cpipeinflate.cpp

研读AxCrypt对加解密的处理方法

/*! \file
    \brief Implementation of AxPipe::Stock::CPipeInflate

    @(#) $Id: CPipeInflate.cpp,v 1.2 2004/02/02 12:10:47 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
    E-mail                          YYYY-MM-DD              Reason
    [e-mail]              2003-12-15              Initial
\endverbatim
*/
#include "stdafx.h"
#include "CPipeInflate.h"
#include "AxAssert.h"
#define AXLIB_ASSERT_FILE "CPipeInflate.cpp"

// Can't use this for convenient notation below:
// using AxPipe::Stock::CPipeInflate;
// because the Doxygen get's confused.

namespace AxPipe {
    namespace Stock {
        static voidpf zalloc OF((voidpf opaque, uInt items, uInt size)) {
            // The semantics of zalloc are a bit unclear, so we always zero the memory...
            return memset(new unsigned char[items * size], 0, items * size);
        }

        static void zfree OF((voidpf opaque, voidpf address)) {
            delete[] static_cast<unsigned char *>(address);
        }

        /// \brief Initialize member variables
        CPipeInflate::CPipeInflate() {
            m_pOutSeg = NULL;
            m_cb = 0;
            ZeroMemory(&m_Zstream, sizeof m_Zstream);
        }

        /// Clean up if necessary, should only need
        /// work to be done on error.
        CPipeInflate::~CPipeInflate() {
            if (m_pOutSeg) {
                m_pOutSeg->Release();
            }
        }

        /// Initialize zlib for this inflation.
        /// \return true to continue cascading of Open()
        bool
        CPipeInflate::OutOpen() {
            bool fReturn = CPipe::OutOpen();        // Open base first, like constructor
            m_cb = 0;                               // Total output bytes counter
            ZeroMemory(&m_Zstream, sizeof m_Zstream);
            m_Zstream.next_in = Z_NULL;	            // Defer check to first call to inflate
            m_Zstream.zalloc = zalloc;              // Use our custom alloc()
            m_Zstream.zfree = zfree;                // Use our custom free()

            if (inflateInit(&m_Zstream) != Z_OK) {
                SetError(ERROR_CODE_STOCK, _T("ZLIB initialization error"));
            }
            ASSCHK(m_pOutSeg == NULL, _T("CPipeInflate::OutOpen() [m_pOutSeg non-NULL]"));

            return fReturn;                         // Return the saved return code.
        }

        /// Clean up and call base class CPipe::OutClose()
        /// \return true to continue cascading the Open()
        bool
        CPipeInflate::OutClose() {
            // This is a safety first measure, should not really be needed.
            if (m_pOutSeg) {
                m_pOutSeg->Release();
                m_pOutSeg = NULL;
            }

            // Clean up memory allocations etc
            if (inflateEnd(&m_Zstream) != Z_OK) {
                SetError(ERROR_CODE_DERIVED, _T("ZLIB error in inflateEnd error"));
                return false;
            }

            return CPipe::OutClose();               // End by closing base, like destructor
        }

        /// Accept each segment as it is passed. It's important that you do not
        /// send more data than needed. The compression format is self-terminating,
        /// and there must be no data sent after the last byte of the compressed
        /// stream. If so, an error is set and that data is discarded. The output
        /// is decompressed, but may be sent in multiple segments.
        /// \param pSeg A segment with compressed data, and no trailing if last
        void
        CPipeInflate::Out(AxPipe::CSeg *pSeg) {
            m_Zstream.next_in = (unsigned char *)pSeg->PtrRd();
            m_Zstream.avail_in = (UINT)pSeg->Len();
            while (true) {
                if (!m_pOutSeg) {
                    // Allocate the output segment, and point the Zstream structure to it
                    m_pOutSeg = GetSeg(m_Zstream.avail_in + m_Zstream.avail_in);
                    ASSPTR(m_pOutSeg);
                    m_Zstream.avail_out = (UINT)m_pOutSeg->Size();
                    m_Zstream.next_out = m_pOutSeg->PtrWr();
                }
                int iZerror = inflate(&m_Zstream, 0);
                m_cb += m_Zstream.total_out;        // Update total output bytes ctr
                m_Zstream.total_out = 0;            // can't use total_out since it's 32-bit
                switch (iZerror) {
                case Z_OK:
                    // ZLib guarantees to either use all input or all output buffer.
                    if (m_Zstream.avail_in && m_Zstream.avail_out) {
                        SetError(ERROR_CODE_DERIVED, _T("ZLIB sequence error"));
                    }
                    if (!m_Zstream.avail_out) {
                        Pump(m_pOutSeg);
                        m_pOutSeg = NULL;
                    }
                    if (m_Zstream.avail_in) {
                        continue;                   // More data to inflate!
                    }
                    // If we have no more input, we need to return and wait for more
                    break;
                case Z_STREAM_END:
                    m_pOutSeg->Len(m_pOutSeg->Size() - m_Zstream.avail_out);
                    Pump(m_pOutSeg);
                    m_pOutSeg = NULL;
                    if (m_Zstream.avail_in) {
                        SetError(ERROR_CODE_STOCK, _T("Trailing data"));
                    }
                    break;
                default:
                    SetError(ERROR_CODE_STOCK, _T("ZLIB inflate error"));
                    break;
                }
                break;
            }
            pSeg->Release();
        }
    }
}