cjoin.cpp

研读AxCrypt对加解密的处理方法

/*! \file
    \brief Implementation of AxPipe::CJoin, a base class for joining n-streams into one.

    @(#) $Id: CJoin.cpp,v 1.2 2004/01/01 20:05:53 svante Exp $

    AxPipe - Binary Stream Framework

    Copyright (C) 2003 Svante Seleborg/Axon Data, All rights reserved.

    This program is free software; you can redistribute it and/or modify it under the terms
    of the GNU General Public License as published by the Free Software Foundation;
    either version 2 of the License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
    without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    See the GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along with this program;
    if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
    Boston, MA 02111-1307 USA

    The author may be reached at mailto:[e-mail] and http://axpipe.sourceforge.net

    Why is this framework released as GPL and not LGPL? See http://www.gnu.org/philosophy/why-not-lgpl.html

----
\verbatim
    CJoin.cpp                       Implementation of CJoin, a base class for joining n-streams into one.

    E-mail                          YYYY-MM-DD              Reason
    [e-mail]              2003-12-01              Initial
\endverbatim
*/
#include "stdafx.h"

#include "AxAssert.h"
#define AXLIB_ASSERT_FILE "CJoin.cpp"

using AxLib::OutputDebugStringF;

namespace AxPipe {
    /// \brief Send the data to the CJoin, along with the index
    /// \param pSeg The segment of data from the input stream to pass along.
    void
    CJoin::CTSinkJoin::Out(CSeg *pSeg) {
        OutputDebugStringF(_T("CJoin::CTSinkJoin::Out()\n"));
        // Only send data if we're not empty - otherwise we may be locked up
        if (!m_fEmpty) {
            m_Sync.WorkStart();
            m_pNextSeg = pSeg;
            m_Sync.WorkSignal();
        } else {
            SetError(ERROR_CODE_GENERIC, _T("CJoin::CTSinkJoin::Out [Unexpected call]"));
            // If we're empty, just ignore extra data and report error.
            if (pSeg) {
                pSeg->Release();
            }
        }
    }

    /// Pass a NULL as filter conventions dictate so the CJoin reader
    /// can detect it, and not ask for more.
    /// \return false - never propagate from a sink.
    bool
    CJoin::CTSinkJoin::OutClose() {
        OutputDebugString(_T("CJoin::CTSinkJoin::OutPlug()\n"));
        Out(NULL);
        return false;
    }

    /// \brief Forward a flush request to the CJoin
    ///
    /// Use filter conventions to signal the CJoin, so zero-len segment is sent.
    bool
    CJoin::CTSinkJoin::OutFlush() {
        OutputDebugString(_T("CJoin::CTSinkJoin::OutFlush()\n"));
        Out(new CSeg);
        return false;
    }

    /// Init of member variables.
    CJoin::CTSinkJoin::CTSinkJoin() {
        m_pNextSeg = NULL;
        m_fEmpty = false;
    }

    /// Check for empty condition
    /// \return true if this input stream is marked as empty.
    bool
    CJoin::CTSinkJoin::IsEmpty() {
        return m_fEmpty;
    }

    /// Called by the In() of the CJoin to get the next segment from
    /// this input stream, after returning from SinkWorkWait().
    /// \return A CSeg * to a segment.
    CSeg *
    CJoin::CTSinkJoin::GetSeg() {
        m_fEmpty = m_pNextSeg == NULL;
        return m_pNextSeg;
    }

    /// Called by the worker CJoin thread to wait for the arrival
    /// of more. CJoin expects to block waiting for more, or NULL
    /// if the end of stream is deteced.
    void
    CJoin::CTSinkJoin::SinkWorkWait() {
        m_Sync.WorkWait();
    }

    /// Called by the worker CJoin thread to signal that it's done
    /// with it's work and potentially ready for more.
    void
    CJoin::CTSinkJoin::SinkWorkEnd() {
        m_Sync.WorkEnd();
    }

