外置sd卡相关功能的时候遇到了在9.0上外置SD卡写入权限的问题,在 9.0 之前的平台，申请了 WRITE_MEDIA_STORAGE 的权限后，平台签名的应用就可以通过 java.io.File 接口写入外置 SD 卡了。但之后，想要写入外置 SD 卡，就需要像第三方应用一样，使用 DocumentFile 的接口，
可以阅读 API 文档 存储访问框架 和 使用作用域目录访问 。
android 9加入权限和动态申请都无法对外置SD卡创建文件夹
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />如果是APP开发，可以做兼容 , 以下是对DocumentFile 类调用的封装
贴代码
package com.mw.test;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.storage.StorageManager;
import android.os.storage.StorageVolume;
import android.provider.Settings;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private static final String TAG = "MainActivity-Test";
String rootPath = ""; //外置 SD 卡路径
private List<String> unPermissionList = new ArrayList<String>(); //申请未得到授权的权限列表
private final int RequestCode = 100;//权限请求码
private AlertDialog mPermissionDialog;
private String mPackName ; //获取 a'p'k 包名
private String[] permissionList = new String[]{ //申请的权限列表
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE,
};
private Button mButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
checkPermission();
mPackName = getPackageName();
rootPath = getStoragePath(this,true); //获取 可以插拔的 sd 卡 路径
Log.i(TAG," rootPath： " + rootPath);
if (DocumentsUtils.checkWritableRootPath(this, rootPath)) { //检查sd卡路径是否有 权限 没有显示dialog
showOpenDocumentTree();
}
mButton = (Button) findViewById(R.id.creatDir);
mButton.setOnClickListener(this);
}
@Override
public void onClick(View view) {
switch (view.getId()){
case R.id.creatDir:
Log.i(TAG,"点击");
try {
writeDataToSD();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void showOpenDocumentTree() {
Intent intent = null;
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {
StorageManager sm = getSystemService(StorageManager.class);
StorageVolume volume = sm.getStorageVolume(new File(rootPath));
if (volume != null) {
intent = volume.createAccessIntent(null);
}
}
if (intent == null) {
intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
}
startActivityForResult(intent, DocumentsUtils.OPEN_DOCUMENT_TREE_CODE);
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
switch (requestCode) {
case DocumentsUtils.OPEN_DOCUMENT_TREE_CODE:
if (data != null && data.getData() != null) {
Uri uri = data.getData();
DocumentsUtils.saveTreeUri(this, rootPath, uri);
}
break;
default:
break;
}
}
//权限判断和申请
public void checkPermission() {
unPermissionList.clear();//清空申请的没有通过的权限
//逐个判断是否还有未通过的权限
for (int i = 0; i < permissionList.length; i++) {
if (ContextCompat.checkSelfPermission(this, permissionList[i]) !=
PackageManager.PERMISSION_GRANTED) {
unPermissionList.add(permissionList[i]);//添加还未授予的权限到unPermissionList中
}
}
//有权限没有通过，需要申请
if (unPermissionList.size() > 0) {
ActivityCompat.requestPermissions( this,permissionList, 100);
Log.i(TAG, "check 有权限未通过");
} else {
//权限已经都通过了，可以将程序继续打开了
Log.i(TAG, "check 权限都已经申请通过");
}
}
/**
* 5.请求权限后回调的方法
*
* @param requestCode 是我们自己定义的权限请求码
* @param permissions 是我们请求的权限名称数组
* @param grantResults 是我们在弹出页面后是否允许权限的标识数组，数组的长度对应的是权限
* 名称数组的长度，数组的数据0表示允许权限，-1表示我们点击了禁止权限
*/
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions,
int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
Log.i(TAG,"申请结果反馈");
boolean hasPermissionDismiss = false;
if (100 == requestCode) {
for (int i = 0; i < grantResults.length; i++) {
if (grantResults[i] == -1) {
hasPermissionDismiss = true; //有权限没有通过
Log.i(TAG,"有权限没有被通过");
break;
}
}
}
if (hasPermissionDismiss) {//如果有没有被允许的权限
showPermissionDialog();
} else {
//权限已经都通过了，可以将程序继续打开了
Log.i(TAG, "onRequestPermissionsResult 权限都已经申请通过");
}
}
/**
* 不再提示权限时的展示对话框
*/
private void showPermissionDialog() {
Log.i(TAG,"mPackName: " + mPackName);
if (mPermissionDialog == null) {
mPermissionDialog = new AlertDialog.Builder(this)
.setMessage("已禁用权限，请手动授予")
.setPositiveButton("设置", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
cancelPermissionDialog();
Uri packageURI = Uri.parse("package:" + mPackName); //去设置里面设置
Intent intent = new Intent(Settings.
