libreoffice/sot/source/sdstor/stgcache.cxx

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you under the Apache
 *   License, Version 2.0 (the "License"); you may not use this file
 *   except in compliance with the License. You may obtain a copy of
 *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
 */

#include <string.h>
#include <o3tl/safeint.hxx>
#include <osl/endian.h>
#include <osl/diagnose.h>

#include <sot/stg.hxx>
#include "stgcache.hxx"

#include <algorithm>

////////////////////////////// class StgPage
// This class implements buffer functionality. The cache will always return
// a page buffer, even if a read fails. It is up to the caller to determine
// the correctness of the I/O.

StgPage::StgPage( short nSize, sal_Int32 nPage )
    : mnPage( nPage )
    , mpData( new sal_uInt8[ nSize ] )
    , mnSize( nSize )
{
    OSL_ENSURE( mnSize >= 512, "Unexpected page size is provided!" );
    // We will write this data to a permanent file later
    // best to clear if first.
    memset( mpData.get(), 0, mnSize );
}

StgPage::~StgPage()
{
}

rtl::Reference< StgPage > StgPage::Create( short nData, sal_Int32 nPage )
{
    return rtl::Reference< StgPage >( new StgPage( nData, nPage ) );
}

void StgCache::SetToPage ( const rtl::Reference< StgPage >& rPage, short nOff, sal_Int32 nVal )
{
    if( nOff >= 0 && ( o3tl::make_unsigned(nOff) < rPage->GetSize() / sizeof( sal_Int32 ) ) )
    {
#ifdef OSL_BIGENDIAN
        nVal = OSL_SWAPDWORD(nVal);
#endif
        static_cast<sal_Int32*>(rPage->GetData())[ nOff ] = nVal;
        SetDirty( rPage );
    }
}

bool StgPage::IsPageGreater( const StgPage *pA, const StgPage *pB )
{
    return pA->mnPage < pB->mnPage;
}

//////////////////////////////// class StgCache

// The disk cache holds the cached sectors. The sector type differ according
// to their purpose.

static sal_Int32 lcl_GetPageCount( sal_uInt64 nFileSize, short nPageSize )
{
//    return (nFileSize >= 512) ? (nFileSize - 512) / nPageSize : 0;
    // #i61980# real life: last page may be incomplete, return number of *started* pages
    return (nFileSize >= 512) ? (nFileSize - 512 + nPageSize - 1) / nPageSize : 0;
}

StgCache::StgCache()
   : m_nError( ERRCODE_NONE )
   , m_nPages( 0 )
   , m_nRef( 0 )
   , m_nReplaceIdx( 0 )
   , maLRUPages( 8 ) // entries in the LRU lookup
   , m_nPageSize( 512 )
   , m_pStorageStream( nullptr )
   , m_pStrm( nullptr )
   , m_bMyStream( false )
   , m_bFile( false )
{
}

StgCache::~StgCache()
{
    Clear();
    SetStrm( nullptr, false );
}

void StgCache::SetPhysPageSize( short n )
{
    OSL_ENSURE( n >= 512, "Unexpected page size is provided!" );
    if ( n >= 512 )
    {
        m_nPageSize = n;
        sal_uInt64 nFileSize = m_pStrm->TellEnd();
        m_nPages = lcl_GetPageCount( nFileSize, m_nPageSize );
    }
}

// Create a new cache element

rtl::Reference< StgPage > StgCache::Create( sal_Int32 nPg )
{
    rtl::Reference< StgPage > xElem( StgPage::Create( m_nPageSize, nPg ) );
    maLRUPages[ m_nReplaceIdx++ % maLRUPages.size() ] = xElem;
    return xElem;
}

// Delete the given element

void StgCache::Erase( const rtl::Reference< StgPage > &xElem )
{
    OSL_ENSURE( xElem.is(), "The pointer should not be NULL!" );
    if ( xElem.is() ) {
        auto it = std::find_if(maLRUPages.begin(), maLRUPages.end(),
            [xElem](const rtl::Reference<StgPage>& rxPage) { return rxPage.is() && rxPage->GetPage() == xElem->GetPage(); });
        if (it != maLRUPages.end())
            it->clear();
    }
}

