Linux kernel mirror (for testing)
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1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2#ifndef _UAPI_LINUX_MSG_H
3#define _UAPI_LINUX_MSG_H
4
5#include <linux/ipc.h>
6
7/* ipcs ctl commands */
8#define MSG_STAT 11
9#define MSG_INFO 12
10
11/* msgrcv options */
12#define MSG_NOERROR 010000 /* no error if message is too big */
13#define MSG_EXCEPT 020000 /* recv any msg except of specified type.*/
14#define MSG_COPY 040000 /* copy (not remove) all queue messages */
15
16/* Obsolete, used only for backwards compatibility and libc5 compiles */
17struct msqid_ds {
18 struct ipc_perm msg_perm;
19 struct msg *msg_first; /* first message on queue,unused */
20 struct msg *msg_last; /* last message in queue,unused */
21 __kernel_time_t msg_stime; /* last msgsnd time */
22 __kernel_time_t msg_rtime; /* last msgrcv time */
23 __kernel_time_t msg_ctime; /* last change time */
24 unsigned long msg_lcbytes; /* Reuse junk fields for 32 bit */
25 unsigned long msg_lqbytes; /* ditto */
26 unsigned short msg_cbytes; /* current number of bytes on queue */
27 unsigned short msg_qnum; /* number of messages in queue */
28 unsigned short msg_qbytes; /* max number of bytes on queue */
29 __kernel_ipc_pid_t msg_lspid; /* pid of last msgsnd */
30 __kernel_ipc_pid_t msg_lrpid; /* last receive pid */
31};
32
33/* Include the definition of msqid64_ds */
34#include <asm/msgbuf.h>
35
36/* message buffer for msgsnd and msgrcv calls */
37struct msgbuf {
38 __kernel_long_t mtype; /* type of message */
39 char mtext[1]; /* message text */
40};
41
42/* buffer for msgctl calls IPC_INFO, MSG_INFO */
43struct msginfo {
44 int msgpool;
45 int msgmap;
46 int msgmax;
47 int msgmnb;
48 int msgmni;
49 int msgssz;
50 int msgtql;
51 unsigned short msgseg;
52};
53
54/*
55 * MSGMNI, MSGMAX and MSGMNB are default values which can be
56 * modified by sysctl.
57 *
58 * MSGMNI is the upper limit for the number of messages queues per
59 * namespace.
60 * It has been chosen to be as large possible without facilitating
61 * scenarios where userspace causes overflows when adjusting the limits via
62 * operations of the form retrieve current limit; add X; update limit".
63 *
64 * MSGMNB is the default size of a new message queue. Non-root tasks can
65 * decrease the size with msgctl(IPC_SET), root tasks
66 * (actually: CAP_SYS_RESOURCE) can both increase and decrease the queue
67 * size. The optimal value is application dependent.
68 * 16384 is used because it was always used (since 0.99.10)
69 *
70 * MAXMAX is the maximum size of an individual message, it's a global
71 * (per-namespace) limit that applies for all message queues.
72 * It's set to 1/2 of MSGMNB, to ensure that at least two messages fit into
73 * the queue. This is also an arbitrary choice (since 2.6.0).
74 */
75
76#define MSGMNI 32000 /* <= IPCMNI */ /* max # of msg queue identifiers */
77#define MSGMAX 8192 /* <= INT_MAX */ /* max size of message (bytes) */
78#define MSGMNB 16384 /* <= INT_MAX */ /* default max size of a message queue */
79
80/* unused */
81#define MSGPOOL (MSGMNI * MSGMNB / 1024) /* size in kbytes of message pool */
82#define MSGTQL MSGMNB /* number of system message headers */
83#define MSGMAP MSGMNB /* number of entries in message map */
84#define MSGSSZ 16 /* message segment size */
85#define __MSGSEG ((MSGPOOL * 1024) / MSGSSZ) /* max no. of segments */
86#define MSGSEG (__MSGSEG <= 0xffff ? __MSGSEG : 0xffff)
87
88
89#endif /* _UAPI_LINUX_MSG_H */