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    40 ****************************************************************************/

    41 

    42 #include "qwssharedmemory_p.h"

    43 

    44 #if !defined(QT_NO_QWS_MULTIPROCESS)

    45 

    46 #include <sys/shm.h>

    47 

    48 QT_BEGIN_NAMESPACE

    49 

    50 QWSSharedMemory::QWSSharedMemory()

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

    52 {

    53 }

    54 

    55 

    56 QWSSharedMemory::~QWSSharedMemory()

    57 {

    58     detach();

    59 }

    60 

    61 /*

    62   man page says:

    63     On  Linux,  it is possible to attach a shared memory segment even if it

    64     is already marked to be deleted.  However, POSIX.1-2001 does not  spec-

    65     ify this behaviour and many other implementations do not support it.

    66 */

    67 

    68 bool QWSSharedMemory::create(int size)

    69 {

    70     if (shmId != -1)

    71         detach();

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

    73 

    74     if (shmId == -1) {

    75 #ifdef QT_SHM_DEBUG

    76         perror("QWSSharedMemory::create allocating shared memory");

    77         qWarning("Error allocating shared memory of size %d", size);

    78 #endif

    79         return false;

    80     }

    81     shmBase = shmat(shmId,0,0);

    82     shmctl(shmId, IPC_RMID, 0);

    83     if (shmBase == (void*)-1) {

    84 #ifdef QT_SHM_DEBUG

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

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

    87 #endif

    88         shmBase = 0;

    89         return false;

    90     }

    91     return true;

    92 }

    93 

    94 bool QWSSharedMemory::attach(int id)

    95 {

    96     if (shmId == id)

    97         return id != -1;

    98     if (shmId != -1)

    99         detach();

   100 

   101     shmBase = shmat(id,0,0);

   102     if (shmBase == (void*)-1) {

   103 #ifdef QT_SHM_DEBUG

   104         perror("QWSSharedMemory::attach attaching to shared memory");

   105         qWarning("Error attaching to shared memory 0x%x of size %d",

   106                  id, size());

   107 #endif

   108         shmBase = 0;

   109         return false;

   110     }

   111     shmId = id;

   112     return true;

   113 }

   114 

   115 

   116 void QWSSharedMemory::detach ()

   117 {

   118     if (!shmBase)

   119         return;

   120     shmdt (shmBase);

   121     shmBase = 0;

   122     shmSize = 0;

   123     shmId = -1;

   124 }

   125 

   126 void QWSSharedMemory::setPermissions (mode_t mode)

   127 {

   128   struct shmid_ds shm;

   129   shmctl (shmId, IPC_STAT, &shm);

   130   shm.shm_perm.mode = mode;

   131   shmctl (shmId, IPC_SET, &shm);

   132 }

   133 

   134 int QWSSharedMemory::size () const

   135 {

   136     struct shmid_ds shm;

   137     shmctl (shmId, IPC_STAT, &shm);

   138     return shm.shm_segsz;

   139 }

   140 

   141 

   142 // old API

   143 

   144 

   145 

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

   147 {

   148   shmSize = size;

   149   shmFile = filename;

   150   shmBase = 0;

   151   shmId = -1;

   152   character = c;

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

   154 }

   155 

   156 

   157 

   158 bool QWSSharedMemory::create ()

   159 {

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

   161   return (shmId != -1);

   162 }

   163 

   164 void QWSSharedMemory::destroy ()

   165 {

   166     if (shmId != -1)

   167         shmctl(shmId, IPC_RMID, 0);

   168 }

   169 

   170 bool QWSSharedMemory::attach ()

   171 {

   172   if (shmId == -1)

   173     shmId = shmget (key, shmSize, 0);

   174 

   175   shmBase = shmat (shmId, 0, 0);

   176   if ((long)shmBase == -1)

   177       shmBase = 0;

   178 

   179   return (long)shmBase != 0;

   180 }

   181 

   182 

   183 QT_END_NAMESPACE

   184 

   185 #endif // QT_NO_QWS_MULTIPROCESS