ACTION_APPLICATION_DETAILS_SETTINGS, packageURI);
startActivity(intent);
}
})
.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//关闭页面或者做其他操作
cancelPermissionDialog();
}
})
.create();
}
mPermissionDialog.show();
}
private void cancelPermissionDialog() {
mPermissionDialog.cancel();
}
/**
* 通过反射调用获取内置存储和外置sd卡根路径(通用)
*
* @param mContext 上下文
* @param is_removale 是否可移除，false返回内部存储路径，true返回外置SD卡路径
* @return
*/
private static String getStoragePath(Context mContext, boolean is_removale) {
String path = "";
//使用getSystemService(String)检索一个StorageManager用于访问系统存储功能。
StorageManager mStorageManager = (StorageManager) mContext.getSystemService(Context.STORAGE_SERVICE);
Class<?> storageVolumeClazz = null;
try {
storageVolumeClazz = Class.forName("android.os.storage.StorageVolume");
Method getVolumeList = mStorageManager.getClass().getMethod("getVolumeList");
Method getPath = storageVolumeClazz.getMethod("getPath");
Method isRemovable = storageVolumeClazz.getMethod("isRemovable");
Object result = getVolumeList.invoke(mStorageManager);
for (int i = 0; i < Array.getLength(result); i++) {
Object storageVolumeElement = Array.get(result, i);
path = (String) getPath.invoke(storageVolumeElement);
boolean removable = (Boolean) isRemovable.invoke(storageVolumeElement);
if (is_removale == removable) {
return path;
}
}
} catch (Exception e) {
e.printStackTrace();
}
return path;
}
public void writeDataToSD() throws IOException {
//写文件的例子 文件不存在,会创建
String str = "just a test\n";
String strRead = "";
String sdkOut = getStoragePath(this,true); //获取 可以插拔的 sd 卡 路径
Log.i(TAG,"sdkOut:"+sdkOut);
String filePath = sdkOut + "/test";
Log.i(TAG," sdkOut: " + filePath);
File file = new File(filePath);
if (!file.exists()){
if(DocumentsUtils.mkdirs(this,file)){
Log.i(TAG,"创建文件夹：" + filePath);
}else{
Log.i(TAG,"创建文件夹失败：" + filePath);
}
}
String fileWritePath = filePath + "/test.txt";
File fileWrite = new File(fileWritePath);
Log.i(TAG," 准备写入" );
try {
OutputStream outputStream = DocumentsUtils.getOutputStream(this,fileWrite); //获取输出流
// OutputStream outputStream = new FileOutputStream(fileWrite);
outputStream.write(str.getBytes());
outputStream.close();
Log.i(TAG," 写入成功" );
Toast.makeText(this,"路径：" + fileWritePath + "成功",Toast.LENGTH_SHORT ).show();
} catch (IOException e) {
e.printStackTrace();
Log.i(TAG," 写入失败" );
Toast.makeText(this,"路径：" + fileWritePath + "失败",Toast.LENGTH_SHORT ).show();
}
}
}package com.test.multicamera.utils;
import android.annotation.TargetApi;
import android.content.Context;
import android.content.SharedPreferences;
import android.net.Uri;
import android.os.Build;
import android.preference.PreferenceManager;
import android.provider.DocumentsContract;
import android.util.Log;
import androidx.documentfile.provider.DocumentFile;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
public class DocumentsUtils {
private static final String TAG = DocumentsUtils.class.getSimpleName();
public static final int OPEN_DOCUMENT_TREE_CODE = 8000;
private static List<String> sExtSdCardPaths = new ArrayList<>();
private DocumentsUtils() {
}
public static void cleanCache() {
sExtSdCardPaths.clear();
}
/**
* Get a list of external SD card paths. (Kitkat or higher.)