    /// \brief Construct the CJoin, but Init() must also be called
    CJoin::CJoin() {
        m_nMaxStreams = 0;
        m_ppInSinks = NULL;
    }

    /// \brief Also destruct all the CTSinkJoin sink-objects.
    CJoin::~CJoin() {
        OutputDebugString(_T("CJoin::~CJoin()\n"));
        ASSCHK(m_fExit, _T("CJoin::~CJoin() with worker still active"));
        if (m_ppInSinks) {
            for (int i = 0; i < m_nMaxStreams; i++) {
                delete m_ppInSinks[i];
                m_ppInSinks[i] = NULL;
            }
            delete[] m_ppInSinks;
            m_ppInSinks = NULL;
        }
    }

    /// Handle Plug() of the stream, checking all input streams for errors too.
    void
    CJoin::OutPlug() {
        if (GetErrorCode() == ERROR_CODE_SUCCESS) {
            for (int i = 0; i < m_nMaxStreams; i++) {
                if (m_ppInSinks[i] && m_ppInSinks[i]->GetErrorCode() != ERROR_CODE_SUCCESS) {
                    SetError(m_ppInSinks[i]->GetErrorCode(), m_ppInSinks[i]->GetErrorMsg());
                    return;
                }
            }
        }
    }
    
    /// \brief Define how many streams you want here.
    /// \param nMaxStreams Specify how many streams at the max you want to join.
    CJoin *
    CJoin::Init(int nMaxStreams) {
        m_ppInSinks = new CTSinkJoin *[m_nMaxStreams = nMaxStreams];
        for (int i = 0; i < m_nMaxStreams; i++) {
            m_ppInSinks[i] = NULL;
        }
        return this;
    }

    /// Get a CSink that can be used to terminate an input stream, passing
    /// the data to the CJoin. A reference is returned, do not take the
    /// address of it and use as a pointer. This object must be destructed
    /// by the CJoin code, not the pipe it gets CPipe::Append()'ed to.
    /// \param ix The index of the input stream to get the CSink for.
    /// \return A reference to a CSink.
    CSink &
    CJoin::GetSink(int ix) {
        ASSCHK(ix < m_nMaxStreams, _T("CJoin::GetSink() [Invalid stream index]"));
        if (!m_ppInSinks[ix]) {
            return *(m_ppInSinks[ix] = new CTSinkJoin);
        }
        return *m_ppInSinks[ix];
    }

    /// \brief Wait for data from the in-stream, get it and indicate when done.
    /// \return The next segment, NULL if empty.
    CSeg *
    CJoin::StreamSeg(int ix) {
        ASSCHK(ix > m_nMaxStreams || m_ppInSinks[ix] != NULL, _T("CJoin::StreamSeg() [Invalid stream index]"));
        if (m_ppInSinks[ix]->IsEmpty()) {
            return NULL;
        }
        m_ppInSinks[ix]->SinkWorkWait();
        CSeg *pSeg = m_ppInSinks[ix]->GetSeg();
        m_ppInSinks[ix]->SinkWorkEnd();
        return pSeg;
    }

    /// \brief Set and return the current input stream index.
    /// \param ix The stream you want, it'll get reduced modulo the number of streams.
    /// \return The actual stream used guaranteed in the range 0 - (MaxIx() - 1)
    int
    CJoin::StreamIx(int ix) {
        return ix % m_nMaxStreams;
    }
    
    /// \brief Get the number of streams.
    /// \returns The number of streams.
    int
    CJoin::StreamNum() {
        return m_nMaxStreams;
    }
    
    /// \brief Tell if an indexed stream is marked as empty.
    /// \param ix The index, in the range 0 - (MaxIx() - 1)
    /// \return true if the indexed stream is marked as empty.
    bool
    CJoin::StreamEmpty(int ix) {
        return m_ppInSinks[ix]->IsEmpty();
    }
};