History log of /frameworks/base/core/java/android/app/backup/BackupAgent.java
Revision Date Author Comments (<<< Hide modified files) (Show modified files >>>)
61fd1e8d8c3ccf2d6b7d4af1c19e8f0988d5a1ec 26-Oct-2011 Joe Fernandez <joefernandez@google.com> docs: add developer guide cross references, Project ACRE, round 3

Change-Id: I6125315ecdf0f78dd947c514a9944729d723e95d
/frameworks/base/core/java/android/app/backup/BackupAgent.java
78be158ce4b95fa537c6cb60a55dbc9161e53ef1 29-Aug-2011 Christopher Tate <ctate@google.com> Un-hide the new BackupAgent.onFullBackup() API

This is intended to be new public API for ICS, and unbundled app
development needs access to it.

Change-Id: I091b31ae9ec319850a93efc3d5860b87b68d355e
/frameworks/base/core/java/android/app/backup/BackupAgent.java
2efd2dbbac9eac89620683696c6076463c3a1cd6 20-Jul-2011 Christopher Tate <ctate@google.com> Support full-backup encryption and global backup password

If the user has supplied a backup password in Settings, that password
is validated during the full backup process and is used as an encryption
key for encoding the backed-up data itself. This is the fundamental
mechanism whereby users can secure their data even against malicious
parties getting physical unlocked access to their device.

Technically the user-supplied password is not used as the encryption
key for the backed-up data itself. What is actually done is that a
random key is generated to use as the raw encryption key. THAT key,
in turn, is encrypted with the user-supplied password (after random
salting and key expansion with PBKDF2). The encrypted master key
and a checksum are stored in the backup header. At restore time,
the user supplies their password, which allows the system to decrypt
the master key, which in turn allows the decryption of the backup
data itself.

The checksum is part of the archive in order to permit validation
of the user-supplied password. The checksum is the result of running
the user-supplied password through PBKDF2 with a randomly selected
salt. At restore time, the proposed password is run through PBKDF2
with the salt described by the archive header. If the result does
not match the archive's stated checksum, then the user has supplied
the wrong decryption password.

Also, suppress backup consideration for a few packages whose
data is either nonexistent or inapplicable across devices or
factory reset operations.

Bug 4901637

Change-Id: Id0cc9d0fdfc046602b129f273d48e23b7a14df36
/frameworks/base/core/java/android/app/backup/BackupAgent.java
7926a693c4a4f4d2a2d352343bca23e189c7420d 11-Jul-2011 Christopher Tate <ctate@google.com> Compress the backup output stream

Zlib compression, with a full flush between each application's
data. Encryption will be performed on the already-compressed data
once that's implemented.

On restore, the streamed data is similarly uncompressed on the fly.

Change-Id: I19b65c88e759a66527d10913d18fffa9df0bc011
/frameworks/base/core/java/android/app/backup/BackupAgent.java
b848b7a99c81081723077d7fb2006b2a35760259 07-Jul-2011 Christopher Tate <ctate@google.com> Remove unused object

Change-Id: I98c55432c26ccc4e8421db46c9f825cb42772508
/frameworks/base/core/java/android/app/backup/BackupAgent.java
79ec80db70d788f35aa13346e4684ecbd401bd84 24-Jun-2011 Christopher Tate <ctate@google.com> Make full backup API available to apps

New methods for full backup/restore have been added to BackupAgent
(still hidden): onFullBackup() and onRestoreFile(). The former is the
entry point for a full app backup to adb/socket/etc: the app then writes
all of its files, entire, to the output. During restore, the latter
new callback is invoked, once for each file being restored.

The full backup/restore interface does not use the previously-defined
BackupDataInput / BackupDataOutput classes, because those classes
provide an API designed for incremental key/value data structuring.
Instead, a new FullBackupDataOutput class has been introduced, through
which we restrict apps' abilities to write data during a full backup
operation to *only* writing entire on-disk files via a new BackupAgent
method called fullBackupFile().

