1/*
2 * Copyright �� 2018 Alexey Dobriyan <adobriyan@gmail.com>
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16// Test
17// 1) read and lseek on every file in /proc
18// 2) readlink of every symlink in /proc
19// 3) recursively (1) + (2) for every directory in /proc
20// 4) write to /proc/*/clear_refs and /proc/*/task/*/clear_refs
21// 5) write to /proc/sysrq-trigger
22#undef NDEBUG
23#include <assert.h>
24#include <errno.h>
25#include <sys/types.h>
26#include <dirent.h>
27#include <stdbool.h>
28#include <stdlib.h>
29#include <stdio.h>
30#include <string.h>
31#include <sys/stat.h>
32#include <sys/vfs.h>
33#include <fcntl.h>
34#include <unistd.h>
35
36#include "proc.h"
37
38static void f_reg(DIR *d, const char *filename)
39{
40	char buf[4096];
41	int fd;
42	ssize_t rv;
43
44	/* read from /proc/kmsg can block */
45	fd = openat(dirfd(d), filename, O_RDONLY|O_NONBLOCK);
46	if (fd == -1)
47		return;
48	/* struct proc_ops::proc_lseek is mandatory if file is seekable. */
49	(void)lseek(fd, 0, SEEK_SET);
50	rv = read(fd, buf, sizeof(buf));
51	assert((0 <= rv && rv <= sizeof(buf)) || rv == -1);
52	close(fd);
53}
54
55static void f_reg_write(DIR *d, const char *filename, const char *buf, size_t len)
56{
57	int fd;
58	ssize_t rv;
59
60	fd = openat(dirfd(d), filename, O_WRONLY);
61	if (fd == -1)
62		return;
63	rv = write(fd, buf, len);
64	assert((0 <= rv && rv <= len) || rv == -1);
65	close(fd);
66}
67
68static void f_lnk(DIR *d, const char *filename)
69{
70	char buf[4096];
71	ssize_t rv;
72
73	rv = readlinkat(dirfd(d), filename, buf, sizeof(buf));
74	assert((0 <= rv && rv <= sizeof(buf)) || rv == -1);
75}
76
77static void f(DIR *d, unsigned int level)
78{
79	struct dirent *de;
80
81	de = xreaddir(d);
82	assert(de->d_type == DT_DIR);
83	assert(streq(de->d_name, "."));
84
85	de = xreaddir(d);
86	assert(de->d_type == DT_DIR);
87	assert(streq(de->d_name, ".."));
88
89	while ((de = xreaddir(d))) {
90		assert(!streq(de->d_name, "."));
91		assert(!streq(de->d_name, ".."));
92
93		switch (de->d_type) {
94			DIR *dd;
95			int fd;
96
97		case DT_REG:
98			if (level == 0 && streq(de->d_name, "sysrq-trigger")) {
99				f_reg_write(d, de->d_name, "h", 1);
100			} else if (level == 1 && streq(de->d_name, "clear_refs")) {
101				f_reg_write(d, de->d_name, "1", 1);
102			} else if (level == 3 && streq(de->d_name, "clear_refs")) {
103				f_reg_write(d, de->d_name, "1", 1);
104			} else {
105				f_reg(d, de->d_name);
106			}
107			break;
108		case DT_DIR:
109			fd = openat(dirfd(d), de->d_name, O_DIRECTORY|O_RDONLY);
110			if (fd == -1)
111				continue;
112			dd = fdopendir(fd);
113			if (!dd)
114				continue;
115			f(dd, level + 1);
116			closedir(dd);
117			break;
118		case DT_LNK:
119			f_lnk(d, de->d_name);
120			break;
121		default:
122			assert(0);
123		}
124	}
125}
126
127int main(void)
128{
129	DIR *d;
130	struct statfs sfs;
131
132	d = opendir("/proc");
133	if (!d)
134		return 4;
135
136	/* Ensure /proc is proc. */
137	if (fstatfs(dirfd(d), &sfs) == -1) {
138		return 1;
139	}
140	if (sfs.f_type != 0x9fa0) {
141		fprintf(stderr, "error: unexpected f_type %lx\n", (long)sfs.f_type);
142		return 2;
143	}
144
145	f(d, 0);
146
147	return 0;
148}
149