bool IORequestGenerator::_CreateFile()

in IORequestGenerator/IORequestGenerator.cpp [1735:1878]

• 117 lines of code
• 22 McCabe index (conditional complexity)

bool IORequestGenerator::_CreateFile(UINT64 ullFileSize, const char *pszFilename, bool fZeroBuffers, bool fVerbose) const
{
    bool fSlowWrites = false;
    PrintVerbose(fVerbose, "Creating file '%s' of size %I64u.\n", pszFilename, ullFileSize);

    //enable SE_MANAGE_VOLUME_NAME privilege, required to set valid size of a file
    if (!SetPrivilege(SE_MANAGE_VOLUME_NAME, "WARNING:"))
    {
        PrintError("WARNING: Could not set privileges for setting valid file size; will use a slower method of preparing the file\n", GetLastError());
        fSlowWrites = true;
    }

    // there are various forms of paths we do not support creating subdir hierarchies
    // for - relative and unc paths specifically. this is fine, and not neccesary to
    // warn about. we can add support in the future.
    DWORD dwError = _CreateDirectoryPath(pszFilename);
    if (dwError != ERROR_SUCCESS && dwError != ERROR_NOT_SUPPORTED)
    {
        PrintError("WARNING: Could not create intermediate directory (error code: %u)\n", dwError);
    }

    // create handle to the file
    HANDLE hFile = CreateFile(pszFilename,
                              GENERIC_READ | GENERIC_WRITE,
                              FILE_SHARE_READ | FILE_SHARE_WRITE,
                              nullptr,
                              CREATE_ALWAYS,
                              FILE_ATTRIBUTE_NORMAL,
                              nullptr);
    if (INVALID_HANDLE_VALUE == hFile)
    {
        PrintError("Could not create the file (error code: %u)\n", GetLastError());
        return false;
    }

    if (ullFileSize > 0)
    {
        LARGE_INTEGER li;
        li.QuadPart = ullFileSize;

        LARGE_INTEGER liNewFilePointer;

        if (!SetFilePointerEx(hFile, li, &liNewFilePointer, FILE_BEGIN))
        {
            PrintError("Could not set file pointer during file creation when extending file (error code: %u)\n", GetLastError());
            CloseHandle(hFile);
            return false;
        }
        if (liNewFilePointer.QuadPart != li.QuadPart)
        {
            PrintError("File pointer improperly moved during file creation when extending file\n");
            CloseHandle(hFile);
            return false;
        }

        //extends file (warning! this is a kind of "reservation" of space; valid size of the file is still 0!)
        if (!SetEndOfFile(hFile))
        {
            PrintError("Error setting end of file (error code: %u)\n", GetLastError());
            CloseHandle(hFile);
            return false;
        }
        //try setting valid size of the file (privileges for that are enabled before CreateFile)
        if (!fSlowWrites && !SetFileValidData(hFile, ullFileSize))
        {
            PrintError("WARNING: Could not set valid file size (error code: %u); trying a slower method of filling the file"
                       " (this does not affect performance, just makes the test preparation longer)\n",
                       GetLastError());
            fSlowWrites = true;
        }

        //if setting valid size couldn't be performed, fill in the file by simply writing to it (slower)
        if (fSlowWrites)
        {
            li.QuadPart = 0;
            if (!SetFilePointerEx(hFile, li, &liNewFilePointer, FILE_BEGIN))
            {
                PrintError("Could not set file pointer during file creation (error code: %u)\n", GetLastError());
                CloseHandle(hFile);
                return false;
            }
            if (liNewFilePointer.QuadPart != li.QuadPart)
            {
                PrintError("File pointer improperly moved during file creation\n");
                CloseHandle(hFile);
                return false;
            }

            UINT32 ulBufSize;
            UINT64 ullRemainSize;

            ulBufSize = 1024*1024;
            if (ullFileSize < (UINT64)ulBufSize)
            {
                ulBufSize = (UINT32)ullFileSize;
            }

            vector<BYTE> vBuf(ulBufSize);
            for (UINT32 i=0; i<ulBufSize; ++i)
            {
                vBuf[i] = fZeroBuffers ? 0 : (BYTE)(i&0xFF);
            }

            ullRemainSize = ullFileSize;
            while (ullRemainSize > 0)
            {
                DWORD dwBytesWritten;
                if ((UINT64)ulBufSize > ullRemainSize)
                {
                    ulBufSize = (UINT32)ullRemainSize;
                }

                if (!WriteFile(hFile, &vBuf[0], ulBufSize, &dwBytesWritten, NULL))
                {
                    PrintError("Error while writng during file creation (error code: %u)\n", GetLastError());
                    CloseHandle(hFile);
                    return false;
                }

                if (dwBytesWritten != ulBufSize)
                {
                    PrintError("Improperly written data during file creation\n");
                    CloseHandle(hFile);
                    return false;
                }

                ullRemainSize -= ulBufSize;
            }
        }
    }

    //if compiled with debug support, check file size
#ifndef NDEBUG
    LARGE_INTEGER li;
    if( GetFileSizeEx(hFile, &li) )
    {
        assert(li.QuadPart == (LONGLONG)ullFileSize);
    }
#endif

    CloseHandle(hFile);

    return true;
}