105c3f292SAlexey Dobriyan /*
2ee9294d6SAlexey Dobriyan * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
305c3f292SAlexey Dobriyan *
405c3f292SAlexey Dobriyan * Permission to use, copy, modify, and distribute this software for any
505c3f292SAlexey Dobriyan * purpose with or without fee is hereby granted, provided that the above
605c3f292SAlexey Dobriyan * copyright notice and this permission notice appear in all copies.
705c3f292SAlexey Dobriyan *
805c3f292SAlexey Dobriyan * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
905c3f292SAlexey Dobriyan * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
1005c3f292SAlexey Dobriyan * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
1105c3f292SAlexey Dobriyan * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
1205c3f292SAlexey Dobriyan * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
1305c3f292SAlexey Dobriyan * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
1405c3f292SAlexey Dobriyan * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
1505c3f292SAlexey Dobriyan */
1605c3f292SAlexey Dobriyan // Test
17*d4455facSAlexey Dobriyan // 1) read and lseek on every file in /proc
1805c3f292SAlexey Dobriyan // 2) readlink of every symlink in /proc
1905c3f292SAlexey Dobriyan // 3) recursively (1) + (2) for every directory in /proc
2005c3f292SAlexey Dobriyan // 4) write to /proc/*/clear_refs and /proc/*/task/*/clear_refs
2105c3f292SAlexey Dobriyan // 5) write to /proc/sysrq-trigger
2205c3f292SAlexey Dobriyan #undef NDEBUG
2305c3f292SAlexey Dobriyan #include <assert.h>
2405c3f292SAlexey Dobriyan #include <errno.h>
2505c3f292SAlexey Dobriyan #include <sys/types.h>
2605c3f292SAlexey Dobriyan #include <dirent.h>
2705c3f292SAlexey Dobriyan #include <stdbool.h>
2805c3f292SAlexey Dobriyan #include <stdlib.h>
29332e0e80SAlexey Dobriyan #include <stdio.h>
3005c3f292SAlexey Dobriyan #include <string.h>
3105c3f292SAlexey Dobriyan #include <sys/stat.h>
32332e0e80SAlexey Dobriyan #include <sys/vfs.h>
3305c3f292SAlexey Dobriyan #include <fcntl.h>
3405c3f292SAlexey Dobriyan #include <unistd.h>
3505c3f292SAlexey Dobriyan
36b2f5de03SAlexey Dobriyan #include "proc.h"
3705c3f292SAlexey Dobriyan
f_reg(DIR * d,const char * filename)3805c3f292SAlexey Dobriyan static void f_reg(DIR *d, const char *filename)
3905c3f292SAlexey Dobriyan {
4005c3f292SAlexey Dobriyan char buf[4096];
4105c3f292SAlexey Dobriyan int fd;
4205c3f292SAlexey Dobriyan ssize_t rv;
4305c3f292SAlexey Dobriyan
4405c3f292SAlexey Dobriyan /* read from /proc/kmsg can block */
4505c3f292SAlexey Dobriyan fd = openat(dirfd(d), filename, O_RDONLY|O_NONBLOCK);
4605c3f292SAlexey Dobriyan if (fd == -1)
4705c3f292SAlexey Dobriyan return;
48*d4455facSAlexey Dobriyan /* struct proc_ops::proc_lseek is mandatory if file is seekable. */
49*d4455facSAlexey Dobriyan (void)lseek(fd, 0, SEEK_SET);
5005c3f292SAlexey Dobriyan rv = read(fd, buf, sizeof(buf));
5105c3f292SAlexey Dobriyan assert((0 <= rv && rv <= sizeof(buf)) || rv == -1);
5205c3f292SAlexey Dobriyan close(fd);
5305c3f292SAlexey Dobriyan }
5405c3f292SAlexey Dobriyan
f_reg_write(DIR * d,const char * filename,const char * buf,size_t len)5505c3f292SAlexey Dobriyan static void f_reg_write(DIR *d, const char *filename, const char *buf, size_t len)
5605c3f292SAlexey Dobriyan {
5705c3f292SAlexey Dobriyan int fd;
5805c3f292SAlexey Dobriyan ssize_t rv;
5905c3f292SAlexey Dobriyan
6005c3f292SAlexey Dobriyan fd = openat(dirfd(d), filename, O_WRONLY);
6105c3f292SAlexey Dobriyan if (fd == -1)
6205c3f292SAlexey Dobriyan return;
6305c3f292SAlexey Dobriyan rv = write(fd, buf, len);
6405c3f292SAlexey Dobriyan assert((0 <= rv && rv <= len) || rv == -1);
6505c3f292SAlexey Dobriyan close(fd);
6605c3f292SAlexey Dobriyan }
6705c3f292SAlexey Dobriyan
