/frameworks/base/core/java/android/content/ContentResolver.java

/*
 * Copyright (C) 2006 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.content;

import dalvik.system.CloseGuard;

import android.accounts.Account;
import android.app.ActivityManagerNative;
import android.app.AppGlobals;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.res.AssetFileDescriptor;
import android.content.res.Resources;
import android.database.ContentObserver;
import android.database.CrossProcessCursorWrapper;
import android.database.Cursor;
import android.database.IContentObserver;
import android.net.Uri;
import android.os.Bundle;
import android.os.CancellationSignal;
import android.os.DeadObjectException;
import android.os.IBinder;
import android.os.ICancellationSignal;
import android.os.OperationCanceledException;
import android.os.ParcelFileDescriptor;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.SystemClock;
import android.os.UserHandle;
import android.text.TextUtils;
import android.util.EventLog;
import android.util.Log;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;


/**
 * This class provides applications access to the content model.
 *
 * <div class="special reference">
 * <h3>Developer Guides</h3>
 * <p>For more information about using a ContentResolver with content providers, read the
 * <a href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers</a>
 * developer guide.</p>
 */
public abstract class ContentResolver {
    /**
     * @deprecated instead use
     * {@link #requestSync(android.accounts.Account, String, android.os.Bundle)}
     */
    @Deprecated
    public static final String SYNC_EXTRAS_ACCOUNT = "account";
    public static final String SYNC_EXTRAS_EXPEDITED = "expedited";
    /**
     * @deprecated instead use
     * {@link #SYNC_EXTRAS_MANUAL}
     */
    @Deprecated
    public static final String SYNC_EXTRAS_FORCE = "force";

    /**
     * If this extra is set to true then the sync settings (like getSyncAutomatically())
     * are ignored by the sync scheduler.
     */
    public static final String SYNC_EXTRAS_IGNORE_SETTINGS = "ignore_settings";

    /**
     * If this extra is set to true then any backoffs for the initial attempt (e.g. due to retries)
     * are ignored by the sync scheduler. If this request fails and gets rescheduled then the
     * retries will still honor the backoff.
     */
    public static final String SYNC_EXTRAS_IGNORE_BACKOFF = "ignore_backoff";

    /**
     * If this extra is set to true then the request will not be retried if it fails.
     */
    public static final String SYNC_EXTRAS_DO_NOT_RETRY = "do_not_retry";

    /**
     * Setting this extra is the equivalent of setting both {@link #SYNC_EXTRAS_IGNORE_SETTINGS}
     * and {@link #SYNC_EXTRAS_IGNORE_BACKOFF}
     */
    public static final String SYNC_EXTRAS_MANUAL = "force";

    public static final String SYNC_EXTRAS_UPLOAD = "upload";
    public static final String SYNC_EXTRAS_OVERRIDE_TOO_MANY_DELETIONS = "deletions_override";
    public static final String SYNC_EXTRAS_DISCARD_LOCAL_DELETIONS = "discard_deletions";

    /**
     * Set by the SyncManager to request that the SyncAdapter initialize itself for
     * the given account/authority pair. One required initialization step is to
     * ensure that {@link #setIsSyncable(android.accounts.Account, String, int)} has been
     * called with a >= 0 value. When this flag is set the SyncAdapter does not need to
     * do a full sync, though it is allowed to do so.
     */
    public static final String SYNC_EXTRAS_INITIALIZE = "initialize";

    public static final String SCHEME_CONTENT = "content";
    public static final String SCHEME_ANDROID_RESOURCE = "android.resource";
    public static final String SCHEME_FILE = "file";

    /**
     * This is the Android platform's base MIME type for a content: URI
     * containing a Cursor of a single item.  Applications should use this
     * as the base type along with their own sub-type of their content: URIs
     * that represent a particular item.  For example, hypothetical IMAP email
     * client may have a URI
     * <code>content://com.company.provider.imap/inbox/1</code> for a particular
     * message in the inbox, whose MIME type would be reported as
     * <code>CURSOR_ITEM_BASE_TYPE + "/vnd.company.imap-msg"</code>
     *
     * <p>Compare with {@link #CURSOR_DIR_BASE_TYPE}.
     */
    public static final String CURSOR_ITEM_BASE_TYPE = "vnd.android.cursor.item";

    /**
     * This is the Android platform's base MIME type for a content: URI
     * containing a Cursor of zero or more items.  Applications should use this
     * as the base type along with their own sub-type of their content: URIs
     * that represent a directory of items.  For example, hypothetical IMAP email
     * client may have a URI
     * <code>content://com.company.provider.imap/inbox</code> for all of the
     * messages in its inbox, whose MIME type would be reported as
     * <code>CURSOR_DIR_BASE_TYPE + "/vnd.company.imap-msg"</code>
     *
     * <p>Note how the base MIME type varies between this and
     * {@link #CURSOR_ITEM_BASE_TYPE} depending on whether there is
     * one single item or multiple items in the data set, while the sub-type
     * remains the same because in either case the data structure contained
     * in the cursor is the same.
     */
    public static final String CURSOR_DIR_BASE_TYPE = "vnd.android.cursor.dir";

