app: implement basic signal handling

2 files changed, 27 insertions, 4 deletions

diff --git a/ttwhy/main.cpp b/ttwhy/main.cpp
index 32324c0..c210bee 100644
--- a/ttwhy/main.cpp
+++ b/ttwhy/main.cpp
@@ -1,15 +1,35 @@
-#include <asio/io_context.hpp>
-
+#include <asio.hpp>
 #include <stdio.h>
 
 import ttwhy;
 
+auto handle_signals(asio::cancellation_signal & cancellation_signal) -> asio::awaitable<void>
+{
+  co_await asio::this_coro::reset_cancellation_state(asio::disable_cancellation());
+  co_await asio::this_coro::throw_if_cancelled(false);
+
+  auto executor = co_await asio::this_coro::executor;
+  auto signals = asio::signal_set{executor, SIGINT, SIGTERM};
+  auto log_stream = asio::posix::stream_descriptor{executor, fileno(stdout)};
+
+  auto [error, signal] = co_await signals.async_wait(asio::as_tuple(asio::use_awaitable));
+
+  if (!error)
+  {
+    co_await asio::async_write(log_stream, asio::buffer("shutting down...\n"), asio::as_tuple(asio::use_awaitable));
+    cancellation_signal.emit(asio::cancellation_type::all);
+  }
+}
+
 auto main() -> int
 {
   auto terminal_attributes = ttwhy::scoped_attributes{fileno(stdin)}  //
                                  .canonical_mode(false)
                                  .echo(false);
-
   auto context = asio::io_context{};
+  auto cancellation_signal = asio::cancellation_signal{};
+
+  asio::co_spawn(context, handle_signals(cancellation_signal), asio::detached);
+
   context.run();
 }
diff --git a/ttwhy/scoped_attributes.cppm b/ttwhy/scoped_attributes.cppm
index dd66b54..7c32ddf 100644
--- a/ttwhy/scoped_attributes.cppm
+++ b/ttwhy/scoped_attributes.cppm
@@ -45,7 +45,10 @@ namespace ttwhy
       active_attributes.c_lflag = active_attributes.c_lflag & ~flag;
     }
 
-    tcsetattr(file_descriptor, TCSANOW, &active_attributes);
+    if (tcsetattr(file_descriptor, TCSANOW, &active_attributes))
+    {
+      throw std::system_error(errno, std::system_category(), "failed to write termios attributes");
+    }
   }
 
   //! Store the current TC attributes and restore them on destruction.