support ByteBuffers that have hasArray=false

avro4s-core/src/main/scala/com/sksamuel/avro4s/AvroInputStream.scala

@@ -4,6 +4,7 @@ import java.io.{ByteArrayInputStream, File, InputStream}
 import java.nio.ByteBuffer
 import java.nio.file.{Files, Path, Paths}
 
+import com.sksamuel.avro4s.avroutils.ByteBufferHelper
 import org.apache.avro.Schema
 
 import scala.util.Try
@@ -55,7 +56,8 @@ class AvroInputStreamBuilder[T: Decoder](format: AvroFormat) {
   def from(file: File): AvroInputStreamBuilderWithSource[T] = from(file.toPath)
   def from(in: InputStream): AvroInputStreamBuilderWithSource[T] = new AvroInputStreamBuilderWithSource(format, in)
   def from(bytes: Array[Byte]): AvroInputStreamBuilderWithSource[T] = from(new ByteArrayInputStream(bytes))
-  def from(buffer: ByteBuffer): AvroInputStreamBuilderWithSource[T] = from(new ByteArrayInputStream(buffer.array))
+  def from(buffer: ByteBuffer): AvroInputStreamBuilderWithSource[T] = from(
+    new ByteArrayInputStream(ByteBufferHelper.asArray(buffer)))
 }
 
 

avro4s-core/src/main/scala/com/sksamuel/avro4s/DefaultResolver.scala

@@ -4,8 +4,9 @@ import java.nio.ByteBuffer
 import java.time.Instant
 import java.util.UUID
 
+import com.sksamuel.avro4s.avroutils.ByteBufferHelper
 import org.apache.avro.LogicalTypes.Decimal
-import org.apache.avro.generic.{GenericEnumSymbol, GenericFixed}
+import org.apache.avro.generic.GenericFixed
 import org.apache.avro.util.Utf8
 import org.apache.avro.{Conversions, Schema}
 //import CustomDefaults._
@@ -35,7 +36,7 @@ object DefaultResolver {
       val decimalConversion = new Conversions.DecimalConversion
       val bd = decimalConversion.fromBytes(byteBuffer, schema, schema.getLogicalType)
       java.lang.Double.valueOf(bd.doubleValue)
-    case byteBuffer: ByteBuffer => byteBuffer.array()
+    case byteBuffer: ByteBuffer => ByteBufferHelper.asArray(byteBuffer)
     case x: scala.Long => java.lang.Long.valueOf(x)
     case x: scala.Boolean => java.lang.Boolean.valueOf(x)
     case x: scala.Int => java.lang.Integer.valueOf(x)

avro4s-core/src/main/scala/com/sksamuel/avro4s/avroutils/ByteBufferHelper.scala

@@ -0,0 +1,15 @@
+package com.sksamuel.avro4s.avroutils
+
+import java.nio.ByteBuffer
+
+private[avro4s] object ByteBufferHelper {
+  def asArray(byteBuffer: ByteBuffer): Array[Byte] = {
+    if (byteBuffer.hasArray) {
+      byteBuffer.array()
+    } else {
+      val bytes = new Array[Byte](byteBuffer.remaining)
+      byteBuffer.get(bytes)
+      bytes
+    }
+  }
+}

avro4s-core/src/main/scala/com/sksamuel/avro4s/decoders/bytes.scala

@@ -1,5 +1,6 @@
 package com.sksamuel.avro4s.decoders
 
+import com.sksamuel.avro4s.avroutils.ByteBufferHelper
 import com.sksamuel.avro4s.{Avro4sDecodingException, Decoder}
 import org.apache.avro.Schema
 
@@ -18,7 +19,7 @@ trait ByteDecoders:
 object ArrayByteDecoder extends Decoder[Array[Byte]] :
   override def decode(schema: Schema): Any => Array[Byte] = { value =>
     value match {
-      case buffer: ByteBuffer => buffer.array
+      case buffer: ByteBuffer => ByteBufferHelper.asArray(buffer)
       case array: Array[Byte] => array
       case fixed: org.apache.avro.generic.GenericFixed => fixed.bytes
       case _ => throw new Avro4sDecodingException(s"ArrayByteDecoder cannot decode '$value'", value)

avro4s-core/src/main/scala/com/sksamuel/avro4s/decoders/strings.scala

@@ -1,10 +1,10 @@
 package com.sksamuel.avro4s.decoders
 
-import com.sksamuel.avro4s.encoders.{ByteStringEncoder, StringEncoder, UTF8StringEncoder}
-import com.sksamuel.avro4s.{Avro4sConfigurationException, Avro4sDecodingException, Decoder, Encoder}
-import org.apache.avro.generic.{GenericData, GenericFixed}
+import com.sksamuel.avro4s.avroutils.ByteBufferHelper
+import com.sksamuel.avro4s.{Avro4sConfigurationException, Avro4sDecodingException, Decoder}
+import org.apache.avro.generic.GenericFixed
 import org.apache.avro.util.Utf8
-import org.apache.avro.{AvroRuntimeException, Schema}
+import org.apache.avro.Schema
 
