Date: Fri, 6 May 2016 17:55:11 +0000 (UTC) From: Benedict Reuschling <bcr@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r299190 - stable/10/lib/libc/sys Message-ID: <201605061755.u46HtBEQ050653@repo.freebsd.org>
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Author: bcr (doc committer) Date: Fri May 6 17:55:11 2016 New Revision: 299190 URL: https://svnweb.freebsd.org/changeset/base/299190 Log: MFC r298893: Provide an example to the kqueue man page, showing a basic usage example. Although it is an untypical example for the use of kqueue, it is better than nothing and should get people started. PR: 196844 Submitted by: fernando.apesteguia@gmail.com Reviewed by: kib Approved by: kib Differential Revision: https://reviews.freebsd.org/D6082 Modified: stable/10/lib/libc/sys/kqueue.2 Directory Properties: stable/10/ (props changed) Modified: stable/10/lib/libc/sys/kqueue.2 ============================================================================== --- stable/10/lib/libc/sys/kqueue.2 Fri May 6 17:39:12 2016 (r299189) +++ stable/10/lib/libc/sys/kqueue.2 Fri May 6 17:55:11 2016 (r299190) @@ -24,7 +24,7 @@ .\" .\" $FreeBSD$ .\" -.Dd March 29, 2015 +.Dd May 1, 2016 .Dt KQUEUE 2 .Os .Sh NAME @@ -577,6 +577,57 @@ will be set to indicate the error condit If the time limit expires, then .Fn kevent returns 0. +.Sh EXAMPLES +.Bd -literal -compact +#include <sys/types.h> +#include <sys/event.h> +#include <sys/time.h> +#include <err.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +int +main(int argc, char **argv) +{ + struct kevent event; /* Event we want to monitor */ + struct kevent tevent; /* Event triggered */ + int kq, fd, ret; + + if (argc != 2) + err(EXIT_FAILURE, "Usage: %s path\en", argv[0]); + fd = open(argv[1], O_RDONLY); + if (fd == -1) + err(EXIT_FAILURE, "Failed to open '%s'", argv[1]); + + /* Create kqueue. */ + kq = kqueue(); + if (kq == -1) + err(EXIT_FAILURE, "kqueue() failed"); + + /* Initialize kevent structure. */ + EV_SET(&event, fd, EVFILT_VNODE, EV_ADD | EV_CLEAR, NOTE_WRITE, + 0, NULL); + /* Attach event to the kqueue. */ + ret = kevent(kq, &event, 1, NULL, 0, NULL); + if (ret == -1) + err(EXIT_FAILURE, "kevent register"); + if (event.flags & EV_ERROR) + errx(EXIT_FAILURE, "Event error: %s", strerror(event.data)); + + for (;;) { + /* Sleep until something happens. */ + ret = kevent(kq, NULL, 0, &tevent, 1, NULL); + if (ret == -1) { + err(EXIT_FAILURE, "kevent wait"); + } else if (ret > 0) { + printf("Something was written in '%s'\en", argv[1]); + } + } +} +.Ed .Sh ERRORS The .Fn kqueue
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