*
* @return A list of external SD card paths.
*/
@TargetApi(Build.VERSION_CODES.KITKAT)
private static String[] getExtSdCardPaths(Context context) {
if (sExtSdCardPaths.size() > 0) {
return sExtSdCardPaths.toArray(new String[0]);
}
for (File file : context.getExternalFilesDirs("external")) {
if (file != null && !file.equals(context.getExternalFilesDir("external"))) {
int index = file.getAbsolutePath().lastIndexOf("/Android/data");
if (index < 0) {
Log.w(TAG, "Unexpected external file dir: " + file.getAbsolutePath());
} else {
String path = file.getAbsolutePath().substring(0, index);
try {
path = new File(path).getCanonicalPath();
} catch (IOException e) {
// Keep non-canonical path.
}
sExtSdCardPaths.add(path);
}
}
}
if (sExtSdCardPaths.isEmpty()) sExtSdCardPaths.add("/storage/sdcard1");
return sExtSdCardPaths.toArray(new String[0]);
}
/**
* Determine the main folder of the external SD card containing the given file.
*
* @param file the file.
* @return The main folder of the external SD card containing this file, if the file is on an SD
* card. Otherwise,
* null is returned.
*/
@TargetApi(Build.VERSION_CODES.KITKAT)
private static String getExtSdCardFolder(final File file, Context context) {
String[] extSdPaths = getExtSdCardPaths(context);
try {
for (int i = 0; i < extSdPaths.length; i++) {
if (file.getCanonicalPath().startsWith(extSdPaths[i])) {
return extSdPaths[i];
}
}
} catch (IOException e) {
return null;
}
return null;
}
/**
* Determine if a file is on external sd card. (Kitkat or higher.)
*
* @param file The file.
* @return true if on external sd card.
*/
@TargetApi(Build.VERSION_CODES.KITKAT)
public static boolean isOnExtSdCard(final File file, Context c) {
return getExtSdCardFolder(file, c) != null;
}
/**
* Get a DocumentFile corresponding to the given file (for writing on ExtSdCard on Android 5).
* If the file is not
* existing, it is created.
*
* @param file The file.
* @param isDirectory flag indicating if the file should be a directory.
* @return The DocumentFile
*/
public static DocumentFile getDocumentFile(final File file, final boolean isDirectory,
Context context) {
if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.KITKAT) {
return DocumentFile.fromFile(file);
}
String baseFolder = getExtSdCardFolder(file, context);
Log.i(TAG," baseFolder " + baseFolder);
boolean originalDirectory = false;
if (baseFolder == null) {
return null;
}
String relativePath = null;
try {
String fullPath = file.getCanonicalPath();
if (!baseFolder.equals(fullPath)) {
relativePath = fullPath.substring(baseFolder.length() + 1);
} else {
originalDirectory = true;
}
} catch (IOException e) {
return null;
} catch (Exception f) {
originalDirectory = true;
//continue
}
String as = PreferenceManager.getDefaultSharedPreferences(context).getString(baseFolder,
null);
Uri treeUri = null;
if (as != null) treeUri = Uri.parse(as);
if (treeUri == null) {
return null;
}
// start with root of SD card and then parse through document tree.
