1 /*
2 * Copyright (c) International Business Machines Corp., 2001
3 * 07/2001 Ported by Wayne Boyer
4 * Copyright (c) 2018 Cyril Hrubis <chrubis@suse.cz>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
14 * the GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /*
22 * Check if many children can read what is written to a pipe by the parent.
23 *
24 * ALGORITHM
25 * For a different nchilds number:
26 * 1. Open a pipe and write nchilds * (PIPE_BUF/nchilds) bytes into it
27 * 2. Fork nchilds children
28 * 3. Each child reads PIPE_BUF/nchilds characters and checks that the
29 * bytes read are correct
30 */
31 #include <stdlib.h>
32 #include "tst_test.h"
33
34 static int fds[2];
35 static unsigned char buf[PIPE_BUF];
36 static size_t read_per_child;
37
do_child(void)38 void do_child(void)
39 {
40 size_t nread;
41 unsigned char rbuf[read_per_child];
42 unsigned int i;
43
44 SAFE_CLOSE(fds[1]);
45
46 nread = SAFE_READ(0, fds[0], rbuf, sizeof(rbuf));
47
48 if (nread != read_per_child) {
49 tst_res(TFAIL, "Invalid read size child %i size %zu",
50 getpid(), nread);
51 return;
52 }
53
54 for (i = 0; i < read_per_child; i++) {
55 if (rbuf[i] != (i % 256)) {
56 tst_res(TFAIL,
57 "Invalid byte read child %i byte %i have %i expected %i",
58 getpid(), i, rbuf[i], i % 256);
59 return;
60 }
61 }
62
63 tst_res(TPASS, "Child %i read pipe buffer correctly", getpid());
64 }
65
66 static unsigned int childs[] = {
67 1,
68 2,
69 3,
70 4,
71 10,
72 50
73 };
74
run(unsigned int tcase)75 static void run(unsigned int tcase)
76 {
77 pid_t pid;
78 unsigned int nchilds = childs[tcase];
79 read_per_child = PIPE_BUF/nchilds;
80 unsigned int i, j;
81
82 tst_res(TINFO, "Reading %zu per each of %u children",
83 read_per_child, nchilds);
84
85 for (i = 0; i < nchilds; i++) {
86 for (j = 0; j < read_per_child; j++) {
87 buf[i * read_per_child + j] = j % 256;
88 }
89 }
90
91 SAFE_PIPE(fds);
92
93 SAFE_WRITE(1, fds[1], buf, read_per_child * nchilds);
94
95 for (i = 0; i < nchilds; i++) {
96 pid = SAFE_FORK();
97
98 if (!pid) {
99 do_child();
100 exit(0);
101 }
102 }
103
104 tst_reap_children();
105
106 SAFE_CLOSE(fds[0]);
107 SAFE_CLOSE(fds[1]);
108 }
109
110 static struct tst_test test = {
111 .forks_child = 1,
112 .test = run,
113 .tcnt = ARRAY_SIZE(childs),
114 };
115