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man pages section 3: Basic Library Functions

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Updated: Thursday, June 13, 2019
 
 

sendmmsg (3C)

Name

sendmmsg - send multiple messages from a socket

Synopsis

#include <sys/socket.h>

int sendmmsg(int s, struct mmsghdr *msgvec, unsigned int vlen,
	unsigned int flags);

Parameters

s

The socket descriptor

msgvec

Pointer to an array of mmsghdr structures

vlen

The number of elements in the array of mmsghdr structures

flags

Flags for sending as in the sendmsg() function.

Description

The sendmmsg() function is an extension to the existing sendmsg() function that allows the caller to transmit multiple messages on a socket in a single invocation. The s socket is created using the socket() function. For more information, see the socket(3C) man page.

A blocking sendmmsg() function call blocks until vlen messages have been sent.

A non-blocking call sends as many messages as possible, up to vlen, and returns immediately.

The mmsghdr structure is defined as:

struct mmsghdr {
        	struct msghdr   msg_hdr;  /* Message header */
        	ssize_t         msg_len;  /* Number of bytes transmitted */
	};
msg_hdr

msghdr structure as described in <sys/socket.h>

msg_len

Is used to return the number of bytes sent from the message in msg_hdr. This is equivalent to the return value from a single sendmsg() function call.

Return Values

Upon successful completion, the sendmmsg() function returns the number of messages sent. The number of bytes sent is the arithmetic sum of the msg_len members of each mmsghdr structure.

The functions returns -1 if an error occurs and errno is set to indicate the error.

Errors

Errors are the same as per the sendmsg() function.

For more information, see the sendmsg(3C) man page.

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
MT-Level
Async-Signal-Safe

See Also

fcntl(2), poll(2), recvmmsg(3C), select(3C), socket(3C), sendmsg(3C), socket.h(3HEAD), attributes(7)

HISTORY

The recvmmsg() and sendmmsg() functions were added to Oracle Solaris in the 11.3 SRU 32 release.