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"Enhanced" FileProvider with support for external secondary paths (based on 27.0.2)
/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.support.v4.content;
import static org.xmlpull.v1.XmlPullParser.END_DOCUMENT;
import static org.xmlpull.v1.XmlPullParser.START_TAG;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.xmlpull.v1.XmlPullParserException;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ProviderInfo;
import android.content.res.XmlResourceParser;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.net.Uri;
import android.os.Environment;
import android.os.ParcelFileDescriptor;
import android.provider.OpenableColumns;
import android.support.annotation.GuardedBy;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.text.TextUtils;
import android.webkit.MimeTypeMap;
/**
* FileProvider is a special subclass of {@link ContentProvider} that facilitates secure sharing
* of files associated with an app by creating a <code>content://</code> {@link Uri} for a file
* instead of a <code>file:///</code> {@link Uri}.
* <p>
* A content URI allows you to grant read and write access using
* temporary access permissions. When you create an {@link Intent} containing
* a content URI, in order to send the content URI
* to a client app, you can also call {@link Intent#setFlags(int) Intent.setFlags()} to add
* permissions. These permissions are available to the client app for as long as the stack for
* a receiving {@link android.app.Activity} is active. For an {@link Intent} going to a
* {@link android.app.Service}, the permissions are available as long as the
* {@link android.app.Service} is running.
* <p>
* In comparison, to control access to a <code>file:///</code> {@link Uri} you have to modify the
* file system permissions of the underlying file. The permissions you provide become available to
* <em>any</em> app, and remain in effect until you change them. This level of access is
* fundamentally insecure.
* <p>
* The increased level of file access security offered by a content URI
* makes FileProvider a key part of Android's security infrastructure.
* <p>
* This overview of FileProvider includes the following topics:
* </p>
* <ol>
* <li><a href="#ProviderDefinition">Defining a FileProvider</a></li>
* <li><a href="#SpecifyFiles">Specifying Available Files</a></li>
* <li><a href="#GetUri">Retrieving the Content URI for a File</li>
* <li><a href="#Permissions">Granting Temporary Permissions to a URI</a></li>
* <li><a href="#ServeUri">Serving a Content URI to Another App</a></li>
* </ol>
* <h3 id="ProviderDefinition">Defining a FileProvider</h3>
* <p>
* Since the default functionality of FileProvider includes content URI generation for files, you
* don't need to define a subclass in code. Instead, you can include a FileProvider in your app
* by specifying it entirely in XML. To specify the FileProvider component itself, add a
* <code><a href="{@docRoot}guide/topics/manifest/provider-element.html">&lt;provider&gt;</a></code>
* element to your app manifest. Set the <code>android:name</code> attribute to
* <code>android.support.v4.content.FileProvider</code>. Set the <code>android:authorities</code>
* attribute to a URI authority based on a domain you control; for example, if you control the
* domain <code>mydomain.com</code> you should use the authority
* <code>com.mydomain.fileprovider</code>. Set the <code>android:exported</code> attribute to
* <code>false</code>; the FileProvider does not need to be public. Set the
* <a href="{@docRoot}guide/topics/manifest/provider-element.html#gprmsn"
* >android:grantUriPermissions</a> attribute to <code>true</code>, to allow you
* to grant temporary access to files. For example:
* <pre class="prettyprint">
* &lt;manifest&gt;
* ...
* &lt;application&gt;
* ...
* &lt;provider
* android:name="android.support.v4.content.FileProvider"
* android:authorities="com.mydomain.fileprovider"
* android:exported="false"
* android:grantUriPermissions="true"&gt;
* ...
* &lt;/provider&gt;
* ...
* &lt;/application&gt;
* &lt;/manifest&gt;</pre>
* <p>
* If you want to override any of the default behavior of FileProvider methods, extend
* the FileProvider class and use the fully-qualified class name in the <code>android:name</code>
* attribute of the <code>&lt;provider&gt;</code> element.
