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/*
* Copyright (C) 2016 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "system-shutdown-utils.h"
#include <errno.h> // errno, sys_errlist
#include <fcntl.h> // open
#include <linux/loop.h> // LOOP_CLR_FD
#include <linux/major.h>
#include <stdarg.h> // va_*
#include <stdio.h> // fprintf, stderr
#include <stdlib.h> // exit
#include <string.h> // strcmp, strncmp
#include <sys/ioctl.h> // ioctl
#include <sys/mount.h> // umount
#include <sys/reboot.h> // reboot, RB_*
#include <sys/stat.h> // mkdir
#include <unistd.h> // getpid, close
#include "../libsnap-confine-private/mountinfo.h"
#include "../libsnap-confine-private/string-utils.h"
#include "../libsnap-confine-private/utils.h"
__attribute__((format(printf, 1, 2))) void kmsg(const char *fmt, ...) {
static FILE *kmsg = NULL;
static char *head = NULL;
if (!kmsg) {
// TODO: figure out why writing to /dev/kmsg doesn't work from here
kmsg = stderr;
head = "snapd system-shutdown helper: ";
}
va_list va;
va_start(va, fmt);
fputs(head, kmsg);
vfprintf(kmsg, fmt, va);
fprintf(kmsg, "\n");
va_end(va);
}
int sc_read_reboot_arg(char *arg, size_t max_size) {
FILE *f;
// This file is used by systemd to pass around a reboot parameter See
// https://github.com/systemd/systemd/blob/v229/src/basic/def.h#L44
f = fopen("/run/systemd/reboot-param", "r");
if (!f) {
return -1;
}
if (!fgets(arg, max_size, f)) {
fclose(f);
return -1;
}
arg[strcspn(arg, "\n")] = '\0';
kmsg("reboot arg is %s", arg);
fclose(f);
return 0;
}
static void detach_loop(const char *src) {
int fd = open(src, O_RDONLY);
if (fd < 0) {
kmsg("* unable to open loop device %s: %s", src, strerror(errno));
} else {
if (ioctl(fd, LOOP_CLR_FD) < 0) {
kmsg("* unable to disassociate loop device %s: %s", src, strerror(errno));
}
close(fd);
}
}
// tries to umount all (well, most) things. Returns whether in the last pass it
// no longer found writable.
bool umount_all(void) {
bool did_umount = true;
bool had_writable = false;
for (int i = 0; i < 10 && did_umount; i++) {
sc_mountinfo *mounts = sc_parse_mountinfo(NULL);
if (!mounts) {
// oh dear
die("unable to get mount info; giving up");
}
sc_mountinfo_entry *cur = sc_first_mountinfo_entry(mounts);
had_writable = false;
did_umount = false;
while (cur) {
const char *dir = cur->mount_dir;
const char *src = cur->mount_source;
unsigned major = cur->dev_major;
cur = sc_next_mountinfo_entry(cur);
if (sc_streq("/", dir)) {
continue;
}
if (sc_streq("/dev", dir)) {
continue;
}
if (sc_streq("/proc", dir)) {
continue;
}
if (major != 0 && major != LOOP_MAJOR && sc_endswith(dir, "/writable")) {
had_writable = true;
}
if (umount(dir) == 0) {
if (major == LOOP_MAJOR) {
detach_loop(src);
}
did_umount = true;
}
}
sc_cleanup_mountinfo(&mounts);
}
return !had_writable;
}
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