Adding upstream version 4:7.4.7.upstream/4%7.4.7upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 818 insertions, 0 deletions

diff --git a/desktop/source/deployment/registry/help/README.md b/desktop/source/deployment/registry/help/README.md
new file mode 100644
index 000000000..24ea19518
--- /dev/null
+++ b/desktop/source/deployment/registry/help/README.md
@@ -0,0 +1 @@
+Support for help integrated in extensions. Also see /README.help.md.
diff --git a/desktop/source/deployment/registry/help/dp_help.cxx b/desktop/source/deployment/registry/help/dp_help.cxx
new file mode 100644
index 000000000..9e1a75fb9
--- /dev/null
+++ b/desktop/source/deployment/registry/help/dp_help.cxx
@@ -0,0 +1,621 @@
+/* -*- 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 <memory>
+#include <config_features.h>
+
+#include <strings.hrc>
+#include <dp_backend.h>
+#include <dp_misc.h>
+#include "dp_helpbackenddb.hxx"
+#include <dp_ucb.h>
+#include <rtl/uri.hxx>
+#include <osl/file.hxx>
+#include <ucbhelper/content.hxx>
+#include <svl/inettype.hxx>
+#include <unotools/pathoptions.hxx>
+#include <cppuhelper/supportsservice.hxx>
+#include <o3tl/string_view.hxx>
+
+#if HAVE_FEATURE_XMLHELP
+#include <helpcompiler/compilehelp.hxx>
+#include <helpcompiler/HelpIndexer.hxx>
+#endif
+#include <com/sun/star/deployment/DeploymentException.hpp>
+#include <com/sun/star/deployment/ExtensionRemovedException.hpp>
+#include <com/sun/star/ucb/SimpleFileAccess.hpp>
+#include <com/sun/star/util/XMacroExpander.hpp>
+#include <optional>
+#include <string_view>
+
+using namespace ::dp_misc;
+using namespace ::com::sun::star;
+using namespace ::com::sun::star::uno;
+using namespace ::com::sun::star::ucb;
+
+namespace dp_registry::backend::help {
+namespace {
+
+
+class BackendImpl : public ::dp_registry::backend::PackageRegistryBackend
+{
+    class PackageImpl : public ::dp_registry::backend::Package
+    {
+        BackendImpl * getMyBackend() const;
+
+        // Package
+        virtual beans::Optional< beans::Ambiguous<sal_Bool> > isRegistered_(
+            ::osl::ResettableMutexGuard & guard,
+            ::rtl::Reference<AbortChannel> const & abortChannel,
+            Reference<XCommandEnvironment> const & xCmdEnv ) override;
+        virtual void processPackage_(
+            ::osl::ResettableMutexGuard & guard,
+            bool registerPackage,
+            bool startup,
+            ::rtl::Reference<AbortChannel> const & abortChannel,
+            Reference<XCommandEnvironment> const & xCmdEnv ) override;
+
+
+    public:
+        PackageImpl(
+            ::rtl::Reference<PackageRegistryBackend> const & myBackend,
+            OUString const & url, OUString const & name,
+            Reference<deployment::XPackageTypeInfo> const & xPackageType,
+            bool bRemoved, OUString const & identifier);
+
+        bool extensionContainsCompiledHelp();
+
+        //XPackage
+        virtual css::beans::Optional< OUString > SAL_CALL getRegistrationDataURL() override;
+    };
+    friend class PackageImpl;
+
+    // PackageRegistryBackend
+    virtual Reference<deployment::XPackage> bindPackage_(
+        OUString const & url, OUString const & mediaType,
+        bool bRemoved, OUString const & identifier,
+        Reference<XCommandEnvironment> const & xCmdEnv ) override;
+
+    void implProcessHelp( PackageImpl * package, bool doRegisterPackage,
+                          Reference<ucb::XCommandEnvironment> const & xCmdEnv);
+    void implCollectXhpFiles( const OUString& aDir,
+        std::vector< OUString >& o_rXhpFileVector );
+
+    ::std::optional<HelpBackendDb::Data> readDataFromDb(std::u16string_view url);
+    bool hasActiveEntry(std::u16string_view url);
+    bool activateEntry(std::u16string_view url);
+
+    Reference< ucb::XSimpleFileAccess3 > const & getFileAccess();
+    Reference< ucb::XSimpleFileAccess3 > m_xSFA;
+
+    const Reference<deployment::XPackageTypeInfo> m_xHelpTypeInfo;
+    Sequence< Reference<deployment::XPackageTypeInfo> > m_typeInfos;
+    std::unique_ptr<HelpBackendDb> m_backendDb;
+
+public:
+    BackendImpl( Sequence<Any> const & args,
+                 Reference<XComponentContext> const & xComponentContext );
+
