From 10c549a0b950db55eb9bf9cb90cef92c393282f8 Mon Sep 17 00:00:00 2001
From: Ethan Atkins <contact@ethanatkins.com>
Date: Tue, 6 Oct 2020 07:17:16 -0700
Subject: [PATCH] Fix sbt hangs with invalid build.sbt and --batch

When sbt is starting up and there is an error with the build loading, we
need to read input from the user to determine to restart the build or
not. What is tricky is that there are potentially two sources of input:
thin clients connected through the boot server socket and the actual sbt
console process. If there are not connected thin clients and no system
console is available, we should return -1 in System.in.read, which will
cause sbt to exit.
---
 .../src/main/scala/sbt/internal/util/Terminal.scala         | 6 ++++++
 .../src/main/java/sbt/internal/BootServerSocket.java        | 1 +
 2 files changed, 7 insertions(+)

diff --git a/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala b/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala
index 829b2f3cb..e28f0ea54 100644
--- a/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala
+++ b/internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala
@@ -179,6 +179,7 @@ trait Terminal extends AutoCloseable {
 }
 
 object Terminal {
+  val NO_BOOT_CLIENTS_CONNECTED: Int = -2
   // Disable noisy jline log spam
   if (System.getProperty("sbt.jline.verbose", "false") != "true")
     jline.internal.Log.setOutput(new PrintStream(_ => {}, false))
@@ -618,6 +619,11 @@ object Terminal {
                 if (running.get) {
                   inputStream.read match {
                     case -1 =>
+                    case `NO_BOOT_CLIENTS_CONNECTED` =>
+                      if (System.console == null) {
+                        result.put(-1)
+                        running.set(false)
+                      }
                     case i =>
                       result.put(i)
                       running.set(false)
diff --git a/main-command/src/main/java/sbt/internal/BootServerSocket.java b/main-command/src/main/java/sbt/internal/BootServerSocket.java
index b153f32f9..3cda9e830 100644
--- a/main-command/src/main/java/sbt/internal/BootServerSocket.java
+++ b/main-command/src/main/java/sbt/internal/BootServerSocket.java
@@ -216,6 +216,7 @@ public class BootServerSocket implements AutoCloseable {
       new InputStream() {
         @Override
         public int read() {
+          if (clientSockets.isEmpty()) return Terminal.NO_BOOT_CLIENTS_CONNECTED();
           try {
             synchronized (needInput) {
               needInput.set(true);