"FullBackupAgent" exists now solely as a concrete shell class that
can be instantiated in the case of apps that do not have their own
BackupAgent implementations.

Along with the API change, responsibility for backing up the .apk
file and OBB container has been moved into the framework rather than
have the application side of the transaction do it.

Change-Id: I12849b06b1a6e4c44d080587c1e9828a52b70dae
/frameworks/base/core/java/android/app/backup/BackupAgent.java
b0628bfd5aac480a0d412ac96b8af1d97ac01c30 03-Jun-2011 Christopher Tate <ctate@google.com> Implement shared-storage full backup/restore

Every available shared-storage volume is backed up, tagged with its
ordinal in the set of mounted shared volumes. This is an approximation
of "internal + the external card". This lets us restore things to the
same volume [or "equivalent" volume, in the case of a cross-model
restore] as they originated on.

Also fixed a bug in the handling of files/dirs with spaces in
their names.

Change-Id: I380019da8d0bb5b3699bd7c11eeff621a88e78c3
/frameworks/base/core/java/android/app/backup/BackupAgent.java
75a99709accef8cf221fd436d646727e7c8dd1f1 19-May-2011 Christopher Tate <ctate@google.com> Restore from a previous full backup's tarfile

Usage: adb restore [tarfilename]

Restores app data [and installs the apps if necessary from the backup
file] captured in a previous invocation of 'adb backup'. The user
must explicitly acknowledge the action on-device before it is allowed
to proceed; this prevents any "invisible" pushes of content from the
host to the device.

Known issues:

* The settings databases and wallpaper are saved/restored, but lots
of other system state is not yet captured in the full backup. This
means that for practical purposes this is usable for 3rd party
apps at present but not for full-system cloning/imaging.

Change-Id: I0c748b645845e7c9178e30bf142857861a64efd3
/frameworks/base/core/java/android/app/backup/BackupAgent.java
4a627c71ff53a4fca1f961f4b1dcc0461df18a06 01-Apr-2011 Christopher Tate <ctate@google.com> Full local backup infrastructure

This is the basic infrastructure for pulling a full(*) backup of the
device's data over an adb(**) connection to the local device. The
basic process consists of these interacting pieces:

1. The framework's BackupManagerService, which coordinates the
collection of app data and routing to the destination.

2. A new framework-provided BackupAgent implementation called
FullBackupAgent, which is instantiated in the target applications'
processes in turn, and knows how to emit a datastream that contains
all of the app's saved data files.

3. A new shell-level program called "bu" that is used to bridge from
adb to the framework's Backup Manager.

4. adb itself, which now knows how to use 'bu' to kick off a backup
operation and pull the resulting data stream to the desktop host.

5. A system-provided application that verifies with the user that
an attempted backup/restore operation is in fact expected and to
be allowed.

The full agent implementation is not used during normal operation of
the delta-based app-customized remote backup process. Instead it's
used during user-confirmed *full* backup of applications and all their
data to a local destination, e.g. via the adb connection.

The output format is 'tar'. This makes it very easy for the end
user to examine the resulting dataset, e.g. for purpose of extracting
files for debug purposes; as well as making it easy to contemplate
adding things like a direct gzip stage to the data pipeline during
backup/restore. It also makes it convenient to construct and maintain
synthetic backup datasets for testing purposes.

Within the tar format, certain artificial conventions are used.
All files are stored within top-level directories according to
their semantic origin:

apps/pkgname/a/ : Application .apk file itself
apps/pkgname/obb/: The application's associated .obb containers
apps/pkgname/f/ : The subtree rooted at the getFilesDir() location
apps/pkgname/db/ : The subtree rooted at the getDatabasePath() parent
apps/pkgname/sp/ : The subtree rooted at the getSharedPrefsFile() parent
apps/pkgname/r/ : Files stored relative to the root of the app's file tree
apps/pkgname/c/ : Reserved for the app's getCacheDir() tree; not stored.

