implement 'hideInput' on posix systems (#63)

mordant/build.gradle.kts

@@ -64,13 +64,13 @@ kotlin {
         }
 
         val nativeMain by creating { dependsOn(commonMain) }
-        val macosMain by creating { dependsOn(nativeMain) }
+        val mingwX64Main by getting { dependsOn(nativeMain) }
+        val posixMain by creating { dependsOn(nativeMain) }
+        val linuxX64Main by getting { dependsOn(posixMain) }
+        val macosMain by creating { dependsOn(posixMain) }
         listOf("macosX64", "macosArm64").forEach { target ->
             getByName(target + "Main").dependsOn(macosMain)
         }
-        listOf("macos", "linuxX64", "mingwX64").forEach { target ->
-            getByName(target + "Main").dependsOn(nativeMain)
-        }
 
         targets.withType<KotlinNativeTargetWithTests<*>> {
             binaries {

mordant/src/mingwX64Main/kotlin/com/github/ajalt/mordant/internal/tty.kt

@@ -0,0 +1,6 @@
+package com.github.ajalt.mordant.internal
+
+// hideInput is not currently implemented
+internal actual fun ttySetEcho(echo: Boolean) {
+
+}

mordant/src/nativeMain/kotlin/com/github/ajalt/mordant/internal/MppImpl.kt

@@ -54,9 +54,19 @@ internal actual fun printStderr(message: String, newline: Boolean) {
     fflush(stderr)
 }
 
+internal expect fun ttySetEcho(echo: Boolean)
 
-// hideInput is not currently implemented
-internal actual fun readLineOrNullMpp(hideInput: Boolean): String? = readlnOrNull()
+internal actual fun readLineOrNullMpp(hideInput: Boolean): String? {
+    if (hideInput) {
+        ttySetEcho(false)
+    }
+    val lineOrNull = readlnOrNull()
+    if (hideInput) {
+        ttySetEcho(true)
+    }
+
+    return lineOrNull
+}
 
 internal actual fun makePrintingTerminalCursor(terminal: Terminal): TerminalCursor = NativeTerminalCursor(terminal)
 

mordant/src/posixMain/kotlin/com/github/ajalt/mordant/internal/tty.kt

@@ -0,0 +1,30 @@
+package com.github.ajalt.mordant.internal
+
+import kotlinx.cinterop.*
+import platform.posix.*
+
+@OptIn(UnsafeNumber::class)
+internal actual fun ttySetEcho(echo: Boolean) {
+  updateTermios {
+    c_lflag = if (echo) {
+      c_lflag.or(ECHO.convert())
+    } else {
+      c_lflag.and(ECHO.inv().convert())
+    }
+  }
+}
+
+private fun updateTermios(block: termios.() -> Unit) {
+  memScoped {
+    val termios = alloc<termios>()
+    check(tcgetattr(0, termios.ptr) == 0) {
+      error("tcgetattr() error: $errno")
+    }
+
+    block(termios)
+
+    check(tcsetattr(0, TCSADRAIN, termios.ptr) == 0) {
+      error("tcsetattr() error: $errno")
+    }
+  }
+}