Android 5.1 AppOps总结
-
- 什么是AppOps
- 涉及的类
- 常用名词
- 权限管理是如何触发的
- 系统默认应用权限
- AppOps Policy 文件
- AppOpsService准备工作
- 详细分析权限管理的触发
- 应用层对权限的设置
什么是AppOps
Android App在AndroidManifest.xml中申请了很多运行时需要获取的权限，例如
<uses-permission android:name="android.permission.NFC" />
用户在使用某个新安装的App的时候，经常会有弹窗弹出是否允许App获取某个权限，当确认获取后，用户才能正常使用该功能。而AppOps是framework提供给用户，确切点说是开发人员，更多操作应用权限的一个途径。用户可以对某个App的权限根据自己的需求进行禁止或者放行等。
在我理解，android系统中涉及App应用权限的主要涉及3个部分：
1. 系统默认的应用权限；
2. AppOps Policy文件；
3. 通过调用AppOpsManager中的接口对某一权限进行设置；
开发人员可以利用Policy文件和AppOpsManager中的接口对默认的应用权限进行修改。后续文章将会按照上面三部分进行展开。
涉及的类
以AppOps名字开始的类包括
Settings上层
packages/apps/Settings/src/com/android/settings/applications/AppOpsCategory.java
packages/apps/Settings/src/com/android/settings/applications/AppOpsDetails.java
packages/apps/Settings/src/com/android/settings/applications/AppOpsState.java
packages/apps/Settings/src/com/android/settings/applications/AppOpsSummary.java
frameworks/base/cmds/appops下面有个appops的应用程序
frameworks/native/libs/binder/AppOpsManager.cpp
frameworks/native/include/binder/AppOpsManager.h
Appops核心实现类，AppOpsService是功能具体实现，AppOpsManager是Service相关的Manager，是SDK中的一部分。AppOpsPolicy大概意思是，系统出厂时预制的系统App(System-app)和用户app（User-app）的一些默认的权限。非常有用，我们可以把我们一些预制的信任apk的权限都设置为允许，而不用老是弹窗提示。
frameworks/base/services/core/java/com/android/server/AppOpsService.java
frameworks/base/services/core/java/com/android/server/AppOpsPolicy.java
frameworks/base/core/java/android/app/AppOpsManager.java
常用名词
在framework中，
将某一权限称为Op，即operation，操作的意思。在AppOpsManager类中用以OP_开头的int表示具体权限，例如OP_COARSE_LOCATION，既表示coarse gps权限；
将某一权限的所对应的动作称为mode。在AppOpsManager类中用以MODE_开头的int表示动作，例如MODE_ALLOWED，表示允许相关权限的执行，即获取了相应的权限。
权限管理是如何触发的
当我们第一次在使用App的时候，访问某些系统权限时，例如访问wifi，都会弹出一个对话框询问用户是否允许访问wifi等。下面是WifiManager.java中打开WiFi的代码，
public boolean setWifiEnabled(boolean enabled) {
if (mAppOps.noteOp(AppOpsManager.OP_WIFI_CHANGE) !=
AppOpsManager.MODE_ALLOWED)
return false;
try {
return mService.setWifiEnabled(enabled);
} catch (RemoteException e) {
return false;
}
}在打开wifi前，首先会去调用AppOpsManager中的noteOp函数，如果返回值不是允许，即MODE_ALLOWED，直接返回false，不允许打开wifi。从MODE_ALLOWED的注释我们就能看出，系统一般都是通过checkOp、noteOp、startOp去检测权限，但是使用的地方不同。关于noteOp，见后文。
/**
* Result from {@link #checkOp}, {@link #noteOp}, {@link #startOp}: the given caller is
* allowed to perform the given operation.
*/
public static final int MODE_ALLOWED = 0;
系统默认应用权限
android系统中包含了strict模式和普通模式。什么是strict模式？
在AppOpsService类中有个变量，顾名思义，判断系统是否开启strict模式。
final boolean mStrictEnable;
而
mStrictEnable = AppOpsManager.isStrictEnable();
public static boolean isStrictEnable() {
return SystemProperties.getBoolean("persist.sys.strict_op_enable", false);
}可以看出，通过设置persist.sys.strict_op_enable为true，即开启了strict模式。那么strict模式和普通模式有什么差异？我们下面接着上一段(权限管理是如何触发的)分析。
调用–>
public int noteOp(int op) {
return noteOp(op, Process.myUid(), mContext.getOpPackageName());
}调用–>
/**
* Make note of an application performing an operation. Note that you must pass
* in both the uid and name of the application to be checked; this function will verify
* that these two match, and if not, return {@link #MODE_IGNORED}. If this call
* succeeds, the last execution time of the operation for this app will be updated to
* the current time.
