Hello Elie,
On Thu, Dec 20, 2012 at 7:47 PM, Elie De Brauwer
<eliedebrauwer@xxxxxxxxx> wrote:
> Hi all,
>
> Please find below a patch with the comments in below (including two
> other typo's I seem to have missed yesterday).
>
> Thanks for the comments.
Thanks for the update. I've applied this for 3.46.
Cheers,
Michael
> ---
> man2/recvmmsg.2 | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 92 insertions(+), 2 deletions(-)
>
> diff --git a/man2/recvmmsg.2 b/man2/recvmmsg.2
> index a7b00d4..0c6db49 100644
> --- a/man2/recvmmsg.2
> +++ b/man2/recvmmsg.2
> @@ -21,8 +21,6 @@
> .\" Formatted or processed versions of this manual, if unaccompanied by
> .\" the source, must acknowledge the copyright and authors of this work.
> .\"
> -.\" FIXME: This page could be improved with an example program.
> -.\"
> .TH RECVMMSG 2 2012-05-02 "Linux" "Linux Programmer's Manual"
> .SH NAME
> recvmmsg \- receive multiple messages on a socket
> @@ -165,6 +163,98 @@ Support in glibc was added in version 2.12.
> .SH CONFORMING TO
> .BR recvmmsg ()
> is Linux-specific.
> +.SH EXAMPLE
> +.PP
> +The following program uses
> +.BR recvmmsg ()
> +to receive multiple messages on a socket and stores
> +them in multiple buffers.
> +The call returns if all buffers are filled or if the
> +timeout specified is expired.
> +
> +The following snippet periodically generates UDP datagrams
> +containing a random number:
> +.in +4n
> +.nf
> +.RB "$" " while true; do echo $RANDOM > /dev/udp/127.0.0.1/1234; sleep 0.25; done"
> +.fi
> +.in
> +
> +These datagrams are read by the example application which
> +can give the following output:
> +.in +4n
> +.nf
> +.RB "$" " ./a.out"
> +5 messages received
> +1 11782
> +2 11345
> +3 304
> +4 13514
> +5 28421
> +.fi
> +.in
> +.SS Program source
> +\&
> +.nf
> +#define _GNU_SOURCE
> +#include <netinet/ip.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/socket.h>
> +
> +int
> +main()
> +{
> +#define VLEN 10
> +#define BUFSIZE 200
> +#define TIMEOUT 1
> + int sockfd, retval, i;
> + struct sockaddr_in sa;
> + struct mmsghdr msgs[VLEN];
> + struct iovec iovecs[VLEN];
> + char bufs[VLEN][BUFSIZE+1];
> + struct timespec timeout;
> +
> + sockfd = socket(AF_INET, SOCK_DGRAM, 0);
> + if (sockfd == \-1) {
> + perror("socket()");
> + exit(EXIT_FAILURE);
> + }
> +
> + sa.sin_family = AF_INET;
> + sa.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
> + sa.sin_port = htons(1234);
> + if (bind(sockfd, (struct sockaddr *) &sa, sizeof(sa)) == \-1) {
> + perror("bind()");
> + exit(EXIT_FAILURE);
> + }
> +
> + memset(msgs, 0, sizeof(msgs));
> + for (i = 0; i < VLEN; i++) {
> + iovecs[i].iov_base = bufs[i];
> + iovecs[i].iov_len = BUFSIZE;
> + msgs[i].msg_hdr.msg_iov = &iovecs[i];
> + msgs[i].msg_hdr.msg_iovlen = 1;
> + }
> +
> + timeout.tv_sec = TIMEOUT;
> + timeout.tv_nsec = 0;
> +
> + retval = recvmmsg(sockfd, msgs, VLEN, 0, &timeout);
> + if (retval == \-1) {
> + perror("recvmmsg()");
> + exit(EXIT_FAILURE);
> + }
> +
> + printf("%d messages received\\n", retval);
> + for (i = 0; i < retval; i++) {
> + bufs[i][msgs[i].msg_len] = 0;
> + printf("%d %s", i+1, bufs[i]);
> + }
> + exit(EXIT_SUCCESS);
> +}
> +.fi
> .SH SEE ALSO
> .BR clock_gettime (2),
> .BR recvmsg (2),
> --
> 1.7.10.4
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Author of "The Linux Programming Interface"; http://man7.org/tlpi/
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