Terminal: add explicit handling of sgr0 + sgr seq

sgr0 is currently implemented as a wrapper of sgr(0) which
seems to work fine.

For now we accept but ignore certain sgr sequences like for
example [0;10;1m which is generated by lynx even when using
TERM=linux (I am not sure yet if that's actually valid at all).

gems/include/terminal/character_screen.h

@@ -181,6 +181,11 @@ namespace Terminal {
 		 */
 		virtual void sgr(int) = 0;
 
+		/**
+ 		 * Turn of all attributes
+		 */
+		virtual void sgr0() = 0;
+
 		/**
 		 * Save current cursor position
 		 */

gems/include/terminal/decoder.h

@@ -343,12 +343,49 @@ namespace Terminal {
 						_screen.setaf(p2 - 30);
 						return true;
 					}
+					if ((p1 == 0 && p2 == 10)) {
+						/* turn of all attributes */
+						_screen.sgr0();
+						return true;
+					}
 					return false;
 				case 'R': return (_screen.u6(p1, p2), true);
 				default: return false;
 				}
 			}
 
+			bool _handle_esc_seq_7()
+			{
+				/*
+				 * All six-element escape sequences have the form
+				 * \E[<NUMBER1>;<NUMBER2>;<NUMBER3><COMMAND>
+				 */
+
+				if ((_escape_stack[0].value != '[')
+				 || (_escape_stack[1].type  != Escape_stack::Entry::NUMBER)
+				 || (_escape_stack[2].value != ';')
+				 || (_escape_stack[3].type  != Escape_stack::Entry::NUMBER)
+				 || (_escape_stack[4].value != ';')
+				 || (_escape_stack[5].type  != Escape_stack::Entry::NUMBER))
+					return false;
+
+				int const command = _escape_stack[6].value;
+
+				switch (command) {
+				case 'm':
+
+					/*
+					 * Currently returning true w/o actually handling the
+					 * sequence
+					 */
+					PDBG("Sequence '[X;Y;Zm' is not implemented");
+					return true;
+				default: return false;
+				}
+
+				return true;
+			}
+
 		public:
 
 			Decoder(Character_screen &screen)
@@ -425,7 +462,8 @@ namespace Terminal {
 				 || ((_escape_stack.num_elem() == 2) && _handle_esc_seq_2())
 				 || ((_escape_stack.num_elem() == 3) && _handle_esc_seq_3())
 				 || ((_escape_stack.num_elem() == 4) && _handle_esc_seq_4())
-				 || ((_escape_stack.num_elem() == 5) && _handle_esc_seq_5()))
+				 || ((_escape_stack.num_elem() == 5) && _handle_esc_seq_5())
+				 || ((_escape_stack.num_elem() == 7) && _handle_esc_seq_7()))
 					_enter_state_idle();
 			};
 	};

gems/src/server/terminal/main.cc

@@ -619,6 +619,11 @@ class Char_cell_array_character_screen : public Terminal::Character_screen
 				_color_index = DEFAULT_COLOR_INDEX;
 		}
 
+		void sgr0()
+		{
+			sgr(0);
+		}
+
 		void sc()
 		{
 			PDBG("not implemented");

gems/src/test/terminal_decoder/main.cc

@@ -185,6 +185,10 @@ class Static_character_screen : public Terminal::Character_screen
 		{
 		}
 
+		virtual void sgr0()
+		{
+		}
+
 		void sc()
 		{
 		}