xref: /aoo4110/main/store/source/stordata.cxx (revision b1cdbd2c)

/**************************************************************
 *
 * 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
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 *************************************************************/



// MARKER(update_precomp.py): autogen include statement, do not remove
#include "precompiled_store.hxx"

#include "stordata.hxx"

#include "sal/types.h"
#include "osl/diagnose.h"

#include "store/types.h"
#include "storbase.hxx"
#include "storbios.hxx"

using namespace store;

/*========================================================================
 *
 * OStoreDataPageObject implementation.
 *
 *======================================================================*/
/*
 * guard.
 */
storeError OStoreDataPageObject::guard (sal_uInt32 nAddr)
{
    return PageHolderObject< page >::guard (m_xPage, nAddr);
}

/*
 * verify.
 */
storeError OStoreDataPageObject::verify (sal_uInt32 nAddr) const
{
    return PageHolderObject< page >::verify (m_xPage, nAddr);
}

/*========================================================================
 *
 * OStoreIndirectionPageObject implementation.
 *
 *======================================================================*/
/*
  * store_truncate_Impl (single indirect page).
  */
static storeError store_truncate_Impl (
    sal_uInt32      nAddr,
    sal_uInt16      nSingle,
    OStorePageBIOS &rBIOS)
{
	if (nAddr != STORE_PAGE_NULL)
	{
		// Load single indirect page.
		OStoreIndirectionPageObject aSingle;
		storeError eErrCode = rBIOS.loadObjectAt (aSingle, nAddr);
		if (eErrCode == store_E_None)
		{
			// Truncate to 'nSingle' direct pages.
			eErrCode = aSingle.truncate (nSingle, rBIOS);
			if (eErrCode != store_E_None)
				return eErrCode;
		}
		else
		{
			if (eErrCode != store_E_InvalidChecksum)
				return eErrCode;
		}

		// Check for complete truncation.
		if (nSingle == 0)
		{
			// Free single indirect page.
			eErrCode = rBIOS.free (nAddr);
			if (eErrCode != store_E_None)
				return eErrCode;
		}
	}
    return store_E_None;
}

/*
 * store_truncate_Impl (double indirect page).
 */
static storeError store_truncate_Impl (
    sal_uInt32       nAddr,
    sal_uInt16       nDouble,
    sal_uInt16       nSingle,
    OStorePageBIOS  &rBIOS)
{
    if (nAddr != STORE_PAGE_NULL)
    {
		// Load double indirect page.
		OStoreIndirectionPageObject aDouble;
		storeError eErrCode = rBIOS.loadObjectAt (aDouble, nAddr);
		if (eErrCode == store_E_None)
		{
			// Truncate to 'nDouble', 'nSingle' pages.
			eErrCode = aDouble.truncate (nDouble, nSingle, rBIOS);
			if (eErrCode != store_E_None)
				return eErrCode;
		}
		else
		{
			if (eErrCode != store_E_InvalidChecksum)
				return eErrCode;
		}

		// Check for complete truncation.
		if ((nDouble + nSingle) == 0)
		{
			// Free double indirect page.
			eErrCode = rBIOS.free (nAddr);
			if (eErrCode != store_E_None)
				return eErrCode;
		}
    }
    return store_E_None;
}

/*
 * store_truncate_Impl (triple indirect page).
 */
static storeError store_truncate_Impl (
    sal_uInt32       nAddr,
    sal_uInt16       nTriple,
    sal_uInt16       nDouble,
    sal_uInt16       nSingle,
    OStorePageBIOS  &rBIOS)
{
    if (nAddr != STORE_PAGE_NULL)
    {
        // Load triple indirect page.
        OStoreIndirectionPageObject aTriple;
        storeError eErrCode = rBIOS.loadObjectAt (aTriple, nAddr);
        if (eErrCode != store_E_None)
            return eErrCode;

        // Truncate to 'nTriple', 'nDouble', 'nSingle' pages.
        eErrCode = aTriple.truncate (nTriple, nDouble, nSingle, rBIOS);
        if (eErrCode != store_E_None)
            return eErrCode;

        // Check for complete truncation.
        if ((nTriple + nDouble + nSingle) == 0)
        {
            // Free triple indirect page.
			eErrCode = rBIOS.free (nAddr);
            if (eErrCode != store_E_None)
                return eErrCode;
        }
    }
    return store_E_None;
}