    /** @hide */
    public static final int SYNC_ERROR_SYNC_ALREADY_IN_PROGRESS = 1;
    /** @hide */
    public static final int SYNC_ERROR_AUTHENTICATION = 2;
    /** @hide */
    public static final int SYNC_ERROR_IO = 3;
    /** @hide */
    public static final int SYNC_ERROR_PARSE = 4;
    /** @hide */
    public static final int SYNC_ERROR_CONFLICT = 5;
    /** @hide */
    public static final int SYNC_ERROR_TOO_MANY_DELETIONS = 6;
    /** @hide */
    public static final int SYNC_ERROR_TOO_MANY_RETRIES = 7;
    /** @hide */
    public static final int SYNC_ERROR_INTERNAL = 8;

    public static final int SYNC_OBSERVER_TYPE_SETTINGS = 1<<0;
    public static final int SYNC_OBSERVER_TYPE_PENDING = 1<<1;
    public static final int SYNC_OBSERVER_TYPE_ACTIVE = 1<<2;
    /** @hide */
    public static final int SYNC_OBSERVER_TYPE_STATUS = 1<<3;
    /** @hide */
    public static final int SYNC_OBSERVER_TYPE_ALL = 0x7fffffff;

    // Always log queries which take 500ms+; shorter queries are
    // sampled accordingly.
    private static final int SLOW_THRESHOLD_MILLIS = 500;
    private final Random mRandom = new Random();  // guarded by itself

    public ContentResolver(Context context) {
        mContext = context;
    }

    /** @hide */
    protected abstract IContentProvider acquireProvider(Context c, String name);
    /** Providing a default implementation of this, to avoid having to change
     * a lot of other things, but implementations of ContentResolver should
     * implement it. @hide */
    protected IContentProvider acquireExistingProvider(Context c, String name) {
        return acquireProvider(c, name);
    }
    /** @hide */
    public abstract boolean releaseProvider(IContentProvider icp);
    /** @hide */
    protected abstract IContentProvider acquireUnstableProvider(Context c, String name);
    /** @hide */
    public abstract boolean releaseUnstableProvider(IContentProvider icp);
    /** @hide */
    public abstract void unstableProviderDied(IContentProvider icp);

    /**
     * Return the MIME type of the given content URL.
     *
     * @param url A Uri identifying content (either a list or specific type),
     * using the content:// scheme.
     * @return A MIME type for the content, or null if the URL is invalid or the type is unknown
     */
    public final String getType(Uri url) {
        // XXX would like to have an acquireExistingUnstableProvider for this.
        IContentProvider provider = acquireExistingProvider(url);
        if (provider != null) {
            try {
                return provider.getType(url);
            } catch (RemoteException e) {
                return null;
            } catch (java.lang.Exception e) {
                Log.w(TAG, "Failed to get type for: " + url + " (" + e.getMessage() + ")");
                return null;
            } finally {
                releaseProvider(provider);
            }
        }

        if (!SCHEME_CONTENT.equals(url.getScheme())) {
            return null;
        }

        try {
            String type = ActivityManagerNative.getDefault().getProviderMimeType(
                    url, UserHandle.myUserId());
            return type;
        } catch (RemoteException e) {
            // Arbitrary and not worth documenting, as Activity
            // Manager will kill this process shortly anyway.
            return null;
        } catch (java.lang.Exception e) {
            Log.w(TAG, "Failed to get type for: " + url + " (" + e.getMessage() + ")");
            return null;
        }
    }

    /**
     * Query for the possible MIME types for the representations the given
     * content URL can be returned when opened as as stream with
     * {@link #openTypedAssetFileDescriptor}.  Note that the types here are
     * not necessarily a superset of the type returned by {@link #getType} --
     * many content providers can not return a raw stream for the structured
     * data that they contain.
     *
     * @param url A Uri identifying content (either a list or specific type),
     * using the content:// scheme.
     * @param mimeTypeFilter The desired MIME type.  This may be a pattern,
     * such as *\/*, to query for all available MIME types that match the
     * pattern.
     * @return Returns an array of MIME type strings for all available
     * data streams that match the given mimeTypeFilter.  If there are none,
     * null is returned.
     */
    public String[] getStreamTypes(Uri url, String mimeTypeFilter) {
        IContentProvider provider = acquireProvider(url);
        if (provider == null) {
            return null;
        }

        try {
            return provider.getStreamTypes(url, mimeTypeFilter);
        } catch (RemoteException e) {
            // Arbitrary and not worth documenting, as Activity
            // Manager will kill this process shortly anyway.
            return null;
        } finally {
            releaseProvider(provider);
        }
    }

