Add a -password switch to :prompt to allow for more secure password entering

Fixes #660

README.asciidoc

@@ -1391,7 +1391,8 @@ Some helper commands can be used to define composite commands:
 
  * `prompt <prompt> <register> <command>`: Prompt the user for a string, when
      the user validates, store the result in given <register> and run <commmand>.
-     the -init <str> switch allows setting initial content.
+     the -init <str> switch allows setting initial content and -password allow
+     not to show the entered text (and clears the register after command execution).
  * `onkey <register> <command>`: Wait for next key from user, writes it into given
      <register> and execute commands.
  * `menu <label1> <commands1> <label2> <commands2>...`: display a menu using

doc/manpages/commands.asciidoc

@@ -137,7 +137,8 @@ commands:
 *prompt* <prompt> <register> <command>::
 	prompt the user for a string, when the user validates, store the
 	result in given *register* and run *commmand*. the *-init <str>*
-	switch allows setting initial content
+	switch allows setting initial content, the *-password* switch hides
+        the entered text and clears the register after command execution.
 
 *onkey* <register> <command>::
 	wait for next key from user, writes it into given <register> and

src/commands.cc

@@ -1524,6 +1524,7 @@ const CommandDesc prompt_cmd = {
     "stores it in <register> and then executes <command>",
     ParameterDesc{
         { { "init", { true, "set initial prompt content" } },
+          { "password", { false, "Do not display entered text and clear reg after command" } },
           { "file-completion", { false, "use file completion for prompt" } },
           { "client-completion", { false, "use client completion for prompt" } },
           { "buffer-completion", { false, "use buffer completion for prompt" } },
@@ -1568,9 +1569,11 @@ const CommandDesc prompt_cmd = {
                     context, flags, prefix, cursor_pos);
             };
 
+        const bool password = (bool)parser.get_switch("password");
 
         context.input_handler().prompt(
-            parser[0], initstr.str(), get_face("Prompt"), std::move(completer),
+            parser[0], initstr.str(), get_face("Prompt"),
+            password, std::move(completer),
             [=](StringView str, PromptEvent event, Context& context)
             {
                 if (event != PromptEvent::Validate)
@@ -1580,6 +1583,9 @@ const CommandDesc prompt_cmd = {
                 ScopedSetBool disable_history{context.history_disabled()};
 
                 CommandManager::instance().execute(command, context, shell_context);
+
+                if (password)
+                    RegisterManager::instance()[reg] = ConstArrayView<String>("");
             });
     }
 };

src/input_handler.cc

@@ -647,10 +647,10 @@ class Prompt : public InputMode
 {
 public:
     Prompt(InputHandler& input_handler, StringView prompt,
-           String initstr, Face face, Completer completer,
+           String initstr, Face face, bool password,
-           PromptCallback callback)
+           Completer completer, PromptCallback callback)
         : InputMode(input_handler), m_prompt(prompt.str()), m_prompt_face(face),
-          m_completer(completer), m_callback(callback),
+          m_password(password), m_completer(completer), m_callback(callback),
           m_autoshowcompl{context().options()["autoshowcompl"].get<bool>()}
     {
         m_history_it = ms_history[m_prompt].end();
@@ -875,7 +875,9 @@ private:
             return;
 
         auto width = context().client().dimensions().column - m_prompt.char_length();
-        auto display_line = m_line_editor.build_display_line(width);
+        DisplayLine display_line;
+        if (not m_password)
+            display_line = m_line_editor.build_display_line(width);
         display_line.insert(display_line.begin(), { m_prompt, m_prompt_face });
         context().print_status(display_line);
     }
@@ -892,6 +894,7 @@ private:
     String         m_prefix;
     LineEditor     m_line_editor;
     bool           m_autoshowcompl;
+    bool           m_password;
 
