interpreter.cc

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#include "Interpreter.hh"
#include "Command.hh"
#include "TclObject.hh"
#include "CommandException.hh"
#include "MSXCommandController.hh"
#include "MSXMotherBoard.hh"
#include "Setting.hh"
#include "InterpreterOutput.hh"
#include "MSXCPUInterface.hh"
#include "FileOperations.hh"
#include "ranges.hh"
#include "span.hh"
#include "stl.hh"
#include "unreachable.hh"
#include <iostream>
#include <utility>
#include <vector>
#include <cstdint>
//#include <tk.h>

using std::string;
using std::vector;

namespace openmsx {

// See comments in traceProc()
static std::vector<std::pair<uintptr_t, BaseSetting*>> traces; // sorted on first
static uintptr_t traceCount = 0;


static int dummyClose(ClientData /*instanceData*/, Tcl_Interp* /*interp*/)
{
        return 0;
}
static int dummyInput(ClientData /*instanceData*/, char* /*buf*/,
                      int /*bufSize*/, int* /*errorCodePtr*/)
{
        return 0;
}
static void dummyWatch(ClientData /*instanceData*/, int /*mask*/)
{
}
static int dummyGetHandle(ClientData /*instanceData*/, int /*direction*/,
                          ClientData* /*handlePtr*/)
{
        return TCL_ERROR;
}
Tcl_ChannelType Interpreter::channelType = {
        const_cast<char*>("openMSX console"),// Type name
        nullptr,                 // Always non-blocking
        dummyClose,              // Close proc
        dummyInput,              // Input proc
        Interpreter::outputProc, // Output proc
        nullptr,                 // Seek proc
        nullptr,                 // Set option proc
        nullptr,                 // Get option proc
        dummyWatch,              // Watch for events on console
        dummyGetHandle,          // Get a handle from the device
        nullptr,                 // Tcl_DriverClose2Proc
        nullptr,                 // Tcl_DriverBlockModeProc
        nullptr,                 // Tcl_DriverFlushProc
        nullptr,                 // Tcl_DriverHandlerProc
        nullptr,                 // Tcl_DriverWideSeekProc
        nullptr,                 // Tcl_DriverThreadActionProc
        nullptr,                 // Tcl_DriverTruncateProc
};

void Interpreter::init(const char* programName)
{
        Tcl_FindExecutable(programName);
}

Interpreter::Interpreter()
{
        interp = Tcl_CreateInterp();
        Tcl_Preserve(interp);

        // TODO need to investigate this: doesn't work on windows
        /*
        if (Tcl_Init(interp) != TCL_OK) {
                std::cout << "Tcl_Init: " << interp->result << '\n';
        }
        if (Tk_Init(interp) != TCL_OK) {
                std::cout << "Tk_Init error: " << interp->result << '\n';
        }
        if (Tcl_Eval(interp, "wm withdraw .") != TCL_OK) {
                std::cout << "wm withdraw error: " << interp->result << '\n';
        }
        */

        Tcl_Channel channel = Tcl_CreateChannel(&channelType,
                "openMSX console", this, TCL_WRITABLE);
        if (channel) {
                Tcl_SetChannelOption(interp, channel, "-translation", "binary");
                Tcl_SetChannelOption(interp, channel, "-buffering", "line");
                Tcl_SetChannelOption(interp, channel, "-encoding", "utf-8");
        }
        Tcl_SetStdChannel(channel, TCL_STDOUT);

        setVariable(TclObject("env(OPENMSX_USER_DATA)"),
                    TclObject(FileOperations::getUserDataDir()));
        setVariable(TclObject("env(OPENMSX_SYSTEM_DATA)"),
                    TclObject(FileOperations::getSystemDataDir()));
}

Interpreter::~Interpreter()
{
        // see comment in MSXCPUInterface::cleanup()
        MSXCPUInterface::cleanup();

        if (!Tcl_InterpDeleted(interp)) {
                Tcl_DeleteInterp(interp);
        }
        Tcl_Release(interp);