    /**
     * <p>
     * Query the given URI, returning a {@link Cursor} over the result set.
     * </p>
     * <p>
     * For best performance, the caller should follow these guidelines:
     * <ul>
     * <li>Provide an explicit projection, to prevent
     * reading data from storage that aren't going to be used.</li>
     * <li>Use question mark parameter markers such as 'phone=?' instead of
     * explicit values in the {@code selection} parameter, so that queries
     * that differ only by those values will be recognized as the same
     * for caching purposes.</li>
     * </ul>
     * </p>
     *
     * @param uri The URI, using the content:// scheme, for the content to
     *         retrieve.
     * @param projection A list of which columns to return. Passing null will
     *         return all columns, which is inefficient.
     * @param selection A filter declaring which rows to return, formatted as an
     *         SQL WHERE clause (excluding the WHERE itself). Passing null will
     *         return all rows for the given URI.
     * @param selectionArgs You may include ?s in selection, which will be
     *         replaced by the values from selectionArgs, in the order that they
     *         appear in the selection. The values will be bound as Strings.
     * @param sortOrder How to order the rows, formatted as an SQL ORDER BY
     *         clause (excluding the ORDER BY itself). Passing null will use the
     *         default sort order, which may be unordered.
     * @return A Cursor object, which is positioned before the first entry, or null
     * @see Cursor
     */
    public final Cursor query(Uri uri, String[] projection,
            String selection, String[] selectionArgs, String sortOrder) {
        return query(uri, projection, selection, selectionArgs, sortOrder, null);
    }

    /**
     * <p>
     * Query the given URI, returning a {@link Cursor} over the result set.
     * </p>
     * <p>
     * For best performance, the caller should follow these guidelines:
     * <ul>
     * <li>Provide an explicit projection, to prevent
     * reading data from storage that aren't going to be used.</li>
     * <li>Use question mark parameter markers such as 'phone=?' instead of
     * explicit values in the {@code selection} parameter, so that queries
     * that differ only by those values will be recognized as the same
     * for caching purposes.</li>
     * </ul>
     * </p>
     *
     * @param uri The URI, using the content:// scheme, for the content to
     *         retrieve.
     * @param projection A list of which columns to return. Passing null will
     *         return all columns, which is inefficient.
     * @param selection A filter declaring which rows to return, formatted as an
     *         SQL WHERE clause (excluding the WHERE itself). Passing null will
     *         return all rows for the given URI.
     * @param selectionArgs You may include ?s in selection, which will be
     *         replaced by the values from selectionArgs, in the order that they
     *         appear in the selection. The values will be bound as Strings.
     * @param sortOrder How to order the rows, formatted as an SQL ORDER BY
     *         clause (excluding the ORDER BY itself). Passing null will use the
     *         default sort order, which may be unordered.
     * @param cancellationSignal A signal to cancel the operation in progress, or null if none.
     * If the operation is canceled, then {@link OperationCanceledException} will be thrown
     * when the query is executed.
     * @return A Cursor object, which is positioned before the first entry, or null
     * @see Cursor
     */
    public final Cursor query(final Uri uri, String[] projection,
            String selection, String[] selectionArgs, String sortOrder,
            CancellationSignal cancellationSignal) {
        IContentProvider unstableProvider = acquireUnstableProvider(uri);
        if (unstableProvider == null) {
            return null;
        }
        IContentProvider stableProvider = null;
        try {
            long startTime = SystemClock.uptimeMillis();

            ICancellationSignal remoteCancellationSignal = null;
            if (cancellationSignal != null) {
                cancellationSignal.throwIfCanceled();
                remoteCancellationSignal = unstableProvider.createCancellationSignal();
                cancellationSignal.setRemote(remoteCancellationSignal);
            }
            Cursor qCursor;
            try {
                qCursor = unstableProvider.query(uri, projection,
                        selection, selectionArgs, sortOrder, remoteCancellationSignal);
            } catch (DeadObjectException e) {
                // The remote process has died...  but we only hold an unstable
                // reference though, so we might recover!!!  Let's try!!!!
                // This is exciting!!1!!1!!!!1
                unstableProviderDied(unstableProvider);
                stableProvider = acquireProvider(uri);
                if (stableProvider == null) {
                    return null;
                }
                qCursor = stableProvider.query(uri, projection,
                        selection, selectionArgs, sortOrder, remoteCancellationSignal);
            }
            if (qCursor == null) {
                return null;
            }
            // force query execution
            qCursor.getCount();
            long durationMillis = SystemClock.uptimeMillis() - startTime;
            maybeLogQueryToEventLog(durationMillis, uri, projection, selection, sortOrder);
            // Wrap the cursor object into CursorWrapperInner object
            CursorWrapperInner wrapper = new CursorWrapperInner(qCursor,
                    stableProvider != null ? stableProvider : acquireProvider(uri));
            stableProvider = null;
            return wrapper;
        } catch (RemoteException e) {
            // Arbitrary and not worth documenting, as Activity
            // Manager will kill this process shortly anyway.
            return null;
        } finally {
            if (unstableProvider != null) {
                releaseUnstableProvider(unstableProvider);
            }
            if (stableProvider != null) {
                releaseProvider(stableProvider);
            }
        }
    }

