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1 /*
2  * Copyright (C) 2024 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.providers.media;
18 
19 import android.annotation.NonNull;
20 import android.content.ContentResolver;
21 import android.content.res.AssetFileDescriptor;
22 import android.os.Bundle;
23 import android.os.CancellationSignal;
24 import android.os.ParcelFileDescriptor;
25 import android.os.Process;
26 import android.os.RemoteException;
27 import android.provider.IMPCancellationSignal;
28 import android.provider.IOpenAssetFileCallback;
29 import android.provider.IOpenFileCallback;
30 import android.provider.MediaStore;
31 import android.provider.OpenAssetFileRequest;
32 import android.provider.OpenFileRequest;
33 import android.provider.ParcelableException;
34 import android.util.Log;
35 
36 import com.android.providers.media.util.FileUtils;
37 import com.android.providers.media.util.StringUtils;
38 
39 import java.util.concurrent.Executor;
40 import java.util.concurrent.Executors;
41 import java.util.concurrent.ThreadFactory;
42 import java.util.concurrent.ThreadPoolExecutor;
43 import java.util.concurrent.atomic.AtomicInteger;
44 
45 /**
46  * Utility class used to open picker files asynchronously.
47  * It manages a {@link ThreadPoolExecutor} that is being used to schedule
48  * pending open file requests.
49  */
50 public class AsyncPickerFileOpener {
51     private static final String TAG = "AsyncPickerFileOpener";
52     private static final int THREAD_POOL_SIZE = 8;
53 
54     private static Executor sExecutor;
55 
56     private final MediaProvider mMediaProvider;
57     private final PickerUriResolver mPickerUriResolver;
58 
AsyncPickerFileOpener(@onNull MediaProvider mediaProvider, @NonNull PickerUriResolver pickerUriResolver)59     public AsyncPickerFileOpener(@NonNull MediaProvider mediaProvider,
60             @NonNull PickerUriResolver pickerUriResolver) {
61         mMediaProvider = mediaProvider;
62         mPickerUriResolver = pickerUriResolver;
63     }
64 
65     /**
66      * Schedules a new open file request to open the requested file asynchronously.
67      * It validates that the request is valid and the requester has access before enqueueing
68      * the request in the thread pool
69      */
scheduleOpenFileAsync(@onNull OpenFileRequest request, @NonNull LocalCallingIdentity callingIdentity)70     public void scheduleOpenFileAsync(@NonNull OpenFileRequest request,
71             @NonNull LocalCallingIdentity callingIdentity) {
72         Log.i(TAG, "Async open file request created for " + request.getUri());
73 
74         mPickerUriResolver.checkPermissionForRequireOriginalQueryParam(request.getUri(),
75                 callingIdentity);
76         mPickerUriResolver.checkUriPermission(request.getUri(), callingIdentity.pid,
77                 callingIdentity.uid);
78 
79         ensureExecutor();
80         sExecutor.execute(() -> openFileAsync(request, callingIdentity));
81     }
82 
openFileAsync(@onNull OpenFileRequest request, @NonNull LocalCallingIdentity callingIdentity)83     private void openFileAsync(@NonNull OpenFileRequest request,
84             @NonNull LocalCallingIdentity callingIdentity) {
85         final IMPCancellationSignal iCancellationSignal = request.getCancellationSignal();
86         final CancellationSignal cancellationSignal = iCancellationSignal != null
87                 ? ((MPCancellationSignal) iCancellationSignal).mCancellationSignal
88                 // explicitly create cancellation signal to help in case of caller death
89                 : new CancellationSignal();
90 
91         final IOpenFileCallback callback = request.getCallback();
92         try {
93             // cancel the operation in case the requester has died
94             callback.asBinder().linkToDeath(cancellationSignal::cancel, 0);
95         } catch (RemoteException e) {
96             Log.d(TAG, "Caller with uid " + callingIdentity.uid + " that requested opening "
97                     + request.getUri() + " has died already");
98             return;
99         }
100 
101         final int tid = Process.myTid();
102         mMediaProvider.addToPendingOpenMap(tid, callingIdentity.uid);
103 
104         ParcelFileDescriptor pfd = null;
105         try {
106             cancellationSignal.throwIfCanceled();
107             pfd = mPickerUriResolver.openFile(
108                     request.getUri(), "r", cancellationSignal, callingIdentity);
109             callback.onSuccess(pfd);
110         } catch (RemoteException ignore) {
111             // ignore remote Exception as it means that the requester has died
112         } catch (Exception e) {
113             try {
114                 Log.e(TAG, "Open file operation failed. Failed to open " + request.getUri(), e);
115                 callback.onFailure(new ParcelableException(e));
116             } catch (RemoteException ignore) {
117                 // ignore remote exception as it means the requester has died
118             }
119         }  finally {
120             if (pfd != null) {
121                 // Closing the file descriptor on this side as Binder will dup it
122                 FileUtils.closeQuietly(pfd);
123             }
124             mMediaProvider.removeFromPendingOpenMap(tid);
125         }
126     }
127 
128     /**
129      * Schedules a new open asset file request to open the requested file asynchronously.
