5月 282020
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int bindServiceLocked(IApplicationThread caller, IBinder token, Intent service, String resolvedType, final IServiceConnection connection, int flags, String callingPackage, final int userId) throws TransactionTooLargeException { if (DEBUG_SERVICE) Slog.v(TAG_SERVICE, "bindService: " + service + " type=" + resolvedType + " conn=" + connection.asBinder() + " flags=0x" + Integer.toHexString(flags)); // 获取调用bindService的进程信息，如果进程信息不存在，则报异常。为什么会不存在？ final ProcessRecord callerApp = mAm.getRecordForAppLocked(caller); if (callerApp == null) { throw new SecurityException( "Unable to find app for caller " + caller + " (pid=" + Binder.getCallingPid() + ") when binding service " + service); } ActivityRecord activity = null; // 这个token对应的是ContextImpl中的getActivityToken()，如果在一个Service中bind其他的Service，这个token是不是就是null了？ if (token != null) { // 在Activity栈中看是否有调用的Activity，如果没有，则返回 activity = ActivityRecord.isInStackLocked(token); if (activity == null) { Slog.w(TAG, "Binding with unknown activity: " + token); return 0; } } int clientLabel = 0; PendingIntent clientIntent = null; final boolean isCallerSystem = callerApp.info.uid == Process.SYSTEM_UID; // 这里看不太懂 if (isCallerSystem) { // Hacky kind of thing -- allow system stuff to tell us // what they are, so we can report this elsewhere for // others to know why certain services are running. service.setDefusable(true); clientIntent = service.getParcelableExtra(Intent.EXTRA_CLIENT_INTENT); if (clientIntent != null) { clientLabel = service.getIntExtra(Intent.EXTRA_CLIENT_LABEL, 0); if (clientLabel != 0) { // There are no useful extras in the intent, trash them. // System code calling with this stuff just needs to know // this will happen. service = service.cloneFilter(); } } } // 把要绑定的服务看作一个Activity？后面还有相关的判断 if ((flags&Context.BIND_TREAT_LIKE_ACTIVITY) != 0) { // 检查权限，如果没有权限会直接报异常结束函数 mAm.enforceCallingPermission(android.Manifest.permission.MANAGE_ACTIVITY_STACKS, "BIND_TREAT_LIKE_ACTIVITY"); } // 如果要请求管理白名单，但又不是系统应用，则报异常 if ((flags & Context.BIND_ALLOW_WHITELIST_MANAGEMENT) != 0 && !isCallerSystem) { throw new SecurityException( "Non-system caller " + caller + " (pid=" + Binder.getCallingPid() + ") set BIND_ALLOW_WHITELIST_MANAGEMENT when binding service " + service); } // 调用者在前台？ final boolean callerFg = callerApp.setSchedGroup != ProcessList.SCHED_GROUP_BACKGROUND; final boolean isBindExternal = (flags & Context.BIND_EXTERNAL_SERVICE) != 0; //ServiceLookupResult包含一个ServiceRecord成员和一个权限字符串 ServiceLookupResult res = retrieveServiceLocked(service, resolvedType, callingPackage, Binder.getCallingPid(), Binder.getCallingUid(), userId, true, callerFg, isBindExternal); if (res == null) { return 0; } if (res.record == null) { return -1; } ServiceRecord s = res.record; boolean permissionsReviewRequired = false; // 是否需要让用户预览所需权限，这一段没仔细看 // If permissions need a review before any of the app components can run, // we schedule binding to the service but do not start its process, then // we launch a review activity to which is passed a callback to invoke // when done to start the bound service's process to completing the binding. if (mAm.mPermissionReviewRequired) { if (mAm.getPackageManagerInternalLocked().isPermissionsReviewRequired( s.packageName, s.userId)) { permissionsReviewRequired = true; // Show a permission review UI only for binding from a foreground app if (!callerFg) { Slog.w(TAG, "u" + s.userId + " Binding to a service in package" + s.packageName + " requires a permissions review"); return 0; } final ServiceRecord serviceRecord = s; final Intent serviceIntent = service; RemoteCallback callback = new RemoteCallback( new RemoteCallback.OnResultListener() { @Override public void onResult(Bundle result) { synchronized(mAm) { final long identity = Binder.clearCallingIdentity(); try { if (!mPendingServices.contains(serviceRecord)) { return; } // If there is still a pending record, then the service // binding request is still valid, so hook them up. We // proceed only if the caller cleared the review requirement // otherwise we unbind because the user didn't approve. if (!mAm.getPackageManagerInternalLocked() .isPermissionsReviewRequired( serviceRecord.packageName, serviceRecord.userId)) { try { bringUpServiceLocked(serviceRecord, serviceIntent.getFlags(), callerFg, false, false); } catch (RemoteException e) { /* ignore - local call */ } } else { unbindServiceLocked(connection); } } finally { Binder.restoreCallingIdentity(identity); } } } }); final Intent intent = new Intent(Intent.ACTION_REVIEW_PERMISSIONS); intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS); intent.putExtra(Intent.EXTRA_PACKAGE_NAME, s.packageName); intent.putExtra(Intent.EXTRA_REMOTE_CALLBACK, callback); if (DEBUG_PERMISSIONS_REVIEW) { Slog.i(TAG, "u" + s.userId + " Launching permission review for package " + s.packageName); } mAm.mHandler.post(new Runnable() { @Override public void run() { mAm.mContext.startActivityAsUser(intent, new UserHandle(userId)); } }); } } final long origId = Binder.clearCallingIdentity(); try { // 检查这个服务是不是在要重启的列表（还有个这个列表？）