    /**
     * Open a stream on to the content associated with a content URI.  If there
     * is no data associated with the URI, FileNotFoundException is thrown.
     *
     * <h5>Accepts the following URI schemes:</h5>
     * <ul>
     * <li>content ({@link #SCHEME_CONTENT})</li>
     * <li>android.resource ({@link #SCHEME_ANDROID_RESOURCE})</li>
     * <li>file ({@link #SCHEME_FILE})</li>
     * </ul>
     *
     * <p>See {@link #openAssetFileDescriptor(Uri, String)} for more information
     * on these schemes.
     *
     * @param uri The desired URI.
     * @return InputStream
     * @throws FileNotFoundException if the provided URI could not be opened.
     * @see #openAssetFileDescriptor(Uri, String)
     */
    public final InputStream openInputStream(Uri uri)
            throws FileNotFoundException {
        String scheme = uri.getScheme();
        if (SCHEME_ANDROID_RESOURCE.equals(scheme)) {
            // Note: left here to avoid breaking compatibility.  May be removed
            // with sufficient testing.
            OpenResourceIdResult r = getResourceId(uri);
            try {
                InputStream stream = r.r.openRawResource(r.id);
                return stream;
            } catch (Resources.NotFoundException ex) {
                throw new FileNotFoundException("Resource does not exist: " + uri);
            }
        } else if (SCHEME_FILE.equals(scheme)) {
            // Note: left here to avoid breaking compatibility.  May be removed
            // with sufficient testing.
            return new FileInputStream(uri.getPath());
        } else {
            AssetFileDescriptor fd = openAssetFileDescriptor(uri, "r");
            try {
                return fd != null ? fd.createInputStream() : null;
            } catch (IOException e) {
                throw new FileNotFoundException("Unable to create stream");
            }
        }
    }

    /**
     * Synonym for {@link #openOutputStream(Uri, String)
     * openOutputStream(uri, "w")}.
     * @throws FileNotFoundException if the provided URI could not be opened.
     */
    public final OutputStream openOutputStream(Uri uri)
            throws FileNotFoundException {
        return openOutputStream(uri, "w");
    }

    /**
     * Open a stream on to the content associated with a content URI.  If there
     * is no data associated with the URI, FileNotFoundException is thrown.
     *
     * <h5>Accepts the following URI schemes:</h5>
     * <ul>
     * <li>content ({@link #SCHEME_CONTENT})</li>
     * <li>file ({@link #SCHEME_FILE})</li>
     * </ul>
     *
     * <p>See {@link #openAssetFileDescriptor(Uri, String)} for more information
     * on these schemes.
     *
     * @param uri The desired URI.
     * @param mode May be "w", "wa", "rw", or "rwt".
     * @return OutputStream
     * @throws FileNotFoundException if the provided URI could not be opened.
     * @see #openAssetFileDescriptor(Uri, String)
     */
    public final OutputStream openOutputStream(Uri uri, String mode)
            throws FileNotFoundException {
        AssetFileDescriptor fd = openAssetFileDescriptor(uri, mode);
        try {
            return fd != null ? fd.createOutputStream() : null;
        } catch (IOException e) {
            throw new FileNotFoundException("Unable to create stream");
        }
    }

    /**
     * Open a raw file descriptor to access data under a URI.  This
     * is like {@link #openAssetFileDescriptor(Uri, String)}, but uses the
     * underlying {@link ContentProvider#openFile}
     * ContentProvider.openFile()} method, so will <em>not</em> work with
     * providers that return sub-sections of files.  If at all possible,
     * you should use {@link #openAssetFileDescriptor(Uri, String)}.  You
     * will receive a FileNotFoundException exception if the provider returns a
     * sub-section of a file.
     *
     * <h5>Accepts the following URI schemes:</h5>
     * <ul>
     * <li>content ({@link #SCHEME_CONTENT})</li>
     * <li>file ({@link #SCHEME_FILE})</li>
     * </ul>
     *
     * <p>See {@link #openAssetFileDescriptor(Uri, String)} for more information
     * on these schemes.
     *
     * @param uri The desired URI to open.
     * @param mode The file mode to use, as per {@link ContentProvider#openFile
     * ContentProvider.openFile}.
     * @return Returns a new ParcelFileDescriptor pointing to the file.  You
     * own this descriptor and are responsible for closing it when done.
     * @throws FileNotFoundException Throws FileNotFoundException of no
     * file exists under the URI or the mode is invalid.
     * @see #openAssetFileDescriptor(Uri, String)
     */
    public final ParcelFileDescriptor openFileDescriptor(Uri uri,
            String mode) throws FileNotFoundException {
        AssetFileDescriptor afd = openAssetFileDescriptor(uri, mode);
        if (afd == null) {
            return null;
        }

        if (afd.getDeclaredLength() < 0) {
            // This is a full file!
            return afd.getParcelFileDescriptor();
        }

        // Client can't handle a sub-section of a file, so close what
        // we got and bail with an exception.
        try {
            afd.close();
        } catch (IOException e) {
        }