DocumentFile document = DocumentFile.fromTreeUri(context, treeUri);
if (originalDirectory) return document;
String[] parts = relativePath.split("/");
for (int i = 0; i < parts.length; i++) {
DocumentFile nextDocument = document.findFile(parts[i]);
if (nextDocument == null) {
if ((i < parts.length - 1) || isDirectory) {
nextDocument = document.createDirectory(parts[i]);
} else {
nextDocument = document.createFile("image", parts[i]);
}
}
document = nextDocument;
}
return document;
}
public static boolean mkdirs(Context context, File dir) {
boolean res = dir.mkdirs();
if (!res) {
if (DocumentsUtils.isOnExtSdCard(dir, context)) {
DocumentFile documentFile = DocumentsUtils.getDocumentFile(dir, true, context);
res = documentFile != null && documentFile.canWrite();
}
}
return res;
}
public static boolean delete(Context context, File file) {
boolean ret = file.delete();
if (!ret && DocumentsUtils.isOnExtSdCard(file, context)) {
DocumentFile f = DocumentsUtils.getDocumentFile(file, false, context);
if (f != null) {
ret = f.delete();
}
}
return ret;
}
public static boolean canWrite(File file) {
boolean res = file.exists() && file.canWrite();
if (!res && !file.exists()) {
try {
if (!file.isDirectory()) {
res = file.createNewFile() && file.delete();
} else {
res = file.mkdirs() && file.delete();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return res;
}
public static boolean canWrite(Context context, File file) {
boolean res = canWrite(file);
if (!res && DocumentsUtils.isOnExtSdCard(file, context)) {
DocumentFile documentFile = DocumentsUtils.getDocumentFile(file, true, context);
res = documentFile != null && documentFile.canWrite();
}
return res;
}
public static boolean renameTo(Context context, File src, File dest) {
boolean res = src.renameTo(dest);
if (!res && isOnExtSdCard(dest, context)) {
DocumentFile srcDoc;
if (isOnExtSdCard(src, context)) {
srcDoc = getDocumentFile(src, false, context);
} else {
srcDoc = DocumentFile.fromFile(src);
}
DocumentFile destDoc = getDocumentFile(dest.getParentFile(), true, context);
if (srcDoc != null && destDoc != null) {
try {
if (src.getParent().equals(dest.getParent())) {
res = srcDoc.renameTo(dest.getName());
} else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
res = DocumentsContract.moveDocument(context.getContentResolver(),
srcDoc.getUri(),
srcDoc.getParentFile().getUri(),
destDoc.getUri()) != null;
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
return res;
}
public static InputStream getInputStream(Context context, File destFile) {
InputStream in = null;
try {
if (!canWrite(destFile) && isOnExtSdCard(destFile, context)) {
DocumentFile file = DocumentsUtils.getDocumentFile(destFile, false, context);
if (file != null && file.canWrite()) {
in = context.getContentResolver().openInputStream(file.getUri());
}
} else {
in = new FileInputStream(destFile);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return in;
}
public static OutputStream getOutputStream(Context context, File destFile) {
OutputStream out = null;
try {
if (!canWrite(destFile) && isOnExtSdCard(destFile, context)) {
DocumentFile file = DocumentsUtils.getDocumentFile(destFile, false, context);
if (file != null && file.canWrite()) {
out = context.getContentResolver().openOutputStream(file.getUri());
}
} else {
out = new FileOutputStream(destFile);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return out;
}
public static boolean saveTreeUri(Context context, String rootPath, Uri uri) {
DocumentFile file = DocumentFile.fromTreeUri(context, uri);
if (file != null && file.canWrite()) {
SharedPreferences perf = PreferenceManager.getDefaultSharedPreferences(context);
perf.edit().putString(rootPath, uri.toString()).apply();
Log.e(TAG, "save uri" + rootPath);
return true;