+    // XServiceInfo
+    virtual OUString SAL_CALL getImplementationName() override;
+    virtual sal_Bool SAL_CALL supportsService( const OUString& ServiceName ) override;
+    virtual css::uno::Sequence< OUString > SAL_CALL getSupportedServiceNames() override;
+
+    // XPackageRegistry
+    virtual Sequence< Reference<deployment::XPackageTypeInfo> > SAL_CALL
+        getSupportedPackageTypes() override;
+    virtual void SAL_CALL packageRemoved(OUString const & url, OUString const & mediaType) override;
+
+};
+
+
+BackendImpl::BackendImpl(
+    Sequence<Any> const & args,
+    Reference<XComponentContext> const & xComponentContext )
+    : PackageRegistryBackend( args, xComponentContext ),
+      m_xHelpTypeInfo( new Package::TypeInfo("application/vnd.sun.star.help",
+                               OUString(),
+                               DpResId(RID_STR_HELP)
+                               ) ),
+      m_typeInfos{ m_xHelpTypeInfo }
+{
+    if (transientMode())
+        return;
+
+    OUString dbFile = makeURL(getCachePath(), "backenddb.xml");
+    m_backendDb.reset(
+        new HelpBackendDb(getComponentContext(), dbFile));
+
+    //clean up data folders which are no longer used.
+    //This must not be done in the same process where the help files
+    //are still registers. Only after revoking and restarting OOo the folders
+    //can be removed. This works now, because the extension manager is a singleton
+    //and the backends are only create once per process.
+    std::vector<OUString> folders = m_backendDb->getAllDataUrls();
+    deleteUnusedFolders(folders);
+}
+
+// XServiceInfo
+OUString BackendImpl::getImplementationName()
+{
+    return "com.sun.star.comp.deployment.help.PackageRegistryBackend";
+}
+
+sal_Bool BackendImpl::supportsService( const OUString& ServiceName )
+{
+    return cppu::supportsService(this, ServiceName);
+}
+
+css::uno::Sequence< OUString > BackendImpl::getSupportedServiceNames()
+{
+    return { BACKEND_SERVICE_NAME };
+}
+
+// XPackageRegistry
+
+Sequence< Reference<deployment::XPackageTypeInfo> >
+BackendImpl::getSupportedPackageTypes()
+{
+    return m_typeInfos;
+}
+
+void BackendImpl::packageRemoved(OUString const & url, OUString const & /*mediaType*/)
+{
+    if (m_backendDb)
+        m_backendDb->removeEntry(url);
+}
+
+// PackageRegistryBackend
+
+Reference<deployment::XPackage> BackendImpl::bindPackage_(
+    OUString const & url, OUString const & mediaType_,
+    bool bRemoved, OUString const & identifier,
+    Reference<XCommandEnvironment> const & xCmdEnv )
+{
+    // we don't support auto detection:
+    if (mediaType_.isEmpty())
+        throw lang::IllegalArgumentException(
+            StrCannotDetectMediaType() + url,
+            static_cast<OWeakObject *>(this), static_cast<sal_Int16>(-1) );
+
+    OUString type, subType;
+    INetContentTypeParameterList params;
+    if (INetContentTypes::parse( mediaType_, type, subType, &params ))
+    {
+        if (type.equalsIgnoreAsciiCase("application"))
+        {
+            OUString name;
+            if (!bRemoved)
+            {
+                ::ucbhelper::Content ucbContent(
+                    url, xCmdEnv, getComponentContext() );
+                name = StrTitle::getTitle( ucbContent );
+            }
+
+            if (subType.equalsIgnoreAsciiCase( "vnd.sun.star.help"))
+            {
+                return new PackageImpl(
+                    this, url, name, m_xHelpTypeInfo, bRemoved,
+                    identifier);
+            }
+        }
+    }
+    throw lang::IllegalArgumentException(
+        StrUnsupportedMediaType() + mediaType_,
+        static_cast<OWeakObject *>(this),
+        static_cast<sal_Int16>(-1) );
+}
+
+::std::optional<HelpBackendDb::Data> BackendImpl::readDataFromDb(
+    std::u16string_view url)
+{
+    ::std::optional<HelpBackendDb::Data> data;
+    if (m_backendDb)
+        data = m_backendDb->getEntry(url);
+    return data;
+}
+
+bool BackendImpl::hasActiveEntry(std::u16string_view url)
+{
+    if (m_backendDb)
+        return m_backendDb->hasActiveEntry(url);
+    return false;
+}
+
+bool BackendImpl::activateEntry(std::u16string_view url)
+{
+    if (m_backendDb)
