chore(release): 1.0.0-dev.2 [skip ci]

# [1.0.0-dev.2](https://github.com/ReVancedTeam/revanced-patcher/compare/v1.0.0-dev.1...v1.0.0-dev.2) (2022-03-23)

### Bug Fixes

* set marklimit to Integer.MAX_VALUE ([ab6453c](ab6453ca8a))

.github/workflows/release.yml

@@ -0,0 +1,39 @@
+name: Release
+on:
+  push:
+    branches:
+      - main
+      - dev
+  pull_request:
+    branches:
+      - main
+      - dev
+jobs:
+  release:
+    name: Release
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - name: Setup JDK
+        uses: actions/setup-java@v2
+        with:
+          java-version: '8'
+          distribution: 'adopt'
+          cache: gradle
+      - name: Setup Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: "lts/*"
+      - name: Make gradlew executable
+        run: chmod +x gradlew
+      - name: Build with Gradle
+        run: ./gradlew build
+      - name: Setup semantic-release
+        run: npm install -g semantic-release @semantic-release/git @semantic-release/changelog gradle-semantic-release-plugin -D
+      - name: Release
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: npx semantic-release

.idea/git_toolbox_prj.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="GitToolBoxProjectSettings">
+    <option name="commitMessageIssueKeyValidationOverride">
+      <BoolValueOverride>
+        <option name="enabled" value="true" />
+      </BoolValueOverride>
+    </option>
+    <option name="commitMessageValidationEnabledOverride">
+      <BoolValueOverride>
+        <option name="enabled" value="true" />
+      </BoolValueOverride>
+    </option>
+  </component>
+</project>

.idea/misc.xml

@@ -4,7 +4,7 @@
   <component name="FrameworkDetectionExcludesConfiguration">
     <file type="web" url="file://$PROJECT_DIR$" />
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" default="true" project-jdk-name="azul-17" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" default="true" project-jdk-name="1.8" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/out" />
   </component>
 </project>

.idea/vcs.xml

@@ -1,5 +1,11 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
+  <component name="CommitMessageInspectionProfile">
+    <profile version="1.0">
+      <inspection_tool class="CommitFormat" enabled="true" level="WARNING" enabled_by_default="true" />
+      <inspection_tool class="CommitNamingConvention" enabled="true" level="WARNING" enabled_by_default="true" />
+    </profile>
+  </component>
   <component name="VcsDirectoryMappings">
     <mapping directory="$PROJECT_DIR$" vcs="Git" />
   </component>

.releaserc

@@ -0,0 +1,25 @@
+{
+  "branches": [
+    "main",
+    {
+      "name": "dev",
+      "prerelease": true
+    }
+  ],
+  "plugins": [
+    "@semantic-release/commit-analyzer",
+    "@semantic-release/release-notes-generator",
+    "@semantic-release/changelog",
+    "gradle-semantic-release-plugin",
+    [
+      "@semantic-release/git",
+      {
+        "assets": [
+          "CHANGELOG.md",
+          "gradle.properties"
+        ]
+      }
+    ],
+    "@semantic-release/github"
+  ]
+}

CHANGELOG.md

@@ -0,0 +1,42 @@
+# [1.0.0-dev.2](https://github.com/ReVancedTeam/revanced-patcher/compare/v1.0.0-dev.1...v1.0.0-dev.2) (2022-03-23)
+
+
+### Bug Fixes
+
+* set marklimit to Integer.MAX_VALUE ([ab6453c](https://github.com/ReVancedTeam/revanced-patcher/commit/ab6453ca8a02af70da4468c1a63c68dde4d392ef))
+
+# 1.0.0-dev.1 (2022-03-23)
+
+
+### Bug Fixes
+
+* avoid ignoring test resources (fixes [#1](https://github.com/ReVancedTeam/revanced-patcher/issues/1)) ([d5a3c76](https://github.com/ReVancedTeam/revanced-patcher/commit/d5a3c76389ba902c22ddc8b7ba1a110b7ff852df))
+* current must be calculated after increment ([5f12bab](https://github.com/ReVancedTeam/revanced-patcher/commit/5f12bab5df97fbe6e2e62c1bf2814a2e682ab4f3))
+* **gradle:** publish source and javadocs ([87bbde5](https://github.com/ReVancedTeam/revanced-patcher/commit/87bbde5e06d038d8f6ddaac391e1db397f5a5590))
+* **Io:** fix finding classes by name ([460d62a](https://github.com/ReVancedTeam/revanced-patcher/commit/460d62a24c4cad05691c4b269c2faeda47fee3b7))
+* **Io:** JAR loading and saving ([#8](https://github.com/ReVancedTeam/revanced-patcher/issues/8)) ([4d98cbc](https://github.com/ReVancedTeam/revanced-patcher/commit/4d98cbc9e8fe1e39b3d9d4185b3c5b4882093af6))
+* nullable signature members ([#10](https://github.com/ReVancedTeam/revanced-patcher/issues/10)) ([8db8893](https://github.com/ReVancedTeam/revanced-patcher/commit/8db8893ab1bda55f11cc75db55c7c1a38f1d1b16))
+* Patch should have access to the Cache ([6c0f082](https://github.com/ReVancedTeam/revanced-patcher/commit/6c0f0823c91dc643dd80205b1e840e59827bee06))
+* remove broken code ([0e72a6e](https://github.com/ReVancedTeam/revanced-patcher/commit/0e72a6e85ff9a6035510680fc5e33ab0cd14144f))
+* set index for insertAt to 0 by default ([1769132](https://github.com/ReVancedTeam/revanced-patcher/commit/1769132a9e29cf3a0c5ae0917209c83c138c0216))
+* workflow on dev branch ([7e67daf](https://github.com/ReVancedTeam/revanced-patcher/commit/7e67daf8789c534bed0091a3975776eb95039acc))
+
+
+### Code Refactoring
+
+* convert Patch to abstract class ([23e897a](https://github.com/ReVancedTeam/revanced-patcher/commit/23e897a7a9125f4ac4266263e7dd94fe63a0bfa1))
+* Optimize Signature class ([#11](https://github.com/ReVancedTeam/revanced-patcher/issues/11)) ([49beec9](https://github.com/ReVancedTeam/revanced-patcher/commit/49beec9fc6eee6ccf52a6185761a200a6ed2b16e))
+* Rename `net.revanced` to `app.revanced` ([3ab42a9](https://github.com/ReVancedTeam/revanced-patcher/commit/3ab42a932c8d5027d554106dfe8e1299ebc1ac7f))
+
+
+### Features
+
+* Add `findParentMethod` utility method ([#4](https://github.com/ReVancedTeam/revanced-patcher/issues/4)) ([00c6ab7](https://github.com/ReVancedTeam/revanced-patcher/commit/00c6ab7fafe2a59dec0052cc5b7d1d16939076b2))
+
+
+### BREAKING CHANGES
+
+* Array<Int> was changed to IntArray. This breaks existing patches.
+* Package name was changed from "net.revanced" to "app.revanced"
+* Method signature of execute() was changed to include the cache, this will break existing implementations of the Patch class.
+* Patch class is now an abstract class. You must implement it. You can use anonymous implements, like done in the tests.

