Fix SIGABRT on FindClass due to minification

zstd-kmp/build.gradle.kts

@@ -120,6 +120,8 @@ android {
 
     testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
 
+    consumerProguardFiles("src/androidMain/consumer-rules.pro")
+
     ndk {
       abiFilters += listOf("x86", "x86_64", "armeabi-v7a", "arm64-v8a")
     }

zstd-kmp/native/ZstdKmp.cpp

@@ -16,28 +16,6 @@
 #include <jni.h>
 #include <zstd.h>
 
-/**
- * Support for operating on JVM objects from native code.
- *
- * Pass a pointer to this to all JNI functions that operate on JVM objects.
- */
-class JniZstd {
-public:
-  JniZstd(JNIEnv *env, jclass zstdCompressorClass, jclass zstdDecompressorClass);
-
-  jfieldID zstdCompressorOutputBytesProcessed;
-  jfieldID zstdCompressorInputBytesProcessed;
-  jfieldID zstdDecompressorOutputBytesProcessed;
-  jfieldID zstdDecompressorInputBytesProcessed;
-};
-
-JniZstd::JniZstd(JNIEnv *env, jclass zstdCompressorClass, jclass zstdDecompressorClass)
-  : zstdCompressorOutputBytesProcessed(env->GetFieldID(zstdCompressorClass, "outputBytesProcessed", "I")),
-    zstdCompressorInputBytesProcessed(env->GetFieldID(zstdCompressorClass, "inputBytesProcessed", "I")),
-    zstdDecompressorOutputBytesProcessed(env->GetFieldID(zstdDecompressorClass, "outputBytesProcessed", "I")),
-    zstdDecompressorInputBytesProcessed(env->GetFieldID(zstdDecompressorClass, "inputBytesProcessed", "I")) {
-}
-
 extern "C" JNIEXPORT jstring JNICALL
 Java_com_squareup_zstd_JniZstdKt_jniGetErrorName(JNIEnv* env, jobject type, jlong code) {
   auto codeSizeT = static_cast<size_t>(code);
@@ -46,13 +24,6 @@ Java_com_squareup_zstd_JniZstdKt_jniGetErrorName(JNIEnv* env, jobject type, jlon
   return env->NewStringUTF(errorString);
 }
 
-extern "C" JNIEXPORT jlong JNICALL
-Java_com_squareup_zstd_JniZstdKt_createJniZstd(JNIEnv* env, jclass type) {
-  auto zstdCompressorClass = env->FindClass("com/squareup/zstd/ZstdCompressor");
-  auto zstdDecompressorClass = env->FindClass("com/squareup/zstd/ZstdDecompressor");
-  auto jniZstd = new JniZstd(env, zstdCompressorClass, zstdDecompressorClass);
-  return reinterpret_cast<jlong>(jniZstd);
-}
 
 extern "C" JNIEXPORT jlong JNICALL
 Java_com_squareup_zstd_JniZstdKt_createZstdCompressor(JNIEnv* env, jclass type) {
@@ -66,9 +37,8 @@ Java_com_squareup_zstd_JniZstdCompressor_setParameter(JNIEnv* env, jobject type,
   return ZSTD_CCtx_setParameter(cctx, static_cast<ZSTD_cParameter>(param), value);
 }
 
-extern "C" JNIEXPORT jlong JNICALL
-Java_com_squareup_zstd_JniZstdCompressor_compressStream2(JNIEnv* env, jobject type, jlong jniZstdPointer, jlong cctxPointer, jbyteArray outputByteArray, jint outputEnd, jint outputStart, jbyteArray inputByteArray, jint inputEnd, jint inputStart, jint mode) {
-  auto jniZstd = reinterpret_cast<JniZstd*>(jniZstdPointer);
+extern "C" JNIEXPORT jlongArray JNICALL
+Java_com_squareup_zstd_JniZstdCompressor_compressStream2(JNIEnv* env, jobject type, jlong cctxPointer, jbyteArray outputByteArray, jint outputEnd, jint outputStart, jbyteArray inputByteArray, jint inputEnd, jint inputStart, jint mode) {
   auto cctx = reinterpret_cast<ZSTD_CCtx*>(cctxPointer);
 
   auto inputByteArrayElements = env->GetByteArrayElements(inputByteArray, NULL);
@@ -85,13 +55,16 @@ Java_com_squareup_zstd_JniZstdCompressor_compressStream2(JNIEnv* env, jobject ty
     result = -ZSTD_error_GENERIC;
   }
 
-  env->SetIntField(type, jniZstd->zstdCompressorOutputBytesProcessed, static_cast<jint>(zstdOutput.pos) - outputStart);
-  env->SetIntField(type, jniZstd->zstdCompressorInputBytesProcessed, static_cast<jint>(zstdInput.pos) - inputStart);
-
   env->ReleaseByteArrayElements(inputByteArray, inputByteArrayElements, JNI_ABORT);
   env->ReleaseByteArrayElements(outputByteArray, outputByteArrayElements, 0);
 
