Enhance support for replayable instances of [InputStream]

Author: lauzadis

runtime/runtime-core/jvm/src/aws/smithy/kotlin/runtime/content/ByteStreamJVM.kt

@@ -114,11 +114,25 @@ public fun ByteStream.Companion.fromInputStream(
  * @param contentLength If specified, indicates how many bytes remain in this stream. Defaults to `null`.
  */
 public fun InputStream.asByteStream(contentLength: Long? = null): ByteStream.SourceStream {
-    val source = source()
+    if (markSupported() && contentLength != null) {
+        mark(contentLength.toInt())
+    }
+
     return object : ByteStream.SourceStream() {
         override val contentLength: Long? = contentLength
         override val isOneShot: Boolean = !markSupported()
-        override fun readFrom(): SdkSource = source
+        override fun readFrom(): SdkSource {
+            if (markSupported() && contentLength != null) {
+                reset()
+                mark(contentLength.toInt())
+                return object : SdkSource by source() {
+                    // no-op close
+                    override fun close() { }
+                }
+            }
+
+            return source()
+        }
     }
 }
 

runtime/runtime-core/jvm/test/aws/smithy/kotlin/runtime/content/ByteStreamJVMTest.kt

@@ -5,8 +5,11 @@
 
 package aws.smithy.kotlin.runtime.content
 
+import aws.smithy.kotlin.runtime.io.readToByteArray
 import aws.smithy.kotlin.runtime.testing.RandomTempFile
 import kotlinx.coroutines.test.runTest
+import java.io.BufferedInputStream
+import java.io.ByteArrayInputStream
 import java.io.ByteArrayOutputStream
 import java.io.InputStream
 import java.io.OutputStream
@@ -228,6 +231,31 @@ class ByteStreamJVMTest {
         assertFalse(sos.closed)
     }
 
+    // https://github.com/awslabs/aws-sdk-kotlin/issues/1473
+    @Test
+    fun testReplayableInputStreamAsByteStream() = runTest {
+        val content = "Hello, Bytes!".encodeToByteArray()
+        val byteArrayIns = ByteArrayInputStream(content)
+        val nonReplayableIns = NonReplayableInputStream(byteArrayIns)
+
+        // buffer the non-replayable stream, making it replayable...
+        val bufferedIns = BufferedInputStream(nonReplayableIns)
+
+        val byteStream = bufferedIns.asByteStream(content.size.toLong())
+
+        // Test that it can be read at least twice (once for hashing the body, once for transmitting the body)
+        assertContentEquals(content, byteStream.readFrom().use { it.readToByteArray() })
+        assertContentEquals(content, byteStream.readFrom().use { it.readToByteArray() })
+    }
+
+    private class NonReplayableInputStream(val inputStream: InputStream) : InputStream() {
+        override fun markSupported(): Boolean = false // not replayable
+
+        override fun read(): Int = inputStream.read()
+        override fun mark(readlimit: Int)= inputStream.mark(readlimit)
+        override fun reset() = inputStream.reset()
+    }
+
     private class StatusTrackingOutputStream(val os: OutputStream) : OutputStream() {
         var closed: Boolean = false