130      * It validates that the request is valid and the requester has access before enqueueing
131      * the request in the thread pool
132      */
scheduleOpenAssetFileAsync(@onNull OpenAssetFileRequest request, @NonNull LocalCallingIdentity callingIdentity)133     public void scheduleOpenAssetFileAsync(@NonNull OpenAssetFileRequest request,
134             @NonNull LocalCallingIdentity callingIdentity) {
135         Log.i(TAG, "Async open asset file request created for " + request.getUri());
136 
137         mPickerUriResolver.checkPermissionForRequireOriginalQueryParam(request.getUri(),
138                 callingIdentity);
139         mPickerUriResolver.checkUriPermission(request.getUri(), callingIdentity.pid,
140                 callingIdentity.uid);
141 
142         ensureExecutor();
143         sExecutor.execute(() -> openAssetFileAsync(request, callingIdentity));
144     }
145 
openAssetFileAsync(@onNull OpenAssetFileRequest request, @NonNull LocalCallingIdentity callingIdentity)146     private void openAssetFileAsync(@NonNull OpenAssetFileRequest request,
147             @NonNull LocalCallingIdentity callingIdentity) {
148         final IMPCancellationSignal iCancellationSignal = request.getCancellationSignal();
149         final CancellationSignal cancellationSignal = iCancellationSignal != null
150                 ? ((MPCancellationSignal) iCancellationSignal).mCancellationSignal
151                 // explicitly create cancellation signal to help in case of caller death
152                 : new CancellationSignal();
153 
154         final IOpenAssetFileCallback callback = request.getCallback();
155         try {
156             // cancel the operation in case the requester has died
157             callback.asBinder().linkToDeath(cancellationSignal::cancel, 0);
158         } catch (RemoteException e) {
159             Log.d(TAG, "Caller with uid " + request.getUri() + " that requested opening "
160                     + request.getUri() + " has died already");
161             return;
162         }
163 
164         final Bundle opts = request.getOpts();
165         final boolean wantsThumb = (opts != null) && opts.containsKey(ContentResolver.EXTRA_SIZE)
166                 && StringUtils.startsWithIgnoreCase(request.getMimeType(), "image/");
167 
168         if (opts != null) {
169             opts.remove(MediaStore.EXTRA_MODE);
170         }
171 
172         final int tid = Process.myTid();
173         mMediaProvider.addToPendingOpenMap(tid, callingIdentity.uid);
174         AssetFileDescriptor afd = null;
175         try {
176             cancellationSignal.throwIfCanceled();
177             afd = mPickerUriResolver.openTypedAssetFile(
178                     request.getUri(), request.getMimeType(), opts, cancellationSignal,
179                     callingIdentity, wantsThumb);
180             callback.onSuccess(afd);
181         } catch (RemoteException ignore) {
182             // ignore remote Exception as it means that the requester has died
183         } catch (Exception e) {
184             Log.e(TAG, "Open file operation failed. Failed to open " + request.getUri(), e);
185             try {
186                 callback.onFailure(new ParcelableException(e));
187             } catch (RemoteException ignore) {
188                 // ignore remote Exception as it means that the requester has died
189             }
190         }  finally {
191             if (afd != null) {
192                 // Closing the file descriptor on this side as Binder will dup it
193                 FileUtils.closeQuietly(afd);
194             }
195             mMediaProvider.removeFromPendingOpenMap(tid);
196         }
197     }
198 
ensureExecutor()199     private static void ensureExecutor() {
200         synchronized (AsyncPickerFileOpener.class) {
201             if (sExecutor == null) {
202                 sExecutor = Executors.newFixedThreadPool(THREAD_POOL_SIZE, new ThreadFactory() {
203                     final AtomicInteger mCount = new AtomicInteger(1);
204 
205                     @Override
206                     public Thread newThread(Runnable r) {
207                         return new Thread(
208                                 r, "AsyncPickerFileOpener#" + mCount.getAndIncrement());
209                     }
210                 });
211             }
212         }
213     }
214 }
215