recvmmsg - receive multiple messages from a socket
#include <sys/socket.h>
int recvmmsg(int s, struct mmsghdr *msgvec, unsigned int vlen,
unsigned int flags, struct timespec *timeout);
The socket descriptor. For more information, see the socket(3C) man page.
Pointer to an array of mmsghdr structures
The number of elements in the array of mmsghdr structures
Flags for receiving as in the recvmsg(3C) function. In addition the following flag is defined:
Turns on MSG_DONTWAIT after the first message has been received.
Pointer to a struct timespec defining a timeout for the receive operation. The specified timeout is subjected to rounding, based on system clock resolution.
The recvmmsg() function is an extension to the recvmsg(3C) function that allows the caller to receive multiple messages on a socket in a single invocation.
A blocking recvmmsg() function call blocks until the vlen messages have been received or until the timeout expires. A non-blocking call receives 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 received */
};
msghdr structure as described in socket.h(3HEAD)
Is used to return the number of bytes received in the message described in the msg_hdr. This is equivalent to the return value from a single recvmsg() function call.
The contents of the msghdr structure differ depending on whether or not __USE_SUNOS_SOCKETS__ is defined before including the <sys/socket.h> header. All source files accessing msghdr structures or calling the recvmmsg() function must be compiled with either __USE_SUNOS_SOCKETS__ defined or all with it undefined — mixing and matching will not work. See the socket.h(3HEAD) manual page for details.
Upon successful completion, the recvmmsg() function returns the number of messages received. The number of bytes received is the arithmetic sum of the msg_len members of each valid mmsghdr structure.
The function returns -1 if an error occurs and errno is set to indicate the error.
Errors are the same as per the recvmsg() function. In addition, the following error is also returned:
The timeout argument is invalid
For more information, see the recvmsg(3C) man page.
See attributes(7) for descriptions of the following attributes:
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fcntl(2), poll(2), sendmmsg(3C), select(3C), socket(3C), recvmsg(3C), socket.h(3HEAD), attributes(7)
The recvmmsg() function was added to Oracle Solaris in the 11.3 SRU 32 release.