Android 5.1 AppOps總結
什麼是AppOps
Android App在AndroidManifest.xml中申請了很多執行時需要獲取的許可權,例如
<uses-permission android:name="android.permission.NFC" />
使用者在使用某個新安裝的App的時候,經常會有彈窗彈出是否允許App獲取某個許可權,當確認獲取後,使用者才能正常使用該功能。而AppOps是framework提供給使用者,確切點說是開發人員,更多操作應用許可權的一個途徑。使用者可以對某個App的許可權根據自己的需求進行禁止或者放行等。
在我理解,android系統中涉及App應用許可權的主要涉及3個部分:
1. 系統預設的應用許可權;
2. AppOps Policy檔案;
3. 通過呼叫AppOpsManager中的介面對某一許可權進行設定;
開發人員可以利用Policy檔案和AppOpsManager中的介面對預設的應用許可權進行修改。後續文章將會按照上面三部分進行展開。
涉及的類
以AppOps名字開始的類包括
Settings上層
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下面有個appops的應用程式
frameworks/native/libs/binder/AppOpsManager.cpp
frameworks/native/include/binder/AppOpsManager.h
Appops核心實現類,AppOpsService是功能具體實現,AppOpsManager是Service相關的Manager,是SDK中的一部分。AppOpsPolicy大概意思是,系統出廠時預製的系統App(System-app)和使用者app(User-app)的一些預設的許可權。非常有用,我們可以把我們一些預製的信任apk的許可權都設定為允許,而不用老是彈窗提示。
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
常用名詞
在framework中,
將某一許可權稱為Op,即operation,操作的意思。在AppOpsManager類中用以OP_開頭的int表示具體許可權,例如OP_COARSE_LOCATION,既表示coarse gps許可權;
將某一許可權的所對應的動作稱為mode。在AppOpsManager類中用以MODE_開頭的int表示動作,例如MODE_ALLOWED,表示允許相關許可權的執行,即獲取了相應的許可權。
許可權管理是如何觸發的
當我們第一次在使用App的時候,訪問某些系統許可權時,例如訪問wifi,都會彈出一個對話方塊詢問使用者是否允許訪問wifi等。下面是WifiManager.java中開啟WiFi的程式碼,
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;
}
}
在開啟wifi前,首先會去呼叫AppOpsManager中的noteOp函式,如果返回值不是允許,即MODE_ALLOWED,直接返回false,不允許開啟wifi。從MODE_ALLOWED的註釋我們就能看出,系統一般都是通過checkOp、noteOp、startOp去檢測許可權,但是使用的地方不同。關於noteOp,見後文。
/**
* 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;
系統預設應用許可權
android系統中包含了strict模式和普通模式。什麼是strict模式?
在AppOpsService類中有個變數,顧名思義,判斷系統是否開啟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,通過設定persist.sys.strict_op_enable為true,即開啟了strict模式。那麼strict模式和普通模式有什麼差異?我們下面接著上一段(許可權管理是如何觸發的)分析。
呼叫–>
public int noteOp(int op) {
return noteOp(op, Process.myUid(), mContext.getOpPackageName());
}
呼叫–>
/**
* 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;
}
從上面的註釋我們也能證實我們前面的描述,noteOp主要是在一個app執行某個operation時需要note,即檢驗是否能夠執行該操作,擁有該許可權。函式中實際的實現還是呼叫了AppOps的實現類AppOpsService的noteOperation方法。
呼叫–>
@Override
public int noteOperation(int code, int uid, String packageName) {
//我們這裡只看getOpLocked函式,其他省略
Op op = getOpLocked(ops, code, true);
if (isOpRestricted(uid, code, packageName)) {
return AppOpsManager.MODE_IGNORED;
}
}
呼叫–>
private Op getOpLocked(Ops ops, int code, boolean edit) {
int mode;
//如果該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;
}
呼叫–>
private int getDefaultMode(int code, int uid, String packageName) {
int mode = AppOpsManager.opToDefaultMode(code,
isStrict(code, uid, packageName));
//首先檢查某個op是否在strict模式下,mPolicy就是上面提到的policy檔案
//如果op在strict模式下,同時mPolicy存在,則從mPolicy中取預設許可權
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陣列
if (isStrict)
return sOpDefaultStrictMode[op];
//普通模式,返回sOpDefaultMode陣列
return sOpDefaultMode[op];
}
//mStrictEnable是enable的,同時是app,則返回true
private boolean isStrict(int code, int uid, String packageName) {
if (!mStrictEnable)
return false;
return UserHandle.isApp(uid);
}
