vmmemmappedfile.cpp

TOOL (Tiny Object Oriented Language) is an easily-embedded, object-oriented, C++-like-language inter

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/*                             SOURCE FILE                                   */
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/*
       $Archive:   $

      $Revision:   $
          $Date:   $
        $Author:   $

   Description: 

                      TOOL And XML FORMS License
                      ==========================

                      Except where otherwise noted, all of the documentation 
                      and software included in the TOOL package is 
                      copyrighted by Michael Swartzendruber.

                      Copyright (C) 2005 Michael John Swartzendruber. 
                      All rights reserved.

                      Access to this code, whether intentional or accidental,
                      does NOT IMPLY any transfer of rights.

                      This software is provided "as-is," without any express 
                      or implied warranty. In no event shall the author be held
                      liable for any damages arising from the use of this software.

                      Permission is granted to anyone to use this software for 
                      any purpose, including commercial applications, and to 
                      alter and redistribute it, provided that the following 
                      conditions are met:

                      1. All redistributions of source code files must retain 
                         all copyright notices that are currently in place, 
                         and this list of conditions without modification.

                      2. The origin of this software must not be misrepresented;
                         you must not claim that you wrote the original software.

                      3. If you use this software in another product, an acknowledgment
                         in the product documentation would be appreciated but is
                         not required.

                      4. Modified versions in source or binary form must be plainly 
                         marked as such, and must not be misrepresented as being 
                         the original software.
*/
static char OBJECT_ID[] = "$Revision: 1 $ : $Date: 9/12/97 3:30p $";
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#include "../../../stdafx.h"
#include <assert.h>
#include <string.h>
#include "VMMemMappedFile.h"



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/*
     FUNCTION NAME:	VMMemMappedFile

       DESCRIPTION:	ctor. Sets up all variables. 

             INPUT: pchName - The name of the MMF to attach to this class
                    bCreate - Create the MMF during construction
                    dwSizeLow - the size of the mmf to create
	
           RETURNS:	void
*/
VMMemMappedFile::VMMemMappedFile( char* pchName, bool bCreate, DWORD dwSizeLow )
{   
  assert ( NULL != pchName );
  strcpy( m_achName, pchName );

  char   achTemp[ 32 ];
  strcpy( achTemp, m_achName );
  strcat( achTemp, "SemForWrite" );
  strcpy( m_achSemNameWrite, achTemp );

  strcpy( achTemp, m_achName );
  strcat( achTemp, "SemForRead" );
  strcpy( m_achSemNameRead, achTemp );

  assert( 0 < dwSizeLow );
  m_dwSizeHigh = 0; 
  m_dwSizeLow  = dwSizeLow; 

  m_hFileMap          = NULL;
  m_hFileMapReader    = NULL;
  m_bICreatedMapping  = false;
  m_dwSysReturnCode   = 0L;
  m_pvView            = NULL;
  m_hWriteSemaphore   = NULL;
  m_hReadSemaphore    = NULL;
  m_iFlags             = 0;

  if ( true == bCreate )
  {
    Create();
  }
  else
  {
    Open();
  }
}
/*	end of function "VMMemMappedFile" */
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/*
     FUNCTION NAME:	~VMMemMappedFile

       DESCRIPTION:	dtor. closes all object handles

             INPUT: void
           RETURNS:	void
*/
VMMemMappedFile::~VMMemMappedFile()
{
  if ( NULL != m_hFileMap )
  {
    ::CloseHandle( m_hFileMap ); 
  }
  if ( NULL != m_hFileMapReader )
  {
    ::CloseHandle( m_hFileMapReader ); 
  }
  if ( NULL != m_hReadSemaphore )
  {
    ::CloseHandle( m_hReadSemaphore );
  }
  if ( NULL != m_hWriteSemaphore )
  {
    ::CloseHandle( m_hWriteSemaphore );
  }
}
/*	end of function "~VMMemMappedFile" */
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/*****************************************************************************/
/*
     FUNCTION NAME:	GetLastErrorText

       DESCRIPTION:	support function that allows the caller to get a text 
                    message based on the last error encountered in the class