+        return m_backendDb->activateEntry(url);
+    return false;
+}
+
+
+BackendImpl::PackageImpl::PackageImpl(
+    ::rtl::Reference<PackageRegistryBackend> const & myBackend,
+    OUString const & url, OUString const & name,
+    Reference<deployment::XPackageTypeInfo> const & xPackageType,
+    bool bRemoved, OUString const & identifier)
+    : Package( myBackend, url, name, name, xPackageType, bRemoved,
+               identifier)
+{
+}
+
+// Package
+BackendImpl * BackendImpl::PackageImpl::getMyBackend() const
+{
+    BackendImpl * pBackend = static_cast<BackendImpl *>(m_myBackend.get());
+    if (nullptr == pBackend)
+    {
+        //May throw a DisposedException
+        check();
+        //We should never get here...
+        throw RuntimeException("Failed to get the BackendImpl",
+            static_cast<OWeakObject*>(const_cast<PackageImpl *>(this)));
+    }
+    return pBackend;
+}
+
+bool BackendImpl::PackageImpl::extensionContainsCompiledHelp()
+{
+    bool bCompiled = true;
+    OUString aExpandedHelpURL = dp_misc::expandUnoRcUrl(getURL());
+
+    ::osl::Directory helpFolder(aExpandedHelpURL);
+    if ( helpFolder.open() == ::osl::File::E_None)
+    {
+        //iterate over the contents of the help folder
+        //We assume that all folders within the help folder contain language specific
+        //help files. If just one of them does not contain compiled help then this
+        //function returns false.
+        ::osl::DirectoryItem item;
+        ::osl::File::RC errorNext = ::osl::File::E_None;
+        while ((errorNext = helpFolder.getNextItem(item)) == ::osl::File::E_None)
+        {
+            //No find the language folders
+            ::osl::FileStatus stat(osl_FileStatus_Mask_Type | osl_FileStatus_Mask_FileName |osl_FileStatus_Mask_FileURL);
+            if (item.getFileStatus(stat) == ::osl::File::E_None)
+            {
+                if (stat.getFileType() != ::osl::FileStatus::Directory)
+                    continue;
+
+                //look if there is the folder help.idxl in the language folder
+                OUString compUrl(stat.getFileURL() + "/help.idxl");
+                ::osl::Directory compiledFolder(compUrl);
+                if (compiledFolder.open() != ::osl::File::E_None)
+                {
+                    bCompiled = false;
+                    break;
+                }
+            }
+            else
+            {
+                //Error
+                OSL_ASSERT(false);
+                bCompiled = false;
+                break;
+            }
+        }
+        if (errorNext != ::osl::File::E_NOENT
+            && errorNext != ::osl::File::E_None)
+        {
+            //Error
+            OSL_ASSERT(false);
+            bCompiled = false;
+        }
+    }
+    return bCompiled;
+}
+
+
+beans::Optional< beans::Ambiguous<sal_Bool> >
+BackendImpl::PackageImpl::isRegistered_(
+    ::osl::ResettableMutexGuard &,
+    ::rtl::Reference<AbortChannel> const &,
+    Reference<XCommandEnvironment> const & )
+{
+    BackendImpl * that = getMyBackend();
+
+    bool bReg = false;
+    if (that->hasActiveEntry(getURL()))
+        bReg = true;
+
+    return beans::Optional< beans::Ambiguous<sal_Bool> >( true, beans::Ambiguous<sal_Bool>( bReg, false ) );
+}
+
+
+void BackendImpl::PackageImpl::processPackage_(
+    ::osl::ResettableMutexGuard &,
+    bool doRegisterPackage,
+    bool /* startup */,
+    ::rtl::Reference<AbortChannel> const &,
+    Reference<XCommandEnvironment> const & xCmdEnv )
+{
+    BackendImpl* that = getMyBackend();
+    that->implProcessHelp( this, doRegisterPackage, xCmdEnv);
+}
+
+beans::Optional< OUString > BackendImpl::PackageImpl::getRegistrationDataURL()
+{
+    if (m_bRemoved)
+        throw deployment::ExtensionRemovedException();
+
+    ::std::optional<HelpBackendDb::Data> data =
+          getMyBackend()->readDataFromDb(getURL());
+
+    if (data && getMyBackend()->hasActiveEntry(getURL()))
+        return beans::Optional<OUString>(true, data->dataUrl);
+
+    return beans::Optional<OUString>(true, OUString());
+}
+
+void BackendImpl::implProcessHelp(
+    PackageImpl * package, bool doRegisterPackage,
+    Reference<ucb::XCommandEnvironment> const & xCmdEnv)
