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Edit File: msg.h
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ #ifndef _LINUX_MSG_H #define _LINUX_MSG_H #include <linux/ipc.h> /* ipcs ctl commands */ #define MSG_STAT 11 #define MSG_INFO 12 #define MSG_STAT_ANY 13 /* msgrcv options */ #define MSG_NOERROR 010000 /* no error if message is too big */ #define MSG_EXCEPT 020000 /* recv any msg except of specified type.*/ #define MSG_COPY 040000 /* copy (not remove) all queue messages */ /* Obsolete, used only for backwards compatibility and libc5 compiles */ struct msqid_ds { struct ipc_perm msg_perm; struct msg *msg_first; /* first message on queue,unused */ struct msg *msg_last; /* last message in queue,unused */ __kernel_old_time_t msg_stime; /* last msgsnd time */ __kernel_old_time_t msg_rtime; /* last msgrcv time */ __kernel_old_time_t msg_ctime; /* last change time */ unsigned long msg_lcbytes; /* Reuse junk fields for 32 bit */ unsigned long msg_lqbytes; /* ditto */ unsigned short msg_cbytes; /* current number of bytes on queue */ unsigned short msg_qnum; /* number of messages in queue */ unsigned short msg_qbytes; /* max number of bytes on queue */ __kernel_ipc_pid_t msg_lspid; /* pid of last msgsnd */ __kernel_ipc_pid_t msg_lrpid; /* last receive pid */ }; /* Include the definition of msqid64_ds */ #include <asm/msgbuf.h> /* message buffer for msgsnd and msgrcv calls */ struct msgbuf { __kernel_long_t mtype; /* type of message */ char mtext[1]; /* message text */ }; /* buffer for msgctl calls IPC_INFO, MSG_INFO */ struct msginfo { int msgpool; int msgmap; int msgmax; int msgmnb; int msgmni; int msgssz; int msgtql; unsigned short msgseg; }; /* * MSGMNI, MSGMAX and MSGMNB are default values which can be * modified by sysctl. * * MSGMNI is the upper limit for the number of messages queues per * namespace. * It has been chosen to be as large possible without facilitating * scenarios where userspace causes overflows when adjusting the limits via * operations of the form retrieve current limit; add X; update limit". * * MSGMNB is the default size of a new message queue. Non-root tasks can * decrease the size with msgctl(IPC_SET), root tasks * (actually: CAP_SYS_RESOURCE) can both increase and decrease the queue * size. The optimal value is application dependent. * 16384 is used because it was always used (since 0.99.10) * * MAXMAX is the maximum size of an individual message, it's a global * (per-namespace) limit that applies for all message queues. * It's set to 1/2 of MSGMNB, to ensure that at least two messages fit into * the queue. This is also an arbitrary choice (since 2.6.0). */ #define MSGMNI 32000 /* <= IPCMNI */ /* max # of msg queue identifiers */ #define MSGMAX 8192 /* <= INT_MAX */ /* max size of message (bytes) */ #define MSGMNB 16384 /* <= INT_MAX */ /* default max size of a message queue */ /* unused */ #define MSGPOOL (MSGMNI * MSGMNB / 1024) /* size in kbytes of message pool */ #define MSGTQL MSGMNB /* number of system message headers */ #define MSGMAP MSGMNB /* number of entries in message map */ #define MSGSSZ 16 /* message segment size */ #define __MSGSEG ((MSGPOOL * 1024) / MSGSSZ) /* max no. of segments */ #define MSGSEG (__MSGSEG <= 0xffff ? __MSGSEG : 0xffff) #endif /* _LINUX_MSG_H */