*/
public int noteOp(int op, int uid, String packageName) {
try {
int mode = mService.noteOperation(op, uid, packageName);
if (mode == MODE_ERRORED) {
throw new SecurityException(buildSecurityExceptionMsg(op, uid, packageName));
}
return mode;
} catch (RemoteException e) {
}
return MODE_IGNORED;
}
从上面的注释我们也能证实我们前面的描述，noteOp主要是在一个app执行某个operation时需要note，即检验是否能够执行该操作，拥有该权限。函数中实际的实现还是调用了AppOps的实现类AppOpsService的noteOperation方法。
调用–>
@Override
public int noteOperation(int code, int uid, String packageName) {
//我们这里只看getOpLocked函数，其他省略
Op op = getOpLocked(ops, code, true);
if (isOpRestricted(uid, code, packageName)) {
return AppOpsManager.MODE_IGNORED;
}
}
调用–>
private Op getOpLocked(Ops ops, int code, boolean edit) {
int mode;
//如果该app是第一次使用，肯定返回空
Op op = ops.get(code);
if (op == null) {
if (!edit) {
return null;
}
mode = getDefaultMode(code, ops.uid, ops.packageName);
op = new Op(ops.uid, ops.packageName, code, mode);
ops.put(code, op);
}
if (edit) {
scheduleWriteLocked();
}
return op;
}调用–>
private int getDefaultMode(int code, int uid, String packageName) {
int mode = AppOpsManager.opToDefaultMode(code,
isStrict(code, uid, packageName));
//首先检查某个op是否在strict模式下，mPolicy就是上面提到的policy文件
//如果op在strict模式下，同时mPolicy存在，则从mPolicy中取默认权限
if (AppOpsManager.isStrictOp(code) && mPolicy != null) {
int policyMode = mPolicy.getDefualtMode(code, packageName);
if (policyMode != AppOpsManager.MODE_ERRORED) {
mode = policyMode;
}
}
return mode;
} public static int opToDefaultMode(int op, boolean isStrict) {
//是strict模式，返回sOpDefaultStrictMode数组
if (isStrict)
return sOpDefaultStrictMode[op];
//普通模式，返回sOpDefaultMode数组
return sOpDefaultMode[op];
} //mStrictEnable是enable的，同时是app,则返回true
private boolean isStrict(int code, int uid, String packageName) {
if (!mStrictEnable)
return false;
return UserHandle.isApp(uid);
}从上面的分析，我们可以看出在strict模式下，op的对应默认mode在sOpDefaultStrictMode数组中查找，而普通模式下mode在sOpDefaultMode找。例如对于OP_COARSE_LOCATION，在strict模式下默认是询问AppOpsManager.MODE_ASK，而在普通模式下默认是AppOpsManager.MODE_ALLOWED。
AppOps Policy 文件
由上文可知，在获取某个op的默认权限时，如果在strict模式下，同时mPolicy不为null的时候，会去从mPolicy中读取权限。下面分析AppOps Policy 文件，
在AppOpsService中，有个默认的policy文件/system/etc/appops_policy.xml，
static final String DEFAULT_POLICY_FILE = "/system/etc/appops_policy.xml";
同时，在AppOpsService中有个AppOpsPolicy的instance，
AppOpsPolicy mPolicy;
private void readPolicy() {
if (mStrictEnable) {
mPolicy = new AppOpsPolicy(new File(DEFAULT_POLICY_FILE), mContext);
mPolicy.readPolicy();
mPolicy.debugPoilcy();
} else {
mPolicy = null;
}
}在strict模式下，实例化了一个AppOpsPolicy类，一个参数为默认的policy文件
public AppOpsPolicy(File file, Context context) {
super();
mFile = file;
mContext = context;
}调用–>
void readPolicy() {
FileInputStream stream;
synchronized (mFile) {
try {
stream = new FileInputStream(mFile);
} catch (FileNotFoundException e) {
Slog.i(TAG, "App ops policy file (" + mFile.getPath()
+ ") not found; Skipping.");
return;
String tagName = parser.getName();
if (tagName.equals("user-app")
|| tagName.equals("system-app")) {
readDefaultPolicy(parser, tagName);
} else if (tagName.equals("application")) {
readApplicationPolicy(parser);
} else {
Slog.w(TAG, "Unknown element under <appops-policy>: "
+ parser.getName());
XmlUtils.skipCurrentTag(parser);
}
}上面的函数就是读Policy文件的函数，，其实主要包括2个函数readDefaultPolicy(parser, tagName)和readApplicationPolicy(parser)，我们也可以从函数中推测出policy文件的格式，起码包含user-app、system-app、application三个tag，user-app和system-app这两个tag对应的函数是readDefaultPolicy(parser, tagName)，application tag对应的是readApplicationPolicy(parser)，即
<appops-policy version="1">
<user-app permission="ask" show="true"/>
<system-app permission="allowed" show="false"/>
<application>
<!-- Example:
<pkg name="com.android.dialer" type="system-app">
<op name="android:call_phone" permission="ask" show="true"/>
</pkg>
-->
<pkg name="com.android.calendar" type="system-app">
<op name="android:read_contacts" permission="ask" show="true"/>
</pkg>
<pkg name="com.android.email" type="system-app">
<op name="android:read_contacts" permission="ask" show="true"/>
</pkg>
</application>
</appops-policy>
其中permission可以有allowed，ignored，ask和其他值，如下代码
/** @hide */
public static int stringToMode(String permission) {
if ("allowed".equalsIgnoreCase(permission)) {
return AppOpsManager.MODE_ALLOWED;
} else if ("ignored".equalsIgnoreCase(permission)) {
return AppOpsManager.MODE_IGNORED;
} else if ("ask".equalsIgnoreCase(permission)) {
return AppOpsManager.MODE_ASK;
}
return AppOpsManager.MODE_ERRORED;
}分别对应AppOpsManager.MODE_ALLOWED，AppOpsManager.MODE_IGNORED，AppOpsManager.MODE_ASK，其他字符串都会返回AppOpsManager.MODE_ERRORED。
而show表示是否将该权限show给用户，让用户去修改权限，如下所示，true和false分别对应CONTROL_SHOW，CONTROL_NOSHOW，如果为其他值，则对应CONTROL_UNKNOWN。
public static int stringToControl(String show) {
if ("true".equalsIgnoreCase(show)) {
return CONTROL_SHOW;
} else if ("false".equalsIgnoreCase(show)) {
return CONTROL_NOSHOW;
}
return CONTROL_UNKNOWN;
}下面我们分析下推测出的AppOps Policy文件，首先在application标签外，有两个user-app，system-app的标签，分别的意思是：默认user-app（/data/app）的权限是，permission=”ask”，ask即AppOpsManager.MODE_ASK，意思是会有弹出框提示用户去点击是否允许该权限。show=”true”，允许用户去修改该权限，默认user-app的权限是true，允许修改（可以参考设置—安全—应用操作，点开某个app后，即可以修改权限是允许、提示、还是禁止）。同理，system-app（/system/app），permission=”allowed”，默认权限是允许，show=”false”，不允许用户操作。