+{
+    Reference< deployment::XPackage > xPackage(package);
+    OSL_ASSERT(xPackage.is());
+    if (doRegisterPackage)
+    {
+        //revive already processed help if possible
+        if ( !activateEntry(xPackage->getURL()))
+        {
+            HelpBackendDb::Data data;
+            data.dataUrl = xPackage->getURL();
+            if (!package->extensionContainsCompiledHelp())
+            {
+#if HAVE_FEATURE_XMLHELP
+                const OUString sHelpFolder = createFolder(xCmdEnv);
+                data.dataUrl = sHelpFolder;
+
+                Reference< ucb::XSimpleFileAccess3 > xSFA = getFileAccess();
+                OUString aHelpURL = xPackage->getURL();
+                OUString aExpandedHelpURL = dp_misc::expandUnoRcUrl( aHelpURL );
+                if( !xSFA->isFolder( aExpandedHelpURL ) )
+                {
+                    OUString aErrStr = DpResId( RID_STR_HELPPROCESSING_GENERAL_ERROR ) +
+                        "No help folder";
+                    OWeakObject* oWeakThis = this;
+                    throw deployment::DeploymentException( OUString(), oWeakThis,
+                                                           Any( uno::Exception( aErrStr, oWeakThis ) ) );
+                }
+
+                // Scan languages
+                Sequence< OUString > aLanguageFolderSeq = xSFA->getFolderContents( aExpandedHelpURL, true );
+                sal_Int32 nLangCount = aLanguageFolderSeq.getLength();
+                const OUString* pSeq = aLanguageFolderSeq.getConstArray();
+                for( sal_Int32 iLang = 0 ; iLang < nLangCount ; ++iLang )
+                {
+                    OUString aLangURL = pSeq[iLang];
+                    if( xSFA->isFolder( aLangURL ) )
+                    {
+                        std::vector< OUString > aXhpFileVector;
+
+                        // calculate jar file URL
+                        sal_Int32 indexStartSegment = aLangURL.lastIndexOf('/');
+                        // for example "/en"
+                        OUString langFolderURLSegment(
+                            aLangURL.copy(
+                                indexStartSegment + 1, aLangURL.getLength() - indexStartSegment - 1));
+
+                        //create the folder in the "temporary folder"
+                        ::ucbhelper::Content langFolderContent;
+                        const OUString langFolderDest = makeURL(sHelpFolder, langFolderURLSegment);
+                        const OUString langFolderDestExpanded = ::dp_misc::expandUnoRcUrl(langFolderDest);
+                        ::dp_misc::create_folder(
+                            &langFolderContent,
+                            langFolderDest, xCmdEnv);
+
+                        static const OUStringLiteral aHelpStr(u"help");
+
+                        OUString aJarFile(
+                            makeURL(sHelpFolder, langFolderURLSegment + "/" + aHelpStr + ".jar"));
+                        aJarFile = ::dp_misc::expandUnoRcUrl(aJarFile);
+
+                        OUString aEncodedJarFilePath = rtl::Uri::encode(
+                            aJarFile, rtl_UriCharClassPchar,
+                            rtl_UriEncodeIgnoreEscapes,
+                            RTL_TEXTENCODING_UTF8 );
+                        OUString aDestBasePath = "vnd.sun.star.zip://" +
+                            aEncodedJarFilePath + "/" ;
+
+                        sal_Int32 nLenLangFolderURL = aLangURL.getLength() + 1;
+
+                        Sequence< OUString > aSubLangSeq = xSFA->getFolderContents( aLangURL, true );
+                        sal_Int32 nSubLangCount = aSubLangSeq.getLength();
+                        const OUString* pSubLangSeq = aSubLangSeq.getConstArray();
+                        for( sal_Int32 iSubLang = 0 ; iSubLang < nSubLangCount ; ++iSubLang )
+                        {
+                            OUString aSubFolderURL = pSubLangSeq[iSubLang];
+                            if( !xSFA->isFolder( aSubFolderURL ) )
+                                continue;
+
+                            implCollectXhpFiles( aSubFolderURL, aXhpFileVector );
+
+                            // Copy to package (later: move?)