里，如果是就移除 if (unscheduleServiceRestartLocked(s, callerApp.info.uid, false)) { if (DEBUG_SERVICE) Slog.v(TAG_SERVICE, "BIND SERVICE WHILE RESTART PENDING: " + s); } // 是否有自动创建标志 if ((flags&Context.BIND_AUTO_CREATE) != 0) { s.lastActivity = SystemClock.uptimeMillis(); // 如果已连接这个服务的连接都没有BIND_AUTO_CREATE标志 if (!s.hasAutoCreateConnections()) { // This is the first binding, let the tracker know. ServiceState stracker = s.getTracker(); if (stracker != null) { stracker.setBound(true, mAm.mProcessStats.getMemFactorLocked(), s.lastActivity); } } } // 和ActivityManagerService联系起来？ mAm.startAssociationLocked(callerApp.uid, callerApp.processName, callerApp.curProcState, s.appInfo.uid, s.name, s.processName); // Once the apps have become associated, if one of them is caller is ephemeral // the target app should now be able to see the calling app mAm.grantEphemeralAccessLocked(callerApp.userId, service, s.appInfo.uid, UserHandle.getAppId(callerApp.uid)); AppBindRecord b = s.retrieveAppBindingLocked(service, callerApp); ConnectionRecord c = new ConnectionRecord(b, activity, connection, flags, clientLabel, clientIntent); IBinder binder = connection.asBinder(); ArrayList<ConnectionRecord> clist = s.connections.get(binder); if (clist == null) { clist = new ArrayList<ConnectionRecord>(); s.connections.put(binder, clist); } clist.add(c); b.connections.add(c); if (activity != null) { if (activity.connections == null) { activity.connections = new HashSet<ConnectionRecord>(); } activity.connections.add(c); } b.client.connections.add(c); if ((c.flags&Context.BIND_ABOVE_CLIENT) != 0) { b.client.hasAboveClient = true; } if ((c.flags&Context.BIND_ALLOW_WHITELIST_MANAGEMENT) != 0) { s.whitelistManager = true; } if (s.app != null) { updateServiceClientActivitiesLocked(s.app, c, true); } clist = mServiceConnections.get(binder); if (clist == null) { clist = new ArrayList<ConnectionRecord>(); mServiceConnections.put(binder, clist); } clist.add(c); // bringUpServiceLocked这里是启动service的地方，调用路径bringUpServiceLocked->realStartServiceLocked-> // app.thread.scheduleCreateService->ActivityThread.scheduleCreateService->ActivityThread.handleCreateService，如果启动成功则返回0 if ((flags&Context.BIND_AUTO_CREATE) != 0) { s.lastActivity = SystemClock.uptimeMillis(); if (bringUpServiceLocked(s, service.getFlags(), callerFg, false, permissionsReviewRequired) != null) { return 0; } } if (s.app != null) { if ((flags&Context.BIND_TREAT_LIKE_ACTIVITY) != 0) { s.app.treatLikeActivity = true; } if (s.whitelistManager) { s.app.whitelistManager = true; } // This could have made the service more important. mAm.updateLruProcessLocked(s.app, s.app.hasClientActivities || s.app.treatLikeActivity, b.client); mAm.updateOomAdjLocked(s.app, true); } if (DEBUG_SERVICE) Slog.v(TAG_SERVICE, "Bind " + s + " with " + b + ": received=" + b.intent.received + " apps=" + b.intent.apps.size() + " doRebind=" + b.intent.doRebind); if (s.app != null && b.intent.received) { // 如果服务已经运行，则立刻发布connection // Service is already running, so we can immediately // publish the connection. try { c.conn.connected(s.name, b.intent.binder, false); } catch (Exception e) { Slog.w(TAG, "Failure sending service " + s.shortName + " to connection " + c.conn.asBinder() + " (in " + c.binding.client.processName + ")", e); } // If this is the first app connected back to this binding, // and the service had previously asked to be told when // rebound, then do so. if (b.intent.apps.size() == 1 && b.intent.doRebind) { requestServiceBindingLocked(s, b.intent, callerFg, true); } } else if (!b.intent.requested) { requestServiceBindingLocked(s, b.intent, callerFg, false); } getServiceMapLocked(s.userId).ensureNotStartingBackgroundLocked(s); } finally { Binder.restoreCallingIdentity(origId); } return 1; } |
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