149 lines
3.5 KiB
C
149 lines
3.5 KiB
C
/*
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* Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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// Test
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// 1) read and lseek on every file in /proc
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// 2) readlink of every symlink in /proc
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// 3) recursively (1) + (2) for every directory in /proc
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// 4) write to /proc/*/clear_refs and /proc/*/task/*/clear_refs
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// 5) write to /proc/sysrq-trigger
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#undef NDEBUG
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#include <assert.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <dirent.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/vfs.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "proc.h"
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static void f_reg(DIR *d, const char *filename)
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{
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char buf[4096];
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int fd;
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ssize_t rv;
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/* read from /proc/kmsg can block */
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fd = openat(dirfd(d), filename, O_RDONLY|O_NONBLOCK);
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if (fd == -1)
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return;
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/* struct proc_ops::proc_lseek is mandatory if file is seekable. */
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(void)lseek(fd, 0, SEEK_SET);
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rv = read(fd, buf, sizeof(buf));
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assert((0 <= rv && rv <= sizeof(buf)) || rv == -1);
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close(fd);
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}
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static void f_reg_write(DIR *d, const char *filename, const char *buf, size_t len)
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{
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int fd;
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ssize_t rv;
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fd = openat(dirfd(d), filename, O_WRONLY);
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if (fd == -1)
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return;
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rv = write(fd, buf, len);
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assert((0 <= rv && rv <= len) || rv == -1);
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close(fd);
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}
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static void f_lnk(DIR *d, const char *filename)
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{
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char buf[4096];
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ssize_t rv;
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rv = readlinkat(dirfd(d), filename, buf, sizeof(buf));
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assert((0 <= rv && rv <= sizeof(buf)) || rv == -1);
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}
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static void f(DIR *d, unsigned int level)
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{
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struct dirent *de;
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de = xreaddir(d);
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assert(de->d_type == DT_DIR);
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assert(streq(de->d_name, "."));
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de = xreaddir(d);
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assert(de->d_type == DT_DIR);
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assert(streq(de->d_name, ".."));
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while ((de = xreaddir(d))) {
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assert(!streq(de->d_name, "."));
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assert(!streq(de->d_name, ".."));
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switch (de->d_type) {
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DIR *dd;
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int fd;
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case DT_REG:
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if (level == 0 && streq(de->d_name, "sysrq-trigger")) {
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f_reg_write(d, de->d_name, "h", 1);
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} else if (level == 1 && streq(de->d_name, "clear_refs")) {
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f_reg_write(d, de->d_name, "1", 1);
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} else if (level == 3 && streq(de->d_name, "clear_refs")) {
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f_reg_write(d, de->d_name, "1", 1);
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} else {
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f_reg(d, de->d_name);
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}
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break;
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case DT_DIR:
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fd = openat(dirfd(d), de->d_name, O_DIRECTORY|O_RDONLY);
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if (fd == -1)
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continue;
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dd = fdopendir(fd);
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if (!dd)
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continue;
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f(dd, level + 1);
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closedir(dd);
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break;
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case DT_LNK:
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f_lnk(d, de->d_name);
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break;
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default:
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assert(0);
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}
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}
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}
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int main(void)
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{
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DIR *d;
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struct statfs sfs;
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d = opendir("/proc");
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if (!d)
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return 4;
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/* Ensure /proc is proc. */
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if (fstatfs(dirfd(d), &sfs) == -1) {
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return 1;
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}
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if (sfs.f_type != 0x9fa0) {
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fprintf(stderr, "error: unexpected f_type %lx\n", (long)sfs.f_type);
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return 2;
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}
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f(d, 0);
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return 0;
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}
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