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- /*
- * Copyright 2011, The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- #include <unistd.h>
- #include <sys/reboot.h>
- #include <sys/types.h>
- #include <sys/stat.h>
- #include <fcntl.h>
- #include <stdio.h>
- #include <string.h>
- #include <cutils/android_reboot.h>
- /* Check to see if /proc/mounts contains any writeable filesystems
- * backed by a block device.
- * Return true if none found, else return false.
- */
- static int remount_ro_done(void)
- {
- FILE *f;
- char mount_dev[256];
- char mount_dir[256];
- char mount_type[256];
- char mount_opts[256];
- int mount_freq;
- int mount_passno;
- int match;
- int found_rw_fs = 0;
- f = fopen("/proc/mounts", "r");
- if (! f) {
- /* If we can't read /proc/mounts, just give up */
- return 1;
- }
- do {
- match = fscanf(f, "%255s %255s %255s %255s %d %d\n",
- mount_dev, mount_dir, mount_type,
- mount_opts, &mount_freq, &mount_passno);
- mount_dev[255] = 0;
- mount_dir[255] = 0;
- mount_type[255] = 0;
- mount_opts[255] = 0;
- if ((match == 6) && !strncmp(mount_dev, "/dev/block", 10) && strstr(mount_opts, "rw")) {
- found_rw_fs = 1;
- break;
- }
- } while (match != EOF);
- fclose(f);
- return !found_rw_fs;
- }
- /* Remounting filesystems read-only is difficult when there are files
- * opened for writing or pending deletes on the filesystem. There is
- * no way to force the remount with the mount(2) syscall. The magic sysrq
- * 'u' command does an emergency remount read-only on all writable filesystems
- * that have a block device (i.e. not tmpfs filesystems) by calling
- * emergency_remount(), which knows how to force the remount to read-only.
- * Unfortunately, that is asynchronous, and just schedules the work and
- * returns. The best way to determine if it is done is to read /proc/mounts
- * repeatedly until there are no more writable filesystems mounted on
- * block devices.
- */
- static void remount_ro(void)
- {
- int fd, cnt = 0;
- /* Trigger the remount of the filesystems as read-only,
- * which also marks them clean.
- */
- fd = open("/proc/sysrq-trigger", O_WRONLY);
- if (fd < 0) {
- return;
- }
- write(fd, "u", 1);
- close(fd);
- /* Now poll /proc/mounts till it's done */
- while (!remount_ro_done() && (cnt < 50)) {
- usleep(100000);
- cnt++;
- }
- return;
- }
- extern int write_misc(char *reason);
- int android_reboot(int cmd, int flags, char *arg)
- {
- int ret;
- if (!(flags & ANDROID_RB_FLAG_NO_SYNC))
- sync();
- if (!(flags & ANDROID_RB_FLAG_NO_REMOUNT_RO))
- remount_ro();
- switch (cmd) {
- case ANDROID_RB_RESTART:
- ret = reboot(RB_AUTOBOOT);
- break;
- case ANDROID_RB_POWEROFF:
- ret = reboot(RB_POWER_OFF);
- break;
- case ANDROID_RB_RESTART2:
- //ret = __reboot(LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
- // LINUX_REBOOT_CMD_RESTART2, arg);
- write_misc(arg);
- ret = reboot(RB_AUTOBOOT);
- break;
- default:
- ret = -1;
- }
- return ret;
- }
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