// remove all cache elements without flushing them

void StgCache::Clear()
{
    maDirtyPages.clear();
    for (auto& rxPage : maLRUPages)
        rxPage.clear();
}

// Look for a cached page

rtl::Reference< StgPage > StgCache::Find( sal_Int32 nPage )
{
    auto it = std::find_if(maLRUPages.begin(), maLRUPages.end(),
        [nPage](const rtl::Reference<StgPage>& rxPage) { return rxPage.is() && rxPage->GetPage() == nPage; });
    if (it != maLRUPages.end())
        return *it;
    IndexToStgPage::iterator it2 = maDirtyPages.find( nPage );
    if ( it2 != maDirtyPages.end() )
        return it2->second;
    return rtl::Reference< StgPage >();
}

// Load a page into the cache

rtl::Reference< StgPage > StgCache::Get( sal_Int32 nPage, bool bForce )
{
    rtl::Reference< StgPage > p = Find( nPage );
    if( !p.is() )
    {
        p = Create( nPage );
        if( !Read( nPage, p->GetData() ) && bForce )
        {
            Erase( p );
            p.clear();
            SetError( SVSTREAM_READ_ERROR );
        }
    }
    return p;
}

// Copy an existing page into a new page. Use this routine
// to duplicate an existing stream or to create new entries.
// The new page is initially marked dirty. No owner is copied.

rtl::Reference< StgPage > StgCache::Copy( sal_Int32 nNew, sal_Int32 nOld )
{
    rtl::Reference< StgPage > p = Find( nNew );
    if( !p.is() )
        p = Create( nNew );
    if( nOld >= 0 )
    {
        // old page: we must have this data!
        rtl::Reference< StgPage > q = Get( nOld, true );
        if( q.is() )
        {
            OSL_ENSURE( p->GetSize() == q->GetSize(), "Unexpected page size!" );
            memcpy( p->GetData(), q->GetData(), p->GetSize() );
        }
    }
    SetDirty( p );

    return p;
}

// Historically this wrote pages in a sorted, ascending order;
// continue that tradition.
bool StgCache::Commit()
{
    if ( Good() ) // otherwise Write does nothing
    {
        std::vector< StgPage * > aToWrite;
        aToWrite.reserve(maDirtyPages.size());
        for (const auto& rEntry : maDirtyPages)
            aToWrite.push_back( rEntry.second.get() );

        std::sort( aToWrite.begin(), aToWrite.end(), StgPage::IsPageGreater );
        for (StgPage* pWr : aToWrite)
        {
            const rtl::Reference< StgPage > pPage = pWr;
            if ( !Write( pPage->GetPage(), pPage->GetData() ) )
                return false;
        }
    }

    maDirtyPages.clear();

    m_pStrm->Flush();
    SetError( m_pStrm->GetError() );

    return true;
}

// Set a stream

void StgCache::SetStrm( SvStream* p, bool bMy )
{
    if( m_pStorageStream )
    {
        m_pStorageStream->ReleaseRef();
        m_pStorageStream = nullptr;
    }

    if( m_bMyStream )
        delete m_pStrm;
    m_pStrm = p;
    m_bMyStream = bMy;
}

void StgCache::SetStrm( UCBStorageStream* pStgStream )
{
    if( m_pStorageStream )
        m_pStorageStream->ReleaseRef();
    m_pStorageStream = pStgStream;

    if( m_bMyStream )
        delete m_pStrm;

    m_pStrm = nullptr;

    if ( m_pStorageStream )
    {
        m_pStorageStream->AddFirstRef();
        m_pStrm = m_pStorageStream->GetModifySvStream();
    }

    m_bMyStream = false;
}

void StgCache::SetDirty( const rtl::Reference< StgPage > &rPage )
{
    assert( m_pStrm && m_pStrm->IsWritable() );
    maDirtyPages[ rPage->GetPage() ] = rPage;
}

