fix: Allow patcher to run on dex-less APKs

src/main/kotlin/app/revanced/patcher/Patcher.kt

@@ -28,6 +28,9 @@ class Patcher(private val config: PatcherConfig) : Closeable {
      * @param patches The patches to add.
      */
     operator fun plusAssign(patches: Set<Patch<*>>) {
+        // Filter out bytecode patches if bytecodeContext is null
+        val patches = patches.filterNotTo(mutableSetOf()) { (context.bytecodeContext == null && it is BytecodePatch) }
+
         // Add all patches to the executablePatches set.
         context.executablePatches += patches
 
@@ -96,10 +99,12 @@ class Patcher(private val config: PatcherConfig) : Closeable {
             context.resourceContext.decodeResources(config.resourceMode)
         }
 
-        logger.info("Initializing lookup maps")
+        if (context.bytecodeContext != null) {
+            logger.info("Initializing lookup maps")
+        }
 
         // Accessing the lazy lookup maps to initialize them.
-        context.bytecodeContext.lookupMaps
+        context.bytecodeContext?.lookupMaps
 
         logger.info("Executing patches")
 
@@ -156,5 +161,5 @@ class Patcher(private val config: PatcherConfig) : Closeable {
      * @return The [PatcherResult] containing the patched APK files.
      */
     @OptIn(InternalApi::class)
-    fun get() = PatcherResult(context.bytecodeContext.get(), context.resourceContext.get())
+    fun get() = PatcherResult(context.bytecodeContext?.get() ?: setOf(), context.resourceContext.get())
 }

src/main/kotlin/app/revanced/patcher/PatcherContext.kt

@@ -6,6 +6,8 @@ import app.revanced.patcher.patch.ResourcePatchContext
 import brut.androlib.apk.ApkInfo
 import brut.directory.ExtFile
 import java.io.Closeable
+import lanchon.multidexlib2.EmptyMultiDexContainerException
+import java.util.logging.Logger
 
 /**
  * A context for the patcher containing the current state of the patcher.
@@ -14,6 +16,8 @@ import java.io.Closeable
  */
 @Suppress("MemberVisibilityCanBePrivate")
 class PatcherContext internal constructor(config: PatcherConfig): Closeable {
+    private val logger = Logger.getLogger(this::class.java.name)
+
     /**
      * [PackageMetadata] of the supplied [PatcherConfig.apkFile].
      */
@@ -37,7 +41,12 @@ class PatcherContext internal constructor(config: PatcherConfig): Closeable {
     /**
      * The context for patches containing the current state of the bytecode.
      */
-    internal val bytecodeContext = BytecodePatchContext(config)
+    internal val bytecodeContext : BytecodePatchContext? = try {
+        BytecodePatchContext(config)
+    } catch (_: EmptyMultiDexContainerException) {
+        logger.info("The APK contains no DEX files. Skipping bytecode patches")
+        null
+    }
 
-    override fun close() = bytecodeContext.close()
+    override fun close() = bytecodeContext?.close() ?: Unit
 }

src/main/kotlin/app/revanced/patcher/patch/Patch.kt

@@ -155,12 +155,12 @@ class BytecodePatch internal constructor(
     executeBlock,
     finalizeBlock,
 ) {
-    override fun execute(context: PatcherContext) = with(context.bytecodeContext) {
+    override fun execute(context: PatcherContext) = with(context.bytecodeContext!!) {
         mergeExtension(this@BytecodePatch)
         execute(this)
     }
 
-    override fun finalize(context: PatcherContext) = finalize(context.bytecodeContext)
+    override fun finalize(context: PatcherContext) = finalize(context.bytecodeContext!!)
 
