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t_fifo.c revision 1.5 
      1 /* $NetBSD: t_fifo.c,v 1.5 2021/10/02 18:39:15 thorpej Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2021 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jason R. Thorpe.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __COPYRIGHT("@(#) Copyright (c) 2021\
     34  The NetBSD Foundation, inc. All rights reserved.");
     35 __RCSID("$NetBSD: t_fifo.c,v 1.5 2021/10/02 18:39:15 thorpej Exp $");
     36 
     37 #include <sys/event.h>
     38 #include <sys/stat.h>
     39 
     40 #include <errno.h>
     41 #include <fcntl.h>
     42 #include <stdio.h>
     43 #include <stdlib.h>
     44 #include <string.h>
     45 #include <unistd.h>
     46 #include <inttypes.h>
     47 
     48 #include <atf-c.h>
     49 
     50 static const char	fifo_path[] = "fifo";
     51 
     52 static void
     53 fifo_support(void)
     54 {
     55 	errno = 0;
     56 	if (mkfifo(fifo_path, 0600) == 0) {
     57 		ATF_REQUIRE(unlink(fifo_path) == 0);
     58 		return;
     59 	}
     60 
     61 	if (errno == EOPNOTSUPP) {
     62 		atf_tc_skip("the kernel does not support FIFOs");
     63 	} else {
     64 		atf_tc_fail("mkfifo(2) failed");
     65 	}
     66 }
     67 
     68 ATF_TC_WITH_CLEANUP(fifo);
     69 ATF_TC_HEAD(fifo, tc)
     70 {
     71 	atf_tc_set_md_var(tc, "descr", "Checks EVFILT_WRITE on fifo");
     72 }
     73 ATF_TC_BODY(fifo, tc)
     74 {
     75 	const struct timespec to = { 0, 0 };
     76 	struct kevent event[1];
     77 	char *buf;
     78 	int rfd, wfd, kq;
     79 	long pipe_buf;
     80 
     81 	fifo_support();
     82 
     83 	ATF_REQUIRE(mkfifo(fifo_path, 0600) == 0);
     84 	ATF_REQUIRE((rfd = open(fifo_path, O_RDONLY | O_NONBLOCK)) >= 0);
     85 	ATF_REQUIRE((wfd = open(fifo_path, O_WRONLY | O_NONBLOCK)) >= 0);
     86 	ATF_REQUIRE((kq = kqueue()) >= 0);
     87 
     88 	/* Get the maximum atomic pipe write size. */
     89 	pipe_buf = fpathconf(wfd, _PC_PIPE_BUF);
     90 	ATF_REQUIRE(pipe_buf > 1);
     91 
     92 	buf = malloc(pipe_buf);
     93 	ATF_REQUIRE(buf != NULL);
     94 
     95 	EV_SET(&event[0], wfd, EVFILT_WRITE, EV_ADD|EV_ENABLE, 0, 0, 0);
     96 	ATF_REQUIRE(kevent(kq, event, 1, NULL, 0, NULL) == 0);
     97 
     98 	/* We expect the FIFO to be writable. */
     99 	ATF_REQUIRE(kevent(kq, NULL, 0, event, 1, &to) == 1);
    100 	ATF_REQUIRE(event[0].ident == (uintptr_t)wfd);
    101 	ATF_REQUIRE(event[0].filter == EVFILT_WRITE);
    102 
    103 	/*
    104 	 * Write data into the FIFO until it is full, which is
    105 	 * defined as insufficient buffer space to hold the
    106 	 * maximum atomic pipe write size.
    107 	 */
    108 	while (write(wfd, buf, pipe_buf) != -1) {
    109 		continue;
    110 	}
    111 	ATF_REQUIRE(errno == EAGAIN);
    112 
    113 	/* We expect the FIFO to no longer be writable. */
    114 	ATF_REQUIRE(kevent(kq, NULL, 0, event, 1, &to) == 0);
    115 
    116 	/* Read a single byte of data from the FIFO. */
    117 	ATF_REQUIRE(read(rfd, buf, 1) == 1);
    118 
    119 	/*
    120 	 * Because we have read only a single byte out, there will
    121 	 * be insufficient space for a pipe_buf-sized message, so
    122 	 * the FIFO should still not be writable.
    123 	 */
    124 	ATF_REQUIRE(kevent(kq, NULL, 0, event, 1, &to) == 0);
    125 
    126 	/*
    127 	 * Now read enough so that exactly pipe_buf space should be
    128 	 * available.  The FIFO should be writable after that.
    129 	 */
    130 	ATF_REQUIRE(read(rfd, buf, pipe_buf - 1) == pipe_buf - 1);
    131 	ATF_REQUIRE(kevent(kq, NULL, 0, event, 1, &to) == 1);
    132 	ATF_REQUIRE(event[0].ident == (uintptr_t)wfd);
    133 	ATF_REQUIRE(event[0].filter == EVFILT_WRITE);
    134 
    135 	(void)close(wfd);
    136 	(void)close(rfd);
    137 	(void)close(kq);
    138 }
    139 
    140 ATF_TC_CLEANUP(fifo, tc)
    141 {
    142 	(void)unlink(fifo_path);
    143 }
    144 
    145 ATF_TP_ADD_TCS(tp)
    146 {
    147 	ATF_TP_ADD_TC(tp, fifo);
    148 
    149 	return atf_no_error();
    150 }
    151