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