campo-sirio/al/examples/ex12con.cpp

//
// EX12CON.CPP
//
//  C++/DOS Example program for ArchiveLib 2.0
//
//  Copyright (c) Greenleaf Software, Inc. 1994 - 1996
//  All Rights Reserved
//
// MEMBERS/FUNCTIONS DEMONSTRATED
//
//  ALCompressed::ReadHeaderData()
//  ALCompressed::WriteHeaderData()
//
// DESCRIPTION
//
//  This example shows how you can use the ReadHeaderData() and
//  WriteHeaderData() functions to store information in an ALCompressedObject.
//  This example derives a new class of ALCompressedObject that uses
//  the private data area of the compressed object to store the name of
//  the file that is compressed there.  When the object is being extracted,
//  its name is updated in ReadHeaderData.
//
//  You can also read the header data directly, without waiting for the
//  Extract() function to be called.  This requires that you open the
//  compressed object,then seek to location 12.
//
// REVISION HISTORY
//
//  February 1, 1996 : 2.0A  : Second release
//

#include <time.h>
#include <stdlib.h>
#include <conio.h>

#include "al.h"

//
// This new derived class overrides the virtual function ReadHeaderData
// and WriteHeaderData.
//
class AL_CLASS_TYPE MyCompressed : public ALCompressedObject {
    public :
        AL_INLINE_PROTO MyCompressed( ALStorage AL_DLL_FAR & storage,
                                      ALCompressor AL_DLL_FAR &compressor,
                                      ALDecompressor AL_DLL_FAR &decompressor )
                                        : ALCompressedObject( storage, &compressor, &decompressor ){ ; };
        virtual AL_INLINE_PROTO ~MyCompressed(){;}
//
// I use this member function to read the header data whenever I want to.
//
        void AL_PROTO ReadHeader();
//
// These special functions are declared, but not defined.  I don't want the
// compiler to generate default versions of these functions, so I specifically
// declare them here.
//
    protected :
        AL_PROTO MyCompressed( MyCompressed AL_DLL_FAR & );
        MyCompressed AL_DLL_FAR & AL_PROTO operator=( const MyCompressed AL_DLL_FAR & );
//
// The two virtual functions that I override in this class.
//
    protected :
        int AL_PROTO WriteHeaderData( ALStorage AL_DLL_FAR * object );
        int AL_PROTO ReadHeaderData( ALStorage AL_DLL_FAR * object );
};

//
// In the base class, this virtual function does nothing at all.
// In the derived class, I use this function to write the name of
// the input file into the compressed object, using ArchiveLib string
// format.
//
int AL_PROTO MyCompressed::WriteHeaderData(ALStorage AL_DLL_FAR * object )
{
    mpStorageObject->WriteString( (const char *) object->mName );
    return AL_SUCCESS;
}

//
// Before the output file gets extracted, this virtual function gets
// called.  I read the stored file name out of the compressed object,
// and change the name of the output object.  This code is a little
// trickier than I would like because it has to read in data in the
// ArchiveLibrary ReadString format.
//
int AL_PROTO MyCompressed::ReadHeaderData( ALStorage AL_DLL_FAR *output )
{
    short int len;

    if ( mpStorageObject->ReadGlShort( len ) < 0 )
        return AL_READ_ERROR;
    char *new_string = new char[ len + 1 ];
    if ( new_string ) {
        mpStorageObject->ReadBuffer( (unsigned char *) new_string, len );
        new_string[ len ] = '\0';
    } else
        return AL_READ_ERROR;
    cout << "Output object should be named: " << new_string << "\n";
    if ( output )
        output->mName = new_string;
    return AL_SUCCESS;
}

//
// If you want to read the header data in outside of Extract() function,
// this is what you have to do.
//
void AL_PROTO MyCompressed::ReadHeader()
{
    cout << "Calling ReadHeaderData directly:\n";
    mpStorageObject->Open();
    mpStorageObject->Seek( 12 );
    ReadHeaderData( 0 );
    mpStorageObject->Close();
}

main()
{
    cout << "Archive Library 2.0\nEX12CON.CPP\n\n";
    cout << "This example shows how you can use the ReadHeaderData() and\n";
    cout << "WriteHeaderData() functions to store information in an ALCompressedObject.\n";
    cout << "This example derives a new class of ALCompressedObject that uses\n";
    cout << "the private data area of the compressed object to store the name of\n";
    cout << "the file that is compressed there.  When the object is being extracted,\n";
    cout << "its name is updated in ReadHeaderData.\n\n";
    getch();

    ALMemory DataFile( "Memory objects can have long names" );
    ALFile CompressedFile;
    ALMemory OutputFile( "Original output name" );
#if defined( ZIP )
    ALPkCompressor Compressor( 3, 13 );
    ALPkDecompressor Decompressor;
#else
    ALGlCompressor Compressor( AL_GREENLEAF_LEVEL_4 );
    ALGlDecompressor Decompressor;
#endif
    MyCompressed *CompressedObject;

//
// Here is where I create the input data file and the compressed object.
// This is all fairly realistic, you could write code that looks a lot
// like this.
//
    CompressedObject = new MyCompressed( CompressedFile, Compressor, Decompressor );
    DataFile.Create(); // Temporary file
    for ( int i = 0 ; i < 64 ; i++ )
        for ( int j = i; j < 64 ; j++ )
            DataFile.WriteChar( j );
    DataFile.Close();
    cout << "Compressing\n";
//
// When compressed using the derived class, the input object name will get
// stored in the compressed file along with the compressed data.
//
    CompressedObject->Insert( DataFile );
//
// When I extract, the output file name should get set to the same as
// that of the input file.
//
    cout << "Extracting\n";
    cout << "Output object is named: " << OutputFile.mName << "\n";
    CompressedObject->Extract( OutputFile );
    int status = DataFile.Compare( OutputFile );
    cout << "Compare returned : " << status << "\n";
    cout << "Output object is named: " << OutputFile.mName << "\n";
//
// To read the data in the header of a compressed object, you can also
// seek directly:
//
    CompressedObject->ReadHeader();
    delete CompressedObject;
    return status;
}