/*
 * loadOrCreate.
 */
storeError OStoreIndirectionPageObject::loadOrCreate (
    sal_uInt32       nAddr,
    OStorePageBIOS & rBIOS)
{
    if (nAddr == STORE_PAGE_NULL)
    {
        storeError eErrCode = construct<page>(rBIOS.allocator());
        if (eErrCode != store_E_None)
            return eErrCode;

        eErrCode = rBIOS.allocate (*this);
        if (eErrCode != store_E_None)
            return eErrCode;

        // Save location pending at caller.
        return store_E_Pending;
    }
    return rBIOS.loadObjectAt (*this, nAddr);
}

/*
 * guard.
 */
storeError OStoreIndirectionPageObject::guard (sal_uInt32 nAddr)
{
    return PageHolderObject< page >::guard (m_xPage, nAddr);
}

/*
 * verify.
 */
storeError OStoreIndirectionPageObject::verify (sal_uInt32 nAddr) const
{
    return PageHolderObject< page >::verify (m_xPage, nAddr);
}

/*
 * read (single indirect).
 */
storeError OStoreIndirectionPageObject::read (
	sal_uInt16             nSingle,
	OStoreDataPageObject  &rData,
	OStorePageBIOS        &rBIOS)
{
    PageHolderObject< page > xImpl (m_xPage);
    page const & rPage = (*xImpl);

	// Check arguments.
    sal_uInt16 const nLimit = rPage.capacityCount();
	if (!(nSingle < nLimit))
		return store_E_InvalidAccess;

	// Obtain data page location.
	sal_uInt32 const nAddr = store::ntohl(rPage.m_pData[nSingle]);
	if (nAddr == STORE_PAGE_NULL)
		return store_E_NotExists;

	// Load data page and leave.
    return rBIOS.loadObjectAt (rData, nAddr);
}

/*
 * read (double indirect).
 */
storeError OStoreIndirectionPageObject::read (
	sal_uInt16             nDouble,
	sal_uInt16             nSingle,
	OStoreDataPageObject  &rData,
	OStorePageBIOS        &rBIOS)
{
    PageHolderObject< page > xImpl (m_xPage);
    page const & rPage = (*xImpl);

	// Check arguments.
    sal_uInt16 const nLimit = rPage.capacityCount();
	if (!((nDouble < nLimit) && (nSingle < nLimit)))
		return store_E_InvalidAccess;

	// Check single indirect page location.
    sal_uInt32 const nAddr = store::ntohl(rPage.m_pData[nDouble]);
	if (nAddr == STORE_PAGE_NULL)
		return store_E_NotExists;

	// Load single indirect page.
	OStoreIndirectionPageObject aSingle;
	storeError eErrCode = rBIOS.loadObjectAt (aSingle, nAddr);
	if (eErrCode != store_E_None)
		return eErrCode;

	// Read single indirect and leave.
	return aSingle.read (nSingle, rData, rBIOS);
}

/*
 * read (triple indirect).
 */
storeError OStoreIndirectionPageObject::read (
	sal_uInt16             nTriple,
	sal_uInt16             nDouble,
	sal_uInt16             nSingle,
	OStoreDataPageObject  &rData,
	OStorePageBIOS        &rBIOS)
{
    PageHolderObject< page > xImpl (m_xPage);
    page const & rPage = (*xImpl);

	// Check arguments.
    sal_uInt16 const nLimit = rPage.capacityCount();
	if (!((nTriple < nLimit) && (nDouble < nLimit) && (nSingle < nLimit)))
		return store_E_InvalidAccess;

	// Check double indirect page location.
    sal_uInt32 const nAddr = store::ntohl(rPage.m_pData[nTriple]);
	if (nAddr == STORE_PAGE_NULL)
		return store_E_NotExists;

	// Load double indirect page.
	OStoreIndirectionPageObject aDouble;
	storeError eErrCode = rBIOS.loadObjectAt (aDouble, nAddr);
	if (eErrCode != store_E_None)
		return eErrCode;

	// Read double indirect and leave.
	return aDouble.read (nDouble, nSingle, rData, rBIOS);
}

/*
 * write (single indirect).
 */
storeError OStoreIndirectionPageObject::write (
	sal_uInt16             nSingle,
	OStoreDataPageObject  &rData,
	OStorePageBIOS        &rBIOS)
{
    PageHolderObject< page > xImpl (m_xPage);
    page & rPage = (*xImpl);

	// Check arguments.
    sal_uInt16 const nLimit = rPage.capacityCount();
	if (!(nSingle < nLimit))
		return store_E_InvalidAccess;

