【Android】【root & remount】【2】如何判断设备是否remount
前言
高版本的android设备,在remount之后,如果再进行ota升级,会产生异常,从而无法升级成功。
如何判断设备是否remount
当前已android 10 平台为例
当我们执行 adb remount 时,系统调用会调用到system/core/adb/daemon/remount_service.cpp
/*
* Copyright (C) 2008 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 <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <string>
#include "adb.h"
#include "adb_io.h"
#include "adb_unique_fd.h"
static constexpr char kRemountCmd[] = "/system/bin/remount";
static bool do_remount(int fd, const std::string& cmd) {
if (getuid() != 0) {
WriteFdExactly(fd, "Not running as root. Try \"adb root\" first.\n");
return false;
}
auto pid = fork();
if (pid < 0) {
WriteFdFmt(fd, "Failed to fork to %s: %s\n", kRemountCmd, strerror(errno));
return false;
}
if (pid == 0) {
// child side of the fork
dup2(fd, STDIN_FILENO);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
execl(kRemountCmd, kRemountCmd, cmd.empty() ? nullptr : cmd.c_str(), nullptr);
_exit(errno);
}
int wstatus = 0;
auto ret = waitpid(pid, &wstatus, 0);
if (ret == -1) {
WriteFdFmt(fd, "Failed to wait for %s: %s\n", kRemountCmd, strerror(errno));
return false;
} else if (ret != pid) {
WriteFdFmt(fd, "pid %d and waitpid return %d do not match for %s\n",
static_cast<int>(pid), static_cast<int>(ret), kRemountCmd);
return false;
}
if (WIFSIGNALED(wstatus)) {
WriteFdFmt(fd, "%s terminated with signal %s\n", kRemountCmd,
strsignal(WTERMSIG(wstatus)));
return false;
}
if (!WIFEXITED(wstatus)) {
WriteFdFmt(fd, "%s stopped with status 0x%x\n", kRemountCmd, wstatus);
return false;
}
if (WEXITSTATUS(wstatus)) {
WriteFdFmt(fd, "%s exited with status %d\n", kRemountCmd, WEXITSTATUS(wstatus));
return false;
}
return true;
}
void remount_service(unique_fd fd, const std::string& cmd) {
const char* success = do_remount(fd.get(), cmd) ? "succeeded" : "failed";
WriteFdFmt(fd.get(), "remount %s\n", success);
}
当前的思路时,再执行do_remount 函数时,添加一个persist变量来判断记录已经remount了,并记录remount次数。
具体修改如下:
#include <unistd.h>
//add
#include <android-base/properties.h>
//add
#include <string>
......
static bool do_remount(int fd, const std::string& cmd) {
......
//add
std::string prop = android::base::GetProperty("persist.sys.remount.count", "0");
int count = std::stoi(prop) + 1;
android::base::SetProperty("persist.sys.remount.count", std::to_string(count));
// add
return true;
}
获取状态remount状态
java
import android.os.SystemProperties;
public static final String PROP_REMOUNT_COUNT = "persist.sys.remount.count";
/**
* NULL
* @return device remount status
*/
public static boolean isRemounted(){
return getRemountCount() >0;
}
/**
* NULL
* @return get remount count Since first power up
*/
public static int getRemountCount(){
return SystemProperties.getInt(PROP_ROOT_COUNT,0);
}
原文地址:https://blog.csdn.net/wangjicong_215/article/details/137600489
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