f_lnk(DIR * d,const char * filename)6805c3f292SAlexey Dobriyan static void f_lnk(DIR *d, const char *filename)
6905c3f292SAlexey Dobriyan {
7005c3f292SAlexey Dobriyan char buf[4096];
7105c3f292SAlexey Dobriyan ssize_t rv;
7205c3f292SAlexey Dobriyan
7305c3f292SAlexey Dobriyan rv = readlinkat(dirfd(d), filename, buf, sizeof(buf));
7405c3f292SAlexey Dobriyan assert((0 <= rv && rv <= sizeof(buf)) || rv == -1);
7505c3f292SAlexey Dobriyan }
7605c3f292SAlexey Dobriyan
f(DIR * d,unsigned int level)7705c3f292SAlexey Dobriyan static void f(DIR *d, unsigned int level)
7805c3f292SAlexey Dobriyan {
7905c3f292SAlexey Dobriyan struct dirent *de;
8005c3f292SAlexey Dobriyan
8105c3f292SAlexey Dobriyan de = xreaddir(d);
8205c3f292SAlexey Dobriyan assert(de->d_type == DT_DIR);
8305c3f292SAlexey Dobriyan assert(streq(de->d_name, "."));
8405c3f292SAlexey Dobriyan
8505c3f292SAlexey Dobriyan de = xreaddir(d);
8605c3f292SAlexey Dobriyan assert(de->d_type == DT_DIR);
8705c3f292SAlexey Dobriyan assert(streq(de->d_name, ".."));
8805c3f292SAlexey Dobriyan
8905c3f292SAlexey Dobriyan while ((de = xreaddir(d))) {
9005c3f292SAlexey Dobriyan assert(!streq(de->d_name, "."));
9105c3f292SAlexey Dobriyan assert(!streq(de->d_name, ".."));
9205c3f292SAlexey Dobriyan
9305c3f292SAlexey Dobriyan switch (de->d_type) {
9405c3f292SAlexey Dobriyan DIR *dd;
9505c3f292SAlexey Dobriyan int fd;
9605c3f292SAlexey Dobriyan
9705c3f292SAlexey Dobriyan case DT_REG:
9805c3f292SAlexey Dobriyan if (level == 0 && streq(de->d_name, "sysrq-trigger")) {
9905c3f292SAlexey Dobriyan f_reg_write(d, de->d_name, "h", 1);
10005c3f292SAlexey Dobriyan } else if (level == 1 && streq(de->d_name, "clear_refs")) {
10105c3f292SAlexey Dobriyan f_reg_write(d, de->d_name, "1", 1);
10205c3f292SAlexey Dobriyan } else if (level == 3 && streq(de->d_name, "clear_refs")) {
10305c3f292SAlexey Dobriyan f_reg_write(d, de->d_name, "1", 1);
10405c3f292SAlexey Dobriyan } else {
10505c3f292SAlexey Dobriyan f_reg(d, de->d_name);
10605c3f292SAlexey Dobriyan }
10705c3f292SAlexey Dobriyan break;
10805c3f292SAlexey Dobriyan case DT_DIR:
10905c3f292SAlexey Dobriyan fd = openat(dirfd(d), de->d_name, O_DIRECTORY|O_RDONLY);
11005c3f292SAlexey Dobriyan if (fd == -1)
11105c3f292SAlexey Dobriyan continue;
11205c3f292SAlexey Dobriyan dd = fdopendir(fd);
11305c3f292SAlexey Dobriyan if (!dd)
11405c3f292SAlexey Dobriyan continue;
11505c3f292SAlexey Dobriyan f(dd, level + 1);
11605c3f292SAlexey Dobriyan closedir(dd);
11705c3f292SAlexey Dobriyan break;
11805c3f292SAlexey Dobriyan case DT_LNK:
11905c3f292SAlexey Dobriyan f_lnk(d, de->d_name);
12005c3f292SAlexey Dobriyan break;
12105c3f292SAlexey Dobriyan default:
12205c3f292SAlexey Dobriyan assert(0);
12305c3f292SAlexey Dobriyan }
12405c3f292SAlexey Dobriyan }
12505c3f292SAlexey Dobriyan }
12605c3f292SAlexey Dobriyan
main(void)12705c3f292SAlexey Dobriyan int main(void)
12805c3f292SAlexey Dobriyan {
12905c3f292SAlexey Dobriyan DIR *d;
130332e0e80SAlexey Dobriyan struct statfs sfs;
13105c3f292SAlexey Dobriyan
13205c3f292SAlexey Dobriyan d = opendir("/proc");
13305c3f292SAlexey Dobriyan if (!d)
1340338c838SAlexey Dobriyan return 4;
135332e0e80SAlexey Dobriyan
136332e0e80SAlexey Dobriyan /* Ensure /proc is proc. */
137332e0e80SAlexey Dobriyan if (fstatfs(dirfd(d), &sfs) == -1) {
138332e0e80SAlexey Dobriyan return 1;
139332e0e80SAlexey Dobriyan }
140332e0e80SAlexey Dobriyan if (sfs.f_type != 0x9fa0) {
141332e0e80SAlexey Dobriyan fprintf(stderr, "error: unexpected f_type %lx\n", (long)sfs.f_type);
142332e0e80SAlexey Dobriyan return 2;
143332e0e80SAlexey Dobriyan }
144332e0e80SAlexey Dobriyan
14505c3f292SAlexey Dobriyan f(d, 0);
146332e0e80SAlexey Dobriyan
14705c3f292SAlexey Dobriyan return 0;
14805c3f292SAlexey Dobriyan }
149