* <h3 id="SpecifyFiles">Specifying Available Files</h3>
* A FileProvider can only generate a content URI for files in directories that you specify
* beforehand. To specify a directory, specify the its storage area and path in XML, using child
* elements of the <code>&lt;paths&gt;</code> element.
* For example, the following <code>paths</code> element tells FileProvider that you intend to
* request content URIs for the <code>images/</code> subdirectory of your private file area.
* <pre class="prettyprint">
* &lt;paths xmlns:android="http://schemas.android.com/apk/res/android"&gt;
* &lt;files-path name="my_images" path="images/"/&gt;
* ...
* &lt;/paths&gt;
* </pre>
* <p>
* The <code>&lt;paths&gt;</code> element must contain one or more of the following child elements:
* </p>
* <dl>
* <dt>
* <pre class="prettyprint">
* &lt;files-path name="<i>name</i>" path="<i>path</i>" /&gt;
* </pre>
* </dt>
* <dd>
* Represents files in the <code>files/</code> subdirectory of your app's internal storage
* area. This subdirectory is the same as the value returned by {@link Context#getFilesDir()
* Context.getFilesDir()}.
* </dd>
* <dt>
* <pre>
* &lt;cache-path name="<i>name</i>" path="<i>path</i>" /&gt;
* </pre>
* <dt>
* <dd>
* Represents files in the cache subdirectory of your app's internal storage area. The root path
* of this subdirectory is the same as the value returned by {@link Context#getCacheDir()
* getCacheDir()}.
* </dd>
* <dt>
* <pre class="prettyprint">
* &lt;external-path name="<i>name</i>" path="<i>path</i>" /&gt;
* </pre>
* </dt>
* <dd>
* Represents files in the root of the external storage area. The root path of this subdirectory
* is the same as the value returned by
* {@link Environment#getExternalStorageDirectory() Environment.getExternalStorageDirectory()}.
* </dd>
* <dt>
* <pre class="prettyprint">
* &lt;external-files-path name="<i>name</i>" path="<i>path</i>" /&gt;
* </pre>
* </dt>
* <dd>
* Represents files in the root of your app's external storage area. The root path of this
* subdirectory is the same as the value returned by
* {@code Context#getExternalFilesDir(String) Context.getExternalFilesDir(null)}.
* </dd>
* <dt>
* <pre class="prettyprint">
* &lt;external-cache-path name="<i>name</i>" path="<i>path</i>" /&gt;
* </pre>
* </dt>
* <dd>
* Represents files in the root of your app's external cache area. The root path of this
* subdirectory is the same as the value returned by
* {@link Context#getExternalCacheDir() Context.getExternalCacheDir()}.
* </dd>
* </dl>
* <p>
* These child elements all use the same attributes:
* </p>
* <dl>
* <dt>
* <code>name="<i>name</i>"</code>
* </dt>
* <dd>
* A URI path segment. To enforce security, this value hides the name of the subdirectory
* you're sharing. The subdirectory name for this value is contained in the
* <code>path</code> attribute.
* </dd>
* <dt>
* <code>path="<i>path</i>"</code>
* </dt>
* <dd>
* The subdirectory you're sharing. While the <code>name</code> attribute is a URI path
* segment, the <code>path</code> value is an actual subdirectory name. Notice that the
* value refers to a <b>subdirectory</b>, not an individual file or files. You can't
* share a single file by its file name, nor can you specify a subset of files using
* wildcards.
* </dd>
* </dl>
* <p>
* You must specify a child element of <code>&lt;paths&gt;</code> for each directory that contains
* files for which you want content URIs. For example, these XML elements specify two directories:
* <pre class="prettyprint">
* &lt;paths xmlns:android="http://schemas.android.com/apk/res/android"&gt;
* &lt;files-path name="my_images" path="images/"/&gt;
* &lt;files-path name="my_docs" path="docs/"/&gt;
* &lt;/paths&gt;
* </pre>
* <p>
* Put the <code>&lt;paths&gt;</code> element and its children in an XML file in your project.