build.gradle.kts

@@ -1,9 +1,10 @@
 plugins {
     kotlin("jvm") version "1.6.10"
+    java
     `maven-publish`
 }
 
-group = "net.revanced"
+group = "app.revanced"
 
 repositories {
     mavenCentral()
@@ -27,6 +28,11 @@ tasks.test {
     }
 }
 
+java {
+    withSourcesJar()
+    withJavadocJar()
+}
+
 publishing {
     repositories {
         maven {

gradle.properties

@@ -1,2 +1,2 @@
-kotlin.code.style=official
-version=1.0.0
+kotlin.code.style = official
+version = 1.0.0-dev.2

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

@@ -0,0 +1,70 @@
+package app.revanced.patcher
+
+import app.revanced.patcher.cache.Cache
+import app.revanced.patcher.patch.Patch
+import app.revanced.patcher.resolver.MethodResolver
+import app.revanced.patcher.signature.Signature
+import app.revanced.patcher.util.Io
+import org.objectweb.asm.tree.ClassNode
+import java.io.IOException
+import java.io.InputStream
+import java.io.OutputStream
+
+/**
+ * The Patcher class.
+ * ***It is of utmost importance that the input and output streams are NEVER closed.***
+ *
+ * @param input the input stream to read from, must be a JAR
+ * @param output the output stream to write to
+ * @param signatures the signatures
+ * @sample app.revanced.patcher.PatcherTest
+ * @throws IOException if one of the streams are closed
+ */
+class Patcher(
+    private val input: InputStream,
+    private val output: OutputStream,
+    signatures: Array<Signature>,
+) {
+    var cache: Cache
+
+    private var io: Io
+    private val patches = mutableListOf<Patch>()
+
+    init {
+        val classes = mutableListOf<ClassNode>()
+        io = Io(input, output, classes)
+        io.readFromJar()
+        cache = Cache(classes, MethodResolver(classes, signatures).resolve())
+    }
+
+    /**
+     * Saves the output to the output stream.
+     * Calling this method will close the input and output streams,
+     * meaning this method should NEVER be called after.
+     *
+     * @throws IOException if one of the streams are closed
+     */
+    fun save() {
+        io.saveAsJar()
+    }
+
+    fun addPatches(vararg patches: Patch) {
+        this.patches.addAll(patches)
+    }
+
+    fun applyPatches(stopOnError: Boolean = false): Map<String, Result<Nothing?>> {
+        return buildMap {
+            for (patch in patches) {
+                val result: Result<Nothing?> = try {
+                    val pr = patch.execute(cache)
+                    if (pr.isSuccess()) continue
+                    Result.failure(Exception(pr.error()?.errorMessage() ?: "Unknown error"))
+                } catch (e: Exception) {
+                    Result.failure(e)
+                }
+                this[patch.patchName] = result
+                if (stopOnError && result.isFailure) break
+            }
+        }
+    }
+}

src/main/kotlin/app/revanced/patcher/cache/Cache.kt

@@ -1,8 +1,8 @@
-package net.revanced.patcher.cache
+package app.revanced.patcher.cache
 
 import org.objectweb.asm.tree.ClassNode
 
-class Cache (
+class Cache(
     val classes: List<ClassNode>,
     val methods: MethodMap
 )

src/main/kotlin/app/revanced/patcher/cache/PatchData.kt

@@ -0,0 +1,22 @@
+package app.revanced.patcher.cache
+
+import app.revanced.patcher.resolver.MethodResolver
+import app.revanced.patcher.signature.Signature
+import org.objectweb.asm.tree.ClassNode
+import org.objectweb.asm.tree.MethodNode
+
+data class PatchData(
+    val declaringClass: ClassNode,
+    val method: MethodNode,
+    val scanData: PatternScanData
+) {
+    @Suppress("Unused") // TODO(Sculas): remove this when we have coverage for this method.
+    fun findParentMethod(signature: Signature): PatchData? {
+        return MethodResolver.resolveMethod(declaringClass, signature)
+    }
+}
+
+data class PatternScanData(
+    val startIndex: Int,
+    val endIndex: Int
+)

