10.1 Types, Constants and variables :

Variables

 Var
   IPCerror : longint;

The IPCerror variable is used to report errors, by all calls.

Constants

Many constants here are provided for completeness only, and should under normal circumstances not be used by the programmer.

 Const
   IPC_CREAT  =  1 shl 9;  { create if key is nonexistent }
   IPC_EXCL   =  2 shl 9;  { fail if key exists }
   IPC_NOWAIT =  4 shl 9;  { return error on wait }

These constants are used in the various xxxget calls.

   IPC_RMID = 0;     { remove resource }
   IPC_SET  = 1;     { set ipc_perm options }
   IPC_STAT = 2;     { get ipc_perm options }
   IPC_INFO = 3;     { see ipcs }

These constants can be passed to the various xxxctl calls.

 const
   MSG_NOERROR = 1 shl 12;
   MSG_EXCEPT  = 2 shl 12;
   MSGMNI = 128;
   MSGMAX = 4056;
   MSGMNB = 16384;

These constants are used in the messaging system, they are not for use by the programmer.

 const
   SEM_UNDO = $1000;
   GETPID = 11;
   GETVAL = 12;
   GETALL = 13;
   GETNCNT = 14;
   GETZCNT = 15;
   SETVAL = 16;
   SETALL = 17;

These constants call be specified in the semop (271) call.

   SEMMNI = 128;
   SEMMSL = 32;
   SEMMNS = (SEMMNI * SEMMSL);
   SEMOPM = 32;
   SEMVMX = 32767;

These constanst are used internally by the semaphore system, they should not be used by the programmer.

 const
   SHM_R      = 4 shl 6;
   SHM_W      = 2 shl 6;
   SHM_RDONLY = 1 shl 12;
   SHM_RND    = 2 shl 12;
   SHM_REMAP  = 4 shl 12;
   SHM_LOCK   = 11;
   SHM_UNLOCK = 12;

These constants are used in the shmctl (279) call.

Types

The following two types are provided because they are needed. One they they should be defined in the system unit, however.

 Type
   PULong = ^Cardinal;
   PWord  = ^Word;

 Type
    TKey   = Longint;

TKey is the type returned by the ftok (266) key generating function.

 type
   PIPC_Perm = ^TIPC_Perm;
   TIPC_Perm = record
     key : TKey;
     uid,
     gid,
     cuid,
     cgid,
     mode,
     seq : Word;
   end;

The TIPC_Perm structure is used in all IPC systems to specify the permissions.

 Type
   PSHMid_DS = ^TSHMid_ds;
   TSHMid_ds = record
     shm_perm  : TIPC_Perm;
     shm_segsz : longint;
     shm_atime : longint;
     shm_dtime : longint;
     shm_ctime : longint;
     shm_cpid  : word;
     shm_lpid  : word;
     shm_nattch : integer;
     shm_npages : word;
     shm_pages  : Pointer;
     attaches   : pointer;
   end;

The TSHMid_ds strucure is used in the shmctl (279) call to set or retrieve settings concerning shared memory.

 type
   PSHMinfo = ^TSHMinfo;
   TSHMinfo = record
     shmmax : longint;
     shmmin : longint;
     shmmni : longint;
     shmseg : longint;
     shmall : longint;
   end;

The TSHMinfo record is used by the shared memory system, and should not be accessed by the programer directly.

 type
   PMSG = ^TMSG;
   TMSG = record
     msg_next  : PMSG;
     msg_type  : Longint;
     msg_spot  : PChar;
     msg_stime : Longint;
     msg_ts    : Integer;
   end;

The TMSG record is used in the handling of message queues. There should be few cases where the programmer needs to access this data.

 type
   PMSQid_ds = ^TMSQid_ds;
   TMSQid_ds = record
     msg_perm   : TIPC_perm;
     msg_first  : PMsg;
     msg_last   : PMsg;
     msg_stime  : Longint;
     msg_rtime  : Longint;
     msg_ctime  : Longint;
     wwait      : Pointer;
     rwait      : pointer;
     msg_cbytes : word;
     msg_qnum   : word;
     msg_qbytes : word;
     msg_lspid  : word;
     msg_lrpid  : word;
   end;

The TMSQid_ds record is returned by the msgctl (268) call, and contains all data about a message queue.

   PMSGbuf = ^TMSGbuf;
   TMSGbuf = record
     mtype : longint;
     mtext : array[0..0] of char;
   end;

The TMSGbuf record is a record containing the data of a record. you should never use this record directly, instead you should make your own record that follows the structure of the TMSGbuf record, but that has a size that is big enough to accomodate your messages. The mtype field should always be present, and should always be filled.

 Type
   PMSGinfo = ^TMSGinfo;
   TMSGinfo = record
     msgpool : Longint;
     msgmap  : Longint;
     msgmax  : Longint;
     msgmnb  : Longint;
     msgmni  : Longint;
     msgssz  : Longint;
     msgtql  : Longint;
     msgseg  : Word;
   end;

The TMSGinfo record is used internally by the message queue system, and should not be used by the programmer directly.

 Type
   PSEMid_ds = ^PSEMid_ds;
   TSEMid_ds = record
     sem_perm : tipc_perm;
     sem_otime : longint;
     sem_ctime : longint;
     sem_base         : pointer;
     sem_pending      : pointer;
     sem_pending_last : pointer;
     undo             : pointer;
     sem_nsems : word;
   end;

The TSEMid_ds structure is returned by the semctl (272) call, and contains all data concerning a semahore.

 Type
   PSEMbuf = ^TSEMbuf;
   TSEMbuf = record
     sem_num : word;
     sem_op  : integer;
     sem_flg : integer;
   end;

The TSEMbuf record us use in the semop (271) call, and is used to specify which operations you want to do.

 Type
   PSEMinfo = ^TSEMinfo;
   TSEMinfo = record
     semmap : longint;
     semmni : longint;
     semmns : longint;
     semmnu : longint;
     semmsl : longint;
     semopm : longint;
     semume : longint;
     semusz : longint;
     semvmx : longint;
     semaem : longint;
   end;

The TSEMinfo record is used internally by the semaphore system, and should not be used directly.

 Type
   PSEMun = ^TSEMun;
   TSEMun = record
    case longint of
       0 : ( val : longint );
       1 : ( buf : PSEMid_ds );
       2 : ( arr : PWord );
       3 : ( padbuf : PSeminfo );
       4 : ( padpad : pointer );
    end;

The TSEMun variant record (actually a C union) is used in the semctl (272) call.

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