StaticFile.fromFile IllegalArgumentException with large files

The following code results in an IllegalArgumentException when the file is longer than Int.MaxValue

case req@GET -> Root / "file" =>
      StaticFile.fromFile(new File("massive-file.txt"), Some(req)).getOrElseF(NotFound())

And the exceptionis

logtype="application" transaction_id="" req_time="2017-11-15T10:53:34.195+11:00" loglevel="ERROR" threadname="scala-execution-context-global-73" classname="o.h.b.p.Stage" linenumber="Http1ServerStage.scala:226" message="Error writing body"
java.lang.IllegalArgumentException: null
	at java.nio.ByteBuffer.allocate(ByteBuffer.java:334)
	at fs2.io.file.FileHandle$$anon$2.read(FileHandle.scala:160)
	at org.http4s.StaticFile$._readAllFromFileHandle0$1(StaticFile.scala:150)
	at org.http4s.StaticFile$.readAllFromFileHandle$1(StaticFile.scala:145)
	at org.http4s.StaticFile$.$anonfun$fileToBody$7(StaticFile.scala:160)
	at org.http4s.StaticFile$.$anonfun$fileToBody$7$adapted(StaticFile.scala:160)

---

Some background as to how / why I discovered this. I was looking into streaming of large responses and noticed that the JVM CPU usage is very high while doing so. I wasn’t expecting this as I expect that Streaming of a large response is largely IO. To narrow down to the least possible application code I decided just to stream a large file. CPU usage is still higher than what I’d expect. I’m still investigating.

[rossabaker]

That exception happens when you allocate a negative buffer size. I bet the .toInt is the villain of this story.

[rossabaker]

I fixed this while looking at #1555. PR coming.