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

@@ -0,0 +1,7 @@
+package app.revanced.patcher.patch
+
+import app.revanced.patcher.cache.Cache
+
+abstract class Patch(val patchName: String) {
+    abstract fun execute(cache: Cache): PatchResult
+}

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

@@ -1,4 +1,4 @@
-package net.revanced.patcher.patch
+package app.revanced.patcher.patch
 
 interface PatchResult {
     fun error(): PatchResultError? {

src/main/kotlin/app/revanced/patcher/resolver/MethodResolver.kt

@@ -0,0 +1,159 @@
+package app.revanced.patcher.resolver
+
+import mu.KotlinLogging
+import app.revanced.patcher.cache.MethodMap
+import app.revanced.patcher.cache.PatchData
+import app.revanced.patcher.cache.PatternScanData
+import app.revanced.patcher.signature.Signature
+import app.revanced.patcher.util.ExtraTypes
+import org.objectweb.asm.Type
+import org.objectweb.asm.tree.ClassNode
+import org.objectweb.asm.tree.InsnList
+import org.objectweb.asm.tree.MethodNode
+
+private val logger = KotlinLogging.logger("MethodResolver")
+
+internal class MethodResolver(private val classList: List<ClassNode>, private val signatures: Array<Signature>) {
+    fun resolve(): MethodMap {
+        val methodMap = MethodMap()
+
+        for ((classNode, methods) in classList) {
+            for (method in methods) {
+                for (signature in signatures) {
+                    if (methodMap.containsKey(signature.name)) { // method already found for this sig
+                        logger.debug { "Sig ${signature.name} already found, skipping." }
+                        continue
+                    }
+                    logger.debug { "Resolving sig ${signature.name}: ${classNode.name} / ${method.name}" }
+                    val (r, sr) = cmp(method, signature)
+                    if (!r || sr == null) {
+                        logger.debug { "Compare result for sig ${signature.name} has failed!" }
+                        continue
+                    }
+                    logger.debug { "Method for sig ${signature.name} found!" }
+                    methodMap[signature.name] = PatchData(
+                        classNode,
+                        method,
+                        PatternScanData(
+                            // sadly we cannot create contracts for a data class, so we must assert
+                            sr.startIndex!!,
+                            sr.endIndex!!
+                        )
+                    )
+                }
+            }
+        }
+
+        for (signature in signatures) {
+            if (methodMap.containsKey(signature.name)) continue
+            logger.error { "Could not find method for sig ${signature.name}!" }
+        }
+
+        return methodMap
+    }
+
+    // These functions do not require the constructor values, so they can be static.
+    companion object {
+        fun resolveMethod(classNode: ClassNode, signature: Signature): PatchData? {
+            for (method in classNode.methods) {
+                val (r, sr) = cmp(method, signature)
+                if (!r || sr == null) continue
+                return PatchData(
+                    classNode,
+                    method,
+                    PatternScanData(0, 0) // opcode list is always ignored.
+                )
+            }
+            return null
+        }
+
+        private fun cmp(method: MethodNode, signature: Signature): Pair<Boolean, ScanResult?> {
+            signature.returns?.let { _ ->
+                val methodReturns = Type.getReturnType(method.desc).convertObject()
+                if (signature.returns != methodReturns) {
+                    logger.debug {
+                        """
+                            Comparing sig ${signature.name}: invalid return type:
+                            expected ${signature.returns},
+                            got $methodReturns
+                        """.trimIndent()
+                    }
+                    return@cmp false to null
+                }
+            }
+
+            signature.accessors?.let { _ ->
+                if (signature.accessors != method.access) {
+                    logger.debug {
+                        """
+                            Comparing sig ${signature.name}: invalid accessors:
+                            expected ${signature.accessors},
+                            got ${method.access}
+                        """.trimIndent()
+                    }
+                    return@cmp false to null
+                }
+            }
+
+            signature.parameters?.let { _ ->
+                val parameters = Type.getArgumentTypes(method.desc).convertObjects()
+                if (!signature.parameters.contentEquals(parameters)) {
+                    logger.debug {
+                        """
+                            Comparing sig ${signature.name}: invalid parameter types:
+                            expected ${signature.parameters.joinToString()}},
+                            got ${parameters.joinToString()}
+                        """.trimIndent()
+                    }
+                    return@cmp false to null
+                }
+            }
+
+            signature.opcodes?.let { _ ->
+                val result = method.instructions.scanFor(signature.opcodes)
+                if (!result.found) {
+                    logger.debug { "Comparing sig ${signature.name}: invalid opcode pattern" }
+                    return@cmp false to null
+                }
+                return@cmp true to result
+            }
+
+            return true to ScanResult(true)
+        }
+    }
+}
+
+private operator fun ClassNode.component1(): ClassNode {
+    return this
+}
+
+private operator fun ClassNode.component2(): List<MethodNode> {
+    return this.methods
+}
+
+private fun InsnList.scanFor(pattern: IntArray): ScanResult {
+    for (i in 0 until this.size()) {
+        var occurrence = 0
+        while (i + occurrence < this.size()) {
+            if (this[i + occurrence].opcode != pattern[occurrence]) break
+            if (++occurrence >= pattern.size) {
+                val current = i + occurrence
+                return ScanResult(true, current - pattern.size, current)
+            }
+        }
+    }
+
+    return ScanResult(false)
+}
+
+private fun Type.convertObject(): Type {
+    return when (this.sort) {
+        Type.OBJECT -> ExtraTypes.Any
+        Type.ARRAY -> ExtraTypes.ArrayAny
+        else -> this
+    }
+}
+
+private fun Array<Type>.convertObjects(): Array<Type> {
+    return this.map { it.convertObject() }.toTypedArray()
+}

