Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 11ae768c authored by Christopher Tate's avatar Christopher Tate
Browse files

Add payload-size preflight stage to full transport backup 

We now peform a total-size preflight pass before committing data to the
wire.  This is to eliminate the large superfluous network traffic that
would otherwise happen if the transport enforces internal quotas: we
now instead ask the transport up front whether it's prepared to accept
a given payload size for the package.

From the app's perspective this preflight operation is indistinguishable
from a full-data backup pass.  If the app has provided its own full-data
handling in a subclassed backup agent, their usual file-providing code
path will be executed.  However, the files named for backup during this
pass are not opened and read; just measured for their total size.  As
far as component lifecycles, this measurement pass is simply another
call to the agent, immediately after it is bound, with identical
timeout semantics to the existing full-data backup invocation.

Once the app's file set has been measured the preflight operation
invokes a new method on BackupTransport, called checkFullBackupSize().
This method is called after performFullBackup() (which applies any
overall whitelist/blacklist policy) but before any data is delivered
to the transport via sendBackupData().  The return code from
checkFullBackupSize() is similar to the other transport methods:
TRANSPORT_OK to permit the full backup to proceed; or
TRANSPORT_REJECT_PACKAGE to indicate that the requested payload is
unacceptable; or TRANSPORT_ERROR to report a more serious overall
transport-level problem that prevents a full-data backup operation
from occurring right now.

The estimated payload currently does not include the size of the
source-package metadata (technically, the manifest entry in its
archive payload) or the size of any widget metadata associated with
the package's install.  In practice this means the preflighted size
underestimates by 3 to 5 KB.  In addition, the preflight API currently
cannot distinguish between payload sizes larger than 2 gigabytes;
any payload estimate larger than that is passed as Integer.MAX_VALUE
to the checkFullBackupSize() query.

Bug 19846750

Change-Id: I44498201e2d4b07482dcb3ca8fa6935dddc467ca
parent e7f931c4

api/system-current.txt

+3 −0
Original line number Diff line number Diff line
@@ -5908,6 +5908,7 @@ package android.app.backup { 
    ctor public BackupTransport();

    method public int abortFullRestore();

    method public void cancelFullBackup();

    method public int checkFullBackupSize(long);

    method public int clearBackupData(android.content.pm.PackageInfo);

    method public android.content.Intent configurationIntent();

    method public java.lang.String currentDestinationString();
@@ -32771,6 +32772,7 @@ package android.test.mock { 
    method public android.graphics.drawable.Drawable getUserBadgedIcon(android.graphics.drawable.Drawable, android.os.UserHandle);

    method public java.lang.CharSequence getUserBadgedLabel(java.lang.CharSequence, android.os.UserHandle);

    method public android.content.res.XmlResourceParser getXml(java.lang.String, int, android.content.pm.ApplicationInfo);

    method public void grantPermission(java.lang.String, java.lang.String, android.os.UserHandle);

    method public boolean hasSystemFeature(java.lang.String);

    method public boolean isSafeMode();

    method public java.util.List<android.content.pm.ResolveInfo> queryBroadcastReceivers(android.content.Intent, int);
@@ -32786,6 +32788,7 @@ package android.test.mock { 
    method public android.content.pm.ResolveInfo resolveActivity(android.content.Intent, int);

    method public android.content.pm.ProviderInfo resolveContentProvider(java.lang.String, int);

    method public android.content.pm.ResolveInfo resolveService(android.content.Intent, int);

    method public void revokePermission(java.lang.String, java.lang.String, android.os.UserHandle);

    method public void setApplicationEnabledSetting(java.lang.String, int, int);

    method public void setComponentEnabledSetting(android.content.ComponentName, int, int);

    method public void setInstallerPackageName(java.lang.String, java.lang.String);

core/java/android/app/IBackupAgent.aidl

+5 −0
Original line number Diff line number Diff line
@@ -99,6 +99,11 @@ oneway interface IBackupAgent { 
     */

    void doFullBackup(in ParcelFileDescriptor data, int token, IBackupManager callbackBinder);



