fix(input): sanitize incoming text, balance the draw stack (A2, A3)

src/model/input/userInputModel.lua

@@ -82,13 +82,27 @@ function UserInputModel:init_visible(text)
   self.visible:set_default_range()
 end
 
+--- Drop bytes that do not form valid UTF-8
+--- @param s string
+--- @return string
+local function sanitize_utf8(s)
+  local r = s
+  local n, pos = utf8.len(r)
+  while not n do
+    r = string.sub(r, 1, pos - 1) .. string.sub(r, pos + 1)
+    n, pos = utf8.len(r)
+  end
+  return r
+end
+
 ----------------
 --  entered   --
 ----------------
 
 --- @param text string
 function UserInputModel:add_text(text)
   if type(text) == 'string' then
+    text = sanitize_utf8(text)
     self:pop_selected_text()
     local sl, cc    = self:get_cursor_pos()
     local cur_line  = self:get_text_line(sl)
@@ -127,6 +141,7 @@ end
 --- @param keep_cursor boolean
 function UserInputModel:set_text(text, keep_cursor)
   if type(text) == 'string' then
+    text = sanitize_utf8(text)
     local lines = string.lines(text)
     local n_added = #lines
     if n_added == 1 then
@@ -136,7 +151,11 @@ function UserInputModel:set_text(text, keep_cursor)
       self:_update_cursor(true)
     end
   elseif type(text) == 'table' then
-    self.entered = InputText(text)
+    local clean = {}
+    for i, l in ipairs(text) do
+      clean[i] = sanitize_utf8(l)
+    end
+    self.entered = InputText(clean)
   end
   self:text_change()
   if not keep_cursor then

src/view/input/userInputView.lua

@@ -160,7 +160,10 @@ function UserInputView:render_input(input, status, time)
     for l, s in ipairs(visible) do
       local ln = l + vc.offset
       local tl = string.ulen(s)
-      if not tl then return end
+      if not tl then
+        gfx.pop()
+        return
+      end
 
       for c = 1, tl do
         local char = string.usub(s, c, c)

tests/input/user_input_model_spec.lua

@@ -27,6 +27,34 @@ describe("input model spec #input", function()
   }
   mock.mock_love(love)
 
+  describe('invalid UTF-8', function()
+    local invalid = 'abc\195('
+
+    it('add_text drops invalid bytes', function()
+      local model = UserInputModel(mockConf, luaEval)
+      model:add_text(invalid)
+      assert.same({ 'abc(' }, model:get_text())
+    end)
+
+    it('paste drops invalid bytes across lines', function()
+      local model = UserInputModel(mockConf, luaEval)
+      model:paste('abc\ndef' .. invalid)
+      assert.same({ 'abc', 'defabc(' }, model:get_text())
+    end)
+
+    it('set_text drops invalid bytes', function()
+      local model = UserInputModel(mockConf, luaEval)
+      model:set_text(invalid)
+      assert.same({ 'abc(' }, model:get_text())
+    end)
+
+    it('set_text drops invalid bytes in tables', function()
+      local model = UserInputModel(mockConf, luaEval)
+      model:set_text({ 'ok', invalid })
+      assert.same({ 'ok', 'abc(' }, model:get_text())
+    end)
+  end)
+
   -----------------
   --   ASCII     --
   -----------------