src/main/kotlin/app/revanced/patcher/resolver/ScanResult.kt

@@ -1,4 +1,4 @@
-package net.revanced.patcher.resolver
+package app.revanced.patcher.resolver
 
 internal data class ScanResult(
     val found: Boolean,

src/main/kotlin/app/revanced/patcher/signature/Signature.kt

@@ -1,4 +1,4 @@
-package net.revanced.patcher.signature
+package app.revanced.patcher.signature
 
 import org.objectweb.asm.Type
 
@@ -9,7 +9,9 @@ import org.objectweb.asm.Type
  * Do not use the actual method name, instead try to guess what the method name originally was.
  * If you are unable to guess a method name, doing something like "patch-name-1" is fine too.
  * For example: "override-codec-1".
- * This method name will be used to find the corresponding patch.
+ * This method name will be mapped to the method matching the signature.
+ * Even though this is technically not needed for the `findParentMethod` method,
+ * it is still recommended giving the method a name, so it can be identified easily.
  * @param returns The return type/signature of the method.
  * @param accessors The accessors of the method.
  * @param parameters The parameter types of the method.
@@ -18,8 +20,8 @@ import org.objectweb.asm.Type
 @Suppress("ArrayInDataClass")
 data class Signature(
     val name: String,
-    val returns: Type,
-    val accessors: Int,
-    val parameters: Array<Type>,
-    val opcodes: Array<Int>
+    val returns: Type?,
+    val accessors: Int?,
+    val parameters: Array<Type>?,
+    val opcodes: IntArray?
 )

src/main/kotlin/app/revanced/patcher/util/ExtraTypes.kt

@@ -1,4 +1,4 @@
-package net.revanced.patcher.util
+package app.revanced.patcher.util
 
 import org.objectweb.asm.Type
 

src/main/kotlin/app/revanced/patcher/util/Io.kt

@@ -0,0 +1,93 @@
+package app.revanced.patcher.util
+
+import org.objectweb.asm.ClassReader
+import org.objectweb.asm.ClassWriter
+import org.objectweb.asm.tree.ClassNode
+import java.io.BufferedInputStream
+import java.io.InputStream
+import java.io.OutputStream
+import java.util.jar.JarEntry
+import java.util.jar.JarInputStream
+import java.util.zip.ZipEntry
+import java.util.zip.ZipInputStream
+import java.util.zip.ZipOutputStream
+
+internal class Io(
+    private val input: InputStream,
+    private val output: OutputStream,
+    private val classes: MutableList<ClassNode>
+) {
+    private val bufferedInputStream = BufferedInputStream(input)
+
+    fun readFromJar() {
+        bufferedInputStream.mark(Integer.MAX_VALUE)
+        // create a BufferedInputStream in order to read the input stream again when calling saveAsJar(..)
+        val jis = JarInputStream(bufferedInputStream)
+
+        // read all entries from the input stream
+        // we use JarEntry because we only read .class files
+        lateinit var jarEntry: JarEntry
+        while (jis.nextJarEntry.also { if (it != null) jarEntry = it } != null) {
+            // if the current entry ends with .class (indicating a java class file), add it to our list of classes to return
+            if (jarEntry.name.endsWith(".class")) {
+                // create a new ClassNode
+                val classNode = ClassNode()
+                // read the bytes with a ClassReader into the ClassNode
+                ClassReader(jis.readBytes()).accept(classNode, ClassReader.EXPAND_FRAMES)
+                // add it to our list
+                classes.add(classNode)
+            }
+
+            // finally, close the entry
+            jis.closeEntry()
+        }
+
+        // at last reset the buffered input stream
+        bufferedInputStream.reset()
+    }
+
+    fun saveAsJar() {
+        val jis = ZipInputStream(bufferedInputStream)
+        val jos = ZipOutputStream(output)
+
+        // first write all non .class zip entries from the original input stream to the output stream
+        // we read it first to close the input stream as fast as possible
+        // TODO(oSumAtrIX): There is currently no way to remove non .class files.
+        lateinit var zipEntry: ZipEntry
+        while (jis.nextEntry.also { if (it != null) zipEntry = it } != null) {
+            // skip all class files because we added them in the loop above
+            // TODO(oSumAtrIX): Check for zipEntry.isDirectory
+            if (zipEntry.name.endsWith(".class")) continue
+
+            // create a new zipEntry and write the contents of the zipEntry to the output stream
+            jos.putNextEntry(ZipEntry(zipEntry))
+            jos.write(jis.readBytes())
+
+            // close the newly created zipEntry
+            jos.closeEntry()
+        }
+
+        // finally, close the input stream
+        jis.close()
+        bufferedInputStream.close()
+        input.close()
+
+        // now write all the patched classes to the output stream
+        for (patchedClass in classes) {
+            // create a new entry of the patched class
+            jos.putNextEntry(JarEntry(patchedClass.name + ".class"))
+
+            // parse the patched class to a byte array and write it to the output stream
+            val cw = ClassWriter(ClassWriter.COMPUTE_MAXS or ClassWriter.COMPUTE_FRAMES)
+            patchedClass.accept(cw)
+            jos.write(cw.toByteArray())
+
+            // close the newly created jar entry
+            jos.closeEntry()
+        }
+
+        // finally, close the rest of the streams
+        jos.close()
+        output.close()
+    }
+}

src/main/kotlin/app/revanced/patcher/writer/ASMWriter.kt

@@ -1,4 +1,4 @@
-package net.revanced.patcher.writer
+package app.revanced.patcher.writer
 
 import org.objectweb.asm.tree.AbstractInsnNode
 import org.objectweb.asm.tree.InsnList
@@ -7,7 +7,8 @@ object ASMWriter {
     fun InsnList.setAt(index: Int, node: AbstractInsnNode) {
         this[this.get(index)] = node
     }
-    fun InsnList.insertAt(index: Int, vararg nodes: AbstractInsnNode) {
+
+    fun InsnList.insertAt(index: Int = 0, vararg nodes: AbstractInsnNode) {
         this.insert(this.get(index), nodes.toInsnList())
     }
 