+                            std::u16string_view aPureFolderName = aSubFolderURL.subView( nLenLangFolderURL );
+                            OUString aDestPath = aDestBasePath + aPureFolderName;
+                            xSFA->copy( aSubFolderURL, aDestPath );
+                        }
+
+                        // Call compiler
+                        sal_Int32 nXhpFileCount = aXhpFileVector.size();
+                        std::unique_ptr<OUString[]> pXhpFiles(new OUString[nXhpFileCount]);
+                        for( sal_Int32 iXhp = 0 ; iXhp < nXhpFileCount ; ++iXhp )
+                        {
+                            OUString aXhpFile = aXhpFileVector[iXhp];
+                            OUString aXhpRelFile = aXhpFile.copy( nLenLangFolderURL );
+                            pXhpFiles[iXhp] = aXhpRelFile;
+                        }
+
+                        OUString aOfficeHelpPath( SvtPathOptions().GetHelpPath() );
+                        OUString aOfficeHelpPathFileURL;
+                        ::osl::File::getFileURLFromSystemPath( aOfficeHelpPath, aOfficeHelpPathFileURL );
+
+                        HelpProcessingErrorInfo aErrorInfo;
+                        bool bSuccess = compileExtensionHelp(
+                            aOfficeHelpPathFileURL, aHelpStr, aLangURL,
+                            nXhpFileCount, pXhpFiles.get(),
+                            langFolderDestExpanded, aErrorInfo );
+
+                        pXhpFiles.reset();
+
+                        if( bSuccess )
+                        {
+                            OUString aLang;
+                            sal_Int32 nLastSlash = aLangURL.lastIndexOf( '/' );
+                            if( nLastSlash != -1 )
+                                aLang = aLangURL.copy( nLastSlash + 1 );
+                            else
+                                aLang = "en";
+
+                            HelpIndexer aIndexer(aLang, "help", langFolderDestExpanded, langFolderDestExpanded);
+                            aIndexer.indexDocuments();
+                        }
+
+                        if( !bSuccess )
+                        {
+                            TranslateId pErrStrId;
+                            switch( aErrorInfo.m_eErrorClass )
+                            {
+                            case HelpProcessingErrorClass::General:      pErrStrId = RID_STR_HELPPROCESSING_GENERAL_ERROR; break;
+                            case HelpProcessingErrorClass::XmlParsing:   pErrStrId = RID_STR_HELPPROCESSING_XMLPARSING_ERROR; break;
+                            default: ;
+                            };
+
+                            OUString aErrStr;
+                            if (pErrStrId)
+                            {
+                                aErrStr = DpResId(pErrStrId);
+
+                                // Remove CR/LF
+                                OUString aErrMsg( aErrorInfo.m_aErrorMsg );
+                                sal_Unicode const nCR = 13, nLF = 10;
+                                sal_Int32 nSearchCR = aErrMsg.indexOf( nCR );
+                                sal_Int32 nSearchLF = aErrMsg.indexOf( nLF );
+                                if( nSearchCR != -1 || nSearchLF != -1 )
+                                {
+                                    sal_Int32 nCopy;
+                                    if( nSearchCR == -1 )
+                                        nCopy = nSearchLF;
+                                    else if( nSearchLF == -1 )
+                                        nCopy = nSearchCR;
+                                    else
+                                        nCopy = ( nSearchCR < nSearchLF ) ? nSearchCR : nSearchLF;
+
+                                    aErrMsg = aErrMsg.copy( 0, nCopy );
+                                }
+                                aErrStr += aErrMsg;
+                                if (pErrStrId != RID_STR_HELPPROCESSING_XMLPARSING_ERROR && !aErrorInfo.m_aXMLParsingFile.isEmpty() )
+                                {
+                                    aErrStr += " in ";
+
+                                    OUString aDecodedFile = rtl::Uri::decode( aErrorInfo.m_aXMLParsingFile,
+                                                                                   rtl_UriDecodeWithCharset, RTL_TEXTENCODING_UTF8 );
+                                    aErrStr += aDecodedFile;
+                                    if( aErrorInfo.m_nXMLParsingLine != -1 )
+                                    {
+                                        aErrStr += ", line " +
+                                            OUString::number( aErrorInfo.m_nXMLParsingLine );
+                                    }
+                                }
+                            }
+
+                            OWeakObject* oWeakThis = this;
+                            throw deployment::DeploymentException( OUString(), oWeakThis,
+                                                                   Any( uno::Exception( aErrStr, oWeakThis ) ) );
+                        }
+                    }
+                }
+#else
+                (void) xCmdEnv;
+#endif
+            }
+            // Writing the data entry replaces writing the flag file. If we got to this
+            // point the registration was successful.