以上两个是系统和用户app的默认权限，在application标签内，用户可以自定义添加自己app规则（如果没有自定义app规则，默认就是执行上面两个默认规则，如果有当前app自定义规则，则执行该规则，好理解吧），以搜狗输入法为例：
<pkg name="com.sohu.inputmethod.sogou" type="user-app" permission="allowed" show="true">
</pkg>pkg标签包围， name=”com.sohu.inputmethod.sogou”，name是app的包名，type为user-app或者system-app，permission=”allowed”，所有申请的权限默认允许，show=”true”，同时指出用户去修改，show就是展示出来的意思。
通过添加上面的规则，你会发现，搜狗输入法再也不弹出位置这些权限的窗口让你来选择了。
在 AppOpsPolicy中有个成员，用来保存Policy文件所描述的这些规则，HashMap保存的格式为(packageName,PolicyPkg)，每个App是其中的一项。
HashMap<String, PolicyPkg> mPolicy = new HashMap<String, PolicyPkg>();其中PolicyPkg为AppOpsPolicy中的内部类，
//该内部类就是用来保存上面的 <op name="android:read_contacts" permission="ask" show="true"/>
public final static class PolicyOp {
public int op;
public int mode;
public int show;
public PolicyOp(int op, int mode, int show) {
this.op = op;
this.mode = mode;
this.show = show;
}
@Override
public String toString() {
return "PolicyOp [op=" + op + ", mode=" + mode + ", show=" + show
+ "]";
}
}
public final static class PolicyPkg extends SparseArray<PolicyOp> {
public String packageName;
public int mode;
public int show;
public String type;
public PolicyPkg(String packageName, int mode, int show, String type) {
this.packageName = packageName;
this.mode = mode;
this.show = show;
this.type = type;
}
@Override
public String toString() {
return "PolicyPkg [packageName=" + packageName + ", mode=" + mode
+ ", show=" + show + ", type=" + type + "]";
}
}下面先介绍读取user-app和system-app这两个tag的函数，读取完成后，在mPolicy 中保存的格式为(“user-app”,PolicyPkg )或者(“system-app”,PolicyPkg )，
private void readDefaultPolicy(XmlPullParser parser, String packageName)
throws NumberFormatException, XmlPullParserException, IOException {
//必须是user-app或者system-app
if (!"user-app".equalsIgnoreCase(packageName)
&& !"system-app".equalsIgnoreCase(packageName)) {
return;
}
int mode = AppOpsManager.stringToMode(parser.getAttributeValue(null,
"permission"));
int show = stringToControl(parser.getAttributeValue(null, "show"));
if (mode == AppOpsManager.MODE_ERRORED && show == CONTROL_UNKNOWN) {
return;
}
/*如果mPolicy没default policy，则新建一个PolicyPkg，一个hash键值对，这个键值对的格式是("user-app",PolicyPkg )或者("system-app",PolicyPkg )，如果已经存在，则修改mode和show*/
PolicyPkg pkg = this.mPolicy.get(packageName);
if (pkg == null) {
pkg = new PolicyPkg(packageName, mode, show, packageName);
this.mPolicy.put(packageName, pkg);
} else {
Slog.w(TAG, "Duplicate policy found for package: " + packageName
+ " of type: " + packageName);
pkg.mode = mode;
pkg.show = show;
}接着是读取application tag下的元素，
private void readApplicationPolicy(XmlPullParser parser)
throws NumberFormatException, XmlPullParserException, IOException {
......
/*读取下面的pkg tag*/
String tagName = parser.getName();
if (tagName.equals("pkg")) {
readPkgPolicy(parser);
} else {
Slog.w(TAG,
"Unknown element under <application>: "
+ parser.getName());
XmlUtils.skipCurrentTag(parser);
}
}调用–>
读取pkg本身的元素，如果pkg tag下还有op tag，继续读op tag。
private void readPkgPolicy(XmlPullParser parser)
throws NumberFormatException, XmlPullParserException, IOException {
String packageName = parser.getAttributeValue(null, "name");
if (packageName == null)
return;
String appType = parser.getAttributeValue(null, "type");
if (appType == null)
return;
int mode = AppOpsManager.stringToMode(parser.getAttributeValue(null,
"permission"));
int show = stringToControl(parser.getAttributeValue(null, "show"));
String key = packageName + "." + appType;
PolicyPkg pkg = this.mPolicy.get(key);
/*可以看到这里的键值对的键是以packageName + "." + appType形式，例如sogou输入法的键就为com.sohu.inputmethod.sogou.user-app，和default policy相同，如果mPolicy中没有该元素，则新建，否则修改mode和show。*/
if (pkg == null) {
pkg = new PolicyPkg(packageName, mode, show, appType);
this.mPolicy.put(key, pkg);
} else {
Slog.w(TAG, "Duplicate policy found for package: " + packageName
+ " of type: " + appType);
pkg.mode = mode;
pkg.show = show;
}
int outerDepth = parser.getDepth();
int type;
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
String tagName = parser.getName();
if (tagName.equals("op")) {
readOpPolicy(parser, pkg);
} else {
Slog.w(TAG, "Unknown element under <pkg>: " + parser.getName());
XmlUtils.skipCurrentTag(parser);
}
}
}从上可以看出pkg下面的键值对形式为(“com.sohu.inputmethod.sogou.user-app”,PolicyPkg)，下面接着读pkg下面的op tag。
调用–>
由于PolicyPkg extends SparseArray，所以PolicyPkg 内部有个保存pkg下相关op的一个SparseArray，保存的格式为(code,PolicyOp),code是个int,是稀疏数组的键吧。
private void readOpPolicy(XmlPullParser parser, PolicyPkg pkg)
throws NumberFormatException, XmlPullParserException, IOException {
if (pkg == null) {
return;
}
String opName = parser.getAttributeValue(null, "name");
if (opName == null) {
Slog.w(TAG, "Op name is null");
return;
}
int code = AppOpsManager.stringOpToOp(opName);
if (code == AppOpsManager.OP_NONE) {
Slog.w(TAG, "Unknown Op: " + opName);
return;
}
int mode = AppOpsManager.stringToMode(parser.getAttributeValue(null,
"permission"));
int show = stringToControl(parser.getAttributeValue(null, "show"));
if (mode == AppOpsManager.MODE_ERRORED && show == CONTROL_UNKNOWN) {
