d8c1e157ab
git-svn-id: https://crux.nu/svn/tools/prt-get/trunk@9 0b5ae1c7-2405-0410-a7fc-ba219f786e1e
151 lines
3.6 KiB
C++
151 lines
3.6 KiB
C++
////////////////////////////////////////////////////////////////////////
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// FILE: lockfile.cpp
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// AUTHOR: Johannes Winkelmann, jw@tks6.net
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// COPYRIGHT: (c) 2002 by Johannes Winkelmann
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// ---------------------------------------------------------------------
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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////////////////////////////////////////////////////////////////////////
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <cstdio>
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#include "lockfile.h"
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using namespace std;
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string LockFile::LOCK_SUFFIX = ".lock";
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string LockFile::WRITE_LOCK_STRING = "write_lock";
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string LockFile::READ_LOCK_STRING = "read_lock";
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string LockFile::READ_WRITE_LOCK_STRING = "read_write_lock";
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/*!
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\brief a file locking class
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*/
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LockFile::LockFile()
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: m_readLock( false ),
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m_writeLock( false )
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{
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}
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bool LockFile::lockRead()
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{
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if ( m_readLock ) {
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// we already lock it, so it's a good lock
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return true;
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}
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if ( m_writeLock ) {
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// can't lock for read and write separatedly
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return false;
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}
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struct stat buf;
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if ( stat( m_fileName.c_str(), &buf) == 0 ) {
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FILE* fp = fopen( m_fileName.c_str(), "w" );
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if ( fp ) {
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// file did not exist, could be created
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m_writeLock = true;
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fprintf( fp, "%s", READ_LOCK_STRING.c_str() );
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fclose( fp );
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return true;
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}
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} else {
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// file exists, but it could be a read lock
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// TODO: allow locking, increment lock count
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}
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// couldn't lock
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return false;
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}
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/*!
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lock the file
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\return true if we have a lock
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*/
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bool LockFile::lockWrite()
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{
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if ( m_writeLock ) {
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// we already lock it, so it's a good lock
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return true;
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}
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if ( m_readLock ) {
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// can't lock for read and write separatedly
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return false;
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}
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struct stat buf;
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if ( stat( m_fileName.c_str(), &buf) == -1 ) {
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// file can not be stat'ed
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FILE* fp = fopen( m_fileName.c_str(), "w" );
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if ( fp ) {
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// file did not exist, could be created
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m_writeLock = true;
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fprintf( fp, "%s", WRITE_LOCK_STRING.c_str() );
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fclose( fp );
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return true;
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}
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}
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// couldn't lock
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return false;
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}
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bool LockFile::lockReadWrite()
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{
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if ( m_readWriteLock ) {
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// we already lock it, so it's a good lock
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return true;
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}
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if ( m_writeLock || m_readLock ) {
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// can't lock for read and write separatedly
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return false;
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}
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struct stat buf;
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if ( stat( m_fileName.c_str(), &buf) == 0 ) {
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FILE* fp = fopen( m_fileName.c_str(), "w" );
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if ( fp ) {
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// file did not exist, could be created
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m_writeLock = true;
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fprintf( fp, "%s", READ_WRITE_LOCK_STRING.c_str() );
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fclose( fp );
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return true;
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}
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}
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// couldn't lock
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return false;
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}
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bool LockFile::unlock()
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{
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if ( m_readLock || m_writeLock || m_readWriteLock ) {
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// TODO: check whether lock count is 0
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if ( unlink( m_fileName.c_str() ) == 0 ) {
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m_readLock = m_writeLock = m_readWriteLock = false;
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return true;
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}
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}
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return false;
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}
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void LockFile::setFile( const string& fileName )
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{
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m_fileName = fileName + LOCK_SUFFIX;
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}
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