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/* -*- 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/.
*/
#ifndef INCLUDED_COMPHELPER_BACKUPFILEHELPER_HXX
#define INCLUDED_COMPHELPER_BACKUPFILEHELPER_HXX
#include <sal/config.h>
#include <comphelper/comphelperdllapi.h>
#include <rtl/ustring.hxx>
#include <osl/file.hxx>
namespace comphelper
{
/** Helper class to backup/restore a single file
*
* You need to hand over the URL of the file to look at and
* a maximum number of allowed copies. That number is internally
* limited to a max of 10 (see implementation). The number of
* allowed copies is limited to [1..max].
*
* Calling tryPush() will check if there is no backup yet or if
* there is one that the file has changed. If yes, a new copy is
* created on a kind of 'stack' of copies. Tre return value can
* be used to see if a backup was indeed created.
*
* Calling tryPop() will do the opposite: If a backup is available,
* delete the orig file and re-instantiate the backup. The backup
* is taken off the 'stack' of copies. The return value can be
* used to check if this was done.
*
* isPopPossible can be called to see if there is a backup available
* before calling tryPop().
*
* The 'stack' of copies works by using the same path, filename
* and extension, but adding a '_1' -> '_(num_of_copy)' to it.
*/
class COMPHELPER_DLLPUBLIC BackupFileHelper
{
private:
// internal data
const OUString& mrBaseURL;
sal_uInt16 mnNumBackups;
OUString maBase;
OUString maExt;
osl::File maBaseFile;
bool mbBaseFileIsOpen;
// internal flag if _exit() was called already - a hint to evtl.
// not create copies of potentially not well-defined data. This
// may be used in destructors of static instances - which unfortunately
// get called on WNT but not on linux. Thus I thought about encapsulating
// in some '#ifdefs', but it's just more safe to always do it and
// allows to add a SAL_WARN when one of these destructors is called
// after _exit()
static bool mbExitWasCalled;
// internal upper limit (max) of allowed backups
static sal_uInt16 mnMaxAllowedBackups;
public:
/** Constructor to handle Backups of the given file
*
* @param rBaseURL
* URL to an existing file that needs to be backed up
*
* @param nNumBackups
* Specifies the maximum number of backups to allow for
* the file. This value gets truncated to [1..max] where
* max currently is 10 and defined in the implementation.
* It is used in tryPush() and tryPop() calls to cleanup/
* reduce the number of existing backups
*/
BackupFileHelper(const OUString& rBaseURL, sal_uInt16 nNumBackups = 5);
// allow to set flag when app had to call _exit()
static void setExitWasCalled();
static bool getExitWasCalled();
/** tries to create a new backup, if there is none yet, or if the
* last differs from the base file. It will then put a new verion
* on the 'stack' of copies and evtl. delete the oldest backup.
* Also may cleanup older backups when NumBackups given in the
* constructor has changed.
*
* @return bool
* returns true if a new backup was actually created
*/
bool tryPush();
/** finds out if a restore is possible
*
* @return bool
* returns true if a restore to an older backup is possible
*/
bool isPopPossible();
/** tries to execute a restore. Will overwrite the base file
* in that case and take one version off the 'stack' of copies.
* Also may cleanup older backups when NumBackups given in the
* constructor has changed.
*
* @return bool
* returns true if a restore was actually created
*/
bool tryPop();
private:
// internal helper methods
rtl::OUString getName(sal_uInt16 n);
bool firstExists();
void pop();
void push();
bool isDifferentOrNew();
bool equalsBase(osl::File& rLastFile);
bool splitBaseURL();
bool baseFileOpen();
};
}
#endif
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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