return;
}
PolicyOp op = pkg.get(code);
if (op == null) {
op = new PolicyOp(code, mode, show);
pkg.put(code, op);
} else {
Slog.w(TAG, "Duplicate policy found for package: "
+ pkg.packageName + " type: " + pkg.type + " op: " + op.op);
op.mode = mode;
op.show = show;
}
}至此，AppOps Policy文件已经读完。
AppOpsService准备工作
在AppOpsService类中，首先有个稀疏数组的成员mUidOps，顾名思义，涉及到Uid和Ops相关的东西。在android中，uid被赋予linux不同的任务，不同的App享有不同的Uid。作为稀疏数组的键，而对应的值为HashMap
final SparseArray<HashMap<String, Ops>> mUidOps
= new SparseArray<HashMap<String, Ops>>();Op是一个内部类，保存了一个op(权限）的详细信息，例如从什么时候开始运行的，等等。
public final static class Op {
public final int uid;
public final String packageName;
public final int op;
public int mode;
public int duration;
public long time;
public long rejectTime;
public int nesting;
public int noteOpCount;
public int startOpCount;
public PermissionDialogReqQueue dialogReqQueue;
final ArrayList<IBinder> clientTokens;
public Op(int _uid, String _packageName, int _op, int _mode) {
uid = _uid;
packageName = _packageName;
op = _op;
mode = _mode;
dialogReqQueue = new PermissionDialogReqQueue();
clientTokens = new ArrayList<IBinder>();
}
}而Ops也是一个内部类，包含了一个SparseArray，op的稀疏数组。Ops既是Op的复数，很多个Op的意思。
public final static class Ops extends SparseArray<Op> {
public final String packageName;
public final int uid;
public final boolean isPrivileged;
public Ops(String _packageName, int _uid, boolean _isPrivileged) {
packageName = _packageName;
uid = _uid;
isPrivileged = _isPrivileged;
}
}所以，mUidOps保存的数据类似(uid，HashMap
详细分析权限管理的触发
前面讲过，在打开wifi时会调用AppOpsManager中的noteOp函数，进行权限的检测，下面详细分析，
public int noteOp(int op, int uid, String packageName) {
try {
int mode = mService.noteOperation(op, uid, packageName);
if (mode == MODE_ERRORED) {
throw new SecurityException(buildSecurityExceptionMsg(op, uid, packageName));
}
return mode;
} catch (RemoteException e) {
}
return MODE_IGNORED;
}调用–>
调用AppOpsService中的noteOperation,
public int noteOperation(int code, int uid, String packageName) {
final PermissionDialogReq req;
verifyIncomingUid(uid);
verifyIncomingOp(code);
synchronized (this) {
//如果mUidOps中没有该App信息，则建立，否则返回Ops
Ops ops = getOpsLocked(uid, packageName, true);
if (ops == null) {
if (DEBUG) Log.d(TAG, "noteOperation: no op for code " + code + " uid " + uid
+ " package " + packageName);
return AppOpsManager.MODE_ERRORED;
}
//查找或者建立一个Op，放到ops中
//此外在getOpLocked，参数edit为true的情况下回去写/data/system/appops.xml文件，如果这个
//op是新建立的，则会马上更新appops.xml文件
Op op = getOpLocked(ops, code, true);
//至此，如果该app的这个权限是第一次在函数中处理，这时候已经在mUidOps和appops.xml中存在了
if (isOpRestricted(uid, code, packageName)) {
return AppOpsManager.MODE_IGNORED;
}
if (op.duration == -1) {
Slog.w(TAG, "Noting op not finished: uid " + uid + " pkg " + packageName
+ " code " + code + " time=" + op.time + " duration=" + op.duration);
}
op.duration = 0;
/*将code转换为switchcode*/
final int switchCode = AppOpsManager.opToSwitch(code);
/*如果op和switchop不同*/
final Op switchOp = switchCode != code ? getOpLocked(ops,
switchCode, true) : op;
/*如果mode不是allow和ask，则是被拒绝了，将reject的时间保存*/
if (switchOp.mode != AppOpsManager.MODE_ALLOWED
&& switchOp.mode != AppOpsManager.MODE_ASK) {
if (DEBUG)
Log.d(TAG, "noteOperation: reject #" + op.mode
+ " for code " + switchCode + " (" + code
+ ") uid " + uid + " package " + packageName);
op.rejectTime = System.currentTimeMillis();
return switchOp.mode;
} else if (switchOp.mode == AppOpsManager.MODE_ALLOWED) {
if (DEBUG)
Log.d(TAG, "noteOperation: allowing code " + code + " uid "
+ uid + " package " + packageName);
/*如果mode是allow，记录note的时间，并将reject设置为0*/
op.time = System.currentTimeMillis();
op.rejectTime = 0;
return AppOpsManager.MODE_ALLOWED;
} else {
if (Looper.myLooper() == mLooper) {
Log.e(TAG,
"noteOperation: This method will deadlock if called from the main thread. (Code: "
+ code
+ " uid: "
+ uid
+ " package: "
+ packageName + ")");
return switchOp.mode;
}
/*mode是ask，就是跳出来弹窗提醒，这里将op.noteOpCount增加*/
op.noteOpCount++;
req = askOperationLocked(code, uid, packageName, switchOp);
}
}
return req.get();
}先看getOpsLocked函数
private Ops getOpsLocked(int uid, String packageName, boolean edit) {
/*uid为0，包名为root，uid为shell，包名为com.android.shell，uid为system，同时包名为空，则包名为android*/
if (uid == 0) {
packageName = "root";
} else if (uid == Process.SHELL_UID) {
packageName = "com.android.shell";
} else if (uid == Process.SYSTEM_UID) {
if (packageName == null)
packageName = "android";
}
return getOpsRawLocked(uid, packageName, edit);
}接着调用，
/*有个参数edit，应该表示是不是可以修改mUidOps； 返回一个Ops，如果mUidOps中还没有该app相关信息，则新建一个HashMap<String, Ops>，放到mUidOps */
private Ops getOpsRawLocked(int uid, String packageName, boolean edit) {
HashMap<String, Ops> pkgOps = mUidOps.get(uid);
/*mUidOps里面没有这个uid的app*/
if (pkgOps == null) {
/*如果edit为false，不允许修改mUidOps，直接就返回了*/
if (!edit) {
return null;
}
/*如果没有这个uid的app，则新建一个，这时pkgOps还是空的*/
pkgOps = new HashMap<String, Ops>();
mUidOps.put(uid, pkgOps);
}
Ops ops = pkgOps.get(packageName);
if (ops == null) {
if (!edit) {
return null;
}
boolean isPrivileged = false;
// This is the first time we have seen this package name under this uid,
// so let's make sure it is valid.
