116 lines
4.1 KiB
C++
116 lines
4.1 KiB
C++
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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#ifndef INCLUDED_COMPHELPER_BACKUPFILEHELPER_HXX
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#define INCLUDED_COMPHELPER_BACKUPFILEHELPER_HXX
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#include <sal/config.h>
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#include <comphelper/comphelperdllapi.h>
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#include <rtl/ustring.hxx>
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namespace comphelper
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{
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/** Helper class to backup/restore a single file
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*
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* You need to hand over the URL of the file to look at and
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* a maximum number of allowed copies. That number is internally
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* limited to a max of 10 (see implementation). The number of
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* allowed copies is limited to [1..max].
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*
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* Calling tryPush() will check if there is no backup yet or if
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* there is one that the file has changed. If yes, a new copy is
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* created on a kind of 'stack' of copies. Tre return value can
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* be used to see if a backup was indeed created.
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*
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* Calling tryPop() will do the opposite: If a backup is available,
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* delete the orig file and re-instantiate the backup. The backup
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* is taken off the 'stack' of copies. The return value can be
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* used to check if this was done.
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*
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* isPopPossible can be called to see if there is a backup available
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* before calling tryPop().
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*
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* The 'stack' of copies works by using the same path, filename
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* and extension, but adding a '_1' -> '_(num_of_copy)' to it.
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*/
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class COMPHELPER_DLLPUBLIC BackupFileHelper
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{
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private:
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// internal data
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const OUString& mrBaseURL;
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sal_uInt16 mnNumBackups;
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OUString maBase;
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OUString maExt;
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osl::File maBaseFile;
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bool mbBaseFileIsOpen;
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// internal upper limit (max) of allowed backups
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static sal_uInt16 mnMaxAllowedBackups;
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public:
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/** Constructor to handle Backups of the given file
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*
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* @param rBaseURL
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* URL to an existing file that needs to be backed up
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*
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* @param nNumBackups
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* Specifies the maximum number of backups to allow for
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* the file. This value gets truncated to [1..max] where
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* max currently is 10 and defined in the implementation.
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* It is used in tryPush() and tryPop() calls to cleanup/
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* reduce the number of existing backups
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*/
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BackupFileHelper(const OUString& rBaseURL, sal_uInt16 nNumBackups = 5);
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/** tries to create a new backup, if there is none yet, or if the
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* last differs from the base file. It will then put a new verion
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* on the 'stack' of copies and evtl. delete the oldest backup.
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* Also may cleanup older backups when NumBackups given in the
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* constructor has changed.
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*
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* @return bool
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* returns true if a new backup was actually created
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*/
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bool tryPush();
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/** finds out if a restore is possible
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*
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* @return bool
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* returns true if a restore to an older backup is possible
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*/
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bool isPopPossible();
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/** tries to execute a restore. Will overwrite the base file
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* in that case and take one version off the 'stack' of copies.
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* Also may cleanup older backups when NumBackups given in the
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* constructor has changed.
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*
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* @return bool
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* returns true if a restore was actually created
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*/
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bool tryPop();
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private:
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// internal helper methods
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rtl::OUString getName(sal_uInt16 n);
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bool firstExists();
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void pop();
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void push();
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bool isDifferentOrNew();
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bool equalsBase(osl::File& rLastFile);
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bool splitBaseURL();
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bool baseFileOpen();
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};
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}
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#endif
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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