* For example, you can add them to a new file called <code>res/xml/file_paths.xml</code>.
* To link this file to the FileProvider, add a
* <a href="{@docRoot}guide/topics/manifest/meta-data-element.html">&lt;meta-data&gt;</a> element
* as a child of the <code>&lt;provider&gt;</code> element that defines the FileProvider. Set the
* <code>&lt;meta-data&gt;</code> element's "android:name" attribute to
* <code>android.support.FILE_PROVIDER_PATHS</code>. Set the element's "android:resource" attribute
* to <code>&#64;xml/file_paths</code> (notice that you don't specify the <code>.xml</code>
* extension). For example:
* <pre class="prettyprint">
* &lt;provider
* android:name="android.support.v4.content.FileProvider"
* android:authorities="com.mydomain.fileprovider"
* android:exported="false"
* android:grantUriPermissions="true"&gt;
* &lt;meta-data
* android:name="android.support.FILE_PROVIDER_PATHS"
* android:resource="&#64;xml/file_paths" /&gt;
* &lt;/provider&gt;
* </pre>
* <h3 id="GetUri">Generating the Content URI for a File</h3>
* <p>
* To share a file with another app using a content URI, your app has to generate the content URI.
* To generate the content URI, create a new {@link File} for the file, then pass the {@link File}
* to {@link #getUriForFile(Context, String, File) getUriForFile()}. You can send the content URI
* returned by {@link #getUriForFile(Context, String, File) getUriForFile()} to another app in an
* {@link Intent}. The client app that receives the content URI can open the file
* and access its contents by calling
* {@link android.content.ContentResolver#openFileDescriptor(Uri, String)
* ContentResolver.openFileDescriptor} to get a {@link ParcelFileDescriptor}.
* <p>
* For example, suppose your app is offering files to other apps with a FileProvider that has the
* authority <code>com.mydomain.fileprovider</code>. To get a content URI for the file
* <code>default_image.jpg</code> in the <code>images/</code> subdirectory of your internal storage
* add the following code:
* <pre class="prettyprint">
* File imagePath = new File(Context.getFilesDir(), "images");
* File newFile = new File(imagePath, "default_image.jpg");
* Uri contentUri = getUriForFile(getContext(), "com.mydomain.fileprovider", newFile);
* </pre>
* As a result of the previous snippet,
* {@link #getUriForFile(Context, String, File) getUriForFile()} returns the content URI
* <code>content://com.mydomain.fileprovider/my_images/default_image.jpg</code>.
* <h3 id="Permissions">Granting Temporary Permissions to a URI</h3>
* To grant an access permission to a content URI returned from
* {@link #getUriForFile(Context, String, File) getUriForFile()}, do one of the following:
* <ul>
* <li>
* Call the method
* {@link Context#grantUriPermission(String, Uri, int)
* Context.grantUriPermission(package, Uri, mode_flags)} for the <code>content://</code>
* {@link Uri}, using the desired mode flags. This grants temporary access permission for the
* content URI to the specified package, according to the value of the
* the <code>mode_flags</code> parameter, which you can set to
* {@link Intent#FLAG_GRANT_READ_URI_PERMISSION}, {@link Intent#FLAG_GRANT_WRITE_URI_PERMISSION}
* or both. The permission remains in effect until you revoke it by calling
* {@link Context#revokeUriPermission(Uri, int) revokeUriPermission()} or until the device
* reboots.
* </li>
* <li>
* Put the content URI in an {@link Intent} by calling {@link Intent#setData(Uri) setData()}.
* </li>
* <li>
* Next, call the method {@link Intent#setFlags(int) Intent.setFlags()} with either
* {@link Intent#FLAG_GRANT_READ_URI_PERMISSION} or
* {@link Intent#FLAG_GRANT_WRITE_URI_PERMISSION} or both.
