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kabc

lock.cpp
00001 /*
00002     This file is part of libkabc.
00003     Copyright (c) 2001,2003 Cornelius Schumacher <schumacher@kde.org>
00004 
00005     This library is free software; you can redistribute it and/or
00006     modify it under the terms of the GNU Library General Public
00007     License as published by the Free Software Foundation; either
00008     version 2 of the License, or (at your option) any later version.
00009 
00010     This library is distributed in the hope that it will be useful,
00011     but WITHOUT ANY WARRANTY; without even the implied warranty of
00012     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013     Library General Public License for more details.
00014 
00015     You should have received a copy of the GNU Library General Public License
00016     along with this library; see the file COPYING.LIB.  If not, write to
00017     the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
00018     Boston, MA 02110-1301, USA.
00019 */
00020 
00021 #include "lock.h"
00022 
00023 #include <krandom.h>
00024 #include <kcomponentdata.h>
00025 #include <kdebug.h>
00026 #include <klocale.h>
00027 #include <kstandarddirs.h>
00028 
00029 #include <QtCore/QFile>
00030 #include <QtCore/QTextStream>
00031 
00032 #include <errno.h>
00033 #include <signal.h>
00034 #include <sys/types.h>
00035 #include <sys/stat.h>
00036 #include <unistd.h>
00037 
00038 using namespace KABC;
00039 
00040 class Lock::Private
00041 {
00042   public:
00043     Private( const QString &identifier )
00044       : mIdentifier( identifier ),
00045         mOrigIdentifier( identifier )
00046     {
00047       mIdentifier.replace( QLatin1Char( '/' ), QLatin1Char( '_' ) );
00048 #ifdef Q_WS_WIN
00049       mIdentifier.replace( QLatin1Char( ':' ), QLatin1Char( '_' ) );
00050 #endif
00051     }
00052 
00053     QString mIdentifier;
00054     QString mOrigIdentifier;
00055     QString mLockUniqueName;
00056     QString mError;
00057 };
00058 
00059 Lock::Lock( const QString &identifier )
00060   : d( new Private( identifier ) )
00061 {
00062 }
00063 
00064 Lock::~Lock()
00065 {
00066   unlock();
00067 
00068   delete d;
00069 }
00070 
00071 QString Lock::locksDir()
00072 {
00073   return KStandardDirs::locateLocal( "data", QLatin1String( "kabc/lock/" ) );
00074 }
00075 
00076 bool Lock::readLockFile( const QString &filename, int &pid, QString &app )
00077 {
00078   QFile file( filename );
00079   if ( !file.open( QIODevice::ReadOnly ) ) {
00080     return false;
00081   }
00082 
00083   QTextStream t( &file );
00084   t >> pid >> ws >> app;
00085 
00086   return true;
00087 }
00088 
00089 bool Lock::writeLockFile( const QString &filename )
00090 {
00091   QFile file( filename );
00092   if ( !file.open( QIODevice::WriteOnly ) ) {
00093     return false;
00094   }
00095 
00096   QTextStream t( &file );
00097   t << ::getpid() << endl << QString( KGlobal::mainComponent().componentName() );
00098 
00099   return true;
00100 }
00101 
00102 QString Lock::lockFileName() const
00103 {
00104   return locksDir() + d->mIdentifier + QLatin1String( ".lock" );
00105 }
00106 
00107 bool Lock::lock()
00108 {
00109   QString lockName = lockFileName();
00110   kDebug() << "-- lock name:" << lockName;
00111 
00112   if ( QFile::exists( lockName ) ) {  // check if it is a stale lock file
00113     int pid;
00114     QString app;
00115 
00116     if ( !readLockFile( lockFileName(), pid, app ) ) {
00117       d->mError = i18n( "Unable to open lock file." );
00118       return false;
00119     }
00120 
00121     int retval = ::kill( pid, 0 );
00122     if ( retval == -1 && errno == ESRCH ) { // process doesn't exists anymore
00123       QFile::remove( lockName );
00124       kWarning() << "Removed stale lock file from process '" << app << "'";
00125     } else {
00126       d->mError = i18n( "The resource '%1' is locked by application '%2'.",
00127                         d->mOrigIdentifier, app );
00128       return false;
00129     }
00130   }
00131 
00132   QString lockUniqueName;
00133   lockUniqueName = d->mIdentifier + KRandom::randomString( 8 );
00134   d->mLockUniqueName = KStandardDirs::locateLocal(
00135     "data", QLatin1String( "kabc/lock/" ) + lockUniqueName );
00136   kDebug() << "-- lock unique name:" << d->mLockUniqueName;
00137 
00138   // Create unique file
00139   writeLockFile( d->mLockUniqueName );
00140 
00141   // Create lock file
00142   int result = ::link( QFile::encodeName( d->mLockUniqueName ),
00143                        QFile::encodeName( lockName ) );
00144 
00145   if ( result == 0 ) {
00146     d->mError.clear();
00147     emit locked();
00148     return true;
00149   }
00150 
00151   // TODO: check stat
00152 
00153   d->mError = i18n( "Error" );
00154   return false;
00155 }
00156 
00157 bool Lock::unlock()
00158 {
00159   int pid;
00160   QString app;
00161   if ( readLockFile( lockFileName(), pid, app ) ) {
00162     if ( pid == getpid() ) {
00163       QFile::remove( lockFileName() );
00164       QFile::remove( d->mLockUniqueName );
00165       emit unlocked();
00166     } else {
00167       d->mError = i18n( "Unlock failed. Lock file is owned by other process: %1 (%2)", app, pid );
00168       kDebug() << d->mError;
00169       return false;
00170     }
00171   }
00172 
00173   d->mError.clear();
00174 
00175   return true;
00176 }
00177 
00178 QString Lock::error() const
00179 {
00180   return d->mError;
00181 }
00182 
00183 #include "lock.moc"
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