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