* </li>
* <li>
* Finally, send the {@link Intent} to
* another app. Most often, you do this by calling
* {@link android.app.Activity#setResult(int, Intent) setResult()}.
* <p>
* Permissions granted in an {@link Intent} remain in effect while the stack of the receiving
* {@link android.app.Activity} is active. When the stack finishes, the permissions are
* automatically removed. Permissions granted to one {@link android.app.Activity} in a client
* app are automatically extended to other components of that app.
* </p>
* </li>
* </ul>
* <h3 id="ServeUri">Serving a Content URI to Another App</h3>
* <p>
* There are a variety of ways to serve the content URI for a file to a client app. One common way
* is for the client app to start your app by calling
* {@link android.app.Activity#startActivityForResult(Intent, int, Bundle) startActivityResult()},
* which sends an {@link Intent} to your app to start an {@link android.app.Activity} in your app.
* In response, your app can immediately return a content URI to the client app or present a user
* interface that allows the user to pick a file. In the latter case, once the user picks the file
* your app can return its content URI. In both cases, your app returns the content URI in an
* {@link Intent} sent via {@link android.app.Activity#setResult(int, Intent) setResult()}.
* </p>
* <p>
* You can also put the content URI in a {@link android.content.ClipData} object and then add the
* object to an {@link Intent} you send to a client app. To do this, call
* {@link Intent#setClipData(ClipData) Intent.setClipData()}. When you use this approach, you can
* add multiple {@link android.content.ClipData} objects to the {@link Intent}, each with its own
* content URI. When you call {@link Intent#setFlags(int) Intent.setFlags()} on the {@link Intent}
* to set temporary access permissions, the same permissions are applied to all of the content
* URIs.
* </p>
* <p class="note">
* <strong>Note:</strong> The {@link Intent#setClipData(ClipData) Intent.setClipData()} method is
* only available in platform version 16 (Android 4.1) and later. If you want to maintain
* compatibility with previous versions, you should send one content URI at a time in the
* {@link Intent}. Set the action to {@link Intent#ACTION_SEND} and put the URI in data by calling
* {@link Intent#setData setData()}.
* </p>
* <h3 id="">More Information</h3>
* <p>
* To learn more about FileProvider, see the Android training class
* <a href="{@docRoot}training/secure-file-sharing/index.html">Sharing Files Securely with URIs</a>.
* </p>
*/
public class ExtendedFileProvider extends ContentProvider {
private static final String[] COLUMNS = {
OpenableColumns.DISPLAY_NAME, OpenableColumns.SIZE };
private static final String
META_DATA_FILE_PROVIDER_PATHS = "android.support.FILE_PROVIDER_PATHS";
private static final String TAG_ROOT_PATH = "root-path";
private static final String TAG_FILES_PATH = "files-path";
private static final String TAG_CACHE_PATH = "cache-path";
private static final String TAG_EXTERNAL = "external-path";
private static final String TAG_EXTERNAL_FILES = "external-files-path";
private static final String TAG_EXTERNAL_CACHE = "external-cache-path";
private static final String ATTR_NAME = "name";
private static final String ATTR_PATH = "path";
private static final File DEVICE_ROOT = new File("/");
@GuardedBy("sCache")
private static HashMap<String, PathStrategy> sCache = new HashMap<String, PathStrategy>();
private PathStrategy mStrategy;
/**
* The default FileProvider implementation does not need to be initialized. If you want to
* override this method, you must provide your own subclass of FileProvider.
*/
@Override
public boolean onCreate() {
return true;
}
/**
* After the FileProvider is instantiated, this method is called to provide the system with
* information about the provider.
*
* @param context A {@link Context} for the current component.
* @param info A {@link ProviderInfo} for the new provider.