 import java.nio.ByteBuffer
 import java.util.UUID
@@ -28,7 +28,7 @@ object StringDecoder extends Decoder[String] :
       case string: String => string
       case charseq: CharSequence => charseq.toString
       case b: Array[Byte] => new Utf8(b).toString
-      case bytes: ByteBuffer => new Utf8(bytes.array()).toString
+      case bytes: ByteBuffer => new Utf8(ByteBufferHelper.asArray(bytes)).toString
       case fixed: GenericFixed => new Utf8(fixed.bytes()).toString
       case _ => throw new Avro4sDecodingException(s"Unsupported type $string ${string.getClass} for StringDecoder", string)
     }
@@ -41,7 +41,7 @@ object CharSequenceDecoder extends Decoder[CharSequence]:
       case string: String => string
       case charseq: CharSequence => charseq
       case b: Array[Byte] => new Utf8(b)
-      case bytes: ByteBuffer => new Utf8(bytes.array())
+      case bytes: ByteBuffer => new Utf8(ByteBufferHelper.asArray(bytes))
       case fixed: GenericFixed => new Utf8(fixed.bytes())
     }
   }
@@ -58,7 +58,7 @@ object UTF8Decoder extends Decoder[Utf8] :
       case utf8: Utf8 => utf8
       case string: String => new Utf8(string)
       case b: Array[Byte] => new Utf8(b)
-      case bytes: ByteBuffer => new Utf8(bytes.array())
+      case bytes: ByteBuffer => new Utf8(ByteBufferHelper.asArray(bytes))
       case fixed: GenericFixed => new Utf8(fixed.bytes())
     }
   }
@@ -88,7 +88,7 @@ object ByteStringDecoder extends Decoder[String] :
   override def decode(schema: Schema): Any => String = { input =>
     input match {
       case b: Array[Byte] => new Utf8(b).toString
-      case bytes: ByteBuffer => new Utf8(bytes.array()).toString
+      case bytes: ByteBuffer => new Utf8(ByteBufferHelper.asArray(bytes)).toString
     }
   }
 

avro4s-core/src/main/scala/com/sksamuel/avro4s/encoders/bytes.scala

@@ -1,5 +1,6 @@
 package com.sksamuel.avro4s.encoders
 
+import com.sksamuel.avro4s.avroutils.ByteBufferHelper
 import com.sksamuel.avro4s.{Avro4sConfigurationException, Encoder}
 import org.apache.avro.Schema
 import org.apache.avro.generic.GenericData
@@ -37,7 +38,8 @@ object ByteArrayEncoder extends Encoder[Array[Byte]] :
 object FixedByteBufferEncoder extends Encoder[ByteBuffer] {
   override def encode(schema: Schema): ByteBuffer => Any = { value =>
     val array = new Array[Byte](schema.getFixedSize)
-    System.arraycopy(value.array(), 0, array, 0, value.array().length)
+    val bbArray = ByteBufferHelper.asArray(value)
+    System.arraycopy(bbArray, 0, array, 0, bbArray.length)
     GenericData.get.createFixed(null, array, schema)
   }
 }

avro4s-core/src/main/scala/com/sksamuel/avro4s/encoders/strings.scala

@@ -1,8 +1,8 @@
 package com.sksamuel.avro4s.encoders
 
-import com.sksamuel.avro4s.{Avro4sConfigurationException, Avro4sEncodingException, Encoder, FieldMapper}
-import org.apache.avro.Conversions.UUIDConversion
-import org.apache.avro.{Conversions, LogicalTypes, Schema}
+import com.sksamuel.avro4s.avroutils.ByteBufferHelper
+import com.sksamuel.avro4s.{Avro4sConfigurationException, Avro4sEncodingException, Encoder}
+import org.apache.avro.Schema
 import org.apache.avro.generic.GenericData
 import org.apache.avro.util.Utf8
 
@@ -49,4 +49,5 @@ object FixedStringEncoder extends Encoder[String] :
     val bytes = string.getBytes(StandardCharsets.UTF_8)
     if (bytes.length > schema.getFixedSize)
       throw new Avro4sEncodingException(s"Cannot write string with ${bytes.length} bytes to fixed type of size ${schema.getFixedSize}")
-    GenericData.get.createFixed(null, ByteBuffer.allocate(schema.getFixedSize).put(bytes).array, schema).asInstanceOf[GenericData.Fixed]
+    GenericData.get.createFixed(null,
+      ByteBufferHelper.asArray(ByteBuffer.allocate(schema.getFixedSize).put(bytes)), schema).asInstanceOf[GenericData.Fixed]

avro4s-core/src/test/scala/com/sksamuel/avro4s/record/decoder/ByteArrayDecoderTest.scala

@@ -44,6 +44,13 @@ class ByteArrayDecoderTest extends AnyFunSuite with Matchers {
     Decoder[VectorTest].decode(schema).apply(record).z shouldBe Vector[Byte](1, 4, 9)
   }
 
+  test("decode read-only ByteBuffer to Vector[Byte]") {
+    val schema = AvroSchema[VectorTest]
+    val record = new GenericData.Record(schema)
+    record.put("z", ByteBuffer.wrap(Array[Byte](1, 4, 9)).asReadOnlyBuffer())
+    Decoder[VectorTest].decode(schema).apply(record).z shouldBe Vector[Byte](1, 4, 9)
+  }
+
   test("decode Array[Byte] to List[Byte]") {
     val schema = AvroSchema[ListTest]
     val record = new GenericData.Record(schema)

avro4s-core/src/test/scala/com/sksamuel/avro4s/record/encoder/ByteArrayEncoderTest.scala

@@ -90,6 +90,15 @@ class ByteArrayEncoderTest extends AnyFunSuite with Matchers {
     fixed.bytes().length shouldBe 7
   }
 
+  test("encode byte buffers as FIXED (ReadOnlyBuffer)") {
+    val schema = SchemaBuilder.fixed("foo").size(7)
+    val fixed = Encoder[ByteBuffer]
+      .encode(schema)
+      .apply(ByteBuffer.wrap("hello".getBytes).asReadOnlyBuffer())
+      .asInstanceOf[GenericFixed]
+    fixed.bytes().toList shouldBe Seq(104, 101, 108, 108, 111, 0, 0)
+    fixed.bytes().length shouldBe 7
+  }
 
   test("encode top level byte arrays") {
     val encoder = Encoder[Array[Byte]]