        throw new FileNotFoundException("Not a whole file");
    }

    /**
     * Open a raw file descriptor to access data under a URI.  This
     * interacts with the underlying {@link ContentProvider#openAssetFile}
     * method of the provider associated with the given URI, to retrieve any file stored there.
     *
     * <h5>Accepts the following URI schemes:</h5>
     * <ul>
     * <li>content ({@link #SCHEME_CONTENT})</li>
     * <li>android.resource ({@link #SCHEME_ANDROID_RESOURCE})</li>
     * <li>file ({@link #SCHEME_FILE})</li>
     * </ul>
     * <h5>The android.resource ({@link #SCHEME_ANDROID_RESOURCE}) Scheme</h5>
     * <p>
     * A Uri object can be used to reference a resource in an APK file.  The
     * Uri should be one of the following formats:
     * <ul>
     * <li><code>android.resource://package_name/id_number</code><br/>
     * <code>package_name</code> is your package name as listed in your AndroidManifest.xml.
     * For example <code>com.example.myapp</code><br/>
     * <code>id_number</code> is the int form of the ID.<br/>
     * The easiest way to construct this form is
     * <pre>Uri uri = Uri.parse("android.resource://com.example.myapp/" + R.raw.my_resource");</pre>
     * </li>
     * <li><code>android.resource://package_name/type/name</code><br/>
     * <code>package_name</code> is your package name as listed in your AndroidManifest.xml.
     * For example <code>com.example.myapp</code><br/>
     * <code>type</code> is the string form of the resource type.  For example, <code>raw</code>
     * or <code>drawable</code>.
     * <code>name</code> is the string form of the resource name.  That is, whatever the file
     * name was in your res directory, without the type extension.
     * The easiest way to construct this form is
     * <pre>Uri uri = Uri.parse("android.resource://com.example.myapp/raw/my_resource");</pre>
     * </li>
     * </ul>
     *
     * <p>Note that if this function is called for read-only input (mode is "r")
     * on a content: URI, it will instead call {@link #openTypedAssetFileDescriptor}
     * for you with a MIME type of "*\/*".  This allows such callers to benefit
     * from any built-in data conversion that a provider implements.
     *
     * @param uri The desired URI to open.
     * @param mode The file mode to use, as per {@link ContentProvider#openAssetFile
     * ContentProvider.openAssetFile}.
     * @return Returns a new ParcelFileDescriptor pointing to the file.  You
     * own this descriptor and are responsible for closing it when done.
     * @throws FileNotFoundException Throws FileNotFoundException of no
     * file exists under the URI or the mode is invalid.
     */
    public final AssetFileDescriptor openAssetFileDescriptor(Uri uri,
            String mode) throws FileNotFoundException {
        String scheme = uri.getScheme();
        if (SCHEME_ANDROID_RESOURCE.equals(scheme)) {
            if (!"r".equals(mode)) {
                throw new FileNotFoundException("Can't write resources: " + uri);
            }
            OpenResourceIdResult r = getResourceId(uri);
            try {
                return r.r.openRawResourceFd(r.id);
            } catch (Resources.NotFoundException ex) {
                throw new FileNotFoundException("Resource does not exist: " + uri);
            }
        } else if (SCHEME_FILE.equals(scheme)) {
            ParcelFileDescriptor pfd = ParcelFileDescriptor.open(
                    new File(uri.getPath()), modeToMode(uri, mode));
            return new AssetFileDescriptor(pfd, 0, -1);
        } else {
            if ("r".equals(mode)) {
                return openTypedAssetFileDescriptor(uri, "*/*", null);
            } else {
                IContentProvider unstableProvider = acquireUnstableProvider(uri);
                if (unstableProvider == null) {
                    throw new FileNotFoundException("No content provider: " + uri);
                }
                IContentProvider stableProvider = null;
                AssetFileDescriptor fd = null;

                try {
                    try {
                        fd = unstableProvider.openAssetFile(uri, mode);
                        if (fd == null) {
                            // The provider will be released by the finally{} clause
                            return null;
                        }
                    } catch (DeadObjectException e) {
                        // The remote process has died...  but we only hold an unstable
                        // reference though, so we might recover!!!  Let's try!!!!
                        // This is exciting!!1!!1!!!!1
                        unstableProviderDied(unstableProvider);
                        stableProvider = acquireProvider(uri);
                        if (stableProvider == null) {
                            throw new FileNotFoundException("No content provider: " + uri);
                        }
                        fd = stableProvider.openAssetFile(uri, mode);
                        if (fd == null) {
                            // The provider will be released by the finally{} clause
                            return null;
                        }
                    }

                    if (stableProvider == null) {
                        stableProvider = acquireProvider(uri);
                    }
                    releaseUnstableProvider(unstableProvider);
                    ParcelFileDescriptor pfd = new ParcelFileDescriptorInner(
                            fd.getParcelFileDescriptor(), stableProvider);

                    // Success!  Don't release the provider when exiting, let
                    // ParcelFileDescriptorInner do that when it is closed.
                    stableProvider = null;

                    return new AssetFileDescriptor(pfd, fd.getStartOffset(),
                            fd.getDeclaredLength());

                } catch (RemoteException e) {
                    // Whatever, whatever, we'll go away.
                    throw new FileNotFoundException(
                            "Failed opening content provider: " + uri);
                } catch (FileNotFoundException e) {
                    throw e;
                } finally {
                    if (stableProvider != null) {
                        releaseProvider(stableProvider);
                    }
                    if (unstableProvider != null) {
                        releaseUnstableProvider(unstableProvider);
                    }
                }
            }
        }
    }