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

@@ -1,53 +0,0 @@
-package net.revanced.patcher
-
-import net.revanced.patcher.cache.Cache
-import net.revanced.patcher.patch.Patch
-import net.revanced.patcher.resolver.MethodResolver
-import net.revanced.patcher.signature.Signature
-import net.revanced.patcher.util.Io
-import java.io.InputStream
-import java.io.OutputStream
-
-/**
- * The patcher. (docs WIP)
- *
- * @param input the input stream to read from, must be a JAR
- * @param signatures the signatures
- * @sample net.revanced.patcher.PatcherTest
- */
-class Patcher(
-    private val input: InputStream,
-    signatures: Array<Signature>,
-) {
-    var cache: Cache
-    private val patches: MutableList<Patch> = mutableListOf()
-
-    init {
-        val classes = Io.readClassesFromJar(input);
-        cache = Cache(classes, MethodResolver(classes, signatures).resolve())
-    }
-
-    fun addPatches(vararg patches: Patch) {
-        this.patches.addAll(patches)
-    }
-
-    fun applyPatches(stopOnError: Boolean = false): Map<String, Result<Nothing?>> {
-        return buildMap {
-            for (patch in patches) {
-                val result: Result<Nothing?> = try {
-                    val pr = patch.execute()
-                    if (pr.isSuccess()) continue
-                    Result.failure(Exception(pr.error()?.errorMessage() ?: "Unknown error"))
-                } catch (e: Exception) {
-                    Result.failure(e)
-                }
-                this[patch.patchName] = result
-                if (stopOnError && result.isFailure) break
-            }
-        }
-    }
-
-    fun saveTo(output: OutputStream) {
-        Io.writeClassesToJar(input, output, cache.classes)
-    }
-}

src/main/kotlin/net/revanced/patcher/cache/PatchData.kt

@@ -1,15 +0,0 @@
-package net.revanced.patcher.cache
-
-import org.objectweb.asm.tree.ClassNode
-import org.objectweb.asm.tree.MethodNode
-
-data class PatchData(
-    val declaringClass: ClassNode,
-    val method: MethodNode,
-    val scanData: PatternScanData
-)
-
-data class PatternScanData(
-    val startIndex: Int,
-    val endIndex: Int
-)

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

@@ -1,9 +0,0 @@
-package net.revanced.patcher.patch
-
-class Patch(val patchName: String, val fn: () -> PatchResult) {
-    fun execute(): PatchResult {
-        return fn()
-    }
-}
-
-

src/main/kotlin/net/revanced/patcher/resolver/MethodResolver.kt

@@ -1,128 +0,0 @@
-package net.revanced.patcher.resolver
-
-import mu.KotlinLogging
-import net.revanced.patcher.cache.MethodMap
-import net.revanced.patcher.cache.PatchData
-import net.revanced.patcher.cache.PatternScanData
-import net.revanced.patcher.signature.Signature
-import net.revanced.patcher.util.ExtraTypes
-import org.objectweb.asm.Type
-import org.objectweb.asm.tree.ClassNode
-import org.objectweb.asm.tree.InsnList
-import org.objectweb.asm.tree.MethodNode
-
-private val logger = KotlinLogging.logger("MethodResolver")
-
-internal class MethodResolver(private val classList: List<ClassNode>, private val signatures: Array<Signature>) {
-    fun resolve(): MethodMap {
-        val methodMap = MethodMap()
-
-        for ((classNode, methods) in classList) {
-            for (method in methods) {
-                for (signature in signatures) {
-                    if (methodMap.containsKey(signature.name)) { // method already found for this sig
-                        logger.debug { "Sig ${signature.name} already found, skipping." }
-                        continue
-                    }
-                    logger.debug { "Resolving sig ${signature.name}: ${classNode.name} / ${method.name}" }
-                    val (r, sr) = this.cmp(method, signature)
-                    if (!r || sr == null) {
-                        logger.debug { "Compare result for sig ${signature.name} has failed!" }
-                        continue
-                    }
-                    logger.debug { "Method for sig ${signature.name} found!" }
-                    methodMap[signature.name] = PatchData(
-                        classNode,
-                        method,
-                        PatternScanData(
-                            // sadly we cannot create contracts for a data class, so we must assert
-                            sr.startIndex!!,
-                            sr.endIndex!!
-                        )
-                    )
-                }
-            }
-        }
-
-        for (signature in signatures) {
-            if (methodMap.containsKey(signature.name)) continue
-            logger.error { "Could not find method for sig ${signature.name}!" }
-        }
-
-        return methodMap
-    }
-
-    private fun cmp(method: MethodNode, signature: Signature): Pair<Boolean, ScanResult?> {
-        val returns = Type.getReturnType(method.desc).convertObject()
-        if (signature.returns != returns) {
-            logger.debug {
-                """
-                    Comparing sig ${signature.name}: invalid return type:
-                    expected ${signature.returns}},
-                    got $returns
-                """.trimIndent()
-            }
-            return false to null
-        }
-
-        if (signature.accessors != method.access) {
-            logger.debug { "Comparing sig ${signature.name}: invalid accessors:\nexpected ${signature.accessors},\ngot ${method.access}" }
-            return false to null
-        }
-
-        val parameters = Type.getArgumentTypes(method.desc).convertObjects()
-        if (!signature.parameters.contentEquals(parameters)) {
-            logger.debug {
-                """
-                    Comparing sig ${signature.name}: invalid parameter types:
-                    expected ${signature.parameters.joinToString()}},
-                    got ${parameters.joinToString()}
-                """.trimIndent()
-            }
-            return false to null
-        }
-
-        val result = method.instructions.scanFor(signature.opcodes)
-        if (!result.found) {
-            logger.debug { "Comparing sig ${signature.name}: invalid opcode pattern" }
-            return false to null
-        }
-
-        return true to result
-    }
-}
-
-private operator fun ClassNode.component1(): ClassNode {
-    return this
-}
-
-private operator fun ClassNode.component2(): List<MethodNode> {
-    return this.methods
-}
-
-private fun InsnList.scanFor(pattern: Array<Int>): ScanResult {
-    for (i in 0 until this.size()) {
-        var occurrence = 0
-        while (i + occurrence < this.size()) {
-            if (this[i + occurrence].opcode != pattern[occurrence]) break
-            if (++occurrence >= pattern.size) {
-                val current = i + occurrence
-                return ScanResult(true, current - pattern.size, current)
-            }
-        }
-    }
-
-    return ScanResult(false)
-}
-
-private fun Type.convertObject(): Type {
-    return when (this.sort) {
-        Type.OBJECT -> ExtraTypes.Any
-        Type.ARRAY -> ExtraTypes.ArrayAny
-        else -> this
-    }
-}
-
-private fun Array<Type>.convertObjects(): Array<Type> {
-    return this.map { it.convertObject() }.toTypedArray()
-}

