【C/C++】设置磁盘剩余空间

const DWORD g_sysReserveBytes = 5 * 1024;
const tstring g_diskEmulatorFileName = _T("DiskEmulatorFile_1C14D9BC-3056-4fdf-9BE5-CEFC9C7EF074");
tstring GetDiskName(const char* disk)
{
    tstring __disk;
    if (NULL == disk)
    {
        tstring curDir;
        GetMainModuleDir(curDir);
        assert(curDir.size() >= 2);
        __disk = curDir.substr(0, 2);
    }
    else
    {
        __disk = Utf8ToTStr(disk);
    }

    return __disk;
}

bool IsFreeSpaceEnough(DWORD freeSpaceBytes, const char* disk/* = NULL*/)
{
    RemoveDiskEmulatorFile(disk);
    bool result = false;
    tstring __disk = GetDiskName(disk);

    ULARGE_INTEGER avalBytes = {0};
    if (GetDiskFreeSpaceEx(__disk.c_str(), &avalBytes, NULL, NULL))
    {
        result = (avalBytes.HighPart > 0) || ((__int64)avalBytes.LowPart > (__int64(freeSpaceBytes) + g_sysReserveBytes));
    }

    return result;
}

bool SetFreeSpaceBytes(DWORD freeSpaceBytes, const char* disk/* = NULL*/)
{
    RemoveDiskEmulatorFile(disk);
    bool result = false;
    tstring __disk = GetDiskName(disk);

    ULARGE_INTEGER avalBytes = {0};
    if (GetDiskFreeSpaceEx(__disk.c_str(), &avalBytes, NULL, NULL))
    {
        __int64    totalSize = (((__int64)avalBytes.HighPart) << 32) + avalBytes.LowPart;
        if (((__int64)freeSpaceBytes + g_sysReserveBytes) <= totalSize)
        {
            __int64 emulatorFileSize = totalSize - freeSpaceBytes;
            DWORD high = (DWORD)(emulatorFileSize >> 32);
            DWORD low = (DWORD)(emulatorFileSize & 0xffffffff);
            HANDLE file = CreateFile(JoinPath(__disk, g_diskEmulatorFileName).c_str(),
                                    GENERIC_READ | GENERIC_WRITE,
                                    0,
                                    NULL,
                                    CREATE_ALWAYS,
                                    FILE_ATTRIBUTE_NORMAL,
                                    NULL);
            if (file != INVALID_HANDLE_VALUE)
            {
                SetFilePointer(file, low, (PLONG)&high, FILE_BEGIN);
                if (SetEndOfFile(file) != FALSE)
                {
                    result = true;
                }
                CloseHandle(file);
            }
        }
    }

    return result;
}

bool RemoveDiskEmulatorFile(const char* disk/* = NULL*/)
{
    bool result = true;
    tstring filePath = JoinPath(GetDiskName(disk), g_diskEmulatorFileName);
    if (FileExists(filePath))
    {
        result = (_tremove(filePath.c_str()) == 0);
    }

    return result;
}