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
19static int fds[2];
20static int flags;
21
22static 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(SAFE_WRITE_ALL, 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
58static 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(SAFE_WRITE_ALL, fds[1], write_buffer, pipe_size);
88	free(write_buffer);
89}
90
91static 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
99static struct tst_test test = {
100	.test_all = test_pipe2,
101	.setup = setup,
102	.cleanup = cleanup,
103	.forks_child = 1,
104};
105