272 lines
7.8 KiB
C
272 lines
7.8 KiB
C
/*
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* Copyright 2011, The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <mntent.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/cdefs.h>
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#include <sys/mount.h>
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#include <sys/reboot.h>
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#include <sys/stat.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <cutils/android_reboot.h>
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#include <cutils/klog.h>
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#include <cutils/list.h>
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#define TAG "android_reboot"
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#define READONLY_CHECK_MS 5000
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#define READONLY_CHECK_TIMES 50
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typedef struct {
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struct listnode list;
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struct mntent entry;
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} mntent_list;
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static bool is_block_device(const char* fsname)
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{
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return !strncmp(fsname, "/dev/block", 10);
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}
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/* Find all read+write block devices in /proc/mounts and add them to
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* |rw_entries|.
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*/
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static void find_rw(struct listnode* rw_entries)
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{
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FILE* fp;
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struct mntent* mentry;
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if ((fp = setmntent("/proc/mounts", "r")) == NULL) {
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KLOG_WARNING(TAG, "Failed to open /proc/mounts.\n");
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return;
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}
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while ((mentry = getmntent(fp)) != NULL) {
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if (is_block_device(mentry->mnt_fsname) && hasmntopt(mentry, "rw")) {
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mntent_list* item = (mntent_list*)calloc(1, sizeof(mntent_list));
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item->entry = *mentry;
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item->entry.mnt_fsname = strdup(mentry->mnt_fsname);
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item->entry.mnt_dir = strdup(mentry->mnt_dir);
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item->entry.mnt_type = strdup(mentry->mnt_type);
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item->entry.mnt_opts = strdup(mentry->mnt_opts);
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list_add_tail(rw_entries, &item->list);
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}
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}
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endmntent(fp);
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}
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static void free_entries(struct listnode* entries)
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{
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struct listnode* node;
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struct listnode* n;
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list_for_each_safe(node, n, entries) {
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mntent_list* item = node_to_item(node, mntent_list, list);
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free(item->entry.mnt_fsname);
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free(item->entry.mnt_dir);
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free(item->entry.mnt_type);
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free(item->entry.mnt_opts);
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free(item);
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}
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}
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static mntent_list* find_item(struct listnode* rw_entries, const char* fsname_to_find)
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{
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struct listnode* node;
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list_for_each(node, rw_entries) {
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mntent_list* item = node_to_item(node, mntent_list, list);
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if (!strcmp(item->entry.mnt_fsname, fsname_to_find)) {
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return item;
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}
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}
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return NULL;
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}
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/* Remounting filesystems read-only is difficult when there are files
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* opened for writing or pending deletes on the filesystem. There is
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* no way to force the remount with the mount(2) syscall. The magic sysrq
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* 'u' command does an emergency remount read-only on all writable filesystems
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* that have a block device (i.e. not tmpfs filesystems) by calling
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* emergency_remount(), which knows how to force the remount to read-only.
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* Unfortunately, that is asynchronous, and just schedules the work and
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* returns. The best way to determine if it is done is to read /proc/mounts
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* repeatedly until there are no more writable filesystems mounted on
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* block devices.
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*/
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static void remount_ro(void (*cb_on_remount)(const struct mntent*))
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{
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int fd, cnt;
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FILE* fp;
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struct mntent* mentry;
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struct listnode* node;
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list_declare(rw_entries);
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list_declare(ro_entries);
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sync();
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find_rw(&rw_entries);
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/* Trigger the remount of the filesystems as read-only,
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* which also marks them clean.
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*/
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fd = TEMP_FAILURE_RETRY(open("/proc/sysrq-trigger", O_WRONLY));
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if (fd < 0) {
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KLOG_WARNING(TAG, "Failed to open sysrq-trigger.\n");
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/* TODO: Try to remount each rw parition manually in readonly mode.
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* This may succeed if no process is using the partition.
