91 lines · c
1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */2#ifndef _UAPI_LINUX_MSG_H3#define _UAPI_LINUX_MSG_H4 5#include <linux/ipc.h>6 7/* ipcs ctl commands */8#define MSG_STAT 119#define MSG_INFO 1210#define MSG_STAT_ANY 1311 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 */18struct 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 */38struct 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 */44struct 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 be57 * modified by sysctl.58 *59 * MSGMNI is the upper limit for the number of messages queues per60 * namespace.61 * It has been chosen to be as large possible without facilitating62 * scenarios where userspace causes overflows when adjusting the limits via63 * 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 can66 * decrease the size with msgctl(IPC_SET), root tasks67 * (actually: CAP_SYS_RESOURCE) can both increase and decrease the queue68 * 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 global72 * (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 into74 * 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 /* _UAPI_LINUX_MSG_H */91