        // Tcl_Finalize() should only be called once for the whole application
        // tcl8.6 checks for this (tcl8.5 did not).
        // Normally we only create/destroy exactly one Interpreter object for
        // openMSX, and then simply calling Tcl_Finalize() here is fine. Though
        // when running unittest we do create/destroy multiple Interpreter's.
        // Another option is to not call Tcl_Finalize(), but that leaves some
        // memory allocated, and makes memory-leak checkers report more errors.
        static bool scheduled = false;
        if (!scheduled) {
                scheduled = true;
                atexit(Tcl_Finalize);
        }
}

int Interpreter::outputProc(ClientData clientData, const char* buf,
                 int toWrite, int* /*errorCodePtr*/)
{
        try {
                auto* output = static_cast<Interpreter*>(clientData)->output;
                std::string_view text(buf, toWrite);
                if (!text.empty() && output) {
                        output->output(text);
                }
        } catch (...) {
                UNREACHABLE; // we cannot let exceptions pass through Tcl
        }
        return toWrite;
}

void Interpreter::registerCommand(const string& name, Command& command)
{
        auto token = Tcl_CreateObjCommand(
                interp, name.c_str(), commandProc,
                static_cast<ClientData>(&command), nullptr);
        command.setToken(token);
}

void Interpreter::unregisterCommand(Command& command)
{
        Tcl_DeleteCommandFromToken(interp, static_cast<Tcl_Command>(command.getToken()));
}

int Interpreter::commandProc(ClientData clientData, Tcl_Interp* interp,
                           int objc, Tcl_Obj* const objv[])
{
        try {
                auto& command = *static_cast<Command*>(clientData);
                span<const TclObject> tokens(
                        reinterpret_cast<TclObject*>(const_cast<Tcl_Obj**>(objv)),
                        objc);
                int res = TCL_OK;
                TclObject result;
                try {
                        if (!command.isAllowedInEmptyMachine()) {
                                if (auto controller =
                                        dynamic_cast<MSXCommandController*>(
                                                &command.getCommandController())) {
                                        if (!controller->getMSXMotherBoard().getMachineConfig()) {
                                                throw CommandException(
                                                        "Can't execute command in empty machine");
                                        }
                                }
                        }
                        command.execute(tokens, result);
                } catch (MSXException& e) {
                        result = e.getMessage();
                        res = TCL_ERROR;
                }
                Tcl_SetObjResult(interp, result.getTclObject());
                return res;
        } catch (...) {
                UNREACHABLE; // we cannot let exceptions pass through Tcl
                return TCL_ERROR;
        }
}

// Returns
//   - build-in Tcl commands
//   - openmsx commands
//   - user-defined procs
TclObject Interpreter::getCommandNames()
{
        return execute("openmsx::all_command_names");
}

bool Interpreter::isComplete(const string& command) const
{
        return Tcl_CommandComplete(command.c_str()) != 0;
}

TclObject Interpreter::execute(const string& command)
{
        int success = Tcl_Eval(interp, command.c_str());
        if (success != TCL_OK) {
                throw CommandException(Tcl_GetStringResult(interp));
        }
        return TclObject(Tcl_GetObjResult(interp));
}

TclObject Interpreter::executeFile(const string& filename)
{
        int success = Tcl_EvalFile(interp, filename.c_str());
        if (success != TCL_OK) {
                throw CommandException(Tcl_GetStringResult(interp));
        }
        return TclObject(Tcl_GetObjResult(interp));
}

static void setVar(Tcl_Interp* interp, const TclObject& name, const TclObject& value)
{
        if (!Tcl_ObjSetVar2(interp, name.getTclObjectNonConst(), nullptr,
                            value.getTclObjectNonConst(),
                            TCL_GLOBAL_ONLY | TCL_LEAVE_ERR_MSG)) {
                // might contain error message of a trace proc
                std::cerr << Tcl_GetStringResult(interp) << '\n';
        }
}
static Tcl_Obj* getVar(Tcl_Interp* interp, const TclObject& name)
{
        return Tcl_ObjGetVar2(interp, name.getTclObjectNonConst(), nullptr,
                              TCL_GLOBAL_ONLY);
}

