Rom.cc

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#include "Rom.hh"
#include "DeviceConfig.hh"
#include "XMLElement.hh"
#include "RomInfo.hh"
#include "RomDatabase.hh"
#include "FileContext.hh"
#include "Filename.hh"
#include "FileException.hh"
#include "PanasonicMemory.hh"
#include "MSXMotherBoard.hh"
#include "Reactor.hh"
#include "Debugger.hh"
#include "Debuggable.hh"
#include "CliComm.hh"
#include "FilePool.hh"
#include "ConfigException.hh"
#include "EmptyPatch.hh"
#include "IPSPatch.hh"
#include "StringOp.hh"
#include "ranges.hh"
#include "sha1.hh"
#include <cstring>
#include <limits>
#include <memory>

using std::string;
using std::unique_ptr;

namespace openmsx {

class RomDebuggable final : public Debuggable
{
public:
        RomDebuggable(Debugger& debugger, Rom& rom);
        ~RomDebuggable();
        unsigned getSize() const override;
        const std::string& getDescription() const override;
        byte read(unsigned address) override;
        void write(unsigned address, byte value) override;
        void moved(Rom& r);
private:
        Debugger& debugger;
        Rom* rom;
};


Rom::Rom(string name_, string description_,
         const DeviceConfig& config, const string& id /*= {}*/)
        : name(std::move(name_)), description(std::move(description_))
{
        // Try all <rom> tags with matching "id" attribute.
        string errors;
        for (auto& c : config.getXML()->getChildren("rom")) {
                if (c->getAttribute("id", {}) == id) {
                        try {
                                init(config.getMotherBoard(), *c, config.getFileContext());
                                return;
                        } catch (MSXException& e) {
                                // remember error message, and try next
                                if (!errors.empty() && (errors.back() != '\n')) {
                                        errors += '\n';
                                }
                                errors += e.getMessage();
                        }
                }
        }
        if (errors.empty()) {
                // No matching <rom> tag.
                string err = "Missing <rom> tag";
                if (!id.empty()) {
                        strAppend(err, " with id=\"", id, '"');
                }
                throw ConfigException(std::move(err));
        } else {
                // We got at least one matching <rom>, but it failed to load.
                // Report error messages of all failed attempts.
                throw ConfigException(errors);
        }
}

void Rom::init(MSXMotherBoard& motherBoard, const XMLElement& config,
               const FileContext& context)
{
        // (Only) if the content of this ROM depends on state that is not part
        // of a savestate, we want to compare the sha1sum of the ROM from the
        // time the savestate was created with the one from the loaded
        // savestate. External state can be a .rom file or a patch file.
        bool checkResolvedSha1 = false;

        auto sums      = config.getChildren("sha1");
        auto filenames = config.getChildren("filename");
        auto* resolvedFilenameElem = config.findChild("resolvedFilename");
        auto* resolvedSha1Elem     = config.findChild("resolvedSha1");
        if (config.findChild("firstblock")) {
                // part of the TurboR main ROM
                //  If there is a firstblock/lastblock tag, (only) use these to
                //  locate the rom. In the past we would also write add a
                //  resolvedSha1 tag for this type of ROM (before we used
                //  'checkResolvedSha1'). So there are old savestates that have
                //  both type of tags. For such a savestate it's important to
                //  first check firstblock, otherwise it will only load when
                //  there is a file that matches the sha1sums of the
                //  firstblock-lastblock portion of the containing file.
                int first = config.getChildDataAsInt("firstblock");
                int last  = config.getChildDataAsInt("lastblock");
                size = (last - first + 1) * 0x2000;
                rom = motherBoard.getPanasonicMemory().getRomRange(first, last);
                assert(rom);

                // Part of a bigger (already checked) rom, no need to check.
                checkResolvedSha1 = false;