	// Obtain data page location.
	sal_uInt32 const nAddr = store::ntohl(rPage.m_pData[nSingle]);
	if (nAddr == STORE_PAGE_NULL)
	{
        // Allocate data page.
        storeError eErrCode = rBIOS.allocate (rData);
        if (eErrCode != store_E_None)
            return eErrCode;

        // Store data page location.
        rPage.m_pData[nSingle] = store::htonl(rData.location());

        // Save this page.
        return rBIOS.saveObjectAt (*this, location());
	}
	else
	{
		// Save data page.
        return rBIOS.saveObjectAt (rData, nAddr);
	}
}

/*
 * write (double indirect).
 */
storeError OStoreIndirectionPageObject::write (
	sal_uInt16             nDouble,
	sal_uInt16             nSingle,
	OStoreDataPageObject  &rData,
	OStorePageBIOS        &rBIOS)
{
    PageHolderObject< page > xImpl (m_xPage);
    page & rPage = (*xImpl);

	// Check arguments.
    sal_uInt16 const nLimit = rPage.capacityCount();
	if (!((nDouble < nLimit) && (nSingle < nLimit)))
		return store_E_InvalidAccess;

    // Load or create single indirect page.
	OStoreIndirectionPageObject aSingle;
    storeError eErrCode = aSingle.loadOrCreate (store::ntohl(rPage.m_pData[nDouble]), rBIOS);
    if (eErrCode != store_E_None)
    {
        if (eErrCode != store_E_Pending)
            return eErrCode;
        rPage.m_pData[nDouble] = store::htonl(aSingle.location());

        eErrCode = rBIOS.saveObjectAt (*this, location());
        if (eErrCode != store_E_None)
            return eErrCode;
    }

	// Write single indirect and leave.
	return aSingle.write (nSingle, rData, rBIOS);
}

/*
 * write (triple indirect).
 */
storeError OStoreIndirectionPageObject::write (
	sal_uInt16             nTriple,
	sal_uInt16             nDouble,
	sal_uInt16             nSingle,
	OStoreDataPageObject  &rData,
	OStorePageBIOS        &rBIOS)
{
    PageHolderObject< page > xImpl (m_xPage);
    page & rPage = (*xImpl);

	// Check arguments.
    sal_uInt16 const nLimit = rPage.capacityCount();
	if (!((nTriple < nLimit) && (nDouble < nLimit) && (nSingle < nLimit)))
		return store_E_InvalidAccess;

    // Load or create double indirect page.
	OStoreIndirectionPageObject aDouble;
	storeError eErrCode = aDouble.loadOrCreate (store::ntohl(rPage.m_pData[nTriple]), rBIOS);
    if (eErrCode != store_E_None)
    {
        if (eErrCode != store_E_Pending)
            return eErrCode;
        rPage.m_pData[nTriple] = store::htonl(aDouble.location());

        eErrCode = rBIOS.saveObjectAt (*this, location());
        if (eErrCode != store_E_None)
            return eErrCode;
    }

	// Write double indirect and leave.
	return aDouble.write (nDouble, nSingle, rData, rBIOS);
}

/*
 * truncate (single indirect).
 */
storeError OStoreIndirectionPageObject::truncate (
	sal_uInt16       nSingle,
	OStorePageBIOS & rBIOS)
{
    PageHolderObject< page > xImpl (m_xPage);
    page & rPage = (*xImpl);

	// Check arguments.
	sal_uInt16 const nLimit = rPage.capacityCount();
	if (!(nSingle < nLimit))
		return store_E_InvalidAccess;

	// Truncate.
	storeError eErrCode = store_E_None;
	for (sal_uInt16 i = nLimit; i > nSingle; i--)
	{
		// Obtain data page location.
		sal_uInt32 const nAddr = store::ntohl(rPage.m_pData[i - 1]);
		if (nAddr != STORE_PAGE_NULL)
        {
            // Free data page.
            eErrCode = rBIOS.free (nAddr);
            if (eErrCode != store_E_None)
                return eErrCode;

            // Clear pointer to data page.
            rPage.m_pData[i - 1] = STORE_PAGE_NULL;
            touch();
        }
	}

	// Check for modified page.
	if (dirty())
	{
		// Save this page.
        eErrCode = rBIOS.saveObjectAt (*this, location());
	}