    /**

     * Estimate how much data a full backup will deliver

     */

    void doMeasureFullBackup(int token, IBackupManager callbackBinder);



    /**

     * Restore a single "file" to the application.  The file was typically obtained from

     * a full-backup dataset.  The agent reads 'size' bytes of file content

core/java/android/app/backup/BackupAgent.java

+42 −13
Original line number Diff line number Diff line
@@ -424,10 +424,12 @@ public abstract class BackupAgent extends ContextWrapper { 
        }



        // And now that we know where it lives, semantically, back it up appropriately

        Log.i(TAG, "backupFile() of " + filePath + " => domain=" + domain

        // In the measurement case, backupToTar() updates the size in output and returns

        // without transmitting any file data.

        if (DEBUG) Log.i(TAG, "backupFile() of " + filePath + " => domain=" + domain

                + " rootpath=" + rootpath);

        FullBackup.backupToTar(getPackageName(), domain, null, rootpath, filePath,

                output.getData());

        

        FullBackup.backupToTar(getPackageName(), domain, null, rootpath, filePath, output);

    }



    /**
@@ -477,9 +479,8 @@ public abstract class BackupAgent extends ContextWrapper { 
                    continue;

                }



                // Finally, back this file up before proceeding

                FullBackup.backupToTar(packageName, domain, null, rootPath, filePath,

                        output.getData());

                // Finally, back this file up (or measure it) before proceeding

                FullBackup.backupToTar(packageName, domain, null, rootPath, filePath, output);

            }

        }

    }
@@ -640,7 +641,7 @@ public abstract class BackupAgent extends ContextWrapper { 


                Binder.restoreCallingIdentity(ident);

                try {

                    callbackBinder.opComplete(token);

                    callbackBinder.opComplete(token, 0);

                } catch (RemoteException e) {

                    // we'll time out anyway, so we're safe

                }
@@ -670,7 +671,7 @@ public abstract class BackupAgent extends ContextWrapper { 


                Binder.restoreCallingIdentity(ident);

                try {

                    callbackBinder.opComplete(token);

                    callbackBinder.opComplete(token, 0);

                } catch (RemoteException e) {

                    // we'll time out anyway, so we're safe

                }
@@ -692,10 +693,10 @@ public abstract class BackupAgent extends ContextWrapper { 
            try {

                BackupAgent.this.onFullBackup(new FullBackupDataOutput(data));

            } catch (IOException ex) {

                Log.d(TAG, "onBackup (" + BackupAgent.this.getClass().getName() + ") threw", ex);

                Log.d(TAG, "onFullBackup (" + BackupAgent.this.getClass().getName() + ") threw", ex);

                throw new RuntimeException(ex);

            } catch (RuntimeException ex) {

                Log.d(TAG, "onBackup (" + BackupAgent.this.getClass().getName() + ") threw", ex);

                Log.d(TAG, "onFullBackup (" + BackupAgent.this.getClass().getName() + ") threw", ex);

                throw ex;

            } finally {

                // ... and then again after, as in the doBackup() case
@@ -713,13 +714,37 @@ public abstract class BackupAgent extends ContextWrapper { 


                Binder.restoreCallingIdentity(ident);

                try {

                    callbackBinder.opComplete(token);

                    callbackBinder.opComplete(token, 0);

                } catch (RemoteException e) {

                    // we'll time out anyway, so we're safe

                }

            }

        }



        public void doMeasureFullBackup(int token, IBackupManager callbackBinder) {

            // Ensure that we're running with the app's normal permission level

            final long ident = Binder.clearCallingIdentity();

            FullBackupDataOutput measureOutput = new FullBackupDataOutput();



            waitForSharedPrefs();

            try {

                BackupAgent.this.onFullBackup(measureOutput);

            } catch (IOException ex) {

                Log.d(TAG, "onFullBackup[M] (" + BackupAgent.this.getClass().getName() + ") threw", ex);

                throw new RuntimeException(ex);

            } catch (RuntimeException ex) {

                Log.d(TAG, "onFullBackup[M] (" + BackupAgent.this.getClass().getName() + ") threw", ex);

                throw ex;