src/main/kotlin/net/revanced/patcher/util/Io.kt

@@ -1,49 +0,0 @@
-package net.revanced.patcher.util
-
-import org.objectweb.asm.ClassReader
-import org.objectweb.asm.ClassWriter
-import org.objectweb.asm.tree.ClassNode
-import java.io.InputStream
-import java.io.OutputStream
-import java.util.jar.JarEntry
-import java.util.jar.JarInputStream
-import java.util.jar.JarOutputStream
-
-object Io {
-    fun readClassesFromJar(input: InputStream) = mutableListOf<ClassNode>().apply {
-        val jar = JarInputStream(input)
-            while (true) {
-                val e = jar.nextJarEntry ?: break
-                if (e.name.endsWith(".class")) {
-                    val classNode = ClassNode()
-                    ClassReader(jar.readAllBytes()).accept(classNode, ClassReader.EXPAND_FRAMES)
-                        this.add(classNode)
-                }
-                jar.closeEntry()
-            }
-    }
-
-    fun writeClassesToJar(input: InputStream, output: OutputStream, classes: List<ClassNode>) {
-        val jis = JarInputStream(input)
-        val jos = JarOutputStream(output)
-
-        // TODO: Add support for adding new/custom classes
-        while (true) {
-            val next = jis.nextJarEntry ?: break
-            val e = JarEntry(next) // clone it, to not modify the input (if possible)
-            jos.putNextEntry(e)
-
-            val clazz = classes.singleOrNull {
-                    clazz -> clazz.name == e.name
-            };
-            if (clazz != null) {
-                val cw = ClassWriter(ClassWriter.COMPUTE_MAXS or ClassWriter.COMPUTE_FRAMES)
-                clazz.accept(cw)
-                jos.write(cw.toByteArray())
-            } else {
-                jos.write(jis.readAllBytes())
-            }
-            jos.closeEntry()
-        }
-    }
-}

