Function AllocateFileStream

3rdParty/StormLib/src/FileStream.cpp:1007–1062

This function allocates an empty structure for the file stream The stream structure is created as flat block, variable length The file name is placed after the end of the stream structure data

// The stream structure is created as flat block, variable length
// The file name is placed after the end of the stream structure data
static TFileStream * AllocateFileStream(
    const TCHAR * szFileName,
    size_t StreamSize,
    DWORD dwStreamFlags)
{
    TFileStream * pMaster = NULL;
    TFileStream * pStream;
    const TCHAR * szNextFile = szFileName;
    size_t FileNameSize;

    // Sanity check
    assert(StreamSize != 0);

    // The caller can specify chain of files in the following form:
    // C:\archive.MPQ*http://www.server.com/MPQs/archive-server.MPQ
    // In that case, we use the part after "*" as master file name
    while(szNextFile[0] != 0 && szNextFile[0] != _T('*'))
        szNextFile++;
    FileNameSize = (size_t)((szNextFile - szFileName) * sizeof(TCHAR));

    // If we have a next file, we need to open it as master stream
    // Note that we don't care if the master stream exists or not,
    // If it doesn't, later attempts to read missing file block will fail
    if(szNextFile[0] == _T('*'))
    {
        // Don't allow another master file in the string
        if(_tcschr(szNextFile + 1, _T('*')) != NULL)
        {
            SetLastError(ERROR_INVALID_PARAMETER);
            return NULL;
        }

        // Open the master file
        pMaster = FileStream_OpenFile(szNextFile + 1, STREAM_FLAG_READ_ONLY);
    }

    // Allocate the stream structure for the given stream type
    pStream = (TFileStream *)STORM_ALLOC(BYTE, StreamSize + FileNameSize + sizeof(TCHAR));
    if(pStream != NULL)
    {
        // Zero the entire structure
        memset(pStream, 0, StreamSize);
        pStream->pMaster = pMaster;
        pStream->dwFlags = dwStreamFlags;

        // Initialize the file name
        pStream->szFileName = (TCHAR *)((BYTE *)pStream + StreamSize);
        memcpy(pStream->szFileName, szFileName, FileNameSize);
        pStream->szFileName[FileNameSize / sizeof(TCHAR)] = 0;

        // Initialize the stream functions
        StreamBaseInit[dwStreamFlags & 0x03](pStream);
    }

    return pStream;
}

//-----------------------------------------------------------------------------