} else {
Log.e(TAG, "no write permission: " + rootPath);
}
return false;
}
public static boolean checkWritableRootPath(Context context, String rootPath) {
File root = new File(rootPath);
if (!root.canWrite()) {
if (DocumentsUtils.isOnExtSdCard(root, context)) {
Log.i(TAG,"isOnExtSdCard");
DocumentFile documentFile = DocumentsUtils.getDocumentFile(root, true, context);
return documentFile == null || !documentFile.canWrite();
} else {
Log.i(TAG," get perf");
SharedPreferences perf = PreferenceManager.getDefaultSharedPreferences(context);
String documentUri = perf.getString(rootPath, "");
if (documentUri == null || documentUri.isEmpty()) {
return true;
} else {
DocumentFile file = DocumentFile.fromTreeUri(context, Uri.parse(documentUri));
return !(file != null && file.canWrite());
}
}
}
return false;
}
}
对于系统定制开发,为了不想改所有的APP做兼容，所以直接修改系统文件
Android 从6.0 开始引入了Runtime permission，应用对于storage 进行读取、存储的时候，需要注册、申请对应的权限。
Android 8.0中对于sdcard 读写只需要申请权限即可使用，可以在Android 9.0 中同样的应用执行同样的步骤，却提示了Permission denied。
APP应用外置SD卡读写失败selinux造成的报avc权限拒绝,
我这边试着关闭selinux 没有成功，只好再想其它办法
adb logcat | grep avc
01-01 02:21:28.269 6995 6995 W zsj.multicamera: type=1400 audit(0.0:44): avc: denied { setattr } for name="base.vdex" dev="mmcblk0p56" ino=3885 scontext=u:r:system_app:s0 tcontext=u:object_r:apk_data_file:s0 tclass=file permissive=001-01 00:05:57.110 4047 4047 W tel.multicamera: type=1400 audit(0.0:24): avc: denied { unlink } for name="base.apk.arm64.flock" dev="mmcblk0p56" ino=2151 scontext=u:r:system_app:s0 tcontext=u:object_r:apk_data_file:s0 tclass=file permissive=0修改系统文件-以下两个地址的内容要一致
system\sepolicy\private\system_app.te
system\sepolicy\prebuilts\api\28.0\private\system_app.te直接新增了好几样权限(也可以根接日志avc 提示来增加)
allow system_app apk_data_file:file {create write unlink setattr};修改完成后，make 系统，然后只用推送相应的包就可以了
adb push SC200Y\out\target\product\msm8953_64\system\etc\selinux /system/etc/
adb reboot重启后 重试 还是不行
// Copyright (C) 2016 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.
#define LOG_TAG "sdcard"
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/fuse.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <sys/inotify.h>
#include <sys/mount.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/macros.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <cutils/fs.h>
#include <cutils/multiuser.h>
#include <cutils/properties.h>
#include <libminijail.h>
#include <scoped_minijail.h>
#include <private/android_filesystem_config.h>
#define PROP_SDCARDFS_DEVICE "ro.sys.sdcardfs"
#define PROP_SDCARDFS_USER "persist.sys.sdcardfs"
static bool supports_esdfs(void) {
std::string filesystems;
if (!android::base::ReadFileToString("/proc/filesystems", &filesystems)) {
PLOG(ERROR) << "Could not read /proc/filesystems";
return false;
}
for (const auto& fs : android::base::Split(filesystems, "\n")) {
if (fs.find("esdfs") != std::string::npos) return true;
}
return false;
}
static bool should_use_sdcardfs(void) {
char property[PROPERTY_VALUE_MAX];
// Allow user to have a strong opinion about state
property_get(PROP_SDCARDFS_USER, property, "");
if (!strcmp(property, "force_on")) {
LOG(WARNING) << "User explicitly enabled sdcardfs";
return true;
} else if (!strcmp(property, "force_off")) {
LOG(WARNING) << "User explicitly disabled sdcardfs";
return !supports_esdfs();
}
// Fall back to device opinion about state
if (property_get_bool(PROP_SDCARDFS_DEVICE, true)) {
LOG(WARNING) << "Device explicitly enabled sdcardfs";
return true;
} else {
LOG(WARNING) << "Device explicitly disabled sdcardfs";
return !supports_esdfs();
}
}
// NOTE: This is a vestigial program that simply exists to mount the in-kernel
// sdcardfs filesystem. The older FUSE-based design that used to live here has
// been completely removed to avoid confusion.