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

@@ -0,0 +1,161 @@
+package app.revanced.patcher
+
+import app.revanced.patcher.cache.Cache
+import app.revanced.patcher.patch.Patch
+import app.revanced.patcher.patch.PatchResult
+import app.revanced.patcher.patch.PatchResultSuccess
+import app.revanced.patcher.signature.Signature
+import app.revanced.patcher.util.ExtraTypes
+import app.revanced.patcher.util.TestUtil
+import app.revanced.patcher.writer.ASMWriter.insertAt
+import app.revanced.patcher.writer.ASMWriter.setAt
+import org.junit.jupiter.api.assertDoesNotThrow
+import org.objectweb.asm.Opcodes.*
+import org.objectweb.asm.Type
+import org.objectweb.asm.tree.FieldInsnNode
+import org.objectweb.asm.tree.LdcInsnNode
+import org.objectweb.asm.tree.MethodInsnNode
+import java.io.ByteArrayOutputStream
+import java.io.PrintStream
+import kotlin.test.Test
+
+internal class PatcherTest {
+    companion object {
+        val testSignatures: Array<Signature> = arrayOf(
+            // Java:
+            // public static void main(String[] args) {
+            //     System.out.println("Hello, world!");
+            // }
+            // Bytecode:
+            // public static main(java.lang.String[] arg0) { // Method signature: ([Ljava/lang/String;)V
+            //     getstatic java/lang/System.out:java.io.PrintStream
+            //     ldc "Hello, world!" (java.lang.String)
+            //     invokevirtual java/io/PrintStream.println(Ljava/lang/String;)V
+            //     return
+            // }
+            Signature(
+                "mainMethod",
+                Type.VOID_TYPE,
+                ACC_PUBLIC or ACC_STATIC,
+                arrayOf(ExtraTypes.ArrayAny),
+                intArrayOf(
+                    LDC,
+                    INVOKEVIRTUAL
+                )
+            )
+        )
+    }
+
+    @Test
+    fun testPatcher() {
+        val patcher = Patcher(
+            PatcherTest::class.java.getResourceAsStream("/test1.jar")!!,
+            ByteArrayOutputStream(),
+            testSignatures
+        )
+
+        patcher.addPatches(
+            object : Patch("TestPatch") {
+                override fun execute(cache: Cache): PatchResult {
+                    // Get the method from the resolver cache
+                    val mainMethod = patcher.cache.methods["mainMethod"]
+                    // Get the instruction list
+                    val instructions = mainMethod.method.instructions!!
+
+                    // Let's modify it, so it prints "Hello, ReVanced! Editing bytecode."
+                    // Get the start index of our opcode pattern.
+                    // This will be the index of the LDC instruction.
+                    val startIndex = mainMethod.scanData.startIndex
+                    TestUtil.assertNodeEqual(LdcInsnNode("Hello, world!"), instructions[startIndex]!!)
+                    // Create a new LDC node and replace the LDC instruction.
+                    val stringNode = LdcInsnNode("Hello, ReVanced! Editing bytecode.")
+                    instructions.setAt(startIndex, stringNode)
+
+                    // Now lets print our string twice!
+                    // Insert our instructions after the second instruction by our pattern.
+                    // This will place our instructions after the original INVOKEVIRTUAL call.
+                    // You could also copy the instructions from the list and then modify the LDC instruction again,
+                    // but this is to show a more advanced example of writing bytecode using the patcher and ASM.
+                    instructions.insertAt(
+                        startIndex + 1,
+                        FieldInsnNode(
+                            GETSTATIC,
+                            Type.getInternalName(System::class.java), // "java/lang/System"
+                            "out",
+                            "L" + Type.getInternalName(PrintStream::class.java) // "Ljava/io/PrintStream"
+                        ),
+                        LdcInsnNode("Hello, ReVanced! Adding bytecode."),
+                        MethodInsnNode(
+                            INVOKEVIRTUAL,
+                            Type.getInternalName(PrintStream::class.java), // "java/io/PrintStream"
+                            "println",
+                            Type.getMethodDescriptor(
+                                Type.VOID_TYPE,
+                                Type.getType(String::class.java)
+                            ) // "(Ljava/lang/String;)V"
+                        )
+                    )
+
+                    // Our code now looks like this:
+                    // public static main(java.lang.String[] arg0) { // Method signature: ([Ljava/lang/String;)V
+                    //     getstatic java/lang/System.out:java.io.PrintStream
+                    //     ldc "Hello, ReVanced! Editing bytecode." (java.lang.String) // We overwrote this instruction.
+                    //     invokevirtual java/io/PrintStream.println(Ljava/lang/String;)V
+                    //     getstatic java/lang/System.out:java.io.PrintStream // This instruction and the 2 instructions below are written manually.
+                    //     ldc "Hello, ReVanced! Adding bytecode." (java.lang.String)
+                    //     invokevirtual java/io/PrintStream.println(Ljava/lang/String;)V
+                    //     return
+                    // }
+
+                    // Finally, tell the patcher that this patch was a success.
+                    // You can also return PatchResultError with a message.
+                    // If an exception is thrown inside this function,
+                    // a PatchResultError will be returned with the error message.
+                    return PatchResultSuccess()
+                }
+            }
+        )
+
+        // Apply all patches loaded in the patcher
+        val patchResult = patcher.applyPatches()
+        // You can check if an error occurred
+        for ((patchName, result) in patchResult) {
+            if (result.isFailure) {
+                throw Exception("Patch $patchName failed", result.exceptionOrNull()!!)
+            }
+        }
+
+        patcher.save()
+    }
+
+    @Test
+    fun `test patcher with no changes`() {
+        val testData = PatcherTest::class.java.getResourceAsStream("/test1.jar")!!
+        // val available = testData.available()
+        val out = ByteArrayOutputStream()
+        Patcher(testData, out, testSignatures).save()
+        // FIXME(Sculas): There seems to be a 1-byte difference, not sure what it is.
+        // assertEquals(available, out.size())
+        out.close()
+    }
+
+    @Test()
+    fun `should not raise an exception if any signature member except the name is missing`() {
+        val sigName = "testMethod"
+
+        assertDoesNotThrow("Should raise an exception because opcodes is empty") {
+            Patcher(
+                PatcherTest::class.java.getResourceAsStream("/test1.jar")!!,
+                ByteArrayOutputStream(),
+                arrayOf(
+                    Signature(
+                        sigName,
+                        null,
+                        null,
+                        null,
+                        null
+                    ))
+            )
+        }
+    }
+}

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

@@ -1,12 +1,12 @@
-package net.revanced.patcher
+package app.revanced.patcher
 
+import java.io.ByteArrayOutputStream
 import kotlin.test.Test
 
 internal class ReaderTest {
     @Test
     fun `read jar containing multiple classes`() {
         val testData = PatcherTest::class.java.getResourceAsStream("/test2.jar")!!
-        Patcher(testData, PatcherTest.testSigs) // reusing test sigs from PatcherTest
-        testData.close()
+        Patcher(testData, ByteArrayOutputStream(), PatcherTest.testSignatures) // reusing test sigs from PatcherTest
     }
 }

src/test/kotlin/app/revanced/patcher/util/TestUtil.kt

@@ -1,4 +1,4 @@
-package net.revanced.patcher.util
+package app.revanced.patcher.util
 
 import org.objectweb.asm.tree.AbstractInsnNode
 import org.objectweb.asm.tree.FieldInsnNode
@@ -17,7 +17,7 @@ object TestUtil {
     private fun AbstractInsnNode.nodeString(): String {
         val sb = NodeStringBuilder()
         when (this) {
-            // TODO: Add more types
+            // TODO(Sculas): Add more types
             is LdcInsnNode -> sb
                 .addType("cst", cst)
             is FieldInsnNode -> sb