+            if (m_backendDb)
+                m_backendDb->addEntry(xPackage->getURL(), data);
+        }
+    } //if (doRegisterPackage)
+    else
+    {
+        if (m_backendDb)
+            m_backendDb->revokeEntry(xPackage->getURL());
+    }
+}
+
+void BackendImpl::implCollectXhpFiles( const OUString& aDir,
+    std::vector< OUString >& o_rXhpFileVector )
+{
+    Reference< ucb::XSimpleFileAccess3 > xSFA = getFileAccess();
+
+    // Scan xhp files recursively
+    Sequence< OUString > aSeq = xSFA->getFolderContents( aDir, true );
+    sal_Int32 nCount = aSeq.getLength();
+    const OUString* pSeq = aSeq.getConstArray();
+    for( sal_Int32 i = 0 ; i < nCount ; ++i )
+    {
+        OUString aURL = pSeq[i];
+        if( xSFA->isFolder( aURL ) )
+        {
+            implCollectXhpFiles( aURL, o_rXhpFileVector );
+        }
+        else
+        {
+            sal_Int32 nLastDot = aURL.lastIndexOf( '.' );
+            if( nLastDot != -1 )
+            {
+                std::u16string_view aExt = aURL.subView( nLastDot + 1 );
+                if( o3tl::equalsIgnoreAsciiCase( aExt, u"xhp" ) )
+                    o_rXhpFileVector.push_back( aURL );
+            }
+        }
+    }
+}
+
+Reference< ucb::XSimpleFileAccess3 > const & BackendImpl::getFileAccess()
+{
+    if( !m_xSFA.is() )
+    {
+        Reference<XComponentContext> const & xContext = getComponentContext();
+        if( xContext.is() )
+        {
+            m_xSFA = ucb::SimpleFileAccess::create(xContext);
+        }
+        if( !m_xSFA.is() )
+        {
+            throw RuntimeException(
+                "dp_registry::backend::help::BackendImpl::getFileAccess(), "
+                "could not instantiate SimpleFileAccess."  );
+        }
+    }
+    return m_xSFA;
+}
+
+} // anon namespace
+
+} // namespace dp_registry
+
+extern "C" SAL_DLLPUBLIC_EXPORT css::uno::XInterface*
+com_sun_star_comp_deployment_help_PackageRegistryBackend_get_implementation(
+    css::uno::XComponentContext* context, css::uno::Sequence<css::uno::Any> const& args)
+{
+    return cppu::acquire(new dp_registry::backend::help::BackendImpl(args, context));
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/desktop/source/deployment/registry/help/dp_helpbackenddb.cxx b/desktop/source/deployment/registry/help/dp_helpbackenddb.cxx
new file mode 100644
index 000000000..19bb3c3ce
--- /dev/null
+++ b/desktop/source/deployment/registry/help/dp_helpbackenddb.cxx
@@ -0,0 +1,126 @@
+/* -*- 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 <cppuhelper/exc_hlp.hxx>
+#include <com/sun/star/deployment/DeploymentException.hpp>
+#include <com/sun/star/uno/XComponentContext.hpp>
+
+#include "dp_helpbackenddb.hxx"
+
+
+using namespace ::com::sun::star::uno;
+
+constexpr OUStringLiteral EXTENSION_REG_NS = u"http://openoffice.org/extensionmanager/help-registry/2010";
+constexpr OUStringLiteral NS_PREFIX = u"help";
+constexpr OUStringLiteral ROOT_ELEMENT_NAME = u"help-backend-db";
+constexpr OUStringLiteral KEY_ELEMENT_NAME = u"help";
+
+namespace dp_registry::backend::help {
+
+HelpBackendDb::HelpBackendDb(
+    Reference<XComponentContext> const &  xContext,
+    OUString const & url):BackendDb(xContext, url)
+{
+
+}
+
+OUString HelpBackendDb::getDbNSName()
+{
+    return EXTENSION_REG_NS;
+}
+
+OUString HelpBackendDb::getNSPrefix()
+{
+    return NS_PREFIX;
+}
+
+OUString HelpBackendDb::getRootElementName()
+{
+    return ROOT_ELEMENT_NAME;