            } finally {

                Binder.restoreCallingIdentity(ident);

                try {

                    callbackBinder.opComplete(token, measureOutput.getSize());

                } catch (RemoteException e) {

                    // timeout, so we're safe

                }

            }

        }



        @Override

        public void doRestoreFile(ParcelFileDescriptor data, long size,

                int type, String domain, String path, long mode, long mtime,
@@ -728,6 +753,7 @@ public abstract class BackupAgent extends ContextWrapper { 
            try {

                BackupAgent.this.onRestoreFile(data, size, type, domain, path, mode, mtime);

            } catch (IOException e) {

                Log.d(TAG, "onRestoreFile (" + BackupAgent.this.getClass().getName() + ") threw", e);

                throw new RuntimeException(e);

            } finally {

                // Ensure that any side-effect SharedPreferences writes have landed
@@ -735,7 +761,7 @@ public abstract class BackupAgent extends ContextWrapper { 


                Binder.restoreCallingIdentity(ident);

                try {

                    callbackBinder.opComplete(token);

                    callbackBinder.opComplete(token, 0);

                } catch (RemoteException e) {

                    // we'll time out anyway, so we're safe

                }
@@ -747,13 +773,16 @@ public abstract class BackupAgent extends ContextWrapper { 
            long ident = Binder.clearCallingIdentity();

            try {

                BackupAgent.this.onRestoreFinished();

            } catch (Exception e) {

                Log.d(TAG, "onRestoreFinished (" + BackupAgent.this.getClass().getName() + ") threw", e);

                throw e;

            } finally {

                // Ensure that any side-effect SharedPreferences writes have landed

                waitForSharedPrefs();



                Binder.restoreCallingIdentity(ident);

                try {

                    callbackBinder.opComplete(token);

                    callbackBinder.opComplete(token, 0);

                } catch (RemoteException e) {

                    // we'll time out anyway, so we're safe

                }

core/java/android/app/backup/BackupTransport.java

+25 −0
Original line number Diff line number Diff line
@@ -392,6 +392,26 @@ public class BackupTransport { 
        return BackupTransport.TRANSPORT_PACKAGE_REJECTED;

    }



    /**

     * Called after {@link #performFullBackup} to make sure that the transport is willing to

     * handle a full-data backup operation of the specified size on the current package.

     * If the transport returns anything other than TRANSPORT_OK, the package's backup

     * operation will be skipped (and {@link #finishBackup() invoked} with no data for that

     * package being passed to {@link #sendBackupData}.

     *

     * Added in MNC (API 23).

     *

     * @param size The estimated size of the full-data payload for this app.  This includes

     *         manifest and archive format overhead, but is not guaranteed to be precise.

     * @return TRANSPORT_OK if the platform is to proceed with the full-data backup,

     *         TRANSPORT_PACKAGE_REJECTED if the proposed payload size is too large for

     *         the transport to handle, or TRANSPORT_ERROR to indicate a fatal error

     *         condition that means the platform cannot perform a backup at this time.

     */

    public int checkFullBackupSize(long size) {

        return BackupTransport.TRANSPORT_OK;

    }



    /**

     * Tells the transport to read {@code numBytes} bytes of data from the socket file

     * descriptor provided in the {@link #performFullBackup(PackageInfo, ParcelFileDescriptor)}
@@ -587,6 +607,11 @@ public class BackupTransport { 
            return BackupTransport.this.performFullBackup(targetPackage, socket);

        }



        @Override

        public int checkFullBackupSize(long size) {

            return BackupTransport.this.checkFullBackupSize(size);

        }



        @Override

        public int sendBackupData(int numBytes) throws RemoteException {

            return BackupTransport.this.sendBackupData(numBytes);

core/java/android/app/backup/FullBackup.java

+1 −1
Original line number Diff line number Diff line
@@ -58,7 +58,7 @@ public class FullBackup { 
     * @hide

     */

    static public native int backupToTar(String packageName, String domain,

            String linkdomain, String rootpath, String path, BackupDataOutput output);

            String linkdomain, String rootpath, String path, FullBackupDataOutput output);



    /**

     * Copy data from a socket to the given File location on permanent storage.  The