projects/linux·blob master · refs

148 lines · 3.5 KiB

1/*
2 * Copyright © 2018 Alexey Dobriyan <[email protected]>
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}