Function SFileSetFilePointer

3rdParty/StormLib/src/SFileReadFile.cpp:809–907

}

DWORD STORMAPI SFileSetFilePointer(HANDLE hFile, LONG lFilePos, LONG * plFilePosHigh, DWORD dwMoveMethod)
{
    TMPQFile * hf = (TMPQFile *)hFile;
    ULONGLONG OldPosition;
    ULONGLONG NewPosition;
    ULONGLONG FileSize;
    ULONGLONG DeltaPos;

    // If the hFile is not a valid file handle, return an error.
    if(!IsValidFileHandle(hFile))
    {
        SetLastError(ERROR_INVALID_HANDLE);
        return SFILE_INVALID_POS;
    }

    // Retrieve the file size for handling the limits
    if(hf->pStream != NULL)
    {
        FileStream_GetSize(hf->pStream, &FileSize);
    }
    else
    {
        FileSize = SFileGetFileSize(hFile, NULL);
    }

    // Handle the NULL and non-NULL values of plFilePosHigh
    // Non-NULL: The DeltaPos is combined from lFilePos and *lpFilePosHigh
    // NULL: The DeltaPos is sign-extended value of lFilePos
    DeltaPos = (plFilePosHigh != NULL) ? MAKE_OFFSET64(plFilePosHigh[0], lFilePos) : (ULONGLONG)(LONGLONG)lFilePos;

    // Get the relative point where to move from
    switch(dwMoveMethod)
    {
        case FILE_BEGIN:

            // Move relative to the file begin.
            OldPosition = 0;
            break;

        case FILE_CURRENT:

            // Retrieve the current file position
            if(hf->pStream != NULL)
            {
                FileStream_GetPos(hf->pStream, &OldPosition);
            }
            else
            {
                OldPosition = hf->dwFilePos;
            }
            break;

        case FILE_END:

            // Move relative to the end of the file
            OldPosition = FileSize;
            break;