sys/msg.h - XSI message queue structures
[XSI] #include <sys/msg.h>
The <sys/msg.h> header shall define the following data types through typedef:
- Used for the number of messages in the message queue.
- Used for the number of bytes allowed in a message queue.
These types shall be unsigned integer types that are able to store values at least as large as a type unsigned short.
The <sys/msg.h> header shall define the following constant as a message operation flag:
- No error if big message.
The msqid_ds structure shall contain the following members:struct ipc_perm msg_perm Operation permission structure. msgqnum_t msg_qnum Number of messages currently on queue. msglen_t msg_qbytes Maximum number of bytes allowed on queue. pid_t msg_lspid Process ID of last msgsnd (). pid_t msg_lrpid Process ID of last msgrcv (). time_t msg_stime Time of last msgsnd (). time_t msg_rtime Time of last msgrcv (). time_t msg_ctime Time of last change.
The pid_t, time_t, key_t, size_t, and ssize_t types shall be defined as described in <sys/types.h>.
The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.int msgctl(int, int, struct msqid_ds *); int msgget(key_t, int); ssize_t msgrcv(int, void *, size_t, long, int); int msgsnd(int, const void *, size_t, int);
In addition, all of the symbols from <sys/ipc.h> shall be defined when this header is included.
<sys/ipc.h>, <sys/types.h>, msgctl(), msgget(), msgrcv(), msgsnd()
First released in Issue 2. Derived from System V Release 2.0.