Fix: Ignore R8 minified libs from instrumentation

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Fixes
+
+* Ignore R8 minified libs from instrumentation (#316)
+
 ## 3.1.0-beta.1
 
 * Fix: obfuscated libs instrumentation (adcolony) (#307)

plugin-build/src/main/kotlin/io/sentry/android/gradle/instrumentation/util/ConstantPoolHelpers.kt

@@ -0,0 +1,86 @@
+package io.sentry.android.gradle.instrumentation.util
+
+import java.lang.reflect.Field
+import org.objectweb.asm.ClassReader
+import org.objectweb.asm.ClassVisitor
+import org.objectweb.asm.ClassWriter
+
+/**
+ * Looks up for the original [ClassWriter] up the visitor chain by looking at the private `cv` field
+ * of the [ClassVisitor].
+ */
+internal fun ClassVisitor.findClassWriter(): ClassWriter? {
+    var classWriter: ClassVisitor = this
+    while (!ClassWriter::class.java.isAssignableFrom(classWriter::class.java)) {
+        val cvField: Field = try {
+            classWriter::class.java.allFields.find { it.name == "cv" } ?: return null
+        } catch (e: Throwable) {
+            return null
+        }
+        cvField.isAccessible = true
+        classWriter = (cvField.get(classWriter) as? ClassVisitor) ?: return null
+    }
+    return classWriter as ClassWriter
+}
+
+/**
+ * Looks up for [ClassReader] of the [ClassWriter] through intermediate SymbolTable field.
+ */
+internal fun ClassWriter.findClassReader(): ClassReader? {
+    val clazz: Class<out ClassWriter> = this::class.java
+    val symbolTableField: Field = try {
+        clazz.allFields.find { it.name == "symbolTable" } ?: return null
+    } catch (e: Throwable) {
+        return null
+    }
+    symbolTableField.isAccessible = true
+    val symbolTable = symbolTableField.get(this)
+    val classReaderField: Field = try {
+        symbolTable::class.java.getDeclaredField("sourceClassReader")
+    } catch (e: Throwable) {
+        return null
+    }
+    classReaderField.isAccessible = true
+    return (classReaderField.get(symbolTable) as? ClassReader)
+}
+
+/**
+ * Looks at the constant pool entries and searches for R8 markers
+ */
+internal fun ClassReader.isMinifiedClass(): Boolean {
+    val charBuffer = CharArray(maxStringLength)
+    // R8 marker is usually in the first 3-5 entries, so we limit it at 10 to speed it up
+    // (constant pool size can be huge otherwise)
+    val poolSize = minOf(10, itemCount)
+    for (i in 1 until poolSize) {
+        try {
+            val constantPoolEntry = readConst(i, charBuffer)
+            if (constantPoolEntry is String && "~~R8" in constantPoolEntry) {
+                // ~~R8 is a marker in the class' constant pool, which r8 itself is looking at when
+                // parsing a .class file. See here -> https://r8.googlesource.com/r8/+/refs/heads/main/src/main/java/com/android/tools/r8/dex/Marker.java#53
+                return true
+            }
+        } catch (e: Throwable) {
+            // we ignore exceptions here, because some constant pool entries are nulls and the
+            // readConst method throws IllegalArgumentException when trying to read those
+        }
+    }
+    return false
+}
+
+/**
+ * Gets all fields of the given class and its parents (if any).
+ *
+ * Adapted from https://github.com/apache/commons-lang/blob/master/src/main/java/org/apache/commons/lang3/reflect/FieldUtils.java
+ */
+private val Class<*>.allFields: List<Field>
+    get() {
+        val allFields = mutableListOf<Field>()
+        var currentClass: Class<*>? = this
+        while (currentClass != null) {
+            val declaredFields = currentClass.declaredFields
+            allFields += declaredFields
+            currentClass = currentClass.superclass
+        }
+        return allFields
+    }

plugin-build/src/main/kotlin/io/sentry/android/gradle/instrumentation/wrap/WrappingInstrumentable.kt