//由上面的注释，主要是为了检验合法性
if (uid != 0) {
final long ident = Binder.clearCallingIdentity();
try {
int pkgUid = -1;
try {
ApplicationInfo appInfo = ActivityThread.getPackageManager()
.getApplicationInfo(packageName, 0, UserHandle.getUserId(uid));
if (appInfo != null) {
pkgUid = appInfo.uid;
isPrivileged = (appInfo.flags & ApplicationInfo.FLAG_PRIVILEGED) != 0;
} else {
if ("media".equals(packageName)) {
pkgUid = Process.MEDIA_UID;
isPrivileged = false;
}
}
} catch (RemoteException e) {
Slog.w(TAG, "Could not contact PackageManager", e);
}
if (pkgUid != uid) {
// Oops! The package name is not valid for the uid they are calling
// under. Abort.
Slog.w(TAG, "Bad call: specified package " + packageName
+ " under uid " + uid + " but it is really " + pkgUid);
return null;
}
} finally {
Binder.restoreCallingIdentity(ident);
}
}
//这里新建一个Ops，然后放到pkgOps中
ops = new Ops(packageName, uid, isPrivileged);
pkgOps.put(packageName, ops);
}
return ops;
}通过上面两步，如果mUidOps中还没有该app相关信息，则新建一个HashMap
private Op getOpLocked(Ops ops, int code, boolean edit) {
int mode;
Op op = ops.get(code);
//如果这个App是第一次进入这个函数，那么op肯定是空的
if (op == null) {
if (!edit) {
return null;
}
//获取默认的Mode，然后put到ops中
mode = getDefaultMode(code, ops.uid, ops.packageName);
op = new Op(ops.uid, ops.packageName, code, mode);
ops.put(code, op);
}
//如果允许edit，则执行scheduleWriteLocked
if (edit) {
scheduleWriteLocked();
}
return op;
}调用–>getDefaultMode
获取默认Mode前面已经讲过，这里如果这个op是strict的，同时mPolicy不为空，即Policy文件存在，则调用 mPolicy.getDefualtMode(code, packageName);
private int getDefaultMode(int code, int uid, String packageName) {
int mode = AppOpsManager.opToDefaultMode(code,
isStrict(code, uid, packageName));
if (AppOpsManager.isStrictOp(code) && mPolicy != null) {
int policyMode = mPolicy.getDefualtMode(code, packageName);
//如果返回值是MODE_ERRORED，那么会返回上面的opToDefaultMode的Mode
//感觉这种情况唯有mPolicy文件存在，但是没啥东西的时候，getDefualtMode返回MODE_ERRORED
if (policyMode != AppOpsManager.MODE_ERRORED) {
mode = policyMode;
}
}
return mode;
}注释很明确，就是先从默认规则读相关的Mode，如果还有pkg，那么继续读pkg下面的能匹配的mode，如果有匹配的则会覆盖前面mode的值。mode的默认值是AppOpsManager.MODE_ERRORED。
public int getDefualtMode(int code, String packageName) {
int mode = AppOpsManager.MODE_ERRORED;
PolicyPkg pkg;
String key;
String type;
if (mPolicy == null) {
return mode;
}
if (DEBUG)
Slog.d(TAG, "Default mode requested for op=" + code + " package="
+ packageName);
type = getAppType(packageName);
if (type != null) {
// Get value based on 'type'
key = type;
pkg = mPolicy.get(key);
if (pkg != null && pkg.mode != AppOpsManager.MODE_ERRORED) {
if (DEBUG)
Slog.d(TAG, "Setting value based on type: " + pkg);
mode = pkg.mode;
}
}
// Get value based on 'pkg'.
key = packageName;
if (type != null) {
key = key + "." + type;
}
pkg = mPolicy.get(key);
if (pkg != null) {
if (pkg.mode != AppOpsManager.MODE_ERRORED) {
if (DEBUG)
Slog.d(TAG, "Setting value based on packageName: " + pkg);
mode = pkg.mode;
}
// Get value base on 'op'
PolicyOp op = pkg.get(code);
if (op != null) {
if (op.mode != AppOpsManager.MODE_ERRORED) {
if (DEBUG)
Slog.d(TAG, "Setting value based on op: " + op);
mode = op.mode;
}
}
}
if (DEBUG)
Slog.d(TAG, "Returning mode=" + mode);
return mode;
}在上面函数getOpLocked中最后会调用scheduleWriteLocked，会调用写线程去更新一个权限文件，
private void scheduleWriteLocked() {
if (!mWriteScheduled) {
mWriteScheduled = true;
mHandler.postDelayed(mWriteRunner, WRITE_DELAY);
}
}而
final Runnable mWriteRunner = new Runnable() {
public void run() {
synchronized (AppOpsService.this) {
mWriteScheduled = false;
mFastWriteScheduled = false;
AsyncTask<Void, Void, Void> task = new AsyncTask<Void, Void, Void>() {
@Override protected Void doInBackground(Void... params) {
//线程调用writeState写各个app相关权限的相关信息
writeState();
return null;
}
};
task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, (Void[])null); } } };AppOpsService中有个成员mFile，是在构造函数中初始化的
public AppOpsService(File storagePath, Handler handler) { mFile = new AtomicFile(storagePath);
mHandler = handler;
mLooper = Looper.myLooper();
mStrictEnable = AppOpsManager.isStrictEnable();
readState();
}而AppOpsService是在ActivityManagerService中实例化的，systemDir为/data/system，则上述需要更新的文件为/data/system/appops.xml
mAppOpsService = new AppOpsService(new File(systemDir, "appops.xml"), mHandler);这个文件里面的内容，摘抄如下：
<app-ops>
<pkg n="com.android.providers.calendar">
<uid n="10001" p="true">
<op n="8" dm="0" t="1920100182" />
<op n="9" dm="0" t="1920062956" />
<op n="40" dm="0" t="1920100252" d="93" />
<op n="53" dm="0" t="1920062763" />
</uid>
</pkg>
<pkg n="com.android.dialer">
<uid n="10006" p="true">
<op n="6" dm="0" t="1920062244" />
<op n="53" dm="0" t="1920061743" />