    // Done.
    return eErrCode;
}

/*
 * truncate (double indirect).
 */
storeError OStoreIndirectionPageObject::truncate (
	sal_uInt16             nDouble,
	sal_uInt16             nSingle,
	OStorePageBIOS        &rBIOS)
{
    PageHolderObject< page > xImpl (m_xPage);
    page & rPage = (*xImpl);

	// Check arguments.
    sal_uInt16 const nLimit = rPage.capacityCount();
	if (!((nDouble < nLimit) && (nSingle < nLimit)))
		return store_E_InvalidAccess;

	// Truncate.
	storeError eErrCode = store_E_None;
	for (sal_uInt16 i = nLimit; i > nDouble + 1; i--)
	{
        // Truncate single indirect page to zero direct pages.
        eErrCode = store_truncate_Impl (store::ntohl(rPage.m_pData[i - 1]), 0, rBIOS);
        if (eErrCode != store_E_None)
            return eErrCode;

		// Clear pointer to single indirect page.
		rPage.m_pData[i - 1] = STORE_PAGE_NULL;
		touch();
	}

	// Truncate last single indirect page to 'nSingle' direct pages.
    eErrCode = store_truncate_Impl (store::ntohl(rPage.m_pData[nDouble]), nSingle, rBIOS);
    if (eErrCode != store_E_None)
        return eErrCode;

    // Check for complete truncation.
    if (nSingle == 0)
    {
        // Clear pointer to last single indirect page.
        rPage.m_pData[nDouble] = STORE_PAGE_NULL;
        touch();
    }

	// Check for modified page.
	if (dirty())
	{
		// Save this page.
        eErrCode = rBIOS.saveObjectAt (*this, location());
	}

	// Done.
	return eErrCode;
}

/*
 * truncate (triple indirect).
 */
storeError OStoreIndirectionPageObject::truncate (
	sal_uInt16             nTriple,
	sal_uInt16             nDouble,
	sal_uInt16             nSingle,
	OStorePageBIOS        &rBIOS)
{
    PageHolderObject< page > xImpl (m_xPage);
    page & rPage = (*xImpl);

	// Check arguments.
    sal_uInt16 const nLimit = rPage.capacityCount();
	if (!((nTriple < nLimit) && (nDouble < nLimit) && (nSingle < nLimit)))
		return store_E_InvalidAccess;

	// Truncate.
	storeError eErrCode = store_E_None;
	for (sal_uInt16 i = nLimit; i > nTriple + 1; i--)
	{
        // Truncate double indirect page to zero single indirect pages.
        eErrCode = store_truncate_Impl (store::ntohl(rPage.m_pData[i - 1]), 0, 0, rBIOS);
		if (eErrCode != store_E_None)
            return eErrCode;

		// Clear pointer to double indirect page.
		rPage.m_pData[i - 1] = STORE_PAGE_NULL;
		touch();
	}

    // Truncate last double indirect page to 'nDouble', 'nSingle' pages.
    eErrCode = store_truncate_Impl (store::ntohl(rPage.m_pData[nTriple]), nDouble, nSingle, rBIOS);
    if (eErrCode != store_E_None)
        return eErrCode;

    // Check for complete truncation.
    if ((nDouble + nSingle) == 0)
    {
        // Clear pointer to last double indirect page.
        rPage.m_pData[nTriple] = STORE_PAGE_NULL;
        touch();
    }

	// Check for modified page.
	if (dirty())
	{
		// Save this page.
        eErrCode = rBIOS.saveObjectAt (*this, location());
	}

	// Done.
	return eErrCode;
}

/*========================================================================
 *
 * OStoreDirectoryPageObject implementation.
 *
 *======================================================================*/
/*
 * guard.
 */
storeError OStoreDirectoryPageObject::guard (sal_uInt32 nAddr)
{
    return PageHolderObject< page >::guard (m_xPage, nAddr);
}

/*
 * verify.
 */
storeError OStoreDirectoryPageObject::verify (sal_uInt32 nAddr) const
{
	return PageHolderObject< page >::verify (m_xPage, nAddr);
	// OLD: m_rPage.verifyVersion (STORE_MAGIC_DIRECTORYPAGE);
}

/*
 * scope (external data page; private).
 */
OStoreDirectoryPageData::ChunkScope
OStoreDirectoryPageObject::scope (
	sal_uInt32                       nPage,
	page::DataBlock::LinkDescriptor &rDescr) const
{
    page const & rPage = PAGE();
    OStoreDirectoryDataBlock const & rDataBlock = rPage.m_aDataBlock;

	sal_uInt32 index0, index1, index2, index3;