@@ -4,14 +4,19 @@ package io.sentry.android.gradle.instrumentation.wrap
 
 import com.android.build.api.instrumentation.ClassContext
 import com.android.build.api.instrumentation.ClassData
+import io.sentry.android.gradle.SentryPlugin
 import io.sentry.android.gradle.instrumentation.ClassInstrumentable
 import io.sentry.android.gradle.instrumentation.CommonClassVisitor
 import io.sentry.android.gradle.instrumentation.MethodContext
 import io.sentry.android.gradle.instrumentation.MethodInstrumentable
 import io.sentry.android.gradle.instrumentation.SpanAddingClassVisitorFactory
 import io.sentry.android.gradle.instrumentation.util.AnalyzingVisitor
+import io.sentry.android.gradle.instrumentation.util.findClassReader
+import io.sentry.android.gradle.instrumentation.util.findClassWriter
+import io.sentry.android.gradle.instrumentation.util.isMinifiedClass
 import io.sentry.android.gradle.instrumentation.util.isSentryClass
 import io.sentry.android.gradle.instrumentation.wrap.visitor.WrappingVisitor
+import io.sentry.android.gradle.util.info
 import org.objectweb.asm.ClassVisitor
 import org.objectweb.asm.MethodVisitor
 import org.objectweb.asm.tree.MethodNode
@@ -26,6 +31,18 @@ class WrappingInstrumentable : ClassInstrumentable {
     ): ClassVisitor {
         val simpleClassName =
             instrumentableContext.currentClassData.className.substringAfterLast('.')
+
+        val classReader = originalVisitor.findClassWriter()?.findClassReader()
+        val isMinifiedClass = classReader?.isMinifiedClass() ?: false
+        if (isMinifiedClass) {
+            // We only check for minified classes for the WrappingInstrumentable, because it is the
+            // only one which runs over all classes
+            SentryPlugin.logger.info {
+                "$simpleClassName skipped from instrumentation because it's a minified class."
+            }
+            return originalVisitor
+        }
+
         return AnalyzingVisitor(
             apiVersion = apiVersion,
             nextVisitor = { methods ->

plugin-build/src/test/kotlin/io/sentry/android/gradle/BaseSentryPluginTest.kt

@@ -55,12 +55,13 @@ abstract class BaseSentryPluginTest(
               repositories {
                 google()
                 mavenCentral()
+                maven { url 'https://appboy.github.io/appboy-android-sdk/sdk' }
               }
             }
             subprojects {
               pluginManager.withPlugin('com.android.application') {
                 android {
-                  compileSdkVersion 30
+                  compileSdkVersion 31
                   defaultConfig {
                     applicationId "com.example"
                     minSdkVersion 21

plugin-build/src/test/kotlin/io/sentry/android/gradle/SentryPluginWithMinifiedLibsTest.kt

@@ -7,7 +7,7 @@ class SentryPluginWithMinifiedLibsTest :
     BaseSentryPluginTest(androidGradlePluginVersion = "7.1.2", gradleVersion = "7.4") {
 
     @Test
-    fun `does not break when there is a play-core obfuscated dependency`() {
+    fun `does not break when there is a minified jar dependency`() {
         appBuildFile.writeText(
             // language=Groovy
             """
@@ -22,6 +22,7 @@ class SentryPluginWithMinifiedLibsTest :
               implementation 'com.google.android.gms:play-services-vision:20.1.3'
               implementation 'com.google.android.gms:play-services-mlkit-text-recognition:18.0.0'
               implementation 'com.adcolony:sdk:4.7.1'
+              implementation 'com.appboy:android-sdk-ui:19.0.0'
             }
             """.trimIndent()
         )

plugin-build/src/test/kotlin/io/sentry/android/gradle/instrumentation/VisitorTest.kt

@@ -136,6 +136,12 @@ class VisitorTest(
                 ChainedInstrumentable(listOf(WrappingInstrumentable(), RemappingInstrumentable())),
                 null
             ),
+            arrayOf(
+                "fileIO",
+                "BrazeImageUtils",
+                ChainedInstrumentable(listOf(WrappingInstrumentable(), RemappingInstrumentable())),
+                null
+            ),
             arrayOf("okhttp/v3", "RealCall", OkHttp(), null),
             arrayOf("okhttp/v4", "RealCall", OkHttp(), null)
         )