        } else if (resolvedFilenameElem || resolvedSha1Elem ||
                   !sums.empty() || !filenames.empty()) {
                auto& filepool = motherBoard.getReactor().getFilePool();
                // first try already resolved filename ..
                if (resolvedFilenameElem) {
                        try {
                                file = File(resolvedFilenameElem->getData());
                        } catch (FileException&) {
                                // ignore
                        }
                }
                // .. then try the actual sha1sum ..
                auto fileType = context.isUserContext()
                        ? FilePool::ROM : FilePool::SYSTEM_ROM;
                if (!file.is_open() && resolvedSha1Elem) {
                        Sha1Sum sha1(resolvedSha1Elem->getData());
                        file = filepool.getFile(fileType, sha1);
                        if (file.is_open()) {
                                // avoid recalculating same sha1 later
                                originalSha1 = sha1;
                        }
                }
                // .. and then try filename as originally given by user ..
                if (!file.is_open()) {
                        for (auto& f : filenames) {
                                try {
                                        Filename filename(f->getData(), context);
                                        file = File(filename);
                                } catch (FileException&) {
                                        // ignore
                                }
                        }
                }
                // .. then try all alternative sha1sums ..
                // (this might retry the actual sha1sum)
                if (!file.is_open()) {
                        for (auto& s : sums) {
                                Sha1Sum sha1(s->getData());
                                file = filepool.getFile(fileType, sha1);
                                if (file.is_open()) {
                                        // avoid recalculating same sha1 later
                                        originalSha1 = sha1;
                                        break;
                                }
                        }
                }
                // .. still no file, then error
                if (!file.is_open()) {
                        string error = strCat("Couldn't find ROM file for \"", name, '"');
                        if (!filenames.empty()) {
                                strAppend(error, ' ', filenames.front()->getData());
                        }
                        if (resolvedSha1Elem) {
                                strAppend(error, " (sha1: ", resolvedSha1Elem->getData(), ')');
                        } else if (!sums.empty()) {
                               strAppend(error, " (sha1: ", sums.front()->getData(), ')');
                        }
                        strAppend(error, '.');
                        throw MSXException(std::move(error));
                }

                // actually read file content
                if (config.findChild("filesize") ||
                    config.findChild("skip_headerbytes")) {
                        throw MSXException(
                                "The <filesize> and <skip_headerbytes> tags "
                                "inside a <rom> section are no longer "
                                "supported.");
                }
                try {
                        auto mmap = file.mmap();
                        if (mmap.size() > std::numeric_limits<decltype(size)>::max()) {
                                throw MSXException("Rom file too big: ", file.getURL());
                        }
                        rom = mmap.data();
                        size = unsigned(mmap.size());
                } catch (FileException&) {
                        throw MSXException("Error reading ROM image: ", file.getURL());
                }

                // For file-based roms, calc sha1 via File::getSha1Sum(). It can
                // possibly use the FilePool cache to avoid the calculation.
                if (originalSha1.empty()) {
                        originalSha1 = filepool.getSha1Sum(file);
                }

                // verify SHA1
                if (!checkSHA1(config)) {
                        motherBoard.getMSXCliComm().printWarning(
                                "SHA1 sum for '", name,
                                "' does not match with sum of '",
                                file.getURL(), "'.");
                }

                // We loaded an external file, so check.
                checkResolvedSha1 = true;

        } else {
                // for an empty SCC the <size> tag is missing, so take 0
                // for MegaFlashRomSCC the <size> tag is used to specify
                // the size of the mapper (and you don't care about initial
                // content)
                size = config.getChildDataAsInt("size", 0) * 1024; // in kb
                extendedRom.resize(size);
                memset(extendedRom.data(), 0xff, size);
                rom = extendedRom.data();

                // Content does not depend on external files. No need to check
                checkResolvedSha1 = false;
        }

        Sha1Sum patchedSha1;
        if (size != 0) {
                if (auto* patchesElem = config.findChild("patches")) {
                        // calculate before content is altered
                        getOriginalSHA1();

                        unique_ptr<PatchInterface> patch =
                                std::make_unique<EmptyPatch>(rom, size);

                        for (auto& p : patchesElem->getChildren("ips")) {
                                patch = std::make_unique<IPSPatch>(
                                        Filename(p->getData(), context),
                                        std::move(patch));
                        }
                        auto patchSize = unsigned(patch->getSize());
                        if (patchSize <= size) {
                                patch->copyBlock(0, const_cast<byte*>(rom), size);
                        } else {
                                size = patchSize;
                                extendedRom.resize(size);
                                patch->copyBlock(0, extendedRom.data(), size);
                                rom = extendedRom.data();
                        }

                        // calculated because it's different from original
                        patchedSha1 = SHA1::calc(rom, size);

                        // Content altered by external patch file -> check.
                        checkResolvedSha1 = true;
                }
        }

        // TODO fix this, this is a hack that depends heavily on
        //      HardwareConfig::createRomConfig
        if (StringOp::startsWith(name, "MSXRom")) {
                auto& db = motherBoard.getReactor().getSoftwareDatabase();
                string_view title;
                if (const auto* romInfo = db.fetchRomInfo(getOriginalSHA1())) {
                        title = romInfo->getTitle(db.getBufferStart());
                }
                if (!title.empty()) {
                        name = title.str();
                } else {
                        // unknown ROM, use file name
                        name = file.getOriginalName();
                }
        }

