From 324af400623a336eb74f51360822d134cad97537 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@gmail.com>
Date: Thu, 18 Jun 2026 17:19:35 +0200
Subject: lib: improve signal handling

---
 ttwhy/io.cppm  | 47 ++++++++++++++++++++++++++++++++++++++++-------
 ttwhy/main.cpp | 10 ++++++----
 2 files changed, 46 insertions(+), 11 deletions(-)

diff --git a/ttwhy/io.cppm b/ttwhy/io.cppm
index fd84dfd..be87d36 100644
--- a/ttwhy/io.cppm
+++ b/ttwhy/io.cppm
@@ -14,19 +14,48 @@ import :scanner;
 namespace ttwhy::io
 {
 
-  export template<typename Stream>
-  auto handle_signals(Stream & stream) -> asio::awaitable<std::error_code>
+  export template<typename Stream, typename TerminalAttributes>
+  auto handle_signals(Stream & stream, TerminalAttributes & attributes) -> asio::awaitable<std::error_code>
   {
     auto executor = co_await asio::this_coro::executor;
     auto signals = asio::signal_set{executor, SIGINT, SIGTERM};
+    signals.add(SIGTSTP);
+    signals.add(SIGCONT);
 
-    auto [error, signal] = co_await signals.async_wait(asio::as_tuple(asio::use_awaitable));
-    if (!error)
+    while (true)
     {
-      auto message = std::format("Received signal {}, exiting ...\n", signal);
-      co_await asio::async_write(stream, asio::buffer(message), asio::use_awaitable);
+      auto [error, signal] = co_await signals.async_wait(asio::as_tuple(asio::use_awaitable));
+      if (error)
+      {
+        co_return error;
+      }
+
+      switch (signal)
+      {
+        case SIGINT:
+        case SIGTERM:
+        {
+          auto message = std::format("Received signal {}, exiting ...\n", signal);
+          co_await asio::async_write(stream, asio::buffer(message), asio::use_awaitable);
+          co_return asio::error_code{};
+        }
+        case SIGTSTP:
+        {
+          attributes.canonical_mode(true).echo(true);
+          ::raise(SIGSTOP);
+          break;
+        }
+        case SIGCONT:
+        {
+          attributes.canonical_mode(false).echo(false);
+          break;
+        }
+      }
+
+      if (!error)
+      {
+      }
     }
-    co_return error;
   }
 
   export template<typename InputStream, typename AppRouter>
@@ -45,6 +74,10 @@ namespace ttwhy::io
 
       if (error)
       {
+        if (error == asio::error::interrupted)
+        {
+          continue;
+        }
         co_return;
       }
 
diff --git a/ttwhy/main.cpp b/ttwhy/main.cpp
index 6a813c0..53cf16d 100644
--- a/ttwhy/main.cpp
+++ b/ttwhy/main.cpp
@@ -10,6 +10,10 @@ auto app(int in, int out, int error) -> asio::awaitable<void>
 {
   using namespace asio::experimental::awaitable_operators;
 
+  auto terminal_attributes = ttwhy::scoped_attributes{fileno(stdin)}  //
+                                 .canonical_mode(false)
+                                 .echo(false);
+
   auto executor = co_await asio::this_coro::executor;
 
   auto input_stream = asio::posix::stream_descriptor{executor, in};
@@ -18,14 +22,12 @@ auto app(int in, int out, int error) -> asio::awaitable<void>
 
   auto router = ttwhy::routers::echo{input_stream};
 
-  co_await (ttwhy::io::handle_signals(error_stream) || ttwhy::io::read_events(input_stream, router));
+  co_await (ttwhy::io::handle_signals(error_stream, terminal_attributes) ||
+            ttwhy::io::read_events(input_stream, router));
 }
 
 auto main() -> int
 {
-  auto terminal_attributes = ttwhy::scoped_attributes{fileno(stdin)}  //
-                                 .canonical_mode(false)
-                                 .echo(false);
   auto context = asio::io_context{};
 
   asio::co_spawn(context, app(::fileno(::stdin), ::fileno(::stdout), ::fileno(::stderr)), asio::detached);
-- 
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