*/
@Override
public void attachInfo(@NonNull Context context, @NonNull ProviderInfo info) {
super.attachInfo(context, info);
// Sanity check our security
if (info.exported) {
throw new SecurityException("Provider must not be exported");
}
if (!info.grantUriPermissions) {
throw new SecurityException("Provider must grant uri permissions");
}
mStrategy = getPathStrategy(context, info.authority);
}
/**
* Return a content URI for a given {@link File}. Specific temporary
* permissions for the content URI can be set with
* {@link Context#grantUriPermission(String, Uri, int)}, or added
* to an {@link Intent} by calling {@link Intent#setData(Uri) setData()} and then
* {@link Intent#setFlags(int) setFlags()}; in both cases, the applicable flags are
* {@link Intent#FLAG_GRANT_READ_URI_PERMISSION} and
* {@link Intent#FLAG_GRANT_WRITE_URI_PERMISSION}. A FileProvider can only return a
* <code>content</code> {@link Uri} for file paths defined in their <code>&lt;paths&gt;</code>
* meta-data element. See the Class Overview for more information.
*
* @param context A {@link Context} for the current component.
* @param authority The authority of a {@link ExtendedFileProvider} defined in a
* {@code <provider>} element in your app's manifest.
* @param file A {@link File} pointing to the filename for which you want a
* <code>content</code> {@link Uri}.
*
* @return A content URI for the file.
*
* @throws IllegalArgumentException When the given {@link File} is outside
* the paths supported by the provider.
*/
public static Uri getUriForFile(@NonNull Context context, @NonNull String authority,
@NonNull File file) {
final PathStrategy strategy = getPathStrategy(context, authority);
return strategy.getUriForFile(file);
}
/**
* Use a content URI returned by
* {@link #getUriForFile(Context, String, File) getUriForFile()} to get information about a file
* managed by the FileProvider.
* FileProvider reports the column names defined in {@link OpenableColumns}:
* <ul>
* <li>{@link OpenableColumns#DISPLAY_NAME}</li>
* <li>{@link OpenableColumns#SIZE}</li>
* </ul>
* For more information, see
* {@link ContentProvider#query(Uri, String[], String, String[], String)
* ContentProvider.query()}.
*
* @param uri A content URI returned by {@link #getUriForFile}.
* @param projection The list of columns to put into the {@link Cursor}. If null all columns are
* included.
* @param selection Selection criteria to apply. If null then all data that matches the content
* URI is returned.
* @param selectionArgs An array of {@link String}, containing arguments to bind to
* the <i>selection</i> parameter. The <i>query</i> method scans <i>selection</i> from left to
* right and iterates through <i>selectionArgs</i>, replacing the current "?" character in
* <i>selection</i> with the value at the current position in <i>selectionArgs</i>. The
* values are bound to <i>selection</i> as {@link String} values.
* @param sortOrder A {@link String} containing the column name(s) on which to sort
* the resulting {@link Cursor}.
*
* @return A {@link Cursor} containing the results of the query.
*/
@Override
public Cursor query(@NonNull Uri uri, @Nullable String[] projection, @Nullable String selection,
@Nullable String[] selectionArgs,
@Nullable String sortOrder) {
// ContentProvider has already checked granted permissions
final File file = mStrategy.getFileForUri(uri);
if (projection == null) {
projection = COLUMNS;
}
String[] cols = new String[projection.length];
Object[] values = new Object[projection.length];
int i = 0;
for (String col : projection) {
if (OpenableColumns.DISPLAY_NAME.equals(col)) {
cols[i] = OpenableColumns.DISPLAY_NAME;
values[i++] = file.getName();
} else if (OpenableColumns.SIZE.equals(col)) {
cols[i] = OpenableColumns.SIZE;
values[i++] = file.length();
}
}
cols = copyOf(cols, i);
values = copyOf(values, i);
final MatrixCursor cursor = new MatrixCursor(cols, 1);
cursor.addRow(values);
return cursor;
}
/**
* Returns the MIME type of a content URI returned by
* {@link #getUriForFile(Context, String, File) getUriForFile()}.