+}
+
+OUString HelpBackendDb::getKeyElementName()
+{
+    return KEY_ELEMENT_NAME;
+}
+
+
+void HelpBackendDb::addEntry(OUString const & url, Data const & data)
+{
+    try{
+        if (!activateEntry(url))
+        {
+            Reference<css::xml::dom::XNode> helpNode
+                = writeKeyElement(url);
+
+            writeSimpleElement(u"data-url", data.dataUrl, helpNode);
+            save();
+        }
+    }
+    catch ( const css::deployment::DeploymentException& )
+    {
+        throw;
+    }
+    catch(const css::uno::Exception &)
+    {
+        Any exc( ::cppu::getCaughtException() );
+        throw css::deployment::DeploymentException(
+            "Extension Manager: failed to write data entry in help backend db: " + m_urlDb, nullptr, exc);
+    }
+}
+
+
+::std::optional<HelpBackendDb::Data>
+HelpBackendDb::getEntry(std::u16string_view url)
+{
+    try
+    {
+        HelpBackendDb::Data retData;
+        Reference<css::xml::dom::XNode> aNode = getKeyElement(url);
+        if (aNode.is())
+        {
+            retData.dataUrl = readSimpleElement(u"data-url", aNode);
+        }
+        else
+        {
+            return ::std::optional<Data>();
+        }
+        return ::std::optional<Data>(retData);
+    }
+    catch ( const css::deployment::DeploymentException& )
+    {
+        throw;
+    }
+    catch(const css::uno::Exception &)
+    {
+        Any exc( ::cppu::getCaughtException() );
+        throw css::deployment::DeploymentException(
+            "Extension Manager: failed to read data entry in help backend db: " + m_urlDb, nullptr, exc);
+    }
+}
+
+std::vector<OUString> HelpBackendDb::getAllDataUrls()
+{
+    return getOneChildFromAllEntries(u"data-url");
+}
+
+} // namespace dp_registry::backend::help
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/desktop/source/deployment/registry/help/dp_helpbackenddb.hxx b/desktop/source/deployment/registry/help/dp_helpbackenddb.hxx
new file mode 100644
index 000000000..a46bd8663
--- /dev/null
+++ b/desktop/source/deployment/registry/help/dp_helpbackenddb.hxx
@@ -0,0 +1,70 @@
+/* -*- 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 .
+ */
+
+#pragma once
+
+#include <rtl/ustring.hxx>
+#include <optional>
+#include <string_view>
+
+#include <dp_backenddb.hxx>
+
+namespace com::sun::star::uno
+{
+class XComponentContext;
+}
+
+namespace dp_registry::backend::help
+{
+/* The XML file stores the extensions which are currently registered.
+   They will be removed when they are revoked.
+ */
+class HelpBackendDb : public dp_registry::backend::BackendDb
+{
+protected:
+    virtual OUString getDbNSName() override;
+
+    virtual OUString getNSPrefix() override;
+
+    virtual OUString getRootElementName() override;
+
+    virtual OUString getKeyElementName() override;
+
+public:
+    struct Data
+    {
+        /* the URL to the folder containing the compiled help files, etc.
+         */
+        OUString dataUrl;
+    };
+
+public:
+    HelpBackendDb(css::uno::Reference<css::uno::XComponentContext> const& xContext,
+                  OUString const& url);
+
+    void addEntry(OUString const& url, Data const& data);
+
+    ::std::optional<Data> getEntry(std::u16string_view url);
+    //must also return the data urls for entries with @active="false". That is,
+    //those are currently revoked.
+    std::vector<OUString> getAllDataUrls();
+};
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */