1 /* $OpenBSD: test-ping-pong.c,v 1.2 2021/10/22 05:03:57 anton Exp $ */
2
3 /*
4 * Copyright (c) 2019 Anton Lindqvist <anton@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <err.h>
20 #include <errno.h>
21 #include <stdlib.h>
22 #include <string.h>
23 #include <unistd.h>
24
25 #include "pipe.h"
26
27 /*
28 * Basic read/write test invovling two processes, P1 and P2. P1 writes "ping" on
29 * the pipe which is received and verified by P2. P2 writes "pong" as a reply
30 * which is received and verified P1. After N rounds, P1 closes the pipe and
31 * SIGPIPE is expected to be delivered to P2.
32 */
33 int
test_ping_pong(void)34 test_ping_pong(void)
35 {
36 const char ping[] = "ping";
37 const char pong[] = "pong";
38 char buf[5];
39 int pip[2][2], rp, wp;
40 int nrounds = 10;
41 ssize_t n;
42 pid_t pid;
43
44 if (pipe(pip[0]) == -1)
45 err(1, "pipe");
46 if (pipe(pip[1]) == -1)
47 err(1, "pipe");
48
49 pid = fork();
50 if (pid == -1)
51 err(1, "fork");
52 if (pid == 0) {
53 rp = pip[0][0];
54 close(pip[0][1]);
55
56 wp = pip[1][1];
57 close(pip[1][0]);
58
59 for (;;) {
60 n = read(rp, buf, sizeof(buf));
61 if (n == -1)
62 err(1, "[c] read");
63 if (n == 0)
64 break;
65 if (n != sizeof(buf))
66 errx(1, "[c] read: %ld < %zu", n, sizeof(buf));
67 if (strcmp(ping, buf))
68 errx(1, "[c] read: %s != %s\n", ping, buf);
69
70 n = write(wp, pong, sizeof(pong));
71 if (n == -1)
72 err(1, "[c] write");
73 if (n != sizeof(pong))
74 errx(1, "[c] write: %ld < %zu",
75 n, sizeof(pong));
76
77 nrounds--;
78 }
79 if (nrounds != 0)
80 errx(1, "[c] nrounds: %d > 0", nrounds);
81
82 /*
83 * Writing on the pipe must cause delivery of SIGPIPE at this
84 * point since the read end is gone.
85 */
86 n = write(wp, pong, sizeof(pong));
87 if (n != -1)
88 errx(1, "[c] write: %ld != -1", n);
89 else if (errno != EPIPE)
90 errx(1, "[c] write: %d != %d", errno, EPIPE);
91 else if (!gotsigpipe)
92 errx(1, "[c] write: no SIGPIPE");
93
94 _exit(0);
95 } else {
96 rp = pip[1][0];
97 close(pip[1][1]);
98
99 wp = pip[0][1];
100 close(pip[0][0]);
101
102 for (;;) {
103 n = write(wp, ping, sizeof(ping));
104 if (n == -1)
105 err(1, "[p] write");
106 if (n != sizeof(ping))
107 errx(1, "[p] write: %ld < %zu",
108 n, sizeof(ping));
109
110 n = read(rp, buf, sizeof(buf));
111 if (n == -1)
112 err(1, "[p] read");
113 if (n != sizeof(buf))
114 errx(1, "[p] read: %ld < %zu", n, sizeof(buf));
115 if (strcmp(pong, buf))
116 errx(1, "[p] read: %s != %s\n", pong, buf);
117
118 if (--nrounds == 0)
119 break;
120 }
121
122 /* Signal shutdown to the child. */
123 close(rp);
124 close(wp);
125
126 return xwaitpid(pid);
127 }
128
129 return 0;
130 }
131