Use DigestInputStream to spy on backup data

this is to save memory to prevent OOM errors we saw on CI

app/src/androidTest/java/com/stevesoltys/seedvault/e2e/LargeBackupTestBase.kt

@@ -9,7 +9,6 @@ import android.content.pm.PackageInfo
 import android.os.ParcelFileDescriptor
 import androidx.test.uiautomator.Until
 import com.stevesoltys.seedvault.e2e.io.BackupDataInputIntercept
-import com.stevesoltys.seedvault.e2e.io.InputStreamIntercept
 import com.stevesoltys.seedvault.e2e.screen.impl.BackupScreen
 import com.stevesoltys.seedvault.transport.backup.FullBackup
 import com.stevesoltys.seedvault.transport.backup.InputFactory
@@ -21,8 +20,10 @@ import io.mockk.every
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.withTimeout
+import org.calyxos.seedvault.core.toHexString
 import org.koin.core.component.get
-import java.io.ByteArrayOutputStream
+import java.security.DigestInputStream
+import java.security.MessageDigest
 import java.util.concurrent.atomic.AtomicBoolean
 import kotlin.test.fail
 
@@ -154,7 +155,8 @@ internal interface LargeBackupTestBase : LargeTestBase {
 
     private fun spyOnFullBackupData(backupResult: SeedvaultLargeTestResult) {
         var packageName: String? = null
-        var dataIntercept = ByteArrayOutputStream()
+        val messageDigest = MessageDigest.getInstance("SHA-256")
+        var digestInputStream: DigestInputStream? = null
 
         coEvery {
             spyFullBackup.performFullBackup(any(), any(), any())
@@ -166,20 +168,19 @@ internal interface LargeBackupTestBase : LargeTestBase {
         every {
             spyInputFactory.getInputStream(any())
         } answers {
-            InputStreamIntercept(
-                inputStream = callOriginal(),
-                intercept = dataIntercept
-            )
+            digestInputStream = DigestInputStream(callOriginal(), messageDigest)
+            digestInputStream!!
         }
 
         coEvery {
             spyFullBackup.finishBackup()
         } answers {
             val result = callOriginal()
-            backupResult.full[packageName!!] = dataIntercept.toByteArray().sha256()
+            val digest = digestInputStream?.messageDigest ?: fail("No digestInputStream")
+            backupResult.full[packageName!!] = digest.digest().toHexString()
 
             packageName = null
-            dataIntercept = ByteArrayOutputStream()
+            digest.reset()
             result
         }
     }

app/src/androidTest/java/com/stevesoltys/seedvault/e2e/LargeRestoreTestBase.kt

@@ -8,7 +8,6 @@ package com.stevesoltys.seedvault.e2e
 import android.content.pm.PackageInfo
 import android.os.ParcelFileDescriptor
 import com.stevesoltys.seedvault.e2e.io.BackupDataOutputIntercept
-import com.stevesoltys.seedvault.e2e.io.OutputStreamIntercept
 import com.stevesoltys.seedvault.e2e.screen.impl.RecoveryCodeScreen
 import com.stevesoltys.seedvault.e2e.screen.impl.RestoreScreen
 import com.stevesoltys.seedvault.transport.restore.FullRestore
@@ -24,8 +23,11 @@ import kotlinx.coroutines.delay
 import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.withContext
 import kotlinx.coroutines.withTimeout
+import org.calyxos.seedvault.core.toHexString
 import org.koin.core.component.get
-import java.io.ByteArrayOutputStream
+import java.security.DigestOutputStream
+import java.security.MessageDigest
+import kotlin.test.fail
 
 internal interface LargeRestoreTestBase : LargeTestBase {
 
@@ -196,7 +198,8 @@ internal interface LargeRestoreTestBase : LargeTestBase {
 
     private fun spyOnFullRestoreData(restoreResult: SeedvaultLargeTestResult) {
         var packageName: String? = null
-        var dataIntercept = ByteArrayOutputStream()
+        val messageDigest = MessageDigest.getInstance("SHA-256")
+        var digestOutputStream: DigestOutputStream? = null
 
         clearMocks(spyFullRestore)
 
@@ -204,11 +207,13 @@ internal interface LargeRestoreTestBase : LargeTestBase {
             packageInfoIndex: Int
         ): MockKAnswerScope<Unit, Unit>.(Call) -> Unit = {
             packageName?.let {
-                restoreResult.full[it] = dataIntercept.toByteArray().sha256()
+                // sometimes finishRestore() doesn't get called, so get data from last package here
+                digestOutputStream?.messageDigest?.let { digest ->
+                    restoreResult.full[packageName!!] = digest.digest().toHexString()
+                }
             }
 
             packageName = arg<PackageInfo>(packageInfoIndex).packageName
-            dataIntercept = ByteArrayOutputStream()
 
             callOriginal()
         }
@@ -228,27 +233,26 @@ internal interface LargeRestoreTestBase : LargeTestBase {
         every {
             spyOutputFactory.getOutputStream(any())
         } answers {
-            OutputStreamIntercept(
-                outputStream = callOriginal(),
-                intercept = dataIntercept
-            )
+            digestOutputStream = DigestOutputStream(callOriginal(), messageDigest)
+            digestOutputStream!!
         }
 
         every {
             spyFullRestore.abortFullRestore()
         } answers {
             packageName = null
-            dataIntercept = ByteArrayOutputStream()
+            digestOutputStream?.messageDigest?.reset()
             callOriginal()
         }
 
         every {
             spyFullRestore.finishRestore()
         } answers {
-            restoreResult.full[packageName!!] = dataIntercept.toByteArray().sha256()
+            val digest = digestOutputStream?.messageDigest ?: fail("No digestOutputStream")
+            restoreResult.full[packageName!!] = digest.digest().toHexString()
 
             packageName = null
-            dataIntercept = ByteArrayOutputStream()
+            digest.reset()
             callOriginal()
         }
     }

app/src/androidTest/java/com/stevesoltys/seedvault/e2e/io/InputStreamIntercept.kt

@@ -1,31 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2023 The Calyx Institute
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.stevesoltys.seedvault.e2e.io
-
-import java.io.ByteArrayOutputStream
-import java.io.InputStream
-
-class InputStreamIntercept(
-    private val inputStream: InputStream,
-    private val intercept: ByteArrayOutputStream
-) : InputStream() {
-
-    override fun read(): Int {
-        val byte = inputStream.read()
-        if (byte != -1) {
-            intercept.write(byte)
-        }
-        return byte
-    }
-
-    override fun read(buffer: ByteArray, offset: Int, length: Int): Int {
-        val bytesRead = inputStream.read(buffer, offset, length)
-        if (bytesRead != -1) {
-            intercept.write(buffer, offset, bytesRead)
-        }
-        return bytesRead
-    }
-}

app/src/androidTest/java/com/stevesoltys/seedvault/e2e/io/OutputStreamIntercept.kt

@@ -1,25 +0,0 @@
-/*
- * SPDX-FileCopyrightText: 2023 The Calyx Institute
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.stevesoltys.seedvault.e2e.io
-
-import java.io.ByteArrayOutputStream
-import java.io.OutputStream
-
-class OutputStreamIntercept(
-    private val outputStream: OutputStream,
-    private val intercept: ByteArrayOutputStream
-) : OutputStream() {
-
-    override fun write(byte: Int) {
-        intercept.write(byte)
-        outputStream.write(byte)
-    }
-
-    override fun write(buffer: ByteArray, offset: Int, length: Int) {
-        intercept.write(buffer, offset, length)
-        outputStream.write(buffer, offset, length)
-    }
-}