    /**
     * Open a raw file descriptor to access (potentially type transformed)
     * data from a "content:" URI.  This interacts with the underlying
     * {@link ContentProvider#openTypedAssetFile} method of the provider
     * associated with the given URI, to retrieve retrieve any appropriate
     * data stream for the data stored there.
     *
     * <p>Unlike {@link #openAssetFileDescriptor}, this function only works
     * with "content:" URIs, because content providers are the only facility
     * with an associated MIME type to ensure that the returned data stream
     * is of the desired type.
     *
     * <p>All text/* streams are encoded in UTF-8.
     *
     * @param uri The desired URI to open.
     * @param mimeType The desired MIME type of the returned data.  This can
     * be a pattern such as *\/*, which will allow the content provider to
     * select a type, though there is no way for you to determine what type
     * it is returning.
     * @param opts Additional provider-dependent options.
     * @return Returns a new ParcelFileDescriptor from which you can read the
     * data stream from the provider.  Note that this may be a pipe, meaning
     * you can't seek in it.  The only seek you should do is if the
     * AssetFileDescriptor contains an offset, to move to that offset before
     * reading.  You own this descriptor and are responsible for closing it when done.
     * @throws FileNotFoundException Throws FileNotFoundException of no
     * data of the desired type exists under the URI.
     */
    public final AssetFileDescriptor openTypedAssetFileDescriptor(Uri uri,
            String mimeType, Bundle opts) throws FileNotFoundException {
        IContentProvider unstableProvider = acquireUnstableProvider(uri);
        if (unstableProvider == null) {
            throw new FileNotFoundException("No content provider: " + uri);
        }
        IContentProvider stableProvider = null;
        AssetFileDescriptor fd = null;

        try {
            try {
                fd = unstableProvider.openTypedAssetFile(uri, mimeType, opts);
                if (fd == null) {
                    // The provider will be released by the finally{} clause
                    return null;
                }
            } catch (DeadObjectException e) {
                // The remote process has died...  but we only hold an unstable
                // reference though, so we might recover!!!  Let's try!!!!
                // This is exciting!!1!!1!!!!1
                unstableProviderDied(unstableProvider);
                stableProvider = acquireProvider(uri);
                if (stableProvider == null) {
                    throw new FileNotFoundException("No content provider: " + uri);
                }
                fd = stableProvider.openTypedAssetFile(uri, mimeType, opts);
                if (fd == null) {
                    // The provider will be released by the finally{} clause
                    return null;
                }
            }

            if (stableProvider == null) {
                stableProvider = acquireProvider(uri);
            }
            releaseUnstableProvider(unstableProvider);
            ParcelFileDescriptor pfd = new ParcelFileDescriptorInner(
                    fd.getParcelFileDescriptor(), stableProvider);

            // Success!  Don't release the provider when exiting, let
            // ParcelFileDescriptorInner do that when it is closed.
            stableProvider = null;

            return new AssetFileDescriptor(pfd, fd.getStartOffset(),
                    fd.getDeclaredLength());

        } catch (RemoteException e) {
            // Whatever, whatever, we'll go away.
            throw new FileNotFoundException(
                    "Failed opening content provider: " + uri);
        } catch (FileNotFoundException e) {
            throw e;
        } finally {
            if (stableProvider != null) {
                releaseProvider(stableProvider);
            }
            if (unstableProvider != null) {
                releaseUnstableProvider(unstableProvider);
            }
        }
    }

    /**
     * A resource identified by the {@link Resources} that contains it, and a resource id.
     *
     * @hide
     */
    public class OpenResourceIdResult {
        public Resources r;
        public int id;
    }

    /**
     * Resolves an android.resource URI to a {@link Resources} and a resource id.
     *
     * @hide
     */
    public OpenResourceIdResult getResourceId(Uri uri) throws FileNotFoundException {
        String authority = uri.getAuthority();
        Resources r;
        if (TextUtils.isEmpty(authority)) {
            throw new FileNotFoundException("No authority: " + uri);
        } else {
            try {
                r = mContext.getPackageManager().getResourcesForApplication(authority);
            } catch (NameNotFoundException ex) {
                throw new FileNotFoundException("No package found for authority: " + uri);
            }
        }
        List<String> path = uri.getPathSegments();
        if (path == null) {
            throw new FileNotFoundException("No path: " + uri);
        }
        int len = path.size();
        int id;
        if (len == 1) {
            try {
                id = Integer.parseInt(path.get(0));
            } catch (NumberFormatException e) {
                throw new FileNotFoundException("Single path segment is not a resource ID: " + uri);
            }
        } else if (len == 2) {
            id = r.getIdentifier(path.get(1), path.get(0), authority);
        } else {
            throw new FileNotFoundException("More than two path segments: " + uri);
        }
        if (id == 0) {
            throw new FileNotFoundException("No resource found for: " + uri);
        }
        OpenResourceIdResult res = new OpenResourceIdResult();
        res.r = r;
        res.id = id;
        return res;
    }

    /** @hide */
    static public int modeToMode(Uri uri, String mode) throws FileNotFoundException {
        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 FileNotFoundException("Bad mode for " + uri + ": "
                    + mode);
        }
        return modeBits;
    }

    /**
     * Inserts a row into a table at the given URL.
     *
     * If the content provider supports transactions the insertion will be atomic.
     *
     * @param url The URL of the table to insert into.
     * @param values The initial values for the newly inserted row. The key is the column name for
     *               the field. Passing an empty ContentValues will create an empty row.
     * @return the URL of the newly created row.
     */
    public final Uri insert(Uri url, ContentValues values)
    {
        IContentProvider provider = acquireProvider(url);
        if (provider == null) {
            throw new IllegalArgumentException("Unknown URL " + url);
        }
        try {
            long startTime = SystemClock.uptimeMillis();
            Uri createdRow = provider.insert(url, values);
            long durationMillis = SystemClock.uptimeMillis() - startTime;
            maybeLogUpdateToEventLog(durationMillis, url, "insert", null /* where */);
            return createdRow;
        } catch (RemoteException e) {
            // Arbitrary and not worth documenting, as Activity
            // Manager will kill this process shortly anyway.
            return null;
        } finally {
            releaseProvider(provider);
        }
    }