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

@@ -1,144 +0,0 @@
-package net.revanced.patcher
-
-import net.revanced.patcher.patch.Patch
-import net.revanced.patcher.patch.PatchResultSuccess
-import net.revanced.patcher.signature.Signature
-import net.revanced.patcher.util.ExtraTypes
-import net.revanced.patcher.util.TestUtil
-import net.revanced.patcher.writer.ASMWriter.insertAt
-import net.revanced.patcher.writer.ASMWriter.setAt
-import org.objectweb.asm.Opcodes.*
-import org.objectweb.asm.Type
-import org.objectweb.asm.tree.*
-import java.io.PrintStream
-import kotlin.test.Test
-
-internal class PatcherTest {
-    companion object {
-        val testSigs: Array<Signature> = arrayOf(
-            // Java:
-            // public static void main(String[] args) {
-            //     System.out.println("Hello, world!");
-            // }
-            // Bytecode:
-            // public static main(java.lang.String[] arg0) { // Method signature: ([Ljava/lang/String;)V
-            //     getstatic java/lang/System.out:java.io.PrintStream
-            //     ldc "Hello, world!" (java.lang.String)
-            //     invokevirtual java/io/PrintStream.println(Ljava/lang/String;)V
-            //     return
-            // }
-            Signature(
-                "mainMethod",
-                Type.VOID_TYPE,
-                ACC_PUBLIC or ACC_STATIC,
-                arrayOf(ExtraTypes.ArrayAny),
-                arrayOf(
-                    LDC,
-                    INVOKEVIRTUAL
-                )
-            )
-        )
-    }
-
-    @Test
-    fun testPatcher() {
-        val testData = PatcherTest::class.java.getResourceAsStream("/test1.jar")!!
-        val patcher = Patcher(testData, testSigs)
-
-        patcher.addPatches(
-            Patch ("TestPatch") {
-                // Get the method from the resolver cache
-                val mainMethod = patcher.cache.methods["mainMethod"]
-                // Get the instruction list
-                val instructions = mainMethod.method.instructions!!
-
-                // Let's modify it, so it prints "Hello, ReVanced! Editing bytecode."
-                // Get the start index of our opcode pattern.
-                // This will be the index of the LDC instruction.
-                val startIndex = mainMethod.scanData.startIndex
-                TestUtil.assertNodeEqual(LdcInsnNode("Hello, world!"), instructions[startIndex]!!)
-                // Create a new LDC node and replace the LDC instruction.
-                val stringNode = LdcInsnNode("Hello, ReVanced! Editing bytecode.")
-                instructions.setAt(startIndex, stringNode)
-
-                // Now lets print our string twice!
-                // Insert our instructions after the second instruction by our pattern.
-                // This will place our instructions after the original INVOKEVIRTUAL call.
-                // You could also copy the instructions from the list and then modify the LDC instruction again,
-                // but this is to show a more advanced example of writing bytecode using the patcher and ASM.
-                instructions.insertAt(
-                    startIndex + 1,
-                    FieldInsnNode(
-                        GETSTATIC,
-                        Type.getInternalName(System::class.java), // "java/io/System"
-                        "out",
-                        Type.getInternalName(PrintStream::class.java) // "java.io.PrintStream"
-                    ),
-                    LdcInsnNode("Hello, ReVanced! Adding bytecode."),
-                    MethodInsnNode(
-                        INVOKEVIRTUAL,
-                        Type.getInternalName(PrintStream::class.java), // "java/io/PrintStream"
-                        "println",
-                        Type.getMethodDescriptor(
-                            Type.VOID_TYPE,
-                            Type.getType(String::class.java)
-                        ) // "(Ljava/lang/String;)V"
-                    )
-                )
-
-                // Our code now looks like this:
-                // public static main(java.lang.String[] arg0) { // Method signature: ([Ljava/lang/String;)V
-                //     getstatic java/lang/System.out:java.io.PrintStream
-                //     ldc "Hello, ReVanced! Editing bytecode." (java.lang.String) // We overwrote this instruction.
-                //     invokevirtual java/io/PrintStream.println(Ljava/lang/String;)V
-                //     getstatic java/lang/System.out:java.io.PrintStream // This instruction and the 2 instructions below are written manually.
-                //     ldc "Hello, ReVanced! Adding bytecode." (java.lang.String)
-                //     invokevirtual java/io/PrintStream.println(Ljava/lang/String;)V
-                //     return
-                // }
-
-                // Finally, tell the patcher that this patch was a success.
-                // You can also return PatchResultError with a message.
-                // If an exception is thrown inside this function,
-                // a PatchResultError will be returned with the error message.
-                PatchResultSuccess()
-            }
-        )
-
-        // Apply all patches loaded in the patcher
-        val result = patcher.applyPatches()
-        // You can check if an error occurred
-        for ((s, r) in result) {
-            if (r.isFailure) {
-                throw Exception("Patch $s failed", r.exceptionOrNull()!!)
-            }
-        }
-
-        // TODO Doesn't work, needs to be fixed.
-        //val out = ByteArrayOutputStream()
-        //patcher.saveTo(out)
-        //assertTrue(
-        //    // 8 is a random value, it's just weird if it's any lower than that
-        //    out.size() > 8,
-        //    "Output must be at least 8 bytes"
-        //)
-        //
-        //out.close()
-        testData.close()
-    }
-
-    // TODO Doesn't work, needs to be fixed.
-    //@Test
-    //fun `test patcher with no changes`() {
-    //    val testData = PatcherTest::class.java.getResourceAsStream("/test1.jar")!!
-    //    val available = testData.available()
-    //    val patcher = Patcher(testData, testSigs)
-    //
-    //    val out = ByteArrayOutputStream()
-    //    patcher.saveTo(out)
-    //    assertEquals(available, out.size())
-    //
-    //    out.close()
-    //    testData.close()
-    //}
-}