從上面的分析,我們可以看出在strict模式下,op的對應預設mode在sOpDefaultStrictMode陣列中查詢,而普通模式下mode在sOpDefaultMode找。例如對於OP_COARSE_LOCATION,在strict模式下預設是詢問AppOpsManager.MODE_ASK,而在普通模式下預設是AppOpsManager.MODE_ALLOWED。
AppOps Policy 檔案
由上文可知,在獲取某個op的預設許可權時,如果在strict模式下,同時mPolicy不為null的時候,會去從mPolicy中讀取許可權。下面分析AppOps Policy 檔案,
在AppOpsService中,有個預設的policy檔案/system/etc/appops_policy.xml,
static final String DEFAULT_POLICY_FILE = "/system/etc/appops_policy.xml";
同時,在AppOpsService中有個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,例項化了一個AppOpsPolicy類,一個引數為預設的policy檔案
public AppOpsPolicy(File file, Context context) {
super();
mFile = file;
mContext = context;
}
呼叫–>
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);
}
}
上面的函式就是讀Policy檔案的函式,,其實主要包括2個函式readDefaultPolicy(parser, tagName)和readApplicationPolicy(parser),我們也可以從函式中推測出policy檔案的格式,起碼包含user-app、system-app、application三個tag,user-app和system-app這兩個tag對應的函式是readDefaultPolicy(parser, tagName),application tag對應的是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,如下程式碼
/** @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;
}
分別對應AppOpsManager.MODE_ALLOWED,AppOpsManager.MODE_IGNORED,AppOpsManager.MODE_ASK,其他字串都會返回AppOpsManager.MODE_ERRORED。
而show表示是否將該許可權show給使用者,讓使用者去修改許可權,如下所示,true和false分別對應CONTROL_SHOW,CONTROL_NOSHOW,如果為其他值,則對應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;
}
下面我們分析下推測出的AppOps Policy檔案,首先在application標籤外,有兩個user-app,system-app的標籤,分別的意思是:預設user-app(/data/app)的許可權是,permission=”ask”,ask即AppOpsManager.MODE_ASK,意思是會有彈出框提示使用者去點選是否允許該許可權。show=”true”,允許使用者去修改該許可權,預設user-app的許可權是true,允許修改(可以參考設定—安全—應用操作,點開某個app後,即可以修改許可權是允許、提示、還是禁止)。同理,system-app(/system/app),permission=”allowed”,預設許可權是允許,show=”false”,不允許使用者操作。
以上兩個是系統和使用者app的預設許可權,在application標籤內,使用者可以自定義新增自己app規則(如果沒有自定義app規則,預設就是執行上面兩個預設規則,如果有當前app自定義規則,則執行該規則,好理解吧),以搜狗輸入法為例:
<pkg name="com.sohu.inputmethod.sogou" type="user-app" permission="allowed" show="true">
</pkg>
pkg標籤包圍, name=”com.sohu.inputmethod.sogou”,name是app的包名,type為user-app或者system-app,permission=”allowed”,所有申請的許可權預設允許,show=”true”,同時指出使用者去修改,show就是展示出來的意思。
通過新增上面的規則,你會發現,搜狗輸入法再也不彈出位置這些許可權的視窗讓你來選擇了。
在 AppOpsPolicy中有個成員,用來儲存Policy檔案所描述的這些規則,HashMap儲存的格式為(packageName,PolicyPkg),每個App是其中的一項。
HashMap<String, PolicyPkg> mPolicy = new HashMap<String, PolicyPkg>();
其中PolicyPkg為AppOpsPolicy中的內部類,
//該內部類就是用來儲存上面的 <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 + "]";
}
}
下面先介紹讀取user-app和system-app這兩個tag的函式,讀取完成後,在mPolicy 中儲存的格式為(“user-app”,PolicyPkg )或者(“system-app”,PolicyPkg ),
private void readDefaultPolicy(XmlPullParser parser, String packageName)
throws NumberFormatException, XmlPullParserException, IOException {
//必須是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沒default policy,則新建一個PolicyPkg,一個hash鍵值對,這個鍵值對的格式是("user-app",PolicyPkg )或者("system-app",PolicyPkg ),如果已經存在,則修改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;
}
接著是讀取application tag下的元素,
private void readApplicationPolicy(XmlPullParser parser)
throws NumberFormatException, XmlPullParserException, IOException {
......