     override fun toString() = name ?: "Bytecode${super.toString()}"
 }

src/test/kotlin/app/revanced/patcher/PatcherDexlessTest.kt

@@ -0,0 +1,70 @@
+package app.revanced.patcher
+
+import app.revanced.patcher.patch.Patch
+import app.revanced.patcher.patch.PatchResult
+import app.revanced.patcher.patch.ResourcePatchContext
+import app.revanced.patcher.patch.bytecodePatch
+import io.mockk.every
+import io.mockk.mockk
+import kotlinx.coroutines.flow.toList
+import kotlinx.coroutines.runBlocking
+import org.junit.jupiter.api.BeforeEach
+import kotlin.test.Test
+import java.util.logging.Logger
+import kotlin.test.assertEquals
+
+object PatcherDexlessTest {
+    private lateinit var patcher: Patcher
+
+    @BeforeEach
+    fun setUp() {
+        patcher = mockk<Patcher> {
+            // Can't mock private fields, until https://github.com/mockk/mockk/issues/1244 is resolved.
+            setPrivateField(
+                "config",
+                mockk<PatcherConfig> {
+                    every { resourceMode } returns ResourcePatchContext.ResourceMode.NONE
+                },
+            )
+            setPrivateField(
+                "logger",
+                Logger.getAnonymousLogger(),
+            )
+
+            every { context.bytecodeContext } returns null
+            every { this@mockk() } answers { callOriginal() }
+        }
+    }
+
+    @Test
+    fun `doesn't execute bytecode patches`() {
+        val executed = mutableListOf<String>()
+
+        val patch = bytecodePatch { execute { executed += "1" } }
+
+        assert(executed.isEmpty())
+
+        patch()
+
+        assertEquals(
+            emptyList(),
+            executed,
+            "Expected no bytecode patches to be executed.",
+        )
+    }
+
+    private operator fun Set<Patch<*>>.invoke(): List<PatchResult> {
+        every { patcher.context.executablePatches } returns toMutableSet()
+
+        return runBlocking { patcher().toList() }
+    }
+
+    private operator fun Patch<*>.invoke() = setOf(this)().first()
+
+    private fun Any.setPrivateField(field: String, value: Any) {
+        this::class.java.getDeclaredField(field).apply {
+            this.isAccessible = true
+            set(this@setPrivateField, value)
+        }
+    }
+}

src/test/kotlin/app/revanced/patcher/PatcherTest.kt

@@ -34,7 +34,7 @@ internal object PatcherTest {
                 Logger.getAnonymousLogger(),
             )
 
-            every { context.bytecodeContext.classes } returns mockk(relaxed = true)
+            every { context.bytecodeContext!!.classes } returns mockk(relaxed = true)
             every { this@mockk() } answers { callOriginal() }
         }
     }
@@ -165,7 +165,7 @@ internal object PatcherTest {
 
     @Test
     fun `matches fingerprint`() {
-        every { patcher.context.bytecodeContext.classes } returns ProxyClassList(
+        every { patcher.context.bytecodeContext!!.classes } returns ProxyClassList(
             mutableListOf(
                 ImmutableClassDef(
                     "class",
@@ -207,7 +207,7 @@ internal object PatcherTest {
 
         patches()
 
-        with(patcher.context.bytecodeContext) {
+        with(patcher.context.bytecodeContext!!) {
             assertAll(
                 "Expected fingerprints to match.",
                 { assertNotNull(fingerprint.originalClassDefOrNull) },
@@ -219,8 +219,8 @@ internal object PatcherTest {
 
     private operator fun Set<Patch<*>>.invoke(): List<PatchResult> {
         every { patcher.context.executablePatches } returns toMutableSet()
-        every { patcher.context.bytecodeContext.lookupMaps } returns LookupMaps(patcher.context.bytecodeContext.classes)
-        every { with(patcher.context.bytecodeContext) { mergeExtension(any<BytecodePatch>()) } } just runs
+        every { patcher.context.bytecodeContext!!.lookupMaps } returns LookupMaps(patcher.context.bytecodeContext!!.classes)
+        every { with(patcher.context.bytecodeContext!!) { mergeExtension(any<BytecodePatch>()) } } just runs
 
         return runBlocking { patcher().toList() }
     }