</uid>
</pkg>
<pkg n="com.android.providers.media">
<uid n="10007" p="true">
<op n="23" dm="0" t="1920069787" />
<op n="40" dm="0" t="1920070834" d="97" />
<op n="53" dm="0" t="1920063053" />
</uid>
</pkg>
<pkg n="com.android.providers.downloads">
<uid n="10007" p="true">
<op n="53" dm="0" t="1920062960" />
</uid>
</pkg>
<pkg n="com.android.launcher">
<uid n="10009" p="true" />
</pkg>
<pkg n="com.android.managedprovisioning">
<uid n="10010" p="true">
<op n="53" dm="0" t="1920062971" />
</uid>
</pkg>
<pkg n="com.android.mms">
<uid n="10011" p="true">
<op n="14" dm="0" t="1920079185" />
<op n="15" dm="0" t="1920079178" />
<op n="40" dm="0" t="1920079204" d="46" />
<op n="51" dm="0" t="1920064837" />
<op n="53" dm="0" t="1920064530" />
<op n="56" dm="0" t="1920076500" />
</uid>
</pkg>
<pkg n="com.android.onetimeinitializer">
<uid n="10013" p="true">
<op n="53" dm="0" t="1920064547" />
</uid>
</pkg>
<pkg n="com.android.systemui">
<uid n="10016" p="true">
<op n="4" dm="0" t="1920057614" />
<op n="23" dm="0" t="1920057673" />
<op n="40" dm="0" t="1921212577" d="131" />
<op n="53" dm="0" t="1920060458" />
</uid>
</pkg>
<pkg n="com.cyanogenmod.trebuchet">
<uid n="10018" p="true">
<op n="3" dm="0" t="1921174279" d="66" />
<op n="53" dm="0" t="1920064754" />
</uid>
</pkg>
<pkg n="com.android.calendar">
<uid n="10025" p="false">
<op n="8" dm="0" t="1920085515" />
<op n="9" dm="0" t="1920095150" />
<op n="40" dm="0" t="1920085526" d="10112" />
<op n="53" dm="0" t="1920065067" />
</uid>
</pkg>
<pkg n="com.qualcomm.qti.calendarlocalaccount">
<uid n="10026" p="false">
<op n="53" dm="0" t="1920065089" />
</uid>
</pkg>
<pkg n="com.qualcomm.qti.calendarwidget">
<uid n="10027" p="false">
<op n="8" dm="0" t="1920078119" />
</uid>
</pkg>
<pkg n="com.android.camera2">
<uid n="10028" p="false">
<op n="53" dm="0" t="1920065263" />
</uid>
</pkg>
<pkg n="com.qti.cbwidget">
<uid n="10031" p="false" />
</pkg>
<pkg n="com.android.deskclock">
<uid n="10033" p="false">
<op n="40" dm="0" t="1920061737" d="155" />
<op n="53" dm="0" t="1920061562" />
</uid>
</pkg>
<pkg n="com.android.email">
<uid n="10035" p="false">
<op n="53" dm="0" t="1920066104" />
</uid>
</pkg>
<pkg n="com.android.gallery3d">
<uid n="10042" p="false">
<op n="23" dm="0" t="1920067518" />
<op n="53" dm="0" t="1920067465" />
</uid>
</pkg>
<pkg n="com.qcom.gsma.services.nfc">
<uid n="10043" p="false">
<op n="53" dm="0" t="1920067652" />
</uid>
</pkg>
<pkg n="com.android.inputmethod.latin">
<uid n="10047" p="false">
<op n="53" dm="0" t="1920067800" />
</uid>
</pkg>
<pkg n="com.android.music">
<uid n="10051" p="false" />
</pkg>
<pkg n="com.android.provision">
<uid n="10063" p="false">
<op n="23" dm="0" t="1920056281" />
</uid>
</pkg>
<pkg n="com.qualcomm.atuner">
<uid n="10073" p="false">
<op n="53" dm="0" t="1920072364" />
</uid>
</pkg>
<pkg n="com.qualcomm.embms">
<uid n="10074" p="false">
<op n="53" dm="0" t="1920072617" />
</uid>
</pkg>
<pkg n="com.borqs.videocall">
<uid n="10078" p="false">
<op n="53" dm="0" t="1920073353" />
</uid>
</pkg>
</app-ops>其中app-ops tag包含着很多个pkg tag，pkg tag中又包含了很多个op的tag，各个元素的意义见后文分析，例如
<pkg n="com.android.providers.calendar">
<uid n="10001" p="true">
<op n="8" dm="0" t="1920100182" />
<op n="9" dm="0" t="1920062956" />
<op n="40" dm="0" t="1920100252" d="93" />
<op n="53" dm="0" t="1920062763" />
</uid>
</pkg>下面我们看writeState函数，这个函数就说明了如何去写/data/system/appops.xml文件。
void writeState() {
synchronized (mFile) {
/* 调用getPackagesForOps函数，入参为null，即要获取mUidOps所有的数据； 而appops.xml这个文件其实就是mUidOps所有数据的体现。 */
List<AppOpsManager.PackageOps> allOps = getPackagesForOps(null);
FileOutputStream stream;
try {
stream = mFile.startWrite();
} catch (IOException e) {
Slog.w(TAG, "Failed to write state: " + e);
return;
}
try {
XmlSerializer out = new FastXmlSerializer();
out.setOutput(stream, "utf-8");
out.startDocument(null, true);
//写app-ops tag
out.startTag(null, "app-ops");
if (allOps != null) {
String lastPkg = null;
for (int i=0; i<allOps.size(); i++) {
AppOpsManager.PackageOps pkg = allOps.get(i);
if (!pkg.getPackageName().equals(lastPkg)) {
if (lastPkg != null) {
out.endTag(null, "pkg");
}
//<pkg n="com.android.providers.calendar">
lastPkg = pkg.getPackageName();
out.startTag(null, "pkg");
out.attribute(null, "n", lastPkg);
}
//<uid n="10001" p="true">
out.startTag(null, "uid");
out.attribute(null, "n", Integer.toString(pkg.getUid()));
//这个isPrivileged，还不清楚具体意思
synchronized (this) {
Ops ops = getOpsLocked(pkg.getUid(), pkg.getPackageName(), false);
// Should always be present as the list of PackageOps is generated
// from Ops.