*
* @param uri A content URI returned by
* {@link #getUriForFile(Context, String, File) getUriForFile()}.
*
* @return If the associated file has an extension, the MIME type associated with that
* extension; otherwise <code>application/octet-stream</code>.
*/
@Override
public String getType(@NonNull Uri uri) {
// ContentProvider has already checked granted permissions
final File file = mStrategy.getFileForUri(uri);
final int lastDot = file.getName().lastIndexOf('.');
if (lastDot >= 0) {
final String extension = file.getName().substring(lastDot + 1);
final String mime = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
if (mime != null) {
return mime;
}
}
return "application/octet-stream";
}
/**
* By default, this method throws an {@link UnsupportedOperationException}. You must
* subclass FileProvider if you want to provide different functionality.
*/
@Override
public Uri insert(@NonNull Uri uri, ContentValues values) {
throw new UnsupportedOperationException("No external inserts");
}
/**
* By default, this method throws an {@link UnsupportedOperationException}. You must
* subclass FileProvider if you want to provide different functionality.
*/
@Override
public int update(@NonNull Uri uri, ContentValues values, @Nullable String selection,
@Nullable String[] selectionArgs) {
throw new UnsupportedOperationException("No external updates");
}
/**
* Deletes the file associated with the specified content URI, as
* returned by {@link #getUriForFile(Context, String, File) getUriForFile()}. Notice that this
* method does <b>not</b> throw an {@link IOException}; you must check its return value.
*
* @param uri A content URI for a file, as returned by
* {@link #getUriForFile(Context, String, File) getUriForFile()}.
* @param selection Ignored. Set to {@code null}.
* @param selectionArgs Ignored. Set to {@code null}.
*
* @return 1 if the delete succeeds; otherwise, 0.
*/
@Override
public int delete(@NonNull Uri uri, @Nullable String selection,
@Nullable String[] selectionArgs) {
// ContentProvider has already checked granted permissions
final File file = mStrategy.getFileForUri(uri);
return file.delete() ? 1 : 0;
}
/**
* By default, FileProvider automatically returns the
* {@link ParcelFileDescriptor} for a file associated with a <code>content://</code>
* {@link Uri}. To get the {@link ParcelFileDescriptor}, call
* {@link android.content.ContentResolver#openFileDescriptor(Uri, String)
* ContentResolver.openFileDescriptor}.
* <p>
* To override this method, you must provide your own subclass of FileProvider.
*
* @param uri A content URI associated with a file, as returned by
* {@link #getUriForFile(Context, String, File) getUriForFile()}.
* @param mode Access mode for the file. May be "r" for read-only access, "rw" for read and
* write access, or "rwt" for read and write access that truncates any existing file.
*
* @return A new {@link ParcelFileDescriptor} with which you can access the file.
*/
@Override
public ParcelFileDescriptor openFile(@NonNull Uri uri, @NonNull String mode)
throws FileNotFoundException {
// ContentProvider has already checked granted permissions
final File file = mStrategy.getFileForUri(uri);
final int fileMode = modeToMode(mode);
return ParcelFileDescriptor.open(file, fileMode);
}
/**
* Return {@link PathStrategy} for given authority, either by parsing or
* returning from cache.
*/
private static PathStrategy getPathStrategy(Context context, String authority) {
PathStrategy strat;
synchronized (sCache) {
strat = sCache.get(authority);
if (strat == null) {
try {
strat = parsePathStrategy(context, authority);
} catch (IOException e) {
throw new IllegalArgumentException(
"Failed to parse " + META_DATA_FILE_PROVIDER_PATHS + " meta-data", e);
} catch (XmlPullParserException e) {
throw new IllegalArgumentException(
"Failed to parse " + META_DATA_FILE_PROVIDER_PATHS + " meta-data", e);
}
sCache.put(authority, strat);
}
}
return strat;
}
/**
* Parse and return {@link PathStrategy} for given authority as defined in
* {@link #META_DATA_FILE_PROVIDER_PATHS} {@code <meta-data>}.
