gecko-dev/toolkit/mozapps/update/updater/automounter_gonk.cpp

225 lines
5.4 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <android/log.h>
#include <cutils/android_reboot.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/reboot.h>
#include <sys/types.h>
#include <unistd.h>
#include "automounter_gonk.h"
#include "updatedefines.h"
#include "updatelogging.h"
#define LOG_TAG "GonkAutoMounter"
#define GONK_LOG(level, format, ...) \
LOG((LOG_TAG ": " format "\n", ##__VA_ARGS__)); \
__android_log_print(level, LOG_TAG, format, ##__VA_ARGS__)
#define LOGI(format, ...) GONK_LOG(ANDROID_LOG_INFO, format, ##__VA_ARGS__)
#define LOGE(format, ...) GONK_LOG(ANDROID_LOG_ERROR, format, ##__VA_ARGS__)
const char *kGonkMountsPath = "/proc/mounts";
const char *kGonkSystemPath = "/system";
GonkAutoMounter::GonkAutoMounter() : mDevice(nullptr), mAccess(Unknown)
{
if (!RemountSystem(ReadWrite)) {
LOGE("Could not remount %s as read-write.", kGonkSystemPath);
}
}
GonkAutoMounter::~GonkAutoMounter()
{
bool result = RemountSystem(ReadOnly);
free(mDevice);
if (!result) {
// Don't take any chances when remounting as read-only fails, just reboot.
Reboot();
}
}
void
GonkAutoMounter::Reboot()
{
// The android_reboot wrapper provides more safety, doing fancier read-only
// remounting and attempting to sync() the filesystem first. If this fails
// our only hope is to force a reboot directly without these protections.
// For more, see system/core/libcutils/android_reboot.c
LOGE("Could not remount %s as read-only, forcing a system reboot.",
kGonkSystemPath);
LogFlush();
if (android_reboot(ANDROID_RB_RESTART, 0, nullptr) != 0) {
LOGE("Safe system reboot failed, attempting to force");
LogFlush();
if (reboot(RB_AUTOBOOT) != 0) {
LOGE("CRITICAL: Failed to force restart");
}
}
}
static const char *
MountAccessToString(MountAccess access)
{
switch (access) {
case ReadOnly: return "read-only";
case ReadWrite: return "read-write";
default: return "unknown";
}
}
bool
GonkAutoMounter::RemountSystem(MountAccess access)
{
if (!UpdateMountStatus()) {
return false;
}
if (mAccess == access) {
return true;
}
unsigned long flags = MS_REMOUNT;
if (access == ReadOnly) {
flags |= MS_RDONLY;
// Give the system a chance to flush file buffers
sync();
}
if (!MountSystem(flags)) {
return false;
}
// Check status again to verify /system has been properly remounted
if (!UpdateMountStatus()) {
return false;
}
if (mAccess != access) {
LOGE("Updated mount status %s should be %s",
MountAccessToString(mAccess),
MountAccessToString(access));
return false;
}
return true;
}
bool
GonkAutoMounter::UpdateMountStatus()
{
FILE *mountsFile = NS_tfopen(kGonkMountsPath, "r");
if (mountsFile == nullptr) {
LOGE("Error opening %s: %s", kGonkMountsPath, strerror(errno));
return false;
}
// /proc/mounts returns a 0 size from fstat, so we use the same
// pre-allocated buffer size that ADB does here
const int mountsMaxSize = 4096;
char mountData[mountsMaxSize];
size_t read = fread(mountData, 1, mountsMaxSize - 1, mountsFile);
mountData[read + 1] = '\0';
if (ferror(mountsFile)) {
LOGE("Error reading %s, %s", kGonkMountsPath, strerror(errno));
fclose(mountsFile);
return false;
}
char *token, *tokenContext;
bool foundSystem = false;
for (token = strtok_r(mountData, "\n", &tokenContext);
token;
token = strtok_r(nullptr, "\n", &tokenContext))
{
if (ProcessMount(token)) {
foundSystem = true;
break;
}
}
fclose(mountsFile);
if (!foundSystem) {
LOGE("Couldn't find %s mount in %s", kGonkSystemPath, kGonkMountsPath);
}
return foundSystem;
}
bool
GonkAutoMounter::ProcessMount(const char *mount)
{
const int strSize = 256;
char mountDev[strSize];
char mountDir[strSize];
char mountAccess[strSize];
int rv = sscanf(mount, "%255s %255s %*s %255s %*d %*d\n",
mountDev, mountDir, mountAccess);
mountDev[strSize - 1] = '\0';
mountDir[strSize - 1] = '\0';
mountAccess[strSize - 1] = '\0';
if (rv != 3) {
return false;
}
if (strcmp(kGonkSystemPath, mountDir) != 0) {
return false;
}
free(mDevice);
mDevice = strdup(mountDev);
mAccess = Unknown;
char *option, *optionContext;
for (option = strtok_r(mountAccess, ",", &optionContext);
option;
option = strtok_r(nullptr, ",", &optionContext))
{
if (strcmp("ro", option) == 0) {
mAccess = ReadOnly;
break;
} else if (strcmp("rw", option) == 0) {
mAccess = ReadWrite;
break;
}
}
return true;
}
bool
GonkAutoMounter::MountSystem(unsigned long flags)
{
if (!mDevice) {
LOGE("No device was found for %s", kGonkSystemPath);
return false;
}
const char *readOnly = flags & MS_RDONLY ? "read-only" : "read-write";
int result = mount(mDevice, kGonkSystemPath, "none", flags, nullptr);
if (result != 0) {
LOGE("Error mounting %s as %s: %s", kGonkSystemPath, readOnly,
strerror(errno));
return false;
}
LOGI("Mounted %s partition as %s", kGonkSystemPath, readOnly);
return true;
}