    /**
     * Applies each of the {@link ContentProviderOperation} objects and returns an array
     * of their results. Passes through OperationApplicationException, which may be thrown
     * by the call to {@link ContentProviderOperation#apply}.
     * If all the applications succeed then a {@link ContentProviderResult} array with the
     * same number of elements as the operations will be returned. It is implementation-specific
     * how many, if any, operations will have been successfully applied if a call to
     * apply results in a {@link OperationApplicationException}.
     * @param authority the authority of the ContentProvider to which this batch should be applied
     * @param operations the operations to apply
     * @return the results of the applications
     * @throws OperationApplicationException thrown if an application fails.
     * See {@link ContentProviderOperation#apply} for more information.
     * @throws RemoteException thrown if a RemoteException is encountered while attempting
     *   to communicate with a remote provider.
     */
    public ContentProviderResult[] applyBatch(String authority,
            ArrayList<ContentProviderOperation> operations)
            throws RemoteException, OperationApplicationException {
        ContentProviderClient provider = acquireContentProviderClient(authority);
        if (provider == null) {
            throw new IllegalArgumentException("Unknown authority " + authority);
        }
        try {
            return provider.applyBatch(operations);
        } finally {
            provider.release();
        }
    }

    /**
     * Inserts multiple rows into a table at the given URL.
     *
     * This function make no guarantees about the atomicity of the insertions.
     *
     * @param url The URL of the table to insert into.
     * @param values The initial values for the newly inserted rows. The key is the column name for
     *               the field. Passing null will create an empty row.
     * @return the number of newly created rows.
     */
    public final int bulkInsert(Uri url, ContentValues[] values)
    {
        IContentProvider provider = acquireProvider(url);
        if (provider == null) {
            throw new IllegalArgumentException("Unknown URL " + url);
        }
        try {
            long startTime = SystemClock.uptimeMillis();
            int rowsCreated = provider.bulkInsert(url, values);
            long durationMillis = SystemClock.uptimeMillis() - startTime;
            maybeLogUpdateToEventLog(durationMillis, url, "bulkinsert", null /* where */);
            return rowsCreated;
        } catch (RemoteException e) {
            // Arbitrary and not worth documenting, as Activity
            // Manager will kill this process shortly anyway.
            return 0;
        } finally {
            releaseProvider(provider);
        }
    }

    /**
     * Deletes row(s) specified by a content URI.
     *
     * If the content provider supports transactions, the deletion will be atomic.
     *
     * @param url The URL of the row to delete.
     * @param where A filter to apply to rows before deleting, formatted as an SQL WHERE clause
                    (excluding the WHERE itself).
     * @return The number of rows deleted.
     */
    public final int delete(Uri url, String where, String[] selectionArgs)
    {
        IContentProvider provider = acquireProvider(url);
        if (provider == null) {
            throw new IllegalArgumentException("Unknown URL " + url);
        }
        try {
            long startTime = SystemClock.uptimeMillis();
            int rowsDeleted = provider.delete(url, where, selectionArgs);
            long durationMillis = SystemClock.uptimeMillis() - startTime;
            maybeLogUpdateToEventLog(durationMillis, url, "delete", where);
            return rowsDeleted;
        } catch (RemoteException e) {
            // Arbitrary and not worth documenting, as Activity
            // Manager will kill this process shortly anyway.
            return -1;
        } finally {
            releaseProvider(provider);
        }
    }

    /**
     * Update row(s) in a content URI.
     *
     * If the content provider supports transactions the update will be atomic.
     *
     * @param uri The URI to modify.
     * @param values The new field values. The key is the column name for the field.
                     A null value will remove an existing field value.
     * @param where A filter to apply to rows before updating, formatted as an SQL WHERE clause
                    (excluding the WHERE itself).
     * @return the number of rows updated.
     * @throws NullPointerException if uri or values are null
     */
    public final int update(Uri uri, ContentValues values, String where,
            String[] selectionArgs) {
        IContentProvider provider = acquireProvider(uri);
        if (provider == null) {
            throw new IllegalArgumentException("Unknown URI " + uri);
        }
        try {
            long startTime = SystemClock.uptimeMillis();
            int rowsUpdated = provider.update(uri, values, where, selectionArgs);
            long durationMillis = SystemClock.uptimeMillis() - startTime;
            maybeLogUpdateToEventLog(durationMillis, uri, "update", where);
            return rowsUpdated;
        } catch (RemoteException e) {
            // Arbitrary and not worth documenting, as Activity
            // Manager will kill this process shortly anyway.
            return -1;
        } finally {
            releaseProvider(provider);
        }
    }