*
* @see #getPathStrategy(Context, String)
*/
private static PathStrategy parsePathStrategy(Context context, String authority)
throws IOException, XmlPullParserException {
final SimplePathStrategy strat = new SimplePathStrategy(authority);
final ProviderInfo info = context.getPackageManager()
.resolveContentProvider(authority, PackageManager.GET_META_DATA);
final XmlResourceParser in = info.loadXmlMetaData(
context.getPackageManager(), META_DATA_FILE_PROVIDER_PATHS);
if (in == null) {
throw new IllegalArgumentException(
"Missing " + META_DATA_FILE_PROVIDER_PATHS + " meta-data");
}
int type;
while ((type = in.next()) != END_DOCUMENT) {
if (type == START_TAG) {
final String tag = in.getName();
final String name = in.getAttributeValue(null, ATTR_NAME);
String path = in.getAttributeValue(null, ATTR_PATH);
List<File> targets = new ArrayList<>();
if (TAG_ROOT_PATH.equals(tag)) {
targets.add(DEVICE_ROOT);
} else if (TAG_FILES_PATH.equals(tag)) {
targets.add(context.getFilesDir());
} else if (TAG_CACHE_PATH.equals(tag)) {
targets.add(context.getCacheDir());
} else if (TAG_EXTERNAL.equals(tag)) {
targets.add(Environment.getExternalStorageDirectory());
} else if (TAG_EXTERNAL_FILES.equals(tag)) {
File[] externalFilesDirs = ContextCompat.getExternalFilesDirs(context, null);
targets.addAll(Arrays.asList(externalFilesDirs));
} else if (TAG_EXTERNAL_CACHE.equals(tag)) {
File[] externalCacheDirs = ContextCompat.getExternalCacheDirs(context);
targets.addAll(Arrays.asList(externalCacheDirs));
}
for (final File target : targets) {
strat.addRoot(name, buildPath(target, path));
}
}
}
return strat;
}
/**
* Strategy for mapping between {@link File} and {@link Uri}.
* <p>
* Strategies must be symmetric so that mapping a {@link File} to a
* {@link Uri} and then back to a {@link File} points at the original
* target.
* <p>
* Strategies must remain consistent across app launches, and not rely on
* dynamic state. This ensures that any generated {@link Uri} can still be
* resolved if your process is killed and later restarted.
*
* @see SimplePathStrategy
*/
interface PathStrategy {
/**
* Return a {@link Uri} that represents the given {@link File}.
*/
public Uri getUriForFile(File file);
/**
* Return a {@link File} that represents the given {@link Uri}.
*/
public File getFileForUri(Uri uri);
}
/**
* Strategy that provides access to files living under a narrow whitelist of
* filesystem roots. It will throw {@link SecurityException} if callers try
* accessing files outside the configured roots.
* <p>
* For example, if configured with
* {@code addRoot("myfiles", context.getFilesDir())}, then
* {@code context.getFileStreamPath("foo.txt")} would map to
* {@code content://myauthority/myfiles/foo.txt}.
*/
static class SimplePathStrategy implements PathStrategy {
private final String mAuthority;
private final HashMap<String, List<File>> mRoots = new HashMap<String, List<File>>();
public SimplePathStrategy(String authority) {
mAuthority = authority;
}
/**
* Add a mapping from a name to a filesystem root. The provider only offers
* access to files that live under configured roots.