     using History = Vector<String, MemoryDomain::History>;
     static UnorderedMap<String, History, MemoryDomain::History> ms_history;
@@ -1314,11 +1317,11 @@ void InputHandler::repeat_last_insert()
 }
 
 void InputHandler::prompt(StringView prompt, String initstr,
-                          Face prompt_face, Completer completer,
+                          Face prompt_face, bool password,
-                          PromptCallback callback)
+                          Completer completer, PromptCallback callback)
 {
     push_mode(new InputModes::Prompt(*this, prompt, initstr, prompt_face,
-                                     completer, callback));
+                                     password, completer, callback));
 }
 
 void InputHandler::set_prompt_face(Face prompt_face)

src/input_handler.hh

@@ -53,8 +53,8 @@ public:
     // returns to normal mode after validation if callback does
     // not change the mode itself
     void prompt(StringView prompt, String initstr,
-                Face prompt_face, Completer completer,
+                Face prompt_face, bool password,
-                PromptCallback callback);
+                Completer completer, PromptCallback callback);
     void set_prompt_face(Face prompt_face);
 
     // enter menu mode, callback is called on each selection change,

src/normal.cc

@@ -336,7 +336,7 @@ void command(Context& context, NormalParams params)
         return;
 
     context.input_handler().prompt(
-        ":", "", get_face("Prompt"),
+        ":", "", get_face("Prompt"), false,
         [](const Context& context, CompletionFlags flags,
            StringView cmd_line, ByteCount pos) {
                return CommandManager::instance().complete(context, flags, cmd_line, pos);
@@ -373,7 +373,7 @@ template<bool replace>
 void pipe(Context& context, NormalParams)
 {
     const char* prompt = replace ? "pipe:" : "pipe-to:";
-    context.input_handler().prompt(prompt, "", get_face("Prompt"), shell_complete,
+    context.input_handler().prompt(prompt, "", get_face("Prompt"), false, shell_complete,
         [](StringView cmdline, PromptEvent event, Context& context)
         {
             if (event != PromptEvent::Validate)
@@ -427,7 +427,7 @@ template<InsertMode mode>
 void insert_output(Context& context, NormalParams)
 {
     const char* prompt = mode == InsertMode::Insert ? "insert-output:" : "append-output:";
-    context.input_handler().prompt(prompt, "", get_face("Prompt"), shell_complete,
+    context.input_handler().prompt(prompt, "", get_face("Prompt"), false, shell_complete,
         [](StringView cmdline, PromptEvent event, Context& context)
         {
             if (event != PromptEvent::Validate)
@@ -588,7 +588,7 @@ void regex_prompt(Context& context, const String prompt, T func)
 {
     CharCoord position = context.has_window() ? context.window().position() : CharCoord{};
     SelectionList selections = context.selections();
-    context.input_handler().prompt(prompt, "", get_face("Prompt"), complete_nothing,
+    context.input_handler().prompt(prompt, "", get_face("Prompt"), false, complete_nothing,
         [=](StringView str, PromptEvent event, Context& context) mutable {
             try
             {
@@ -815,7 +815,7 @@ void keep(Context& context, NormalParams)
 void keep_pipe(Context& context, NormalParams)
 {
     context.input_handler().prompt(
-        "keep pipe:", "", get_face("Prompt"), shell_complete,
+        "keep pipe:", "", get_face("Prompt"), false, shell_complete,
         [](StringView cmdline, PromptEvent event, Context& context) {
             if (event != PromptEvent::Validate)
                 return;
@@ -957,7 +957,7 @@ void select_object(Context& context, NormalParams params)
                 AutoInfo::Command, context);
 
             context.input_handler().prompt(
-                "object desc:", "", get_face("Prompt"), complete_nothing,
+                "object desc:", "", get_face("Prompt"), false, complete_nothing,
                 [level,info](StringView cmdline, PromptEvent event, Context& context) {
                     if (event != PromptEvent::Change)
                         hide_auto_info_ifn(context, info);