For each package, the first entry in the tar stream is a file called
"_manifest", nominally rooted at apps/pkgname. This file contains some
metadata about the package whose data is stored in the archive.

The contents of shared storage can optionally be included in the tar
stream. It is placed in the synthetic location:

shared/...

uid/gid are ignored; app uids are assigned at install time, and the
app's data is handled from within its own execution environment, so
will automatically have the app's correct uid.

Forward-locked .apk files are never backed up. System-partition
.apk files are not backed up unless they have been overridden by a
post-factory upgrade, in which case the current .apk *is* backed up --
i.e. the .apk that matches the on-disk data. The manifest preceding
each application's portion of the tar stream provides version numbers
and signature blocks for version checking, as well as an indication
of whether the restore logic should expect to install the .apk before
extracting the data.

System packages can designate their own full backup agents. This is
to manage things like the settings provider which (a) cannot be shut
down on the fly in order to do a clean snapshot of their file trees,
and (b) manage data that is not only irrelevant but actively hostile
to non-identical devices -- CDMA telephony settings would seriously
mess up a GSM device if emplaced there blind, for example.

When a full backup or restore is initiated from adb, the system will
present a confirmation UI that the user must explicitly respond to
within a short [~ 30 seconds] timeout. This is to avoid the
possibility of malicious desktop-side software secretly grabbing a copy
of all the user's data for nefarious purposes.

(*) The backup is not strictly a full mirror. In particular, the
settings database is not cloned; it is handled the same way that
it is in cloud backup/restore. This is because some settings
are actively destructive if cloned onto a different (or
especially a different-model) device: telephony settings and
AndroidID are good examples of this.

(**) On the framework side it doesn't care that it's adb; it just
sends the tar stream to a file descriptor. This can easily be
retargeted around whatever transport we might decide to use
in the future.

KNOWN ISSUES:

* the security UI is desperately ugly; no proper designs have yet
been done for it
* restore is not yet implemented
* shared storage backup is not yet implemented
* symlinks aren't yet handled, though some infrastructure for
dealing with them has been put in place.

Change-Id: Ia8347611e23b398af36ea22c36dff0a276b1ce91
/frameworks/base/core/java/android/app/backup/BackupAgent.java
b83a283ac178ab0a72f1d811189d79b26097835e 29-Apr-2010 Scott Main <smain@google.com> docs: add dev guide for backup

Change-Id: I168f6b15d3441c9cbea2cd9699612476c7244530
/frameworks/base/core/java/android/app/backup/BackupAgent.java
d17da43c82c4edb97514d6138bc208eeba321636 30-Apr-2010 Scott Main <smain@google.com> docs: revise and add documentation for backup APIs

Change-Id: I0b015a6de16da07ccd31756b8d2329dc2785c2f7
/frameworks/base/core/java/android/app/backup/BackupAgent.java
4e14a829129feee14ebe453f61a124784c870610 08-Apr-2010 Christopher Tate <ctate@google.com> SDK: more backup/restore documentation work

Still not complete, but here's a lot more of the necessary documentation.
Submitting a checkpoint seems prudent.

Bug #2465360

Change-Id: Ifff60d57e4b24cee21f3a34f5f50e290d377c386
/frameworks/base/core/java/android/app/backup/BackupAgent.java
cc84c69726507a85116f5664e20e2ebfac76edbe 29-Mar-2010 Christopher Tate <ctate@google.com> API CHANGE: rename BackupHelperAgent => BackupAgentHelper per API Council

Part of bug #2545514

Change-Id: Ic775e3b942c485252149c1b6c15c88517fa4e3e5
/frameworks/base/core/java/android/app/backup/BackupAgent.java
4528186e0d65fc68ef0dd1941aa2ac8aefcd55a3 06-Mar-2010 Christopher Tate <ctate@google.com> Refactor android.backup => android.app.backup

Change-Id: I0b21316ff890d7f3c7d4b82837bb60670724c2e8
/frameworks/base/core/java/android/app/backup/BackupAgent.java