/* Supplementary groups to execute with. */
static const gid_t kGroups[1] = { AID_PACKAGE_INFO };
static void drop_privs(uid_t uid, gid_t gid) {
ScopedMinijail j(minijail_new());
minijail_set_supplementary_gids(j.get(), arraysize(kGroups), kGroups);
minijail_change_gid(j.get(), gid);
minijail_change_uid(j.get(), uid);
/* minijail_enter() will abort if priv-dropping fails. */
minijail_enter(j.get());
}
static bool sdcardfs_setup(const std::string& source_path, const std::string& dest_path,
uid_t fsuid, gid_t fsgid, bool multi_user, userid_t userid, gid_t gid,
mode_t mask, bool derive_gid, bool default_normal, bool use_esdfs) {
// Try several attempts, each time with one less option, to gracefully
// handle older kernels that aren't updated yet.
for (int i = 0; i < 4; i++) {
std::string new_opts;
if (multi_user && i < 3) new_opts += "multiuser,";
if (derive_gid && i < 2) new_opts += "derive_gid,";
if (default_normal && i < 1) new_opts += "default_normal,";
auto opts = android::base::StringPrintf("fsuid=%d,fsgid=%d,%smask=%d,userid=%d,gid=%d",
fsuid, fsgid, new_opts.c_str(), mask, userid, gid);
if (mount(source_path.c_str(), dest_path.c_str(), use_esdfs ? "esdfs" : "sdcardfs",
MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_NOATIME, opts.c_str()) == -1) {
PLOG(WARNING) << "Failed to mount sdcardfs with options " << opts;
} else {
return true;
}
}
return false;
}
static bool sdcardfs_setup_bind_remount(const std::string& source_path, const std::string& dest_path,
gid_t gid, mode_t mask) {
std::string opts = android::base::StringPrintf("mask=%d,gid=%d", mask, gid);
if (mount(source_path.c_str(), dest_path.c_str(), nullptr,
MS_BIND, nullptr) != 0) {
PLOG(ERROR) << "failed to bind mount sdcardfs filesystem";
return false;
}
if (mount(source_path.c_str(), dest_path.c_str(), "none",
MS_REMOUNT | MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_NOATIME, opts.c_str()) != 0) {
PLOG(ERROR) << "failed to mount sdcardfs filesystem";
if (umount2(dest_path.c_str(), MNT_DETACH))
PLOG(WARNING) << "Failed to unmount bind";
return false;
}
return true;
}
static bool sdcardfs_setup_secondary(const std::string& default_path, const std::string& source_path,
const std::string& dest_path, uid_t fsuid, gid_t fsgid,
bool multi_user, userid_t userid, gid_t gid, mode_t mask,
bool derive_gid, bool default_normal, bool use_esdfs) {
if (use_esdfs) {
return sdcardfs_setup(source_path, dest_path, fsuid, fsgid, multi_user, userid, gid, mask,
derive_gid, default_normal, use_esdfs);
} else {
return sdcardfs_setup_bind_remount(default_path, dest_path, gid, mask);
}
}
static void run_sdcardfs(const std::string& source_path, const std::string& label, uid_t uid,
gid_t gid, userid_t userid, bool multi_user, bool full_write,
bool derive_gid, bool default_normal, bool use_esdfs) {
std::string dest_path_default = "/mnt/runtime/default/" + label;
std::string dest_path_read = "/mnt/runtime/read/" + label;
std::string dest_path_write = "/mnt/runtime/write/" + label;
umask(0);
//alex 2021-03-20 modify sdcard avc denied [full_write set true and multi_user set false;
full_write =true;
multi_user = false;
if (multi_user) {
// Multi-user storage is fully isolated per user, so "other"
// permissions are completely masked off.
if (!sdcardfs_setup(source_path, dest_path_default, uid, gid, multi_user, userid,
AID_SDCARD_RW, 0006, derive_gid, default_normal, use_esdfs) ||
!sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_read, uid, gid,
multi_user, userid, AID_EVERYBODY, 0027, derive_gid,
default_normal, use_esdfs) ||
!sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_write, uid, gid,
multi_user, userid, AID_EVERYBODY, full_write ? 0007 : 0027,
derive_gid, default_normal, use_esdfs)) {
LOG(FATAL) << "failed to sdcardfs_setup";
}
} else {
// Physical storage is readable by all users on device, but
// the Android directories are masked off to a single user
// deep inside attr_from_stat().