	// direct.
	sal_uInt32 nCount = rDataBlock.directCount();
	sal_uInt32 nLimit = nCount;
	if (nPage < nLimit)
	{
		// Page to index reduction.
		index0 = nPage;

		// Setup LinkDescriptor indices.
		rDescr.m_nIndex0 = (sal_uInt16)(index0 & 0xffff);

		// Done.
		return page::SCOPE_DIRECT;
	}
	nPage -= nLimit;

	// single indirect.
	sal_uInt32 const nCapacity = indirect::capacityCount(rPage.m_aDescr);
	nCount = rDataBlock.singleCount();
	nLimit = nCount * nCapacity;
	if (nPage < nLimit)
	{
		// Page to index reduction.
		sal_uInt32 n = nPage;

		// Reduce to single indirect i(1), direct n = i(0).
		index1 = n / nCapacity;
		index0 = n % nCapacity;

		// Verify reduction.
		n = index1 * nCapacity + index0;
		OSL_POSTCOND(n == nPage, "wrong math on indirect indices");
		if (n != nPage)
			return page::SCOPE_UNKNOWN;

		// Setup LinkDescriptor indices.
		rDescr.m_nIndex0 = (sal_uInt16)(index0 & 0xffff);
		rDescr.m_nIndex1 = (sal_uInt16)(index1 & 0xffff);

		// Done.
		return page::SCOPE_SINGLE;
	}
	nPage -= nLimit;

	// double indirect.
	nCount = rDataBlock.doubleCount();
	nLimit = nCount * nCapacity * nCapacity;
	if (nPage < nLimit)
	{
		// Page to index reduction.
		sal_uInt32 n = nPage;

		// Reduce to double indirect i(2), single indirect n = i(0).
		index2 = n / (nCapacity * nCapacity);
		n      = n % (nCapacity * nCapacity);

		// Reduce to single indirect i(1), direct n = i(0).
		index1 = n / nCapacity;
		index0 = n % nCapacity;

		// Verify reduction.
		n = index2 * nCapacity * nCapacity +
			index1 * nCapacity + index0;
		OSL_POSTCOND(n == nPage, "wrong math on double indirect indices");
		if (n != nPage)
			return page::SCOPE_UNKNOWN;

		// Setup LinkDescriptor indices.
		rDescr.m_nIndex0 = (sal_uInt16)(index0 & 0xffff);
		rDescr.m_nIndex1 = (sal_uInt16)(index1 & 0xffff);
		rDescr.m_nIndex2 = (sal_uInt16)(index2 & 0xffff);

		// Done.
		return page::SCOPE_DOUBLE;
	}
	nPage -= nLimit;

	// triple indirect.
	nCount = rDataBlock.tripleCount();
	nLimit = nCount * nCapacity * nCapacity * nCapacity;
	if (nPage < nLimit)
	{
		// Page to index reduction.
		sal_uInt32 n = nPage;

		// Reduce to triple indirect i(3), double indirect n.
		index3 = n / (nCapacity * nCapacity * nCapacity);
		n      = n % (nCapacity * nCapacity * nCapacity);

		// Reduce to double indirect i(2), single indirect n.
		index2 = n / (nCapacity * nCapacity);
		n      = n % (nCapacity * nCapacity);

		// Reduce to single indirect i(1), direct n = i(0).
		index1 = n / nCapacity;
		index0 = n % nCapacity;

		// Verify reduction.
		n = index3 * nCapacity * nCapacity * nCapacity +
			index2 * nCapacity * nCapacity +
			index1 * nCapacity + index0;
		OSL_POSTCOND(n == nPage, "wrong math on triple indirect indices");
		if (n != nPage)
			return page::SCOPE_UNKNOWN;

		// Setup LinkDescriptor indices.
		rDescr.m_nIndex0 = (sal_uInt16)(index0 & 0xffff);
		rDescr.m_nIndex1 = (sal_uInt16)(index1 & 0xffff);
		rDescr.m_nIndex2 = (sal_uInt16)(index2 & 0xffff);
		rDescr.m_nIndex3 = (sal_uInt16)(index3 & 0xffff);

