Handle SIGINT When Reading User Input (#1082)

* Handle sigint when reading input

* next work

* signaller fix

Author: mgyucht

amm/repl/src/main/scala/ammonite/repl/AmmoniteFrontEnd.scala

@@ -50,7 +50,9 @@ case class AmmoniteFrontEnd(extraFilters: Filter = Filter.empty) extends FrontEn
 
     val autocompleteFilter: Filter = Filter.action(SpecialKeys.Tab){
       case TermState(rest, b, c, _) =>
-        val (newCursor, completions, details) = compilerComplete(c, b.mkString)
+        val (newCursor, completions, details) = TTY.withSttyOverride(TTY.restoreSigInt()) {
+          compilerComplete(c, b.mkString)
+        }
         val details2 = for (d <- details) yield {
 
           Highlighter.defaultHighlight(

amm/repl/src/main/scala/ammonite/repl/Repl.scala

@@ -173,6 +173,14 @@ class Repl(input: InputStream,
       case ex => Res.Exception(ex, "")
     }
 
+    _ <- Signaller("INT") {
+      // Put a fake `ThreadDeath` error in `lastException`, because `Thread#stop`
+      // raises an error with the stack trace of *this interrupt thread*, rather
+      // than the stack trace of *the mainThread*
+      lastException = new ThreadDeath()
+      lastException.setStackTrace(Repl.truncateStackTrace(interp.mainThread.getStackTrace))
+      interp.mainThread.stop()
+    }
     (code, stmts) <- frontEnd().action(
       input,
       reader,
@@ -186,14 +194,6 @@ class Repl(input: InputStream,
         history = history :+ code
       }
     )
-    _ <- Signaller("INT") {
-      // Put a fake `ThreadDeath` error in `lastException`, because `Thread#stop`
-      // raises an error with the stack trace of *this interrupt thread*, rather
-      // than the stack trace of *the mainThread*
-      lastException = new ThreadDeath()
-      lastException.setStackTrace(Repl.truncateStackTrace(interp.mainThread.getStackTrace))
-      interp.mainThread.stop()
-    }
     out <- interp.processLine(code, stmts, currentLine, false, () => currentLine += 1)
   } yield {
     printer.outStream.println()

amm/repl/src/main/scala/ammonite/repl/Signaller.scala

@@ -29,7 +29,8 @@ case class Signaller(sigStr: String)(f: => Unit) extends Scoped{
     finally{
       val head::tail = handlers(sig)
       handlers(sig) = tail
-      sun.misc.Signal.handle(sig, head)
+      val handlerToRegister = tail.headOption.getOrElse(sun.misc.SignalHandler.SIG_DFL)
+      sun.misc.Signal.handle(sig, handlerToRegister)
     }
   }
 }
@@ -41,6 +42,6 @@ case class Signaller(sigStr: String)(f: => Unit) extends Scoped{
 trait Scoped{
   def apply[T](t: => T): T
   def foreach[T](t: Unit => T): T = apply(t(()))
-  def flatMap[T, M[_]](t: Unit => M[T]): M[T] = apply(t(()))
+  def flatMap[T](t: Unit => T): T = apply(t(()))
   def map[T](t: Unit => T): T = apply(t(()))
 }

terminal/src/main/scala/ammonite/terminal/Terminal.scala

@@ -36,20 +36,9 @@ object Terminal {
                filters: Filter,
                displayTransform: (Vector[Char], Int) => (fansi.Str, Int) = LineReader.noTransform)
                : Option[String] = {
-
-
-    val initialConfig = TTY.init()
-    try {
+    TTY.withSttyOverride(TTY.readLineStty()) {
       new LineReader(ConsoleDim.width(), prompt, reader, writer, filters, displayTransform)
         .readChar(TermState(LazyList.continually(reader.read()), Vector.empty, 0, ""), 0)
-    }finally{
-
-      // Don't close these! Closing these closes stdin/stdout,
-      // which seems to kill the entire program
-
-      // reader.close()
-      // writer.close()
-      TTY.stty(initialConfig)
     }
   }
 }

terminal/src/main/scala/ammonite/terminal/Utils.scala

@@ -93,17 +93,6 @@ object TTY{
     import sys.process._
     Seq("sh", "-c", s"$pathedTput $s 2> /dev/tty").!!.trim.toInt
   }
-  def init() = {
-    stty("-a")
-
-    val initialConfig = stty("-g").trim
-    stty("-icanon min 1 -icrnl -inlcr -ixon")
-    sttyFailTolerant("dsusp undef")
-    stty("-echo")
-    stty("intr undef")
-
-    initialConfig
-  }
 
   private def sttyCmd(s: String) = {
     import sys.process._
@@ -121,8 +110,25 @@ object TTY{
   def sttyFailTolerant(s: String) =
     sttyCmd(s ++ " 2> /dev/null").!
 
-  def restore(initialConfig: String) = {
-    stty(initialConfig)
+  def withSttyOverride[A](setupStty: => Unit)(f: => A) = {
+    val initialConfig = stty("-g").trim
+    try {
+      setupStty
+      f
+    } finally {
+      stty(initialConfig)
+    }
+  }
+
+  def readLineStty(): Unit = {
+    stty("-icanon min 1 -icrnl -inlcr -ixon")
+    sttyFailTolerant("dsusp undef")
+    stty("-echo")
+    stty("intr undef")
+  }
+
+  def restoreSigInt(): Unit = {
+    stty("intr ^C")
   }
 }