    /**
     * Call a provider-defined method.  This can be used to implement
     * read or write interfaces which are cheaper than using a Cursor and/or
     * do not fit into the traditional table model.
     *
     * @param method provider-defined method name to call.  Opaque to
     *   framework, but must be non-null.
     * @param arg provider-defined String argument.  May be null.
     * @param extras provider-defined Bundle argument.  May be null.
     * @return a result Bundle, possibly null.  Will be null if the ContentProvider
     *   does not implement call.
     * @throws NullPointerException if uri or method is null
     * @throws IllegalArgumentException if uri is not known
     */
    public final Bundle call(Uri uri, String method, String arg, Bundle extras) {
        if (uri == null) {
            throw new NullPointerException("uri == null");
        }
        if (method == null) {
            throw new NullPointerException("method == null");
        }
        IContentProvider provider = acquireProvider(uri);
        if (provider == null) {
            throw new IllegalArgumentException("Unknown URI " + uri);
        }
        try {
            return provider.call(method, arg, extras);
        } catch (RemoteException e) {
            // Arbitrary and not worth documenting, as Activity
            // Manager will kill this process shortly anyway.
            return null;
        } finally {
            releaseProvider(provider);
        }
    }

    /**
     * Returns the content provider for the given content URI.
     *
     * @param uri The URI to a content provider
     * @return The ContentProvider for the given URI, or null if no content provider is found.
     * @hide
     */
    public final IContentProvider acquireProvider(Uri uri) {
        if (!SCHEME_CONTENT.equals(uri.getScheme())) {
            return null;
        }
        String auth = uri.getAuthority();
        if (auth != null) {
            return acquireProvider(mContext, uri.getAuthority());
        }
        return null;
    }

    /**
     * Returns the content provider for the given content URI if the process
     * already has a reference on it.
     *
     * @param uri The URI to a content provider
     * @return The ContentProvider for the given URI, or null if no content provider is found.
     * @hide
     */
    public final IContentProvider acquireExistingProvider(Uri uri) {
        if (!SCHEME_CONTENT.equals(uri.getScheme())) {
            return null;
        }
        String auth = uri.getAuthority();
        if (auth != null) {
            return acquireExistingProvider(mContext, uri.getAuthority());
        }
        return null;
    }

    /**
     * @hide
     */
    public final IContentProvider acquireProvider(String name) {
        if (name == null) {
            return null;
        }
        return acquireProvider(mContext, name);
    }

    /**
     * Returns the content provider for the given content URI.
     *
     * @param uri The URI to a content provider
     * @return The ContentProvider for the given URI, or null if no content provider is found.
     * @hide
     */
    public final IContentProvider acquireUnstableProvider(Uri uri) {
        if (!SCHEME_CONTENT.equals(uri.getScheme())) {
            return null;
        }
        String auth = uri.getAuthority();
        if (auth != null) {
            return acquireUnstableProvider(mContext, uri.getAuthority());
        }
        return null;
    }

    /**
     * @hide
     */
    public final IContentProvider acquireUnstableProvider(String name) {
        if (name == null) {
            return null;
        }
        return acquireUnstableProvider(mContext, name);
    }

    /**
     * Returns a {@link ContentProviderClient} that is associated with the {@link ContentProvider}
     * that services the content at uri, starting the provider if necessary. Returns
     * null if there is no provider associated wih the uri. The caller must indicate that they are
     * done with the provider by calling {@link ContentProviderClient#release} which will allow
     * the system to release the provider it it determines that there is no other reason for
     * keeping it active.
     * @param uri specifies which provider should be acquired
     * @return a {@link ContentProviderClient} that is associated with the {@link ContentProvider}
     * that services the content at uri or null if there isn't one.
     */
    public final ContentProviderClient acquireContentProviderClient(Uri uri) {
        IContentProvider provider = acquireProvider(uri);
        if (provider != null) {
            return new ContentProviderClient(this, provider, true);
        }

        return null;
    }

    /**
     * Returns a {@link ContentProviderClient} that is associated with the {@link ContentProvider}
     * with the authority of name, starting the provider if necessary. Returns
     * null if there is no provider associated wih the uri. The caller must indicate that they are
     * done with the provider by calling {@link ContentProviderClient#release} which will allow
     * the system to release the provider it it determines that there is no other reason for
     * keeping it active.
     * @param name specifies which provider should be acquired
     * @return a {@link ContentProviderClient} that is associated with the {@link ContentProvider}
     * with the authority of name or null if there isn't one.
     */
    public final ContentProviderClient acquireContentProviderClient(String name) {
        IContentProvider provider = acquireProvider(name);
        if (provider != null) {
            return new ContentProviderClient(this, provider, true);
        }

        return null;
    }

    /**
     * Like {@link #acquireContentProviderClient(Uri)}, but for use when you do
     * not trust the stability of the target content provider.  This turns off
     * the mechanism in the platform clean up processes that are dependent on
     * a content provider if that content provider's process goes away.  Normally
     * you can safely assume that once you have acquired a provider, you can freely
     * use it as needed and it won't disappear, even if your process is in the
     * background.  If using this method, you need to take care to deal with any
     * failures when communicating with the provider, and be sure to close it
     * so that it can be re-opened later.  In particular, catching a
     * {@link android.os.DeadObjectException} from the calls there will let you
     * know that the content provider has gone away;