		// Done.
		return page::SCOPE_TRIPLE;
	}

	// Unreachable (more than triple indirect).
	return page::SCOPE_UNREACHABLE;
}

#if 0  /* NYI */
/*
 * chunk (external data page).
 */
inode::ChunkDescriptor OStoreDirectoryPageObject::chunk (sal_uInt32 nOffset)
{
    // @@@ INSUFFICIENT: NEED SCOPE AS WELL @@@
    sal_uInt32 nCapacity = m_rPage.capacity();
    if (nOffset < nCapacity)
        // Internal scope (inode page).
        return inode::ChunkDescriptor (nOffset, nCapacity);
    else
        // External scope (data page).
        return inode::ChunkDescriptor (nOffset - nCapacity, data::capacity(m_rPage.m_aDescr));

    inode::ChunkScope eScope = m_rPage.scope(nOffset);
    if (eScope == inode::SCOPE_INTERNAL)
        // Inode page (internal scope).
        return inode::ChunkDescriptor (nOffset, m_rPage.capacity());
    else
        // Data page (external scope).
        return inode::ChunkDescriptor (nOffset - m_rPage.capacity(), data::capacity(m_rPage.m_aDescr));
}
#endif /* NYI */

/*
 * read (external data page).
 */
storeError OStoreDirectoryPageObject::read (
	sal_uInt32             nPage,
	OStoreDataPageObject  &rData,
	OStorePageBIOS        &rBIOS)
{
	// Determine scope and link indices.
	page::DataBlock::LinkDescriptor aLink;
	page::ChunkScope eScope = scope (nPage, aLink);

	storeError eErrCode = store_E_None;
	if (eScope == page::SCOPE_DIRECT)
	{
		sal_uInt32 const nAddr = directLink (aLink.m_nIndex0);
		if (nAddr == STORE_PAGE_NULL)
			return store_E_NotExists;

        eErrCode = rBIOS.loadObjectAt (rData, nAddr);
	}
	else if (eScope == page::SCOPE_SINGLE)
	{
		sal_uInt32 const nAddr = singleLink (aLink.m_nIndex1);
		if (nAddr == STORE_PAGE_NULL)
			return store_E_NotExists;

		OStoreIndirectionPageObject aSingle;
		eErrCode = rBIOS.loadObjectAt (aSingle, nAddr);
		if (eErrCode != store_E_None)
			return eErrCode;

		eErrCode = aSingle.read (aLink.m_nIndex0, rData, rBIOS);
	}
	else if (eScope == page::SCOPE_DOUBLE)
	{
		sal_uInt32 const nAddr = doubleLink (aLink.m_nIndex2);
		if (nAddr == STORE_PAGE_NULL)
			return store_E_NotExists;

		OStoreIndirectionPageObject aDouble;
		eErrCode = rBIOS.loadObjectAt (aDouble, nAddr);
		if (eErrCode != store_E_None)
			return eErrCode;

		eErrCode = aDouble.read (aLink.m_nIndex1, aLink.m_nIndex0, rData, rBIOS);
	}
	else if (eScope == page::SCOPE_TRIPLE)
	{
		sal_uInt32 const nAddr = tripleLink (aLink.m_nIndex3);
		if (nAddr == STORE_PAGE_NULL)
			return store_E_NotExists;

		OStoreIndirectionPageObject aTriple;
		eErrCode = rBIOS.loadObjectAt (aTriple, nAddr);
		if (eErrCode != store_E_None)
			return eErrCode;

		eErrCode = aTriple.read (aLink.m_nIndex2, aLink.m_nIndex1, aLink.m_nIndex0, rData, rBIOS);
	}
	else if (eScope == page::SCOPE_UNREACHABLE)
	{
		// Out of scope.
		eErrCode = store_E_CantSeek;
	}
	else
	{
		// Unknown scope.
		OSL_TRACE("OStoreDirectoryPageObject::get(): scope failed");
		eErrCode = store_E_Unknown;
	}

	// Leave.
	return eErrCode;
}

/*
 * write (external data page).
 */
storeError OStoreDirectoryPageObject::write (
	sal_uInt32             nPage,
	OStoreDataPageObject  &rData,
	OStorePageBIOS        &rBIOS)
{
	// Determine scope and link indices.
	page::DataBlock::LinkDescriptor aLink;
	page::ChunkScope eScope = scope (nPage, aLink);

	storeError eErrCode = store_E_None;
	if (eScope == page::SCOPE_DIRECT)
	{
        sal_uInt32 const nAddr = directLink (aLink.m_nIndex0);
		if (nAddr == STORE_PAGE_NULL)
		{
            // Allocate data page.
			eErrCode = rBIOS.allocate (rData);
			if (eErrCode != store_E_None)
				return eErrCode;