if (!sdcardfs_setup(source_path, dest_path_default, uid, gid, multi_user, userid,
AID_SDCARD_RW, 0007, derive_gid, default_normal, use_esdfs) ||
!sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_read, uid, gid,
multi_user, userid, AID_EVERYBODY, full_write ? 0007 : 0022,
derive_gid, default_normal, use_esdfs) ||
!sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_write, uid, gid,
multi_user, userid, AID_EVERYBODY, full_write ? 0007 : 0022,
derive_gid, default_normal, use_esdfs)) {
LOG(FATAL) << "failed to sdcardfs_setup";
}
}
// Will abort if priv-dropping fails.
drop_privs(uid, gid);
if (multi_user) {
std::string obb_path = source_path + "/obb";
fs_prepare_dir(obb_path.c_str(), 0775, uid, gid);
}
exit(0);
}
static int usage() {
LOG(ERROR) << "usage: sdcard [OPTIONS] <source_path> <label>"
<< " -u: specify UID to run as"
<< " -g: specify GID to run as"
<< " -U: specify user ID that owns device"
<< " -m: source_path is multi-user"
<< " -w: runtime write mount has full write access"
<< " -P preserve owners on the lower file system";
return 1;
}
int main(int argc, char **argv) {
const char *source_path = NULL;
const char *label = NULL;
uid_t uid = 0;
gid_t gid = 0;
userid_t userid = 0;
bool multi_user = false;
bool full_write = false;
bool derive_gid = false;
bool default_normal = false;
int i;
struct rlimit rlim;
int fs_version;
setenv("ANDROID_LOG_TAGS", "*:v", 1);
android::base::InitLogging(argv, android::base::LogdLogger(android::base::SYSTEM));
int opt;
while ((opt = getopt(argc, argv, "u:g:U:mwGi")) != -1) {
switch (opt) {
case 'u':
uid = strtoul(optarg, NULL, 10);
break;
case 'g':
gid = strtoul(optarg, NULL, 10);
break;
case 'U':
userid = strtoul(optarg, NULL, 10);
break;
case 'm':
multi_user = true;
break;
case 'w':
full_write = true;
break;
case 'G':
derive_gid = true;
break;
case 'i':
default_normal = true;
break;
case '?':
default:
return usage();
}
}
for (i = optind; i < argc; i++) {
char* arg = argv[i];
if (!source_path) {
source_path = arg;
} else if (!label) {
label = arg;
} else {
LOG(ERROR) << "too many arguments";
return usage();
}
}
if (!source_path) {
LOG(ERROR) << "no source path specified";
return usage();
}
if (!label) {
LOG(ERROR) << "no label specified";
return usage();
}
if (!uid || !gid) {
LOG(ERROR) << "uid and gid must be nonzero";
return usage();
}
rlim.rlim_cur = 8192;
rlim.rlim_max = 8192;
if (setrlimit(RLIMIT_NOFILE, &rlim) == -1) {
PLOG(ERROR) << "setting RLIMIT_NOFILE failed";
}
while ((fs_read_atomic_int("/data/.layout_version", &fs_version) == -1) || (fs_version < 3)) {
LOG(ERROR) << "installd fs upgrade not yet complete; waiting...";
sleep(1);
}
run_sdcardfs(source_path, label, uid, gid, userid, multi_user, full_write, derive_gid,
default_normal, !should_use_sdcardfs());
return 1;
}标红的为被修改的部分
只需要sdcard打包
mmm system/core/sdcard/
只需要推送
adb push SC200Y\out\target\product\msm8953_64\system\bin\sdcard /system/bin
然后杀进程 或 重启系统
ps -A |grep sdcard然后就可以正常读写了
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