Auto-format code style of all files to match official style

This also adds a note to the README
and the Android Studio coding style files.

.gitignore

@@ -9,6 +9,7 @@ out/
 lib/
 .idea/*
 !.idea/runConfigurations*
+!.idea/codeStyles*
 *.ipr
 *.iws
 *.iml

README.md

@@ -32,7 +32,9 @@ It uses the same internal APIs as `adb backup` which is deprecated and thus need
 * `android.permission.INSTALL_PACKAGES` to re-install apps when restoring from backup.
 
 ## Contributing
-Bug reports and pull requests are welcome on GitHub at https://github.com/stevesoltys/seedvault. 
+Bug reports and pull requests are welcome on GitHub at https://github.com/stevesoltys/seedvault.
+
+This project aims to adhere to the [official Kotlin coding style](https://developer.android.com/kotlin/style-guide).
 
 ## License
 This application is available as open source under the terms of the [Apache-2.0 License](https://opensource.org/licenses/Apache-2.0).

app/src/main/java/com/stevesoltys/seedvault/Base64Utils.kt

@@ -1,7 +1,7 @@
 package com.stevesoltys.seedvault
 
 import java.nio.charset.Charset
-import java.util.*
+import java.util.Base64
 
 val Utf8: Charset = Charset.forName("UTF-8")
 

app/src/main/java/com/stevesoltys/seedvault/UsbIntentReceiver.kt

@@ -24,6 +24,8 @@ import java.util.concurrent.TimeUnit.HOURS
 
 private val TAG = UsbIntentReceiver::class.java.simpleName
 
+private const val HOURS_AUTO_BACKUP: Long = 24
+
 class UsbIntentReceiver : UsbMonitor() {
 
     // using KoinComponent would crash robolectric tests :(
@@ -37,7 +39,8 @@ class UsbIntentReceiver : UsbMonitor() {
         val attachedFlashDrive = FlashDrive.from(device)
         return if (savedFlashDrive == attachedFlashDrive) {
             Log.d(TAG, "Matches stored device, checking backup time...")
-            if (System.currentTimeMillis() - metadataManager.getLastBackupTime() >= HOURS.toMillis(24)) {
+            val backupMillis = System.currentTimeMillis() - metadataManager.getLastBackupTime()
+            if (backupMillis >= HOURS.toMillis(HOURS_AUTO_BACKUP)) {
                 Log.d(TAG, "Last backup older than 24 hours, requesting a backup...")
                 true
             } else {
@@ -101,6 +104,7 @@ internal fun UsbDevice.isMassStorage(): Boolean {
 }
 
 private fun UsbInterface.isMassStorage(): Boolean {
+    @Suppress("MagicNumber")
     return interfaceClass == 8 && interfaceProtocol == 80 && interfaceSubclass == 6
 }
 

app/src/main/java/com/stevesoltys/seedvault/crypto/Crypto.kt

@@ -75,8 +75,12 @@ interface Crypto {
      * @return The read [VersionHeader] present in the beginning of the given [InputStream].
      */
     @Throws(IOException::class, SecurityException::class)
-    fun decryptHeader(inputStream: InputStream, expectedVersion: Byte, expectedPackageName: String,
-                      expectedKey: String? = null): VersionHeader
+    fun decryptHeader(
+        inputStream: InputStream,
+        expectedVersion: Byte,
+        expectedPackageName: String,
+        expectedKey: String? = null
+    ): VersionHeader
 
     /**
      * Reads and decrypts a segment from the given [InputStream].
@@ -94,9 +98,10 @@ interface Crypto {
 }
 
 internal class CryptoImpl(
-        private val cipherFactory: CipherFactory,
-        private val headerWriter: HeaderWriter,
-        private val headerReader: HeaderReader) : Crypto {
+    private val cipherFactory: CipherFactory,
+    private val headerWriter: HeaderWriter,
+    private val headerReader: HeaderReader
+) : Crypto {
 
     @Throws(IOException::class)
     override fun encryptHeader(outputStream: OutputStream, versionHeader: VersionHeader) {
@@ -136,16 +141,26 @@ internal class CryptoImpl(
     }
 
     @Throws(IOException::class, SecurityException::class)
-    override fun decryptHeader(inputStream: InputStream, expectedVersion: Byte,
-                               expectedPackageName: String, expectedKey: String?): VersionHeader {
+    override fun decryptHeader(
+        inputStream: InputStream,
+        expectedVersion: Byte,
+        expectedPackageName: String,
+        expectedKey: String?
+    ): VersionHeader {
         val decrypted = decryptSegment(inputStream, MAX_VERSION_HEADER_SIZE)
         val header = headerReader.getVersionHeader(decrypted)
 
         if (header.version != expectedVersion) {
-            throw SecurityException("Invalid version '${header.version.toInt()}' in header, expected '${expectedVersion.toInt()}'.")
+            throw SecurityException(
+                "Invalid version '${header.version.toInt()}' in header, " +
+                    "expected '${expectedVersion.toInt()}'."
+            )
         }
         if (header.packageName != expectedPackageName) {
-            throw SecurityException("Invalid package name '${header.packageName}' in header, expected '$expectedPackageName'.")
+            throw SecurityException(
+                "Invalid package name '${header.packageName}' in header, " +
+                    "expected '$expectedPackageName'."
+            )
         }
         if (header.key != expectedKey) {
             throw SecurityException("Invalid key '${header.key}' in header, expected '$expectedKey'.")

