From 7d4019614addc23946ac6179c6a2576563a2f243 Mon Sep 17 00:00:00 2001
From: Ethan Atkins <contact@ethanatkins.com>
Date: Sun, 27 Sep 2020 09:59:37 -0700
Subject: [PATCH] Bypass some Terminal operations if no System.in

If there is no console attached, it doesn't make sense to enter or exit
raw mode. We also don't want to poll from System.in in CI in
SimpleTerminal because threads can get blocked trying to read from
System.in with no possibility of exiting.
---
 .../scala/sbt/internal/util/Terminal.scala    | 39 +++++++++++++------
 1 file changed, 27 insertions(+), 12 deletions(-)

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 a5706d074..829b2f3cb 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
@@ -306,10 +306,10 @@ object Terminal {
     }
   }
   private[sbt] lazy val formatEnabledInEnv: Boolean = logFormatEnabled.getOrElse(useColorDefault)
+  private[this] val hasConsole = Option(java.lang.System.console).isDefined
   private[this] def useColorDefault: Boolean = {
     // This approximates that both stdin and stdio are connected,
     // so by default color will be turned off for pipes and redirects.
-    val hasConsole = Option(java.lang.System.console).isDefined
     props.map(_.color).orElse(isColorEnabledProp).getOrElse(hasConsole)
   }
   private[this] lazy val isColorEnabledProp: Option[Boolean] =
@@ -779,7 +779,7 @@ object Terminal {
       private[util] val system: org.jline.terminal.Terminal,
   ) extends TerminalImpl(in, out, originalErr, "console0") {
     private[this] val rawMode = new AtomicBoolean(false)
-    enterRawMode()
+    if (hasConsole) enterRawMode()
     override private[sbt] def getSizeImpl: (Int, Int) = {
       val size = system.getSize
       (size.getColumns, size.getRows)
@@ -811,16 +811,22 @@ object Terminal {
     override private[sbt] def setSize(width: Int, height: Int): Unit =
       system.setSize(new org.jline.terminal.Size(width, height))
 
-    override private[sbt] def enterRawMode(): Unit = if (rawMode.compareAndSet(false, true)) {
-      in.setRawMode(true)
-      try JLine3.enterRawMode(system)
-      catch { case _: java.io.IOError => }
-    }
-    override private[sbt] def exitRawMode(): Unit = if (rawMode.compareAndSet(true, false)) {
-      in.setRawMode(false)
-      try JLine3.exitRawMode(system)
-      catch { case _: java.io.IOError => }
+    override def inputStream: InputStream = {
+      if (hasConsole) in else BlockingInputStream
     }
+
+    override private[sbt] def enterRawMode(): Unit =
+      if (rawMode.compareAndSet(false, true) && hasConsole) {
+        in.setRawMode(true)
+        try JLine3.enterRawMode(system)
+        catch { case _: java.io.IOError => }
+      }
+    override private[sbt] def exitRawMode(): Unit =
+      if (rawMode.compareAndSet(true, false) && hasConsole) {
+        in.setRawMode(false)
+        try JLine3.exitRawMode(system)
+        catch { case _: java.io.IOError => }
+      }
     override def isColorEnabled: Boolean =
       props
         .map(_.color)
@@ -970,8 +976,17 @@ object Terminal {
   }
   private[sbt] object NullTerminal extends DefaultTerminal
   private[sbt] object SimpleTerminal extends DefaultTerminal {
-    override lazy val inputStream: InputStream = originalIn
+    override lazy val inputStream: InputStream =
+      if (isCI) BlockingInputStream
+      else originalIn
     override lazy val outputStream: OutputStream = originalOut
     override lazy val errorStream: OutputStream = originalErr
   }
+  private[this] object BlockingInputStream extends SimpleInputStream {
+    override def read(): Int = {
+      try this.synchronized(this.wait)
+      catch { case _: InterruptedException => }
+      -1
+    }
+  }
 }