void Interpreter::setVariable(const TclObject& name, const TclObject& value)
{
        if (!Tcl_ObjSetVar2(interp, name.getTclObjectNonConst(), nullptr,
                            value.getTclObjectNonConst(),
                            TCL_GLOBAL_ONLY | TCL_LEAVE_ERR_MSG)) {
                throw CommandException(Tcl_GetStringResult(interp));
        }
}

void Interpreter::unsetVariable(const char* name)
{
        Tcl_UnsetVar(interp, name, TCL_GLOBAL_ONLY);
}

static TclObject getSafeValue(BaseSetting& setting)
{
        try {
                return setting.getValue();
        } catch (MSXException&) {
                return TclObject(0); // 'safe' value, see comment in registerSetting()
        }
}
void Interpreter::registerSetting(BaseSetting& variable)
{
        const auto& name = variable.getFullNameObj();
        if (Tcl_Obj* tclVarValue = getVar(interp, name)) {
                // Tcl var already existed, use this value
                try {
                        variable.setValueDirect(TclObject(tclVarValue));
                } catch (MSXException&) {
                        // Ignore: can happen in case of proxy settings when
                        // the current machine doesn't have this setting.
                        // E.g.
                        //   (start with cbios machine)
                        //   set renshaturbo 0
                        //   create_machine
                        //   machine2::load_machine Panasonic_FS-A1GT
                }
        } else {
                // define Tcl var
                setVariable(name, getSafeValue(variable));
        }

        // The call setVariable() above can already trigger traces on this
        // variable (in Tcl it's possible to already set traces on a variable
        // before that variable is defined). We didn't yet set a trace on it
        // ourselves. So for example on proxy-settings we don't yet delegate
        // read/writes to the actual setting. This means that inside the trace
        // callback we see the value set above instead of the 'actual' value.
        //
        // This scenario can be triggered in the load_icons script by
        // executing the following commands (interactively):
        //   delete_machine machine1
        //   create_machine
        //   machine2::load_machine msx2
        //
        // Before changing the 'safe-value' (see getSafeValue()) to '0',
        // this gave errors because the load_icons script didn't expect to see
        // 'proxy' (the old 'safe-value') as value.
        //
        // The current solution (choosing '0' as safe value) is not ideal, but
        // good enough for now.
        //
        // A possible better solution is to move Tcl_TraceVar() before
        // setVariable(), I did an initial attempt but there were some
        // problems. TODO investigate this further.

        uintptr_t traceID = traceCount++;
        traces.emplace_back(traceID, &variable); // still in sorted order
        Tcl_TraceVar(interp, name.getString().data(), // 0-terminated
                     TCL_TRACE_READS | TCL_TRACE_WRITES | TCL_TRACE_UNSETS,
                     traceProc, reinterpret_cast<ClientData>(traceID));
}

void Interpreter::unregisterSetting(BaseSetting& variable)
{
        auto it = rfind_if_unguarded(traces, EqualTupleValue<1>(&variable));
        uintptr_t traceID = it->first;
        traces.erase(it);

        const char* name = variable.getFullName().data(); // 0-terminated
        Tcl_UntraceVar(interp, name,
                       TCL_TRACE_READS | TCL_TRACE_WRITES | TCL_TRACE_UNSETS,
                       traceProc, reinterpret_cast<ClientData>(traceID));
        unsetVariable(name);
}

static BaseSetting* getTraceSetting(uintptr_t traceID)
{
        auto it = ranges::lower_bound(traces, traceID, LessTupleElement<0>());
        return ((it != end(traces)) && (it->first == traceID))
                ? it->second : nullptr;
}

