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}