/*讀取下面的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);
}
}
呼叫–>
讀取pkg本身的元素,如果pkg tag下還有op tag,繼續讀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);
/*可以看到這裡的鍵值對的鍵是以packageName + "." + appType形式,例如sogou輸入法的鍵就為com.sohu.inputmethod.sogou.user-app,和default policy相同,如果mPolicy中沒有該元素,則新建,否則修改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);
}
}
}
從上可以看出pkg下面的鍵值對形式為(“com.sohu.inputmethod.sogou.user-app”,PolicyPkg),下面接著讀pkg下面的op tag。
呼叫–>
由於PolicyPkg extends SparseArray,所以PolicyPkg 內部有個儲存pkg下相關op的一個SparseArray,儲存的格式為(code,PolicyOp),code是個int,是稀疏陣列的鍵吧。
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檔案已經讀完。
AppOpsService準備工作
在AppOpsService類中,首先有個稀疏陣列的成員mUidOps,顧名思義,涉及到Uid和Ops相關的東西。在android中,uid被賦予linux不同的任務,不同的App享有不同的Uid。作為稀疏陣列的鍵,而對應的值為HashMap
final SparseArray<HashMap<String, Ops>> mUidOps
= new SparseArray<HashMap<String, Ops>>();
Op是一個內部類,儲存了一個op(許可權)的詳細資訊,例如從什麼時候開始執行的,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也是一個內部類,包含了一個SparseArray,op的稀疏陣列。Ops既是Op的複數,很多個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儲存的資料類似(uid,HashMap
詳細分析許可權管理的觸發
前面講過,在開啟wifi時會呼叫AppOpsManager中的noteOp函式,進行許可權的檢測,下面詳細分析,
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;
}
呼叫–>
呼叫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中沒有該App資訊,則建立,否則返回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;
}
//查詢或者建立一個Op,放到ops中
//此外在getOpLocked,引數edit為true的情況下回去寫/data/system/appops.xml檔案,如果這個
//op是新建立的,則會馬上更新appops.xml檔案
Op op = getOpLocked(ops, code, true);
//至此,如果該app的這個許可權是第一次在函式中處理,這時候已經在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;
/*將code轉換為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,則是被拒絕了,將reject的時間儲存*/
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,記錄note的時間,並將reject設定為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,就是跳出來彈窗提醒,這裡將op.noteOpCount增加*/
op.noteOpCount++;
req = askOperationLocked(code, uid, packageName, switchOp);
}
}
return req.get();
}
先看getOpsLocked函式
private Ops getOpsLocked(int uid, String packageName, boolean edit) {
/*uid為0,包名為root,uid為shell,包名為com.android.shell,uid為system,同時包名為空,則包名為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);
}
接著呼叫,
/*有個引數edit,應該表示是不是可以修改mUidOps;
返回一個Ops,如果mUidOps中還沒有該app相關資訊,則新建一個HashMap<String, Ops>,放到mUidOps
*/
private Ops getOpsRawLocked(int uid, String packageName, boolean edit) {
HashMap<String, Ops> pkgOps = mUidOps.get(uid);
/*mUidOps裡面沒有這個uid的app*/
if (pkgOps == null) {
/*如果edit為false,不允許修改mUidOps,直接就返回了*/
if (!edit) {
return null;
}
/*如果沒有這個uid的app,則新建一個,這時pkgOps還是空的*/
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.
//由上面的註釋,主要是為了檢驗合法性
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);
}
}
//這裡新建一個Ops,然後放到pkgOps中
ops = new Ops(packageName, uid, isPrivileged);
pkgOps.put(packageName, ops);
}
return ops;
}
通過上面兩步,如果mUidOps中還沒有該app相關資訊,則新建一個HashMap
private Op getOpLocked(Ops ops, int code, boolean edit) {
int mode;
Op op = ops.get(code);
//如果這個App是第一次進入這個函式,那麼op肯定是空的
if (op == null) {
if (!edit) {
return null;
}
//獲取預設的Mode,然後put到ops中
mode = getDefaultMode(code, ops.uid, ops.packageName);
op = new Op(ops.uid, ops.packageName, code, mode);
ops.put(code, op);
}
//如果允許edit,則執行scheduleWriteLocked
if (edit) {
scheduleWriteLocked();
}
return op;
}
呼叫–>getDefaultMode
獲取預設Mode前面已經講過,這裡如果這個op是strict的,同時mPolicy不為空,即Policy檔案存在,則呼叫 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,那麼會返回上面的opToDefaultMode的Mode
//感覺這種情況唯有mPolicy檔案存在,但是沒啥東西的時候,getDefualtMode返回MODE_ERRORED
if (policyMode != AppOpsManager.MODE_ERRORED) {
mode = policyMode;
}
}
return mode;
}
註釋很明確,就是先從預設規則讀相關的Mode,如果還有pkg,那麼繼續讀pkg下面的能匹配的mode,如果有匹配的則會覆蓋前面mode的值。mode的預設值是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;
}
在上面函式getOpLocked中最後會呼叫scheduleWriteLocked,會呼叫寫執行緒去更新一個許可權檔案,
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, Vo