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*/
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goto out;
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}
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if (TEMP_FAILURE_RETRY(write(fd, "u", 1)) != 1) {
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close(fd);
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KLOG_WARNING(TAG, "Failed to write to sysrq-trigger.\n");
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/* TODO: The same. Manually remount the paritions. */
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goto out;
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}
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close(fd);
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/* Now poll /proc/mounts till it's done */
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cnt = 0;
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while (cnt < READONLY_CHECK_TIMES) {
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if ((fp = setmntent("/proc/mounts", "r")) == NULL) {
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/* If we can't read /proc/mounts, just give up. */
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KLOG_WARNING(TAG, "Failed to open /proc/mounts.\n");
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goto out;
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}
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while ((mentry = getmntent(fp)) != NULL) {
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if (!is_block_device(mentry->mnt_fsname) || !hasmntopt(mentry, "ro")) {
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continue;
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}
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mntent_list* item = find_item(&rw_entries, mentry->mnt_fsname);
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if (item) {
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/* |item| has now been ro remounted. */
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list_remove(&item->list);
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list_add_tail(&ro_entries, &item->list);
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}
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}
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endmntent(fp);
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if (list_empty(&rw_entries)) {
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/* All rw block devices are now readonly. */
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break;
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}
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TEMP_FAILURE_RETRY(
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usleep(READONLY_CHECK_MS * 1000 / READONLY_CHECK_TIMES));
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cnt++;
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}
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list_for_each(node, &rw_entries) {
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mntent_list* item = node_to_item(node, mntent_list, list);
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KLOG_WARNING(TAG, "Failed to remount %s in readonly mode.\n",
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item->entry.mnt_fsname);
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}
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if (cb_on_remount) {
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list_for_each(node, &ro_entries) {
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mntent_list* item = node_to_item(node, mntent_list, list);
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cb_on_remount(&item->entry);
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}
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}
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out:
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free_entries(&rw_entries);
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free_entries(&ro_entries);
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}
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static void save_reboot_reason(int cmd, const char *arg)
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{
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FILE *fp;
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const char *reason = NULL;
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fp = fopen(LAST_REBOOT_REASON_FILE, "w");
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if (fp == NULL) {
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KLOG_WARNING(TAG, "Error creating " LAST_REBOOT_REASON_FILE
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": %s\n", strerror(errno));
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return;
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}
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switch (cmd) {
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case ANDROID_RB_RESTART:
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reason = "restart";
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break;
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case ANDROID_RB_POWEROFF:
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reason = "power-off";
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break;
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case ANDROID_RB_RESTART2:
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reason = arg && strlen(arg) ? arg : "restart";
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break;
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case ANDROID_RB_THERMOFF:
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reason = "thermal-shutdown";
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break;
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default:
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fprintf(fp,"0x%08X\n", cmd);
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break;
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}
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if (reason) {
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if (fprintf(fp, "%s\n", reason) < 0) {
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KLOG_WARNING(TAG, "Error writing " LAST_REBOOT_REASON_FILE
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": %s\n", strerror(errno));
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}
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}
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fclose(fp);
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}
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int android_reboot_with_callback(
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int cmd, int flags __unused, const char *arg,
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void (*cb_on_remount)(const struct mntent*))
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{
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int ret;
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save_reboot_reason(cmd, arg);
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remount_ro(cb_on_remount);
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switch (cmd) {
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case ANDROID_RB_RESTART:
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ret = reboot(RB_AUTOBOOT);
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break;
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case ANDROID_RB_POWEROFF:
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ret = reboot(RB_POWER_OFF);
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break;
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case ANDROID_RB_RESTART2:
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ret = syscall(__NR_reboot, LINUX_REBOOT_MAGIC1, LINUX_REBOOT_MAGIC2,
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LINUX_REBOOT_CMD_RESTART2, arg);
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break;
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case ANDROID_RB_THERMOFF:
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ret = reboot(RB_POWER_OFF);
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break;
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default:
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ret = -1;
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}
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return ret;
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}
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int android_reboot(int cmd, int flags, const char *arg)
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{
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return android_reboot_with_callback(cmd, flags, arg, NULL);
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}
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