LXR linux/include/uapi/linux/msg.h

   1#ifndef _UAPI_LINUX_MSG_H
   2#define _UAPI_LINUX_MSG_H
   3
   4#include <linux/ipc.h>
   5
   6/* ipcs ctl commands */
   7#define MSG_STAT 11
   8#define MSG_INFO 12
   9
  10/* msgrcv options */
  11#define MSG_NOERROR     010000  /* no error if message is too big */
  12#define MSG_EXCEPT      020000  /* recv any msg except of specified type.*/
  13#define MSG_COPY        040000  /* copy (not remove) all queue messages */
  14
  15/* Obsolete, used only for backwards compatibility and libc5 compiles */
  16struct msqid_ds {
  17        struct ipc_perm msg_perm;
  18        struct msg *msg_first;          /* first message on queue,unused  */
  19        struct msg *msg_last;           /* last message in queue,unused */
  20        __kernel_time_t msg_stime;      /* last msgsnd time */
  21        __kernel_time_t msg_rtime;      /* last msgrcv time */
  22        __kernel_time_t msg_ctime;      /* last change time */
  23        unsigned long  msg_lcbytes;     /* Reuse junk fields for 32 bit */
  24        unsigned long  msg_lqbytes;     /* ditto */
  25        unsigned short msg_cbytes;      /* current number of bytes on queue */
  26        unsigned short msg_qnum;        /* number of messages in queue */
  27        unsigned short msg_qbytes;      /* max number of bytes on queue */
  28        __kernel_ipc_pid_t msg_lspid;   /* pid of last msgsnd */
  29        __kernel_ipc_pid_t msg_lrpid;   /* last receive pid */
  30};
  31
  32/* Include the definition of msqid64_ds */
  33#include <asm/msgbuf.h>
  34
  35/* message buffer for msgsnd and msgrcv calls */
  36struct msgbuf {
  37        __kernel_long_t mtype;          /* type of message */
  38        char mtext[1];                  /* message text */
  39};
  40
  41/* buffer for msgctl calls IPC_INFO, MSG_INFO */
  42struct msginfo {
  43        int msgpool;
  44        int msgmap; 
  45        int msgmax; 
  46        int msgmnb; 
  47        int msgmni; 
  48        int msgssz; 
  49        int msgtql; 
  50        unsigned short  msgseg; 
  51};
  52
  53/*
  54 * MSGMNI, MSGMAX and MSGMNB are default values which can be
  55 * modified by sysctl.
  56 *
  57 * MSGMNI is the upper limit for the number of messages queues per
  58 * namespace.
  59 * It has been chosen to be as large possible without facilitating
  60 * scenarios where userspace causes overflows when adjusting the limits via
  61 * operations of the form retrieve current limit; add X; update limit".
  62 *
  63 * MSGMNB is the default size of a new message queue. Non-root tasks can
  64 * decrease the size with msgctl(IPC_SET), root tasks
  65 * (actually: CAP_SYS_RESOURCE) can both increase and decrease the queue
  66 * size. The optimal value is application dependent.
  67 * 16384 is used because it was always used (since 0.99.10)
  68 *
  69 * MAXMAX is the maximum size of an individual message, it's a global
  70 * (per-namespace) limit that applies for all message queues.
  71 * It's set to 1/2 of MSGMNB, to ensure that at least two messages fit into
  72 * the queue. This is also an arbitrary choice (since 2.6.0).
  73 */
  74
  75#define MSGMNI 32000   /* <= IPCMNI */     /* max # of msg queue identifiers */
  76#define MSGMAX  8192   /* <= INT_MAX */   /* max size of message (bytes) */
  77#define MSGMNB 16384   /* <= INT_MAX */   /* default max size of a message queue */
  78
  79/* unused */
  80#define MSGPOOL (MSGMNI * MSGMNB / 1024) /* size in kbytes of message pool */
  81#define MSGTQL  MSGMNB            /* number of system message headers */
  82#define MSGMAP  MSGMNB            /* number of entries in message map */
  83#define MSGSSZ  16                /* message segment size */
  84#define __MSGSEG ((MSGPOOL * 1024) / MSGSSZ) /* max no. of segments */
  85#define MSGSEG (__MSGSEG <= 0xffff ? __MSGSEG : 0xffff)
  86
  87
  88#endif /* _UAPI_LINUX_MSG_H */
  89