#ifndef NDEBUG
static std::string_view removeColonColon(std::string_view s)
{
        if (StringOp::startsWith(s, "::")) s.remove_prefix(2);
        return s;
}
#endif

char* Interpreter::traceProc(ClientData clientData, Tcl_Interp* interp,
                             const char* part1, const char* /*part2*/, int flags)
{
        try {
                // Lookup Setting object that belongs to this Tcl variable.
                //
                // In a previous implementation we passed this object directly
                // as the clientData. However this went wrong in the following
                // scenario:
                //
                //    proc foo {} { carta eject ; carta spmanbow.rom }
                //    bind Q foo
                //    [press Q twice]
                //
                // The problem is that when a SCC cartridge is removed, we
                // delete several settings (e.g. SCC_ch1_mute). While deleting
                // a setting we unset the corresponsing Tcl variable (see
                // unregisterSetting() above), this in turn triggers a
                // TCL_TRACE_UNSET callback (this function). To prevent this
                // callback from triggering we first remove the trace before
                // unsetting the variable. However it seems when a setting is
                // deleted from within an active Tcl proc (like in the example
                // above), the callback is anyway triggered, but only at the
                // end of the proc (so in the foo proc above, the settings
                // are deleted after the first statement, but the callbacks
                // only happen after the second statement). By that time the
                // Setting object is already deleted and the callback function
                // works on a deleted object.
                //
                // To prevent this we don't anymore pass a pointer to the
                // Setting object as clientData, but we lookup the Setting in
                // a map. If the Setting was deleted, we won't find it anymore
                // in the map and return.

                auto traceID = reinterpret_cast<uintptr_t>(clientData);
                auto* variable = getTraceSetting(traceID);
                if (!variable) return nullptr;

                const TclObject& part1Obj = variable->getFullNameObj();
                assert(removeColonColon(part1) == removeColonColon(part1Obj.getString()));

                static string static_string;
                if (flags & TCL_TRACE_READS) {
                        try {
                                setVar(interp, part1Obj, variable->getValue());
                        } catch (MSXException& e) {
                                static_string = std::move(e).getMessage();
                                return const_cast<char*>(static_string.c_str());
                        }
                }
                if (flags & TCL_TRACE_WRITES) {
                        try {
                                Tcl_Obj* v = getVar(interp, part1Obj);
                                TclObject newValue(v ? v : Tcl_NewObj());
                                variable->setValueDirect(newValue);
                                const TclObject& newValue2 = variable->getValue();
                                if (newValue != newValue2) {
                                        setVar(interp, part1Obj, newValue2);
                                }
                        } catch (MSXException& e) {
                                setVar(interp, part1Obj, getSafeValue(*variable));
                                static_string = std::move(e).getMessage();
                                return const_cast<char*>(static_string.c_str());
                        }
                }
                if (flags & TCL_TRACE_UNSETS) {
                        try {
                                // note we cannot use restoreDefault(), because
                                // that goes via Tcl and the Tcl variable
                                // doesn't exist at this point
                                variable->setValueDirect(TclObject(
                                        variable->getRestoreValue()));
                        } catch (MSXException&) {
                                // for some reason default value is not valid ATM,
                                // keep current value (happened for videosource
                                // setting before turning on (set power on) the
                                // MSX machine)
                        }
                        setVar(interp, part1Obj, getSafeValue(*variable));
                        Tcl_TraceVar(interp, part1, TCL_TRACE_READS |
                                        TCL_TRACE_WRITES | TCL_TRACE_UNSETS,
                                     traceProc,
                                     reinterpret_cast<ClientData>(traceID));
                }
        } catch (...) {
                UNREACHABLE; // we cannot let exceptions pass through Tcl
        }
        return nullptr;
}

void Interpreter::createNamespace(const std::string& name)
{
        execute(strCat("namespace eval ", name, " {}"));
}

void Interpreter::deleteNamespace(const std::string& name)
{
        execute("namespace delete " + name);
}

void Interpreter::poll()
{
        //Tcl_ServiceAll();
        Tcl_DoOneEvent(TCL_DONT_WAIT);
}

TclParser Interpreter::parse(std::string_view command)
{
        return TclParser(interp, command);
}

void Interpreter::wrongNumArgs(unsigned argc, span<const TclObject> tokens, const char* message)
{
        assert(argc <= tokens.size());
        Tcl_WrongNumArgs(interp, argc, reinterpret_cast<Tcl_Obj* const*>(tokens.data()), message);
        // not efficient, but anyway on an error path
        throw CommandException(Tcl_GetStringResult(interp));
}

} // namespace openmsx