terminal: fix signal handling state restore

2 files changed, 31 insertions, 1 deletions

diff --git a/ttwhy/terminal/scoped_attributes.cppm b/ttwhy/terminal/scoped_attributes.cppm
index 56fbe58..2d82826 100644
--- a/ttwhy/terminal/scoped_attributes.cppm
+++ b/ttwhy/terminal/scoped_attributes.cppm
@@ -150,9 +150,38 @@ namespace ttwhy::terminal
       return std::move(*this);
     }
 
+    //! Capture the currently active terminal mode and mark the attributes as suspended.
+    //!
+    //! Must be called before the terminal mode is changed while the process is being stopped.
+    auto suspend() & -> scoped_attributes &
+    {
+      if (m_file_descriptor > 0)
+      {
+        m_suspended = true;
+        m_suspended_canonical = canonical_mode();
+        m_suspended_echo = echo();
+      }
+      return *this;
+    }
+
+    //! Restore the terminal mode captured before suspension.
+    auto resume() & -> scoped_attributes &
+    {
+      if (m_suspended)
+      {
+        canonical_mode(m_suspended_canonical);
+        echo(m_suspended_echo);
+        m_suspended = false;
+      }
+      return *this;
+    }
+
   private:
     int m_file_descriptor;
     termios m_attributes;
+    bool m_suspended{false};
+    bool m_suspended_canonical{false};
+    bool m_suspended_echo{false};
   };
 
 }  // namespace ttwhy::terminal
diff --git a/ttwhy/terminal/signal_handling.cppm b/ttwhy/terminal/signal_handling.cppm
index b0a3542..2921b96 100644
--- a/ttwhy/terminal/signal_handling.cppm
+++ b/ttwhy/terminal/signal_handling.cppm
@@ -49,13 +49,14 @@ namespace ttwhy::terminal
         }
         case SIGTSTP:
         {
+          attributes.suspend();
           attributes.canonical_mode(true).echo(true);
           ::raise(SIGSTOP);
           break;
         }
         case SIGCONT:
         {
-          attributes.canonical_mode(false).echo(false);
+          attributes.resume();
           break;
         }
       }