            // Store data page location.
			directLink (aLink.m_nIndex0, rData.location());
		}
		else
		{
            // Save data page.
            eErrCode = rBIOS.saveObjectAt (rData, nAddr);
		}
	}
	else if (eScope == page::SCOPE_SINGLE)
	{
		OStoreIndirectionPageObject aSingle;
        eErrCode = aSingle.loadOrCreate (singleLink (aLink.m_nIndex1), rBIOS);
        if (eErrCode != store_E_None)
        {
            if (eErrCode != store_E_Pending)
                return eErrCode;
			singleLink (aLink.m_nIndex1, aSingle.location());
        }

		eErrCode = aSingle.write (aLink.m_nIndex0, rData, rBIOS);
	}
	else if (eScope == page::SCOPE_DOUBLE)
	{
		OStoreIndirectionPageObject aDouble;
		eErrCode = aDouble.loadOrCreate (doubleLink (aLink.m_nIndex2), rBIOS);
        if (eErrCode != store_E_None)
        {
            if (eErrCode != store_E_Pending)
				return eErrCode;
			doubleLink (aLink.m_nIndex2, aDouble.location());
		}

		eErrCode = aDouble.write (aLink.m_nIndex1, aLink.m_nIndex0, rData, rBIOS);
	}
	else if (eScope == page::SCOPE_TRIPLE)
	{
		OStoreIndirectionPageObject aTriple;
		eErrCode = aTriple.loadOrCreate (tripleLink (aLink.m_nIndex3), rBIOS);
        if (eErrCode != store_E_None)
        {
            if (eErrCode != store_E_Pending)
				return eErrCode;
			tripleLink (aLink.m_nIndex3, aTriple.location());
		}

		eErrCode = aTriple.write (aLink.m_nIndex2, aLink.m_nIndex1, aLink.m_nIndex0, rData, rBIOS);
	}
	else if (eScope == page::SCOPE_UNREACHABLE)
	{
		// Out of scope.
		eErrCode = store_E_CantSeek;
	}
	else
	{
		// Unknown scope.
		OSL_TRACE("OStoreDirectoryPageObject::put(): scope failed");
		eErrCode = store_E_Unknown;
	}

	// Leave.
	return eErrCode;
}

/*
 * truncate (external data page).
 */
storeError OStoreDirectoryPageObject::truncate (
	sal_uInt32             nPage,
	OStorePageBIOS        &rBIOS)
{
	// Determine scope and link indices.
	page::DataBlock::LinkDescriptor aLink;
	page::ChunkScope eScope = scope (nPage, aLink);

	storeError eErrCode = store_E_None;
	if (eScope == page::SCOPE_DIRECT)
	{
		// Truncate all triple indirect pages.
		eErrCode = truncate (page::SCOPE_TRIPLE, 0, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

		// Truncate all double indirect pages.
		eErrCode = truncate (page::SCOPE_DOUBLE, 0, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

		// Truncate all single indirect pages.
		eErrCode = truncate (page::SCOPE_SINGLE, 0, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

		// Truncate direct pages, including 'aLink.m_nIndex0'.
		eErrCode = truncate (eScope, aLink.m_nIndex0, rBIOS);
	}
	else if (eScope == page::SCOPE_SINGLE)
	{
		// Truncate all triple indirect pages.
		eErrCode = truncate (page::SCOPE_TRIPLE, 0, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

		// Truncate all double indirect pages.
		eErrCode = truncate (page::SCOPE_DOUBLE, 0, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

		// Truncate single indirect pages, downto 'aLink.m_nIndex1'.
		eErrCode = truncate (eScope, aLink.m_nIndex1 + 1, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

        // Truncate last single indirect page to ... pages.
        eErrCode = store_truncate_Impl (singleLink (aLink.m_nIndex1), aLink.m_nIndex0, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

        // Check for complete truncation.
        if (aLink.m_nIndex0 == 0)
        {
            // Clear pointer to last single indirect page.
            singleLink (aLink.m_nIndex1, STORE_PAGE_NULL);
        }
	}
	else if (eScope == page::SCOPE_DOUBLE)
	{
		// Truncate all triple indirect pages.
		eErrCode = truncate (page::SCOPE_TRIPLE, 0, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

		// Truncate double indirect pages, downto 'aLink.m_nIndex2'.
		eErrCode = truncate (eScope, aLink.m_nIndex2 + 1, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