        // Make name unique wrt all registered debuggables.
        auto& debugger = motherBoard.getDebugger();
        if (size) {
                if (debugger.findDebuggable(name)) {
                        unsigned n = 0;
                        string tmp;
                        do {
                                tmp = strCat(name, " (", ++n, ')');
                        } while (debugger.findDebuggable(tmp));
                        name = std::move(tmp);
                }
        }

        if (checkResolvedSha1) {
                auto& mutableConfig = const_cast<XMLElement&>(config);
                auto& psha1 = patchedSha1.empty() ? getOriginalSHA1() : patchedSha1;
                string patchedSha1Str = psha1.toString();
                const auto& actualSha1Elem = mutableConfig.getCreateChild(
                        "resolvedSha1", patchedSha1Str);
                if (actualSha1Elem.getData() != patchedSha1Str) {
                        string tmp = file.is_open() ? file.getURL() : name;
                        // can only happen in case of loadstate
                        motherBoard.getMSXCliComm().printWarning(
                                "The content of the rom ", tmp, " has "
                                "changed since the time this savestate was "
                                "created. This might result in emulation "
                                "problems.");
                }
        }

        // This must come after we store the 'resolvedSha1', because on
        // loadstate we use that tag to search the complete rom in a filepool.
        if (auto* windowElem = config.findChild("window")) {
                unsigned windowBase = windowElem->getAttributeAsInt("base", 0);
                unsigned windowSize = windowElem->getAttributeAsInt("size", size);
                if ((windowBase + windowSize) > size) {
                        throw MSXException(
                                "The specified window [", windowBase, ',',
                                windowBase + windowSize, ") falls outside "
                                "the rom (with size ", size, ").");
                }
                rom = &rom[windowBase];
                size = windowSize;
        }

        // Only create the debuggable once all checks succeeded.
        if (size) {
                romDebuggable = std::make_unique<RomDebuggable>(debugger, *this);
        }
}

bool Rom::checkSHA1(const XMLElement& config)
{
        auto sums = config.getChildren("sha1");
        if (sums.empty()) {
                return true;
        }
        auto& sha1sum = getOriginalSHA1();
        return ranges::any_of(sums, [&](auto& s) {
                return Sha1Sum(s->getData()) == sha1sum;
        });
}

Rom::Rom(Rom&& r) noexcept
        : rom          (std::move(r.rom))
        , extendedRom  (std::move(r.extendedRom))
        , file         (std::move(r.file))
        , originalSha1 (std::move(r.originalSha1))
        , name         (std::move(r.name))
        , description  (std::move(r.description))
        , size         (std::move(r.size))
        , romDebuggable(std::move(r.romDebuggable))
{
        if (romDebuggable) romDebuggable->moved(*this);
}

Rom::~Rom() = default;

string Rom::getFilename() const
{
        return file.is_open() ? file.getURL() : string{};
}

const Sha1Sum& Rom::getOriginalSHA1() const
{
        if (originalSha1.empty()) {
                originalSha1 = SHA1::calc(rom, size);
        }
        return originalSha1;
}

void Rom::addPadding(unsigned newSize, byte filler)
{
        assert(newSize >= size);
        if (newSize == size) return;

        MemBuffer<byte> tmp(newSize);
        auto* newData = tmp.data();
        memcpy(newData, rom, size);
        memset(newData + size, filler, newSize - size);

        extendedRom = std::move(tmp);
        rom = newData;
        size = newSize;
}

RomDebuggable::RomDebuggable(Debugger& debugger_, Rom& rom_)
        : debugger(debugger_), rom(&rom_)
{
        debugger.registerDebuggable(rom->getName(), *this);
}

RomDebuggable::~RomDebuggable()
{
        debugger.unregisterDebuggable(rom->getName(), *this);
}

unsigned RomDebuggable::getSize() const
{
        return rom->getSize();
}

const string& RomDebuggable::getDescription() const
{
        return rom->getDescription();
}

byte RomDebuggable::read(unsigned address)
{
        assert(address < getSize());
        return (*rom)[address];
}

void RomDebuggable::write(unsigned /*address*/, byte /*value*/)
{
        // ignore
}

void RomDebuggable::moved(Rom& r)
{
        rom = &r;
}

} // namespace openmsx