-  return result;
+  jlong results[3];
+  results[0] = static_cast<jlong>(result);
+  results[1] = static_cast<jlong>(zstdInput.pos) - inputStart;
+  results[2] = static_cast<jlong>(zstdOutput.pos) - outputStart;
+  jlongArray resultArray = env->NewLongArray(3);
+  env->SetLongArrayRegion(resultArray, 0, 3, results);
+  return resultArray;
 }
 
 extern "C" JNIEXPORT void JNICALL
@@ -106,9 +79,8 @@ Java_com_squareup_zstd_JniZstdKt_createZstdDecompressor(JNIEnv* env, jclass type
   return reinterpret_cast<jlong>(dctx);
 }
 
-extern "C" JNIEXPORT jlong JNICALL
-Java_com_squareup_zstd_JniZstdDecompressor_decompressStream(JNIEnv* env, jobject type, jlong jniZstdPointer, jlong dctxPointer, jbyteArray outputByteArray, jint outputEnd, jint outputStart, jbyteArray inputByteArray, jint inputEnd, jint inputStart) {
-  auto jniZstd = reinterpret_cast<JniZstd*>(jniZstdPointer);
+extern "C" JNIEXPORT jlongArray JNICALL
+Java_com_squareup_zstd_JniZstdDecompressor_decompressStream(JNIEnv* env, jobject type, jlong dctxPointer, jbyteArray outputByteArray, jint outputEnd, jint outputStart, jbyteArray inputByteArray, jint inputEnd, jint inputStart) {
   auto dctx = reinterpret_cast<ZSTD_DCtx*>(dctxPointer);
 
   auto inputByteArrayElements = env->GetByteArrayElements(inputByteArray, NULL);
@@ -124,13 +96,16 @@ Java_com_squareup_zstd_JniZstdDecompressor_decompressStream(JNIEnv* env, jobject
     result = -ZSTD_error_GENERIC;
   }
 
-  env->SetIntField(type, jniZstd->zstdDecompressorOutputBytesProcessed, static_cast<jint>(zstdOutput.pos) - outputStart);
-  env->SetIntField(type, jniZstd->zstdDecompressorInputBytesProcessed, static_cast<jint>(zstdInput.pos) - inputStart);
-
   env->ReleaseByteArrayElements(inputByteArray, inputByteArrayElements, JNI_ABORT);
   env->ReleaseByteArrayElements(outputByteArray, outputByteArrayElements, 0);
 
-  return result;
+  jlong results[3];
+  results[0] = static_cast<jlong>(result);
+  results[1] = static_cast<jlong>(zstdInput.pos) - inputStart;
+  results[2] = static_cast<jlong>(zstdOutput.pos) - outputStart;
+  jlongArray resultArray = env->NewLongArray(3);
+  env->SetLongArrayRegion(resultArray, 0, 3, results);
+  return resultArray;
 }
 
 extern "C" JNIEXPORT void JNICALL

zstd-kmp/src/androidMain/consumer-rules.pro

@@ -0,0 +1,7 @@
+# Keep classes with native methods so R8 doesn't rename them.
+# JNI function names in the native library are derived from the fully-qualified
+# class and method names, so renaming would break the JNI linkage.
+-keepclasseswithmembers class com.squareup.zstd.** {
+    native <methods>;
+}
+

zstd-kmp/src/jniMain/kotlin/com/squareup/zstd/JniZstd.kt

@@ -15,12 +15,25 @@
  */
 package com.squareup.zstd
 
-internal val jniZstdPointer: Long = run {
-  loadNativeLibrary()
-  createJniZstd()
-}
+internal val jniLibraryLoaded: Unit by lazy { loadNativeLibrary() }
+
+/**
+ * Result of a native stream operation. The native function returns a [LongArray] with three
+ * elements; this class provides named access to each.
+ */
+internal class StreamResult(private val values: LongArray) {
+  /** The zstd result code. */
+  val result: Long
+    get() = values[0]
 
-@JvmName("createJniZstd") internal external fun createJniZstd(): Long
+  /** The number of input bytes consumed. */
+  val inputBytesProcessed: Int
+    get() = values[1].toInt()
+
+  /** The number of output bytes produced. */
+  val outputBytesProcessed: Int
+    get() = values[2].toInt()
+}
 
 @JvmName("jniGetErrorName") internal external fun jniGetErrorName(code: Long): String?
 

zstd-kmp/src/jniMain/kotlin/com/squareup/zstd/JniZstdCompressor.kt

@@ -17,10 +17,12 @@ package com.squareup.zstd
 
 internal class JniZstdCompressor : ZstdCompressor() {
   @JvmField
-  var cctxPointer =
+  var cctxPointer = run {
+    jniLibraryLoaded
     createZstdCompressor().also {
       if (it == 0L) throw OutOfMemoryError("createZstdCompressor failed")
     }
+  }
 
   override fun setParameter(param: Int, value: Int): Long = setParameter(cctxPointer, param, value)
 
