/******************************************************************************** Copyright (C) 1992-2006 Trolltech ASA. All rights reserved.**** This file is part of the QtCore module of the Qt Toolkit.**** This file may be used under the terms of the GNU General Public** License version 2.0 as published by the Free Software Foundation** and appearing in the file LICENSE.GPL included in the packaging of** this file.  Please review the following information to ensure GNU** General Public Licensing requirements will be met:** http://www.trolltech.com/products/qt/opensource.html**** If you are unsure which license is appropriate for your use, please** review the following information:** http://www.trolltech.com/products/qt/licensing.html or contact the** sales department at sales@trolltech.com.**** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.******************************************************************************/#include "qsharedmemory_p.h"#if !defined(QT_NO_QWS_MULTIPROCESS)#include <sys/shm.h>QSharedMemory::QSharedMemory()    : shmBase(0), shmSize(0), character(0),  shmId(-1), key(-1){}QSharedMemory::~QSharedMemory(){    detach();}/*  man page says:    On  Linux,  it is possible to attach a shared memory segment even if it    is already marked to be deleted.  However, POSIX.1-2001 does not  spec-    ify this behaviour and many other implementations do not support it.*/bool QSharedMemory::create(int size){    if (shmId != -1)        detach();    shmId = shmget(IPC_PRIVATE, size, IPC_CREAT|0600);    if (shmId == -1) {#ifdef QT_SHM_DEBUG        perror("QSharedMemory::create allocating shared memory");        qWarning("Error allocating shared memory of size %d", size);#endif        return false;    }    shmBase = shmat(shmId,0,0);    shmctl(shmId, IPC_RMID, 0);    if (shmBase == (void*)-1) {#ifdef QT_SHM_DEBUG        perror("QSharedMemory::create attaching to shared memory");        qWarning("Error attaching to shared memory id %d", shmId);#endif        shmBase = 0;        return false;    }    return true;}bool QSharedMemory::attach(int id){    if (shmId == id)        return id != -1;    if (shmId != -1)        detach();    shmBase = shmat(id,0,0);    if (shmBase == (void*)-1) {#ifdef QT_SHM_DEBUG        perror("QSharedMemory::attach attaching to shared memory");        qWarning("Error attaching to shared memory 0x%x of size %d",                 id, size());#endif        shmBase = 0;        return false;    }    shmId = id;    return true;}void QSharedMemory::detach (){    if (!shmBase)        return;    shmdt (shmBase);    shmBase = 0;    shmSize = 0;    shmId = -1;}void QSharedMemory::setPermissions (mode_t mode){  struct shmid_ds shm;  shmctl (shmId, IPC_STAT, &shm);  shm.shm_perm.mode = mode;  shmctl (shmId, IPC_SET, &shm);}int QSharedMemory::size () const{    struct shmid_ds shm;    shmctl (shmId, IPC_STAT, &shm);    return shm.shm_segsz;}// old APIQSharedMemory::QSharedMemory (int size, const QString &filename, char c){  shmSize = size;  shmFile = filename;  shmBase = 0;  shmId = -1;  character = c;  key = ftok (shmFile.toLatin1().constData(), c);}bool QSharedMemory::create (){  shmId = shmget (key, shmSize, IPC_CREAT | 0666);  return (shmId != -1);}void QSharedMemory::destroy (){    if (shmId != -1)        shmctl(shmId, IPC_RMID, 0);}bool QSharedMemory::attach (){  if (shmId == -1)    shmId = shmget (key, shmSize, 0);  shmBase = shmat (shmId, 0, 0);  return (long)shmBase != -1 && shmBase != 0;}#endif // QT_NO_QWS_MULTIPROCESS