*/
public void addRoot(String name, File root) {
if (TextUtils.isEmpty(name)) {
throw new IllegalArgumentException("Name must not be empty");
}
try {
// Resolve to canonical path to keep path checking fast
root = root.getCanonicalFile();
} catch (IOException e) {
throw new IllegalArgumentException(
"Failed to resolve canonical path for " + root, e);
}
if (mRoots.get(name) == null) {
mRoots.put(name, new ArrayList<>());
}
mRoots.get(name).add(root);
}
@Override
public Uri getUriForFile(File file) {
String path;
try {
path = file.getCanonicalPath();
} catch (IOException e) {
throw new IllegalArgumentException("Failed to resolve canonical path for " + file);
}
// Find the most-specific root path
String mostSpecificName = null;
File mostSpecificFile = null;
for (Map.Entry<String, List<File>> root : mRoots.entrySet()) {
for (final File folder : root.getValue()) {
final String rootPath = folder.getPath();
if (path.startsWith(rootPath) && (mostSpecificFile == null
|| rootPath.length() > mostSpecificFile.getPath().length())) {
mostSpecificName = root.getKey();
mostSpecificFile = folder;
}
}
}
if (mostSpecificName == null) {
throw new IllegalArgumentException(
"Failed to find configured root that contains " + path);
}
// Start at first char of path under root
final String rootPath = mostSpecificFile.getPath();
if (rootPath.endsWith("/")) {
path = path.substring(rootPath.length());
} else {
path = path.substring(rootPath.length() + 1);
}
// Encode the tag and path separately
path = Uri.encode(mostSpecificName) + '/' + Uri.encode(path, "/");
return new Uri.Builder().scheme("content")
.authority(mAuthority).encodedPath(path).build();
}
@Override
public File getFileForUri(Uri uri) {
String path = uri.getEncodedPath();
final int splitIndex = path.indexOf('/', 1);
final String tag = Uri.decode(path.substring(1, splitIndex));
path = Uri.decode(path.substring(splitIndex + 1));
final List<File> roots = mRoots.get(tag);
if (roots == null) {
throw new IllegalArgumentException("Unable to find configured root for " + uri);
}
for (final File root : roots) {
File file = new File(root, path);
try {
file = file.getCanonicalFile();
} catch (IOException e) {
throw new IllegalArgumentException("Failed to resolve canonical path for " + file);
}
if (!file.getPath().startsWith(root.getPath())) {
throw new SecurityException("Resolved path jumped beyond configured root");
}
if (file.exists()) {
return file;
}
}
throw new IllegalArgumentException("Unable to find file for uri " + uri);
}
}
/**
* Copied from ContentResolver.java
*/
private static int modeToMode(String mode) {
int modeBits;
if ("r".equals(mode)) {
modeBits = ParcelFileDescriptor.MODE_READ_ONLY;
} else if ("w".equals(mode) || "wt".equals(mode)) {
modeBits = ParcelFileDescriptor.MODE_WRITE_ONLY
| ParcelFileDescriptor.MODE_CREATE
| ParcelFileDescriptor.MODE_TRUNCATE;
} else if ("wa".equals(mode)) {
modeBits = ParcelFileDescriptor.MODE_WRITE_ONLY
| ParcelFileDescriptor.MODE_CREATE
| ParcelFileDescriptor.MODE_APPEND;
} else if ("rw".equals(mode)) {
modeBits = ParcelFileDescriptor.MODE_READ_WRITE
| ParcelFileDescriptor.MODE_CREATE;
} else if ("rwt".equals(mode)) {
modeBits = ParcelFileDescriptor.MODE_READ_WRITE
| ParcelFileDescriptor.MODE_CREATE
| ParcelFileDescriptor.MODE_TRUNCATE;
} else {
throw new IllegalArgumentException("Invalid mode: " + mode);
}
return modeBits;
}
private static File buildPath(File base, String... segments) {
File cur = base;
for (String segment : segments) {
if (segment != null) {
cur = new File(cur, segment);
}
}
return cur;
}
private static String[] copyOf(String[] original, int newLength) {
final String[] result = new String[newLength];
System.arraycopy(original, 0, result, 0, newLength);
return result;
}
private static Object[] copyOf(Object[] original, int newLength) {
final Object[] result = new Object[newLength];
System.arraycopy(original, 0, result, 0, newLength);
return result;
}
}
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