[BackupRestorer] Handle uncompressed backups (#8988)

[Backups] Handle uncompressed backups

app/src/main/java/eu/kanade/tachiyomi/data/backup/BackupFileValidator.kt

@@ -3,12 +3,9 @@ package eu.kanade.tachiyomi.data.backup
 import android.content.Context
 import android.net.Uri
 import eu.kanade.tachiyomi.R
-import eu.kanade.tachiyomi.data.backup.models.BackupSerializer
 import eu.kanade.tachiyomi.data.track.TrackManager
 import eu.kanade.tachiyomi.source.SourceManager
-import okio.buffer
-import okio.gzip
-import okio.source
+import eu.kanade.tachiyomi.util.BackupUtil
 import uy.kohesive.injekt.Injekt
 import uy.kohesive.injekt.api.get
 
@@ -24,13 +21,8 @@ class BackupFileValidator(
      * @return List of missing sources or missing trackers.
      */
     fun validate(context: Context, uri: Uri): Results {
-        val backupManager = BackupManager(context)
-
         val backup = try {
-            val backupString =
-                context.contentResolver.openInputStream(uri)!!.source().gzip().buffer()
-                    .use { it.readByteArray() }
-            backupManager.parser.decodeFromByteArray(BackupSerializer, backupString)
+            BackupUtil.decodeBackup(context, uri)
         } catch (e: Exception) {
             throw IllegalStateException(e)
         }

app/src/main/java/eu/kanade/tachiyomi/data/backup/BackupRestorer.kt

@@ -6,15 +6,13 @@ import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.data.backup.models.BackupCategory
 import eu.kanade.tachiyomi.data.backup.models.BackupHistory
 import eu.kanade.tachiyomi.data.backup.models.BackupManga
-import eu.kanade.tachiyomi.data.backup.models.BackupSerializer
 import eu.kanade.tachiyomi.data.backup.models.BackupSource
 import eu.kanade.tachiyomi.data.database.models.Chapter
 import eu.kanade.tachiyomi.data.database.models.Manga
 import eu.kanade.tachiyomi.data.database.models.Track
+import eu.kanade.tachiyomi.util.BackupUtil
 import eu.kanade.tachiyomi.util.system.createFileInCacheDir
 import kotlinx.coroutines.Job
-import okio.buffer
-import okio.gzip
 import okio.source
 import java.io.File
 import java.text.SimpleDateFormat
@@ -79,8 +77,7 @@ class BackupRestorer(
 
     @Suppress("BlockingMethodInNonBlockingContext")
     private suspend fun performRestore(uri: Uri): Boolean {
-        val backupString = context.contentResolver.openInputStream(uri)!!.source().gzip().buffer().use { it.readByteArray() }
-        val backup = backupManager.parser.decodeFromByteArray(BackupSerializer, backupString)
+        val backup = BackupUtil.decodeBackup(context, uri)
 
         restoreAmount = backup.backupManga.size + 1 // +1 for categories
 

app/src/main/java/eu/kanade/tachiyomi/util/BackupUtil.kt

@@ -0,0 +1,32 @@
+package eu.kanade.tachiyomi.util
+
+import android.content.Context
+import android.net.Uri
+import eu.kanade.tachiyomi.data.backup.BackupManager
+import eu.kanade.tachiyomi.data.backup.models.Backup
+import eu.kanade.tachiyomi.data.backup.models.BackupSerializer
+import okio.buffer
+import okio.gzip
+import okio.source
+
+object BackupUtil {
+    /**
+     * Decode a potentially-gzipped backup.
+     */
+    fun decodeBackup(context: Context, uri: Uri): Backup {
+        val backupManager = BackupManager(context)
+
+        val backupStringSource = context.contentResolver.openInputStream(uri)!!.source().buffer()
+
+        val peeked = backupStringSource.peek()
+        peeked.require(2)
+        val id1id2 = peeked.readShort()
+        val backupString = if (id1id2.toInt() == 0x1f8b) { // 0x1f8b is gzip magic bytes
+            backupStringSource.gzip().buffer()
+        } else {
+            backupStringSource
+        }.use { it.readByteArray() }
+
+        return backupManager.parser.decodeFromByteArray(BackupSerializer, backupString)
+    }
+}