@@ -32,18 +34,24 @@ internal class JniZstdCompressor : ZstdCompressor() {
     inputEnd: Int,
     inputStart: Int,
     mode: Int,
-  ): Long =
-    compressStream2(
-      jniPointer = jniZstdPointer,
-      cctxPointer = cctxPointer,
-      outputByteArray = outputByteArray,
-      outputEnd = outputEnd,
-      outputStart = outputStart,
-      inputByteArray = inputByteArray,
-      inputEnd = inputEnd,
-      inputStart = inputStart,
-      mode = mode,
-    )
+  ): Long {
+    val streamResult =
+      StreamResult(
+        compressStream2(
+          cctxPointer = cctxPointer,
+          outputByteArray = outputByteArray,
+          outputEnd = outputEnd,
+          outputStart = outputStart,
+          inputByteArray = inputByteArray,
+          inputEnd = inputEnd,
+          inputStart = inputStart,
+          mode = mode,
+        )
+      )
+    inputBytesProcessed = streamResult.inputBytesProcessed
+    outputBytesProcessed = streamResult.outputBytesProcessed
+    return streamResult.result
+  }
 
   override fun close() {
     val cctxPointerToClose = cctxPointer
@@ -56,7 +64,6 @@ internal class JniZstdCompressor : ZstdCompressor() {
   private external fun setParameter(cctxPointer: Long, param: Int, value: Int): Long
 
   private external fun compressStream2(
-    jniPointer: Long,
     cctxPointer: Long,
     outputByteArray: ByteArray,
     outputEnd: Int,
@@ -65,7 +72,7 @@ internal class JniZstdCompressor : ZstdCompressor() {
     inputEnd: Int,
     inputStart: Int,
     mode: Int,
-  ): Long
+  ): LongArray
 
   private external fun close(cctxPointer: Long)
 }

zstd-kmp/src/jniMain/kotlin/com/squareup/zstd/JniZstdDecompressor.kt

@@ -17,10 +17,12 @@ package com.squareup.zstd
 
 internal class JniZstdDecompressor : ZstdDecompressor() {
   @JvmField
-  var dctxPointer =
+  var dctxPointer = run {
+    jniLibraryLoaded
     createZstdDecompressor().also {
       if (it == 0L) throw OutOfMemoryError("createZstdDecompressor failed")
     }
+  }
 
   override fun decompressStream(
     outputByteArray: ByteArray,
@@ -29,17 +31,23 @@ internal class JniZstdDecompressor : ZstdDecompressor() {
     inputByteArray: ByteArray,
     inputEnd: Int,
     inputStart: Int,
-  ): Long =
-    decompressStream(
-      jniPointer = jniZstdPointer,
-      dctxPointer = dctxPointer,
-      outputByteArray = outputByteArray,
-      outputEnd = outputEnd,
-      outputStart = outputStart,
-      inputByteArray = inputByteArray,
-      inputEnd = inputEnd,
-      inputStart = inputStart,
-    )
+  ): Long {
+    val streamResult =
+      StreamResult(
+        decompressStream(
+          dctxPointer = dctxPointer,
+          outputByteArray = outputByteArray,
+          outputEnd = outputEnd,
+          outputStart = outputStart,
+          inputByteArray = inputByteArray,
+          inputEnd = inputEnd,
+          inputStart = inputStart,
+        )
+      )
+    inputBytesProcessed = streamResult.inputBytesProcessed
+    outputBytesProcessed = streamResult.outputBytesProcessed
+    return streamResult.result
+  }
 
   override fun close() {
     val cctxPointerToClose = dctxPointer
@@ -50,15 +58,14 @@ internal class JniZstdDecompressor : ZstdDecompressor() {
   }
 
   private external fun decompressStream(
-    jniPointer: Long,
     dctxPointer: Long,
     outputByteArray: ByteArray,
     outputEnd: Int,
     outputStart: Int,
     inputByteArray: ByteArray,
     inputEnd: Int,
     inputStart: Int,
-  ): Long
+  ): LongArray
 
   private external fun close(cctxPointer: Long)
 }

zstd-kmp/src/jniMain/kotlin/com/squareup/zstd/Zstd.jni.kt

@@ -18,7 +18,10 @@
 
 package com.squareup.zstd
 
-actual fun getErrorName(code: Long): String? = jniGetErrorName(code)
+actual fun getErrorName(code: Long): String? {
+  jniLibraryLoaded
+  return jniGetErrorName(code)
+}
 
 actual fun zstdCompressor(): ZstdCompressor = JniZstdCompressor()