h_nullmnt.c revision 1.1 
1#include <err.h>
2#include <fcntl.h>
3#include <stdlib.h>
4#include <unistd.h>
5
6#include <sys/event.h>
7#include <sys/time.h>
8
9/*
10 * External set-up code is expected to do the equivalent of
11 *	cd $TOPDIR
12 *	mkdir realdir
13 *	mkdir nulldir
14 *	mount -t null $TOPDIR/realdir $TOPDIR/nulldir
15 *	rm -f $TOPDIR/realdir/afile
16 *	touch $TOPDIR/realdir/afile
17 * then execute this test program:
18 *	./h_nullmnt $TOPDIR/realdir/afile $TOPDIR/nulldir/afile
19 *
20 * The expected result is that the write() to the nullfile will
21 * queue up a preexisting kevent which will then be detected by
22 * the (second) call to kevent(); the failure mode is that the
23 * write()'s extension to the file is not seen, and the kevent
24 * call times out after 5 seconds.
25 *
26 * Clean-up code should undo the null mount and delete everything
27 * in the test directory.
28 */
29
30int main(int argc, char **argv)
31{
32	int realfile, nullfile;
33	int kq, nev, rsize;
34	struct timespec timeout;
35	struct kevent eventlist;
36	const char outbuf[] = "new\n";
37	char inbuf[20];
38
39	if (argc <= 2)
40		errx(EXIT_FAILURE, "insufficient args %d", argc);
41
42	realfile = open(argv[1], O_RDONLY);
43	if (realfile == -1)
44		err(EXIT_FAILURE, "failed to open realfile %s",
45		    argv[1]);
46
47	nullfile = open(argv[2], O_WRONLY, O_APPEND);
48	if (nullfile == -1)
49		err(EXIT_FAILURE, "failed to open nullfile %s",
50		    argv[2]);
51
52	if ((kq = kqueue()) == -1)
53		err(EXIT_FAILURE, "Cannot create kqueue");
54
55	timeout.tv_sec = 5;
56	timeout.tv_nsec = 0;
57
58	EV_SET(&eventlist, realfile,
59	    EVFILT_VNODE, EV_ADD | EV_ENABLE | EV_CLEAR,
60	    NOTE_WRITE | NOTE_EXTEND, 0, 0);
61	if (kevent(kq, &eventlist, 1, NULL, 0, NULL) == -1)
62		err(EXIT_FAILURE, "Failed to set eventlist for fd %d",
63		    realfile);
64
65	rsize = read(realfile, &inbuf, sizeof(inbuf));
66	if (rsize)
67		errx(EXIT_FAILURE, "Ooops we got %d bytes of data!\n", rsize);
68
69	write(nullfile, &outbuf, sizeof(outbuf) - 1);
70
71	nev = kevent(kq, NULL, 0, &eventlist, 1, &timeout);
72	if (nev == -1)
73		err(EXIT_FAILURE, "Failed to retrieve event");
74
75	errx((nev == 0) ? EXIT_FAILURE : EXIT_SUCCESS,
76	    "Retrieved %d events, first 0x%x", nev, eventlist.flags);
77}
78