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/*
* Copyright (C) 2021 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 com.android.permissioncontroller.permission.service
import android.app.job.JobScheduler
import android.content.Context
import android.util.AtomicFile
import android.util.Log
import com.android.permissioncontroller.DumpableLog
import com.android.permissioncontroller.permission.data.PermissionEvent
import java.io.File
import java.io.FileOutputStream
import java.io.IOException
import java.io.InputStream
import java.io.OutputStream
import org.xmlpull.v1.XmlPullParserException
/** Thread-safe implementation of [PermissionEventStorage] using an XML file as the database. */
abstract class BasePermissionEventStorage<T : PermissionEvent>(
private val context: Context,
jobScheduler: JobScheduler = context.getSystemService(JobScheduler::class.java)!!
) : PermissionEventStorage<T> {
private val dbFile: AtomicFile = AtomicFile(File(context.filesDir, getDatabaseFileName()))
private val fileLock = Object()
companion object {
private const val LOG_TAG = "BasePermissionEventStorage"
}
init {
PermissionEventCleanupJobService.scheduleOldDataCleanupIfNecessary(context, jobScheduler)
}
override suspend fun storeEvent(event: T): Boolean {
synchronized(fileLock) {
val existingEvents = readData()
val newEvents = mutableListOf<T>()
// add new event first to keep the list ordered
newEvents.add(event)
for (existingEvent in existingEvents) {
// ignore any old events that violate the primary key uniqueness with the database
if (hasTheSamePrimaryKey(existingEvent, event)) {
continue
}
newEvents.add(existingEvent)
}
return writeData(newEvents)
}
}
override suspend fun loadEvents(): List<T> {
synchronized(fileLock) {
return readData()
}
}
override suspend fun clearEvents() {
synchronized(fileLock) { dbFile.delete() }
}
override suspend fun removeOldData(): Boolean {
synchronized(fileLock) {
val existingEvents = readData()
val originalCount = existingEvents.size
val newEvents =
existingEvents.filter {
(System.currentTimeMillis() - it.eventTime) <= getMaxDataAgeMs()
}
DumpableLog.d(
LOG_TAG,
"${originalCount - newEvents.size} old permission events removed"
)
return writeData(newEvents)
}
}
override suspend fun removeEventsForPackage(packageName: String): Boolean {
synchronized(fileLock) {
val existingEvents = readData()
val newEvents = existingEvents.filter { it.packageName != packageName }
return writeData(newEvents)
}
}
override suspend fun updateEventsBySystemTimeDelta(diffSystemTimeMillis: Long): Boolean {
synchronized(fileLock) {
val existingEvents = readData()
val newEvents = existingEvents.map { it.copyWithTimeDelta(diffSystemTimeMillis) }
return writeData(newEvents)
}
}
private fun writeData(events: List<T>): Boolean {
val stream: FileOutputStream =
try {
dbFile.startWrite()
} catch (e: IOException) {
Log.e(LOG_TAG, "Failed to save db file", e)
return false
}
try {
serialize(stream, events)
dbFile.finishWrite(stream)
} catch (e: IOException) {
Log.e(LOG_TAG, "Failed to save db file, restoring backup", e)
dbFile.failWrite(stream)
return false
}
return true
}
private fun readData(): List<T> {
if (!dbFile.baseFile.exists()) {
return emptyList()
}
return try {
parse(dbFile.openRead())
} catch (e: IOException) {
Log.e(LOG_TAG, "Failed to read db file", e)
emptyList()
} catch (e: XmlPullParserException) {
Log.e(LOG_TAG, "Failed to read db file", e)
emptyList()
}
}
/**
* Serialize a list of permission events.
*
* @param stream output stream to serialize events to
* @param events list of permission events to serialize
*/
abstract fun serialize(stream: OutputStream, events: List<T>)
/**
* Parse a list of permission events from the XML parser.
*
* @param inputStream input stream to parse events from
* @return the list of parsed permission events
*/
@Throws(XmlPullParserException::class, IOException::class)
abstract fun parse(inputStream: InputStream): List<T>
/** Returns file name for database. */
abstract fun getDatabaseFileName(): String
/** Returns max time that data should be persisted before being removed. */
abstract fun getMaxDataAgeMs(): Long
/** Returns true if the two events have the same primary key for the database store. */
abstract fun hasTheSamePrimaryKey(first: T, second: T): Boolean
/** Copies the event with the time delta applied to the [PermissionEvent.eventTime]. */
abstract fun T.copyWithTimeDelta(timeDelta: Long): T
}
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