// Open/close the disk file

bool StgCache::Open( const OUString& rName, StreamMode nMode )
{
    // do not open in exclusive mode!
    if( nMode & StreamMode::SHARE_DENYALL )
        nMode = ( ( nMode & ~StreamMode::SHARE_DENYALL ) | StreamMode::SHARE_DENYWRITE );
    SvFileStream* pFileStrm = new SvFileStream( rName, nMode );
    // SvStream "feature" Write Open also successful if it does not work
    bool bAccessDenied = false;
    if( ( nMode & StreamMode::WRITE ) && !pFileStrm->IsWritable() )
    {
        pFileStrm->Close();
        bAccessDenied = true;
    }
    SetStrm( pFileStrm, true );
    if( pFileStrm->IsOpen() )
    {
        sal_uInt64 nFileSize = m_pStrm->TellEnd();
        m_nPages = lcl_GetPageCount( nFileSize, m_nPageSize );
        m_pStrm->Seek( 0 );
    }
    else
        m_nPages = 0;
    m_bFile = true;
    SetError( bAccessDenied ? ERRCODE_IO_ACCESSDENIED : m_pStrm->GetError() );
    return Good();
}

void StgCache::Close()
{
    if( m_bFile )
    {
        static_cast<SvFileStream*>(m_pStrm)->Close();
        SetError( m_pStrm->GetError() );
    }
}

// low level I/O

bool StgCache::Read( sal_Int32 nPage, void* pBuf )
{
    sal_uInt32 nRead = 0, nBytes = m_nPageSize;
    if( Good() )
    {
        /*  #i73846# real life: a storage may refer to a page one-behind the
            last valid page (see document attached to the issue). In that case
            (if nPage==nPages), just do nothing here and let the caller work on
            the empty zero-filled buffer. */
        if ( nPage > m_nPages )
            SetError( SVSTREAM_READ_ERROR );
        else if ( nPage < m_nPages )
        {
            sal_uInt32 nPos;
            sal_Int32 nPg2;
            // fixed address and size for the header
            if( nPage == -1 )
            {
                nPos = 0;
                nPg2 = 1;
                nBytes = 512;
            }
            else
            {
                nPos = Page2Pos(nPage);
                nPg2 = ((nPage + 1) > m_nPages) ? m_nPages - nPage : 1;
            }

            if (m_pStrm->Tell() != nPos)
                m_pStrm->Seek(nPos);

            if (nPg2 != 1)
                SetError(SVSTREAM_READ_ERROR);
            else
            {
                nRead = m_pStrm->ReadBytes(pBuf, nBytes);
                SetError(m_pStrm->GetError());
            }
        }
    }

    if (!Good())
        return false;

    if (nRead != nBytes)
        memset(static_cast<sal_uInt8*>(pBuf) + nRead, 0, nBytes - nRead);
    return true;
}

bool StgCache::Write( sal_Int32 nPage, void const * pBuf )
{
    if( Good() )
    {
        sal_uInt32 nPos = Page2Pos( nPage );
        sal_uInt32 nBytes = m_nPageSize;

        // fixed address and size for the header
        // nPageSize must be >= 512, otherwise the header can not be written here, we check it on import
        if( nPage == -1 )
        {
            nPos = 0;
            nBytes = 512;
        }
        if( m_pStrm->Tell() != nPos )
        {
            m_pStrm->Seek(nPos);
        }
        size_t nRes = m_pStrm->WriteBytes( pBuf, nBytes );
        if( nRes != nBytes )
            SetError( SVSTREAM_WRITE_ERROR );
        else
            SetError( m_pStrm->GetError() );
    }
    return Good();
}

// set the file size in pages

bool StgCache::SetSize( sal_Int32 n )
{
    // Add the file header
    sal_Int32 nSize = n * m_nPageSize + 512;
    m_pStrm->SetStreamSize( nSize );
    SetError( m_pStrm->GetError() );
    if( !m_nError )
        m_nPages = n;
    return Good();
}

void StgCache::SetError( ErrCode n )
{
    if( n && !m_nError )
        m_nError = n;
}

void StgCache::ResetError()
{
    m_nError = ERRCODE_NONE;
    m_pStrm->ResetError();
}

void StgCache::MoveError( StorageBase const & r )
{
    if( m_nError != ERRCODE_NONE )
    {
        r.SetError( m_nError );
        ResetError();
    }
}

// Utility functions

sal_Int32 StgCache::Page2Pos( sal_Int32 nPage ) const
{
    if( nPage < 0 ) nPage = 0;
    return( nPage * m_nPageSize ) + m_nPageSize;
}

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