        // Truncate last double indirect page to ... pages.
        eErrCode = store_truncate_Impl (
            doubleLink (aLink.m_nIndex2), aLink.m_nIndex1, aLink.m_nIndex0, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

        // Check for complete truncation.
        if ((aLink.m_nIndex1 + aLink.m_nIndex0) == 0)
        {
            // Clear pointer to last double indirect page.
            doubleLink (aLink.m_nIndex2, STORE_PAGE_NULL);
        }
	}
	else if (eScope == page::SCOPE_TRIPLE)
	{
		// Truncate triple indirect pages, downto 'aLink.m_nIndex3'.
		eErrCode = truncate (eScope, aLink.m_nIndex3 + 1, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

        // Truncate last triple indirect page to ... pages.
        eErrCode = store_truncate_Impl (
            tripleLink (aLink.m_nIndex3), aLink.m_nIndex2, aLink.m_nIndex1, aLink.m_nIndex0, rBIOS);
		if (eErrCode != store_E_None)
			return eErrCode;

        // Check for complete truncation.
        if ((aLink.m_nIndex2 + aLink.m_nIndex1 + aLink.m_nIndex0) == 0)
        {
            // Clear pointer to last triple indirect page.
            tripleLink (aLink.m_nIndex3, STORE_PAGE_NULL);
        }
	}
	else if (eScope == page::SCOPE_UNREACHABLE)
	{
		// Out of scope.
		eErrCode = store_E_CantSeek;
	}
	else
	{
		// Unknown scope.
		OSL_TRACE("OStoreDirectoryPageObject::put(): scope failed");
		eErrCode = store_E_Unknown;
	}

	// Leave.
	return eErrCode;
}

/*
 * truncate (external data page scope; private).
 */
storeError OStoreDirectoryPageObject::truncate (
	page::ChunkScope       eScope,
	sal_uInt16             nRemain,
	OStorePageBIOS        &rBIOS)
{
    OStoreDirectoryDataBlock const & rDataBlock = PAGE().m_aDataBlock;

	// Enter.
	storeError eErrCode = store_E_None;
	if (eScope == page::SCOPE_DIRECT)
	{
		// Truncate direct data pages.
		sal_uInt16 i, n = rDataBlock.directCount();
		for (i = n; i > nRemain; i--)
		{
			// Obtain data page location.
			sal_uInt32 nAddr = directLink (i - 1);
			if (nAddr == STORE_PAGE_NULL) continue;

			// Free data page.
			eErrCode = rBIOS.free (nAddr);
			if (eErrCode != store_E_None)
				break;

			// Clear pointer to data page.
			directLink (i - 1, STORE_PAGE_NULL);
		}

		// Done.
		return eErrCode;
	}

	if (eScope == page::SCOPE_SINGLE)
	{
		// Truncate single indirect pages.
		sal_uInt16 i, n = rDataBlock.singleCount();
		for (i = n; i > nRemain; i--)
		{
			// Truncate single indirect page to zero data pages.
            eErrCode = store_truncate_Impl (singleLink (i - 1), 0, rBIOS);
			if (eErrCode != store_E_None)
				break;

			// Clear pointer to single indirect page.
			singleLink (i - 1, STORE_PAGE_NULL);
		}

		// Done.
		return eErrCode;
	}

	if (eScope == page::SCOPE_DOUBLE)
	{
		// Truncate double indirect pages.
		sal_uInt16 i, n = rDataBlock.doubleCount();
		for (i = n; i > nRemain; i--)
		{
			// Truncate double indirect page to zero single indirect pages.
            eErrCode = store_truncate_Impl (doubleLink (i - 1), 0, 0, rBIOS);
			if (eErrCode != store_E_None)
				break;

			// Clear pointer to double indirect page.
			doubleLink (i - 1, STORE_PAGE_NULL);
		}

		// Done.
		return eErrCode;
	}

	if (eScope == page::SCOPE_TRIPLE)
	{
		// Truncate triple indirect pages.
		sal_uInt16 i, n = rDataBlock.tripleCount();
		for (i = n; i > nRemain; i--)
		{
			// Truncate to zero double indirect pages.
			eErrCode = store_truncate_Impl (tripleLink (i - 1), 0, 0, 0, rBIOS);
			if (eErrCode != store_E_None)
				break;

			// Clear pointer to triple indirect page.
			tripleLink (i - 1, STORE_PAGE_NULL);
		}

		// Done.
		return eErrCode;
	}

	// Invalid scope.
	return store_E_InvalidAccess;
}