app/src/main/java/com/stevesoltys/seedvault/crypto/KeyManager.kt

@@ -54,7 +54,7 @@ internal class KeyManagerImpl : KeyManager {
     }
 
     override fun hasBackupKey() = keyStore.containsAlias(KEY_ALIAS) &&
-            keyStore.entryInstanceOf(KEY_ALIAS, SecretKeyEntry::class.java)
+        keyStore.entryInstanceOf(KEY_ALIAS, SecretKeyEntry::class.java)
 
     override fun getBackupKey(): SecretKey {
         val ksEntry = keyStore.getEntry(KEY_ALIAS, null) as SecretKeyEntry
@@ -63,9 +63,9 @@ internal class KeyManagerImpl : KeyManager {
 
     private fun getKeyProtection(): KeyProtection {
         val builder = KeyProtection.Builder(PURPOSE_ENCRYPT or PURPOSE_DECRYPT)
-                .setBlockModes(BLOCK_MODE_GCM)
-                .setEncryptionPaddings(ENCRYPTION_PADDING_NONE)
-                .setRandomizedEncryptionRequired(true)
+            .setBlockModes(BLOCK_MODE_GCM)
+            .setEncryptionPaddings(ENCRYPTION_PADDING_NONE)
+            .setRandomizedEncryptionRequired(true)
         // unlocking is required only for decryption, so when restoring from backup
         builder.setUnlockedDeviceRequired(true)
         return builder.build()

app/src/main/java/com/stevesoltys/seedvault/header/Header.kt

@@ -5,16 +5,17 @@ import com.stevesoltys.seedvault.crypto.GCM_AUTHENTICATION_TAG_LENGTH
 internal const val VERSION: Byte = 0
 internal const val MAX_PACKAGE_LENGTH_SIZE = 255
 internal const val MAX_KEY_LENGTH_SIZE = MAX_PACKAGE_LENGTH_SIZE
-internal const val MAX_VERSION_HEADER_SIZE = 1 + Short.SIZE_BYTES * 2 + MAX_PACKAGE_LENGTH_SIZE + MAX_KEY_LENGTH_SIZE
+internal const val MAX_VERSION_HEADER_SIZE =
+    1 + Short.SIZE_BYTES * 2 + MAX_PACKAGE_LENGTH_SIZE + MAX_KEY_LENGTH_SIZE
 
 /**
  * After the first version byte of each backup stream
  * must follow followed this header encrypted with authentication.
  */
 data class VersionHeader(
-        internal val version: Byte = VERSION, //  1 byte
-        internal val packageName: String,     // ?? bytes (max 255)
-        internal val key: String? = null      // ?? bytes
+    internal val version: Byte = VERSION, //  1 byte
+    internal val packageName: String, // ?? bytes (max 255)
+    internal val key: String? = null // ?? bytes
 ) {
     init {
         check(packageName.length <= MAX_PACKAGE_LENGTH_SIZE) {
@@ -26,19 +27,19 @@ data class VersionHeader(
     }
 }
 
-
 internal const val SEGMENT_LENGTH_SIZE: Int = Short.SIZE_BYTES
 internal const val MAX_SEGMENT_LENGTH: Int = Short.MAX_VALUE.toInt()
-internal const val MAX_SEGMENT_CLEARTEXT_LENGTH: Int = MAX_SEGMENT_LENGTH - GCM_AUTHENTICATION_TAG_LENGTH / 8
+internal const val MAX_SEGMENT_CLEARTEXT_LENGTH: Int =
+    MAX_SEGMENT_LENGTH - GCM_AUTHENTICATION_TAG_LENGTH / 8
 internal const val IV_SIZE: Int = 12
 internal const val SEGMENT_HEADER_SIZE = SEGMENT_LENGTH_SIZE + IV_SIZE
 
 /**
  * Each data segment must start with this header
  */
 class SegmentHeader(
-        internal val segmentLength: Short,    //  2 bytes
-        internal val nonce: ByteArray         // 12 bytes
+    internal val segmentLength: Short, //  2 bytes
+    internal val nonce: ByteArray // 12 bytes
 ) {
     init {
         check(nonce.size == IV_SIZE) {

app/src/main/java/com/stevesoltys/seedvault/header/HeaderReader.kt

@@ -36,16 +36,16 @@ internal class HeaderReaderImpl : HeaderReader {
         if (packageLength > MAX_PACKAGE_LENGTH_SIZE) throw SecurityException("Too large package length: $packageLength")
         if (packageLength > buffer.remaining()) throw SecurityException("Not enough bytes for package name")
         val packageName = ByteArray(packageLength)
-                .apply { buffer.get(this) }
-                .toString(Utf8)
+            .apply { buffer.get(this) }
+            .toString(Utf8)
 
         val keyLength = buffer.short.toInt()
         if (keyLength < 0) throw SecurityException("Invalid key length: $keyLength")
         if (keyLength > MAX_KEY_LENGTH_SIZE) throw SecurityException("Too large key length: $keyLength")
         if (keyLength > buffer.remaining()) throw SecurityException("Not enough bytes for key")
         val key = if (keyLength == 0) null else ByteArray(keyLength)
-                .apply { buffer.get(this) }
-                .toString(Utf8)
+            .apply { buffer.get(this) }
+            .toString(Utf8)
 
         if (buffer.remaining() != 0) throw SecurityException("Found extra bytes in header")
 

app/src/main/java/com/stevesoltys/seedvault/header/HeaderWriter.kt

@@ -43,8 +43,8 @@ internal class HeaderWriterImpl : HeaderWriter {
 
     override fun writeSegmentHeader(outputStream: OutputStream, header: SegmentHeader) {
         val buffer = ByteBuffer.allocate(SEGMENT_HEADER_SIZE)
-                .putShort(header.segmentLength)
-                .put(header.nonce)
+            .putShort(header.segmentLength)
+            .put(header.nonce)
         outputStream.write(buffer.array())
     }