UT_Packet.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        UT_Packet.h (Utility Libray, C++)
 *
 * COMMENTS:
 *              This class is used to save and load binary packets of
 *              byte streams. It is assumed that the stream is seekable.
 *
 */

#ifndef __UT_Packet__
#define __UT_Packet__

#include "UT_API.h"
#include "UT_NTStreamUtil.h"
#include "UT_OStream.h"

// streampos is 64 bits on alpha, and 32 bits on the other machines,
// so let's use a 32 bit value
typedef int UT_StreamPos;
class UT_IStream;
class UT_PacketTaint;
class UT_OStringStream;

UT_API short            UTgetClassPacketID(const char *classname);

class UT_API UT_Packet
{
public:
                 UT_Packet();
                ~UT_Packet();

    int          beginWrite(std::ostream &str, short class_id, short signature);
    int          beginWrite(UT_OStream &str, short class_id, short signature);
    int          endWrite();

    bool         beginRead(UT_IStream &stream, short &class_id,
                            short &signature);
    int          cancelRead();
    int          endRead();

    // The following methods can be used if the stream is a pipe (or
    // stdin/stdout).
    std::ostream*beginPipeWrite(std::ostream &str, short class_id, short signature);
    int          endPipeWrite();

    UT_IStream  *beginPipeRead(UT_IStream &stream, short &class_id, short &sig);
    int          endPipeRead();

    void         setHeaderTaint(UT_PacketTaint *taint);

    // compressData will do zlib compression on the source data.  The data
    // should be "smallish" in that a buffer is allocated off the stack which
    // is roughly 1.1 times the size passed in.  There's an internal limit of
    // 8Mb on data to be stored.
    // A malloc'ed buffer is returned, and size is set to the compressed size
    // The packet has a packet header which contains additional information
    // used in decompression.
    static char *compressPacket(const char *src, int &size);

    // decompressData will do zlib uncompression on the source data.  The
    // compressed data must have been created with UTcompressPacket.
    // A malloc'ed buffer is returned, and size is set to the un-compressed size
    static char *uncompressPacket(const char *src, int &size);

    // getHeaderSize() returns the number of bytes used for the packet header.
    static unsigned int  getHeaderSize();


private:
    char                 myState;
    UT_StreamPos         myPacketSize;
    UT_StreamPos         myPacketStart;
    UT_OStringStream    *myOutBuffer;
    UT_IStream          *mySBuffer;     // UT IStreams
    UT_IStream          *mySStreamPtr;
    UT_OStream           myOutStreamRef;
    char                *myData;
    UT_PacketTaint      *myHeaderTaint;
};

// use this function to get the class packet-id for your class
// just include the line: SETUPCLASSPACKETID("LIB_CLASS") or
// whatever in your .C file and also add "LIB_CLASS" to the table
// at the top of UT_Packet.C

#define SETUPCLASSPACKETID(classname) \
static int \
getClassPacketID() \
{ \
    static int classid = UTgetClassPacketID(classname); \
    return classid; \
}

#endif