syncevolution/src/syncevo/SafeOstream.cpp
Patrick Ohly 50101688df DataBlob: abstract access to chunks of data
The goal of the DataBlob base class is encapsulating read/write
access to permanent data storage *on demand*. Comparing it to
files, it is more like a path name than a file handle.

boost::shared_ptr are used a) because it automates deletion of
the actual data streams and b) some implementations of DataBlob
might have to share access to these instances.

One possible implementation (included in this patch) is indeed
a plain file. It writes into a temporary file and only renames
it to the final path name on success, which emulates the behavior
of the FileConfigNode. The actual implementation of this renaming
was moved into a separate class, the SafeOstream.

Another (to be added later) is a chunk of data inside a larger file.
This is needed for embedding different .ini style files inside
one large text file, as required for MBC #1208).
2010-05-04 09:39:19 +02:00

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/*
* Copyright (C) 2008-2009 Patrick Ohly <patrick.ohly@gmx.de>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) version 3.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
#include <syncevo/SafeOstream.h>
#include <syncevo/SyncContext.h>
#include <syncevo/declarations.h>
SE_BEGIN_CXX
SafeOstream::SafeOstream(const std::string filename) :
m_filename(filename)
{
size_t pos = filename.rfind('/');
if (pos == filename.npos) {
m_tmpFilename = ".#";
m_tmpFilename += filename;
} else {
m_tmpFilename.assign(filename, 0, pos + 1);
m_tmpFilename += ".#";
m_tmpFilename += filename.substr(pos + 1);
}
open(m_tmpFilename.c_str());
}
SafeOstream::~SafeOstream()
{
close();
if (bad() ||
rename(m_tmpFilename.c_str(), m_filename.c_str())) {
SyncContext::throwError(m_tmpFilename, errno);
}
}
SE_END_CXX