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#include "qwssharedmemory_p.h"

#if !defined(QT_NO_QWS_MULTIPROCESS)

#include <sys/shm.h>

QT_BEGIN_NAMESPACE

QWSSharedMemory::QWSSharedMemory()

    : shmBase(0), shmSize(0), character(0),  shmId(-1), key(-1)

{

}

QWSSharedMemory::~QWSSharedMemory()

{

    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 QWSSharedMemory::create(int size)

{

    if (shmId != -1)

        detach();

    shmId = shmget(IPC_PRIVATE, size, IPC_CREAT|0600);

    if (shmId == -1) {

#ifdef QT_SHM_DEBUG

        perror("QWSSharedMemory::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("QWSSharedMemory::create attaching to shared memory");

        qWarning("Error attaching to shared memory id %d", shmId);

#endif

        shmBase = 0;

        return false;

    }

    return true;

}

bool QWSSharedMemory::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("QWSSharedMemory::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 QWSSharedMemory::detach ()

{

    if (!shmBase)

        return;

    shmdt (shmBase);

    shmBase = 0;

    shmSize = 0;

    shmId = -1;

}

void QWSSharedMemory::setPermissions (mode_t mode)

{

  struct shmid_ds shm;

  shmctl (shmId, IPC_STAT, &shm);

  shm.shm_perm.mode = mode;

  shmctl (shmId, IPC_SET, &shm);

}

int QWSSharedMemory::size () const

{

    struct shmid_ds shm;

    shmctl (shmId, IPC_STAT, &shm);

    return shm.shm_segsz;

}

// old API

QWSSharedMemory::QWSSharedMemory (int size, const QString &filename, char c)

{

  shmSize = size;

  shmFile = filename;

  shmBase = 0;

  shmId = -1;

  character = c;

  key = ftok (shmFile.toLatin1().constData(), c);

}

bool QWSSharedMemory::create ()

{

  shmId = shmget (key, shmSize, IPC_CREAT | 0666);

  return (shmId != -1);

}

void QWSSharedMemory::destroy ()

{

    if (shmId != -1)

        shmctl(shmId, IPC_RMID, 0);

}

bool QWSSharedMemory::attach ()

{

  if (shmId == -1)

    shmId = shmget (key, shmSize, 0);

  shmBase = shmat (shmId, 0, 0);

  if ((long)shmBase == -1)

      shmBase = 0;

  return (long)shmBase != 0;

}

QT_END_NAMESPACE

#endif // QT_NO_QWS_MULTIPROCESS