if (ops != null) {
out.attribute(null, "p", Boolean.toString(ops.isPrivileged));
} else {
out.attribute(null, "p", Boolean.toString(false));
}
}
List<AppOpsManager.OpEntry> ops = pkg.getOps();
//下面就是一个个<op n="40" dm="0" t="1920100252" d="93" />
//m的意思是该op和defaultmode不同，例如通过上册修改过该op的权限
//dm就是依然是defaultmode
for (int j=0; j<ops.size(); j++) {
AppOpsManager.OpEntry op = ops.get(j);
out.startTag(null, "op");
out.attribute(null, "n", Integer.toString(op.getOp()));
int defaultMode = getDefaultMode(op.getOp(),
pkg.getUid(), pkg.getPackageName());
if (op.getMode() != defaultMode) {
out.attribute(null, "m", Integer.toString(op.getMode()));
} else {
out.attribute(null, "dm", Integer.toString(defaultMode));
}
long time = op.getTime();
//t是op的时间
if (time != 0) {
out.attribute(null, "t", Long.toString(time));
}
time = op.getRejectTime();
if (time != 0) {
out.attribute(null, "r", Long.toString(time));
}
int dur = op.getDuration();
if (dur != 0) {
out.attribute(null, "d", Integer.toString(dur));
}
out.endTag(null, "op");
}
out.endTag(null, "uid");
}
if (lastPkg != null) {
out.endTag(null, "pkg");
}
}
out.endTag(null, "app-ops");
out.endDocument();
mFile.finishWrite(stream);
} catch (IOException e) {
Slog.w(TAG, "Failed to write state, restoring backup.", e);
mFile.failWrite(stream);
}
}
}首先调用getPackagesForOps函数，
/* 通过ops，即权限，找对应的package，也就是拥有这些op的package； PackageOps是AppOpsManager中的一个类，注释很明确，Class holding all of the operation information associated with an app； 如果参数ops为空，则表示要获取mUidOps中的所有数据； */
public List<AppOpsManager.PackageOps> getPackagesForOps(int[] ops) {
mContext.enforcePermission(android.Manifest.permission.GET_APP_OPS_STATS,
Binder.getCallingPid(), Binder.getCallingUid(), null);
ArrayList<AppOpsManager.PackageOps> res = null;
//从mUidOps中查找，循环mUidOps所有的数据
synchronized (this) {
for (int i=0; i<mUidOps.size(); i++) {
HashMap<String, Ops> packages = mUidOps.valueAt(i);
for (Ops pkgOps : packages.values()) {
/* 这里调用collectOps，见下; 而OpEntry，Class holding the information about one unique operation of an application，既是一个op； */
ArrayList<AppOpsManager.OpEntry> resOps = collectOps(pkgOps, ops);
if (resOps != null) {
if (res == null) {
res = new ArrayList<AppOpsManager.PackageOps>();
}
AppOpsManager.PackageOps resPackage = new AppOpsManager.PackageOps(
pkgOps.packageName, pkgOps.uid, resOps);
res.add(resPackage);
}
}
}
}
return res;
}/* 如果ops为空，就表示需要获取所有的op； 而如果ops不为空，则需要通过键值对匹配，pkgOps.get(ops[j])； */
private ArrayList<AppOpsManager.OpEntry> collectOps(Ops pkgOps, int[] ops) {
ArrayList<AppOpsManager.OpEntry> resOps = null;
if (ops == null) {
resOps = new ArrayList<AppOpsManager.OpEntry>();
for (int j=0; j<pkgOps.size(); j++) {
Op curOp = pkgOps.valueAt(j);
resOps.add(new AppOpsManager.OpEntry(curOp.op, curOp.mode, curOp.time,
curOp.rejectTime, curOp.duration));
}
} else {
for (int j=0; j<ops.length; j++) {
Op curOp = pkgOps.get(ops[j]);
if (curOp != null) {
if (resOps == null) {
resOps = new ArrayList<AppOpsManager.OpEntry>();
}
resOps.add(new AppOpsManager.OpEntry(curOp.op, curOp.mode, curOp.time,
curOp.rejectTime, curOp.duration));
}
}
}
return resOps;
}说完writeState函数，顺便看下readState函数，即从/data/system/appops.xml中读取信息，更新mUidOps。
void readState() {
..........
if (tagName.equals("pkg")) {
readPackage(parser);
} else {
Slog.w(TAG, "Unknown element under <app-ops>: "
+ parser.getName());
XmlUtils.skipCurrentTag(parser);
}
}
success = true;
}调用
void readPackage(XmlPullParser parser) throws NumberFormatException,
XmlPullParserException, IOException {
String pkgName = parser.getAttributeValue(null, "n");
int outerDepth = parser.getDepth();
int type;
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
String tagName = parser.getName();
if (tagName.equals("uid")) {
readUid(parser, pkgName);
} else {
Slog.w(TAG, "Unknown element under <pkg>: "
+ parser.getName());
XmlUtils.skipCurrentTag(parser);
}
}
}调用readUid，
void readUid(XmlPullParser parser, String pkgName) throws NumberFormatException,
XmlPullParserException, IOException {
int uid = Integer.parseInt(parser.getAttributeValue(null, "n"));
String isPrivilegedString = parser.getAttributeValue(null, "p");
boolean isPrivileged = false;
//是否拥有Privileged属性
if (isPrivilegedString == null) {
try {
IPackageManager packageManager = ActivityThread.getPackageManager();
if (packageManager != null) {
ApplicationInfo appInfo = ActivityThread.getPackageManager()
.getApplicationInfo(pkgName, 0, UserHandle.getUserId(uid));
if (appInfo != null) {
isPrivileged = (appInfo.flags & ApplicationInfo.FLAG_PRIVILEGED) != 0;
}
} else {
// Could not load data, don't add to cache so it will be loaded later.