             INPUT: pchOutBuffer - a buffer to put the message into 
                    iBufferSize  - the size of the output buffer
           RETURNS:	
*/
void VMMemMappedFile::GetLastErrorText( char* pchOutBuffer, int iBufferSize )
{
  void* pvBuffer = NULL;

  if ( 0 != m_dwSysReturnCode )
  {        
    ::FormatMessage ( FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
                      NULL,
                      m_dwSysReturnCode,
                      MAKELANGID( LANG_NEUTRAL, SUBLANG_DEFAULT ),
                      (LPTSTR) &pvBuffer,
                      0,
                      NULL );
    int iMsgLen;
    if ( 0 != ( iMsgLen = strlen( (const char*)pvBuffer ) ) )
    {
      if ( iMsgLen < iBufferSize )
      {
        strcpy( pchOutBuffer, (char*)pvBuffer );
      }
      else
      {
        strncpy( pchOutBuffer, (char*)pvBuffer, iBufferSize );
      }
    }
    ::LocalFree( pvBuffer );
  }
  else
  {
    strcpy( pchOutBuffer, "No Error Text" );
  }
}
/*	end of function "GetLastErrorText" */
/*****************************************************************************/


/*****************************************************************************/
/*
     FUNCTION NAME:	Create

       DESCRIPTION: creates the mmf and all of the access control objects (single
                    owner semaphores) for the MMF. 	

             INPUT: void
           RETURNS:	true if no errors, false otherwise
*/
bool VMMemMappedFile::Create( void )
{
  m_dwSysReturnCode = 0L;

  SECURITY_ATTRIBUTES   xsa;
  SECURITY_DESCRIPTOR   xsd;

  ::InitializeSecurityDescriptor( &xsd, SECURITY_DESCRIPTOR_REVISION );
  ::SetSecurityDescriptorDacl( &xsd, 
                               TRUE, 
                               NULL, 
                               FALSE );
  xsa.nLength = sizeof( SECURITY_ATTRIBUTES );
  xsa.bInheritHandle = true;
  xsa.lpSecurityDescriptor = &xsd;

  m_hFileMap = ::CreateFileMapping( (HANDLE) 0xFFFFFFFF, 
                                     &xsa, 
                                     PAGE_READWRITE, 
                                     m_dwSizeHigh, 
                                     m_dwSizeLow, 
                                     m_achName );
  if ( m_hFileMap != NULL ) 
  {
    if ( ERROR_ALREADY_EXISTS == ( m_dwSysReturnCode = ::GetLastError() ) ) 
    {
      // this is a non critical error
      //
      ::SetLastError( 0 );
      m_dwSysReturnCode  = 0L;
      m_bICreatedMapping = false;
    }
    else
    { 
      m_bICreatedMapping = true;
    }
    m_hReadSemaphore = ::CreateSemaphore ( &xsa,
                                           (LONG) 1,
                                           (LONG) 2,
                                           m_achSemNameRead );
    DWORD dwError = ::GetLastError();
    if ( ERROR_ALREADY_EXISTS  == dwError )
    {
      ::SetLastError( 0 );
      m_dwSysReturnCode = 0L;
    }
    else
    {
      m_dwSysReturnCode = dwError; 
    }
    m_hWriteSemaphore = ::CreateSemaphore ( &xsa,
                                            (LONG) 1,
                                            (LONG) 2,
                                            m_achSemNameWrite );
    dwError = ::GetLastError();
    if ( ERROR_ALREADY_EXISTS  == dwError )
    {
      ::SetLastError( 0 );
      m_dwSysReturnCode = 0L;
    }
    else
    {
      m_dwSysReturnCode = dwError;
    } 
  } 
  else 
  {
    m_dwSysReturnCode  = ::GetLastError();
    m_bICreatedMapping = false; 
  }

  if ( 0 == m_dwSysReturnCode )
  {
    return( true );
  }
  else
  {
    return( false );
  }
}
/*	end of function "Create" */
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/*****************************************************************************/
/*
     FUNCTION NAME:	Open

       DESCRIPTION:	Opens the file mapping belonging to this class

             INPUT: void
           RETURNS:	true if the operation succeeded, false otherwise
*/
bool VMMemMappedFile::Open()
{
  m_dwSysReturnCode = 0L;

  m_hFileMapReader = ::OpenFileMapping( FILE_MAP_READ | FILE_MAP_WRITE,
                                        FALSE, 
                                        m_achName );
  if ( NULL == m_hFileMapReader )