1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (c) 2020 Francis Laniel. All rights reserved.
4 * Author: Francis Laniel <laniel_francis@privacyrequired.com>
5 *
6 * Test Description:
7 * This Program tests getting and setting the pipe size.
8 * It also tests what happen when you write to a full pipe depending on whether
9 * O_NONBLOCK is set or not.
10 */
11 #define _GNU_SOURCE
12 #include <stdlib.h>
13 #include <features.h>
14 #include <unistd.h>
15 #include <stdio.h>
16 #include "lapi/fcntl.h"
17 #include "tst_test.h"
18
19 static int fds[2];
20 static int flags;
21
test_pipe2(void)22 static void test_pipe2(void)
23 {
24 int ret;
25 pid_t pid;
26
27 /*
28 * This ensures parent process is still in non-block mode when
29 * using -i parameter. Subquent writes hould return -1 and errno
30 * set to either EAGAIN or EWOULDBLOCK because pipe is already full.
31 */
32 SAFE_FCNTL(fds[1], F_SETFL, flags | O_NONBLOCK);
33 ret = write(fds[1], "x", 1);
34 if (ret == -1) {
35 if (errno == EAGAIN)
36 tst_res(TPASS | TERRNO, "write failed as expected");
37 else
38 tst_brk(TFAIL | TERRNO, "write failed expected EAGAIN but got");
39 } else {
40 tst_res(TFAIL, "write() succeeded unexpectedly");
41 }
42
43 pid = SAFE_FORK();
44 if (!pid) {
45 SAFE_FCNTL(fds[1], F_SETFL, flags & ~O_NONBLOCK);
46 SAFE_WRITE(1, fds[1], "x", 1);
47 }
48
49 if (TST_PROCESS_STATE_WAIT(pid, 'S', 1000) < 0)
50 tst_res(TFAIL, "Child process is not blocked");
51 else
52 tst_res(TPASS, "Child process is blocked");
53
54 SAFE_KILL(pid, SIGKILL);
55 SAFE_WAIT(NULL);
56 }
57
setup(void)58 static void setup(void)
59 {
60 int page_size, pipe_size;
61 char *write_buffer;
62
63 SAFE_PIPE2(fds, O_NONBLOCK);
64 page_size = SAFE_SYSCONF(_SC_PAGESIZE);
65
66 flags = SAFE_FCNTL(fds[1], F_GETFL);
67 if (!(flags & O_NONBLOCK))
68 tst_brk(TCONF, "O_NONBLOCK flag must be set");
69 /*
70 * A pipe has two file descriptors.
71 * But in the kernel these two file descriptors point to the same pipe.
72 * So setting size from first file handle set size for the pipe.
73 */
74 SAFE_FCNTL(fds[0], F_SETPIPE_SZ, 0);
75
76 /*
77 * So getting size from the second file descriptor return the size of
78 * the pipe which was changed before with first file descriptor.
79 */
80 pipe_size = SAFE_FCNTL(fds[1], F_GETPIPE_SZ);
81 if (pipe_size != page_size)
82 tst_res(TFAIL, "Pipe size (%d) must be page size (%d)",
83 pipe_size, page_size);
84
85 write_buffer = SAFE_MALLOC(pipe_size);
86 memset(write_buffer, 'x', pipe_size);
87 SAFE_WRITE(1, fds[1], write_buffer, pipe_size);
88 free(write_buffer);
89 }
90
cleanup(void)91 static void cleanup(void)
92 {
93 if (fds[0] > 0)
94 SAFE_CLOSE(fds[0]);
95 if (fds[1] > 0)
96 SAFE_CLOSE(fds[1]);
97 }
98
99 static struct tst_test test = {
100 .min_kver = "2.6.35",
101 .test_all = test_pipe2,
102 .setup = setup,
103 .cleanup = cleanup,
104 .forks_child = 1,
105 };
106