return;
}
} catch (RemoteException e) {
Slog.w(TAG, "Could not contact PackageManager", e);
}
} else {
isPrivileged = Boolean.parseBoolean(isPrivilegedString);
}
int outerDepth = parser.getDepth();
int type;
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
//下面就是具体的写相关tag和attribute什么的
String tagName = parser.getName();
if (tagName.equals("op")) {
int code = Integer
.parseInt(parser.getAttributeValue(null, "n"));
Op op = new Op(uid, pkgName, code, AppOpsManager.MODE_ERRORED);
String mode = parser.getAttributeValue(null, "m");
if (mode != null) {
op.mode = Integer.parseInt(mode);
} else {
String sDefualtMode = parser.getAttributeValue(null, "dm");
int defaultMode;
if (sDefualtMode != null) {
defaultMode = Integer.parseInt(sDefualtMode);
} else {
defaultMode = getDefaultMode(code, uid, pkgName);
}
op.mode = defaultMode;
}
String time = parser.getAttributeValue(null, "t");
if (time != null) {
op.time = Long.parseLong(time);
}
time = parser.getAttributeValue(null, "r");
if (time != null) {
op.rejectTime = Long.parseLong(time);
}
String dur = parser.getAttributeValue(null, "d");
if (dur != null) {
op.duration = Integer.parseInt(dur);
}
HashMap<String, Ops> pkgOps = mUidOps.get(uid);
if (pkgOps == null) {
pkgOps = new HashMap<String, Ops>();
mUidOps.put(uid, pkgOps);
}
Ops ops = pkgOps.get(pkgName);
if (ops == null) {
ops = new Ops(pkgName, uid, isPrivileged);
pkgOps.put(pkgName, ops);
}
ops.put(op.op, op);
} else {
Slog.w(TAG, "Unknown element under <pkg>: "
+ parser.getName());
XmlUtils.skipCurrentTag(parser);
}
}
}下面继续分析noteOperation函数，接着调用，
final int switchCode = AppOpsManager.opToSwitch(code); public static int opToSwitch(int op) {
return sOpToSwitch[op];
}这里的sOpToSwitch[]数组的解释如下
/**
* This maps each operation to the operation that serves as the
* switch to determine whether it is allowed. Generally this is
* a 1:1 mapping, but for some things (like location) that have
* multiple low-level operations being tracked that should be
* presented to the user as one switch then this can be used to
* make them all controlled by the same single operation.
*/
private static int[] sOpToSwitch = new int[] {
OP_COARSE_LOCATION,
OP_COARSE_LOCATION,
OP_COARSE_LOCATION,
.................
}应用层对权限的设置
上面两节已经介绍了App默认权限以及Policy文件的读取，下面将介绍最后一部分，也是最关键的，上层应用调用AppOpsManager的接口对权限进行设置，将会使用到App默认权限和Policy文件部分的内容。
以原生系统setting中AppOpsDetails为例，都是调用AppOpsManager的setMode函数对权限进行设置，
private boolean refreshUi() {
.......
@Override
public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
if(firstMode) {
firstMode = false;
return;
}
mAppOps.setMode(switchOp, entry.getPackageOps().getUid(),
entry.getPackageOps().getPackageName(), positionToMode(position));
}
@Override
public void onNothingSelected(AdapterView<?> parentView) {
// your code here
}
});
sw.setChecked(mAppOps.checkOp(switchOp, entry.getPackageOps()
.getUid(), entry.getPackageOps().getPackageName()) == AppOpsManager.MODE_ALLOWED);
sw.setOnCheckedChangeListener(new Switch.OnCheckedChangeListener() {
public void onCheckedChanged(CompoundButton buttonView,
boolean isChecked) {
mAppOps.setMode(switchOp, entry.getPackageOps()
.getUid(), entry.getPackageOps()
.getPackageName(),
isChecked ? AppOpsManager.MODE_ALLOWED
: AppOpsManager.MODE_IGNORED);
}
});
if (AppOpsManager.isStrictOp(switchOp)) {
sp.setVisibility(View.VISIBLE);
} else {
sw.setVisibility(View.VISIBLE);
}
}
}
return true;
}而AppOpsManager又调用service中的setMode，修改mUidOps中相关权限信息，
public void setMode(int code, int uid, String packageName, int mode) {
try {
mService.setMode(code, uid, packageName, mode);
} catch (RemoteException e) {
}
}即，
public void setMode(int code, int uid, String packageName, int mode) {
if (Binder.getCallingPid() != Process.myPid()) {
mContext.enforcePermission(android.Manifest.permission.UPDATE_APP_OPS_STATS,
Binder.getCallingPid(), Binder.getCallingUid(), null);
}
verifyIncomingOp(code);
ArrayList<Callback> repCbs = null;
code = AppOpsManager.opToSwitch(code);
synchronized (this) {
Op op = getOpLocked(code, uid, packageName, true);
if (op != null) {
if (op.mode != mode) {
/*这里设置mode*/
op.mode = mode;
ArrayList<Callback> cbs = mOpModeWatchers.get(code);
if (cbs != null) {
if (repCbs == null) {
repCbs = new ArrayList<Callback>();
}
repCbs.addAll(cbs);
}
cbs = mPackageModeWatchers.get(packageName);
if (cbs != null) {
if (repCbs == null) {
repCbs = new ArrayList<Callback>();
}
repCbs.addAll(cbs);
}
if (mode == getDefaultMode(code, uid, packageName)) {
// If going into the default mode, prune this op
// if there is nothing else interesting in it.
/*如果这个mode是默认的mode，则在mUidOps中将该op删除*/
pruneOp(op, uid, packageName);
}
scheduleFastWriteLocked();
}
}
}
if (repCbs != null) {
for (int i=0; i<repCbs.size(); i++) {
try {
repCbs.get(i).mCallback.opChanged(code, packageName);
} catch (RemoteException e) {
}
}
}
}