1 /*
2  * Copyright (C) 2012 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.gallery3d.filtershow.provider;
18 
19 import android.content.ContentProvider;
20 import android.content.ContentValues;
21 import android.database.Cursor;
22 import android.database.MatrixCursor;
23 import android.net.Uri;
24 import android.os.ConditionVariable;
25 import android.os.ParcelFileDescriptor;
26 import android.provider.BaseColumns;
27 import android.provider.MediaStore;
28 import android.provider.OpenableColumns;
29 
30 import java.io.File;
31 import java.io.FileNotFoundException;
32 import java.io.IOException;
33 
34 public class SharedImageProvider extends ContentProvider {
35 
36     private static final String LOGTAG = "SharedImageProvider";
37 
38     public static final String MIME_TYPE = "image/jpeg";
39     public static final String AUTHORITY =
40             "com.android.gallery3d.filtershow.provider.SharedImageProvider";
41     public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/image");
42     public static final String PREPARE = "prepare";
43 
44     public static String LOCAL_PATH = (new File(CONTENT_URI.getPath())).getAbsolutePath();
45 
46     private final String[] mMimeStreamType = {
47             MIME_TYPE
48     };
49 
50     private static ConditionVariable mImageReadyCond = new ConditionVariable(false);
51 
52     @Override
delete(Uri arg0, String arg1, String[] arg2)53     public int delete(Uri arg0, String arg1, String[] arg2) {
54         return 0;
55     }
56 
57     @Override
getType(Uri arg0)58     public String getType(Uri arg0) {
59         return MIME_TYPE;
60     }
61 
62     @Override
getStreamTypes(Uri arg0, String mimeTypeFilter)63     public String[] getStreamTypes(Uri arg0, String mimeTypeFilter) {
64         return mMimeStreamType;
65     }
66 
67     @Override
insert(Uri uri, ContentValues values)68     public Uri insert(Uri uri, ContentValues values) {
69         if (values.containsKey(PREPARE)) {
70             if (values.getAsBoolean(PREPARE)) {
71                 mImageReadyCond.close();
72             } else {
73                 mImageReadyCond.open();
74             }
75         }
76         return null;
77     }
78 
79     @Override
update(Uri arg0, ContentValues arg1, String arg2, String[] arg3)80     public int update(Uri arg0, ContentValues arg1, String arg2, String[] arg3) {
81         return 0;
82     }
83 
84     @Override
onCreate()85     public boolean onCreate() {
86         return true;
87     }
88 
89     @Override
query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)90     public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
91             String sortOrder) {
92         String uriPath = uri.getLastPathSegment();
93         if (uriPath == null) {
94             return null;
95         }
96         if (projection == null) {
97             projection = new String[]{
98                     BaseColumns._ID,
99                     MediaStore.MediaColumns.DATA,
100                     OpenableColumns.DISPLAY_NAME,
101                     OpenableColumns.SIZE
102             };
103         }
104         // If we receive a query on display name or size,
105         // we should block until the image is ready
106         mImageReadyCond.block();
107 
108         File path = new File(uriPath);
109 
110         MatrixCursor cursor = new MatrixCursor(projection);
111         Object[] columns = new Object[projection.length];
112         for (int i = 0; i < projection.length; i++) {
113             if (projection[i].equalsIgnoreCase(BaseColumns._ID)) {
114                 columns[i] = 0;
115             } else if (projection[i].equalsIgnoreCase(MediaStore.MediaColumns.DATA)) {
116                 columns[i] = uri;
117             } else if (projection[i].equalsIgnoreCase(OpenableColumns.DISPLAY_NAME)) {
118                 columns[i] = path.getName();
119             } else if (projection[i].equalsIgnoreCase(OpenableColumns.SIZE)) {
120                 columns[i] = path.length();
121             }
122         }
123         cursor.addRow(columns);
124 
125         return cursor;
126     }
127 
128     @Override
openFile(Uri uri, String mode)129     public ParcelFileDescriptor openFile(Uri uri, String mode)
130             throws FileNotFoundException {
131         String uriPath = uri.getLastPathSegment();
132         if (uriPath == null) {
133             return null;
134         }
135         // Here we need to block until the image is ready
136         mImageReadyCond.block();
137         File path = new File(uriPath);
138         ensureValidImagePath(path);
139         int imode = 0;
140         imode |= ParcelFileDescriptor.MODE_READ_ONLY;
141         return ParcelFileDescriptor.open(path, imode);
142     }
143 
144     /**
145      * Ensure that the provided file path is part of the image directory.
146      * Prevent unauthorized access to other directories by path traversal.
147      * Throw security exception for paths outside the directory.
148      *
149      * @param path The path of the file to check. This path is expected to point to the image
150      *             directory.
151      * @throws SecurityException     Throws SecurityException if the path is not part of the image
152      *                               directory.
153      * @throws FileNotFoundException Throws FileNotFoundException if there is
154      *                               no file associated with the given URI.
155      */
ensureValidImagePath(File path)156     private void ensureValidImagePath(File path) throws FileNotFoundException {
157         try {
158             if (!path.getCanonicalPath().startsWith(LOCAL_PATH)) {
159                 throw new SecurityException(
160                         "The requested file path is not part of the image directory");
161             }
162         } catch (IOException e) {
163             throw new FileNotFoundException(e.getMessage());
164         }
165     }
166 }
167