//////////////////////////////////////////////////////////////////////////////
//
//  Copyright (c) 2000-2002 Microsoft Corporation
//
//  Module Name:
//      CBString.h
//
//  Implementation File:
//      CBString.cpp
//
//  Description:
//      BString provides an exception-safe handler for BSTRs; it also wipes
//      clean its contents upon leaving scope, making it usable for short-lived
//      password storage.
//
//      This class is intended to be used instead of CComBSTR since the
//      use of ATL is prohibited in our project.
//
//  Maintained By:
//      John Franco (jfranco) 17-APR-2002
//
//////////////////////////////////////////////////////////////////////////////

#pragma once

class CBString
{
private:

    BSTR    m_bstr;

    static  BSTR    AllocateBuffer( UINT cchIn );
    static  BSTR    CopyString( PCWSTR pcwszIn );
    static  BSTR    CopyBSTR( BSTR bstrIn );
    
public:

    CBString( PCWSTR pcwszIn = NULL );
    CBString( UINT cchIn );
    CBString( const CBString & crbstrOtherIn );
    ~CBString( void );

    CBString &      operator=( const CBString & crbstrOtherIn );
    BSTR *          operator&( void );
    OLECHAR &       operator[]( size_t idxIn );
    const OLECHAR & operator[]( size_t idxIn ) const;
    operator        BSTR( void );
    operator        PCWSTR( void ) const;

    void    Attach( BSTR bstrIn );
    void    Detach( void );
    UINT    Length( void ) const;
    void    Erase( void );
    void    Swap( CBString & rbstrOtherInout );
    BOOL    IsEmpty( void ) const;

}; //*** class CBstring

inline
CBString::CBString( PCWSTR pcwszIn )
    : m_bstr( CopyString( pcwszIn ) )
{
    TraceFunc1( "pcwszIn = '%ws'", pcwszIn == NULL ? L"<NULL>" : pcwszIn );
    TraceFuncExit();

} //*** CBString::CBString( pcwszIn )

inline
CBString::CBString( UINT cchIn )
    : m_bstr( AllocateBuffer( cchIn ) )
{
    TraceFunc1( "cchIn = '%d'", cchIn );
    TraceFuncExit();

} //*** CBString::CBString( cchIn )

inline
CBString::CBString( const CBString & crbstrOtherIn )
    : m_bstr( CopyBSTR( crbstrOtherIn.m_bstr ) )
{
    TraceFunc1( "crbstrOtherIn = '%ws'", crbstrOtherIn );
    TraceFuncExit();

} //*** CBString::CBString( crbstrOtherIn )

inline
void
CBString::Erase( void )
{
    TraceFunc( "" );

    if ( m_bstr != NULL )
    {
        SecureZeroMemory( m_bstr, SysStringLen( m_bstr ) * sizeof( *m_bstr ) );
        TraceSysFreeString( m_bstr );
    }

    TraceFuncExit();

} //*** CBString::Erase

inline
void
CBString::Swap( CBString & rbstrOtherInout )
{
    TraceFunc1( "rbstrOtherInout = '%ws'", rbstrOtherInout );

    BSTR bstrStash = m_bstr;
    m_bstr = rbstrOtherInout.m_bstr;
    rbstrOtherInout.m_bstr = bstrStash;

    TraceFuncExit();

} //*** CBString::Swap

inline
CBString::~CBString( void )
{
    TraceFunc( "" );

    Erase();

    TraceFuncExit();

} //*** CBString::~CBString

inline
CBString &
CBString::operator=( const CBString & crbstrOtherIn )
{
    TraceFunc1( "crbstrOtherIn = '%ws'", crbstrOtherIn );

    if ( this != &crbstrOtherIn )
    {
        CBString bstrCopy( crbstrOtherIn );
        Swap( bstrCopy );
    }

    RETURN( *this );

} //*** CBString::operator=

inline
BSTR *
CBString::operator&( void )
{
    return &m_bstr;

} //*** CBString::operator&

inline
OLECHAR &
CBString::operator[]( size_t idxIn )
{
    return m_bstr[ idxIn ];

} //*** CBString::operator[]

inline
const OLECHAR &
CBString::operator[]( size_t idxIn ) const
{
    return m_bstr[ idxIn ];

} //*** CBString::operator[] const

inline
CBString::operator BSTR( void )
{
    return m_bstr;

} //*** CBString::operator BSTR

inline
CBString::operator PCWSTR( void ) const
{
    return m_bstr;

} //*** CBString::operator PCWSTR

inline
void
CBString::Attach( BSTR bstrIn )
{
    TraceFunc1( "bstrIn = '%ws'", bstrIn );

    if ( m_bstr != bstrIn )
    {
        Erase();
        m_bstr = bstrIn;
    }

    TraceFuncExit();

} //*** CBString::Attach

inline
void
CBString::Detach( void )
{
    TraceFunc( "" );

    m_bstr = NULL;

    TraceFuncExit();

} //*** CBString::Detach

inline
UINT
CBString::Length( void ) const
{
    return SysStringLen( m_bstr );

} //*** CBString::Length

inline
BOOL
CBString::IsEmpty( void ) const
{
    return ( m_bstr == NULL );

} //*** CBString::IsEmpty