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#include "qv4compilationunitmapper_p.h"

#include "qv4compileddata_p.h"
#include <private/qdeferredcleanup_p.h>
#include <QFileInfo>
#include <QDateTime>
#include <qt_windows.h>

QT_BEGIN_NAMESPACE

using namespace QV4;

CompiledData::Unit *CompilationUnitMapper::open(const QString &cacheFileName, const QDateTime &sourceTimeStamp, QString *errorString)
{
    close();

    // ### TODO: fix up file encoding/normalization/unc handling once QFileSystemEntry
    // is exported from QtCore.
    HANDLE handle =
#if defined(Q_OS_WINRT)
        CreateFile2(reinterpret_cast<const wchar_t*>(cacheFileName.constData()),
                   GENERIC_READ | GENERIC_EXECUTE, FILE_SHARE_READ,
                   OPEN_EXISTING, nullptr);
#else
        CreateFile(reinterpret_cast<const wchar_t*>(cacheFileName.constData()),
                   GENERIC_READ | GENERIC_EXECUTE, FILE_SHARE_READ,
                   nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL,
                   nullptr);
#endif
    if (handle == INVALID_HANDLE_VALUE) {
        *errorString = qt_error_string(GetLastError());
        return nullptr;
    }

    QDeferredCleanup fileHandleCleanup([handle]{
        CloseHandle(handle);
    });

    CompiledData::Unit header;
    DWORD bytesRead;
    if (!ReadFile(handle, reinterpret_cast<char *>(&header), sizeof(header), &bytesRead, nullptr)) {
        *errorString = qt_error_string(GetLastError());
        return nullptr;
    }

    if (bytesRead != sizeof(header)) {
        *errorString = QStringLiteral("File too small for the header fields");
        return nullptr;
    }

    if (!header.verifyHeader(sourceTimeStamp, errorString))
        return nullptr;

    const uint mappingFlags = header.flags & QV4::CompiledData::Unit::ContainsMachineCode
                              ? PAGE_EXECUTE_READ : PAGE_READONLY;
    const uint viewFlags = header.flags & QV4::CompiledData::Unit::ContainsMachineCode
                           ? (FILE_MAP_READ | FILE_MAP_EXECUTE) : FILE_MAP_READ;

    // Data structure and qt version matched, so now we can access the rest of the file safely.

    HANDLE fileMappingHandle = CreateFileMapping(handle, 0, mappingFlags, 0, 0, 0);
    if (!fileMappingHandle) {
        *errorString = qt_error_string(GetLastError());
        return nullptr;
    }

    QDeferredCleanup mappingCleanup([fileMappingHandle]{
        CloseHandle(fileMappingHandle);
    });

    dataPtr = MapViewOfFile(fileMappingHandle, viewFlags, 0, 0, 0);
    if (!dataPtr) {
        *errorString = qt_error_string(GetLastError());
        return nullptr;
    }

    return reinterpret_cast<CompiledData::Unit*>(dataPtr);
}

void CompilationUnitMapper::close()
{
    if (dataPtr != nullptr)
        UnmapViewOfFile(dataPtr);
    dataPtr = nullptr;
}

QT_END_NAMESPACE
