FileSystemAccessServer+TextEditor: Implement cross-process modal prompts

This transitions from synchronous IPC calls to asynchronous IPC calls
provided through a synchronous interface in LibFileSystemAccessClient
which allows the parent Application to stay responsive.

It achieves this with Promise which is pumping the Application event
loop while waiting for the Dialog to respond with the user's action.

LibFileSystemAccessClient provides a lazy singleton which also ensures
that FileSystemAccessServer is running in the event of a crash.

This also transitions TextEditor into using LibFileSystemAccessClient.

Userland/Services/FileSystemAccessServer/CMakeLists.txt

@@ -16,3 +16,4 @@ set(SOURCES
 
 serenity_bin(FileSystemAccessServer)
 target_link_libraries(FileSystemAccessServer LibCore LibIPC LibGUI)
+add_dependencies(FileSystemAccessServer WindowServer)

Userland/Services/FileSystemAccessServer/ClientConnection.cpp

@@ -4,6 +4,10 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+// FIXME: LibIPC Decoder and Encoder are sensitive to include order here
+// clang-format off
+#include <LibGUI/WindowServerConnection.h>
+// clang-format on
 #include <AK/Debug.h>
 #include <FileSystemAccessServer/ClientConnection.h>
 #include <LibCore/File.h>
@@ -33,7 +37,20 @@ void ClientConnection::die()
     exit(0);
 }
 
-Messages::FileSystemAccessServer::RequestFileResponse ClientConnection::request_file(String const& path, Core::OpenMode const& requested_access)
+RefPtr<GUI::Window> ClientConnection::create_dummy_child_window(i32 window_server_client_id, i32 parent_window_id)
+{
+    auto window = GUI::Window::construct();
+    window->set_opacity(0);
+    window->set_frameless(true);
+    auto rect = GUI::WindowServerConnection::the().get_window_rect_from_client(window_server_client_id, parent_window_id);
+    window->set_rect(rect);
+    window->show();
+    GUI::WindowServerConnection::the().async_set_window_parent_from_client(window_server_client_id, parent_window_id, window->window_id());
+
+    return window;
+}
+
+void ClientConnection::request_file(i32 window_server_client_id, i32 parent_window_id, String const& path, Core::OpenMode const& requested_access)
 {
     VERIFY(path.starts_with("/"sv));
 
@@ -47,21 +64,23 @@ Messages::FileSystemAccessServer::RequestFileResponse ClientConnection::request_
         approved = has_flag(maybe_permissions.value(), relevant_permissions);
 
     if (!approved) {
-        StringBuilder builder;
-        if (has_flag(requested_access, Core::OpenMode::ReadOnly))
-            builder.append('r');
+        String access_string;
 
-        if (has_flag(requested_access, Core::OpenMode::WriteOnly))
-            builder.append('w');
-
-        auto access_string = builder.to_string();
+        if (has_flag(requested_access, Core::OpenMode::ReadWrite))
+            access_string = "read and write";
+        else if (has_flag(requested_access, Core::OpenMode::ReadOnly))
+            access_string = "read from";
+        else if (has_flag(requested_access, Core::OpenMode::WriteOnly))
+            access_string = "write to";
 
         auto pid = this->socket().peer_pid();
         auto exe_link = LexicalPath("/proc").append(String::number(pid)).append("exe").string();
         auto exe_path = Core::File::real_path_for(exe_link);
         auto exe_name = LexicalPath::basename(exe_path);
 
-        auto result = GUI::MessageBox::show(nullptr, String::formatted("Give {} ({}) \"{}\" access to \"{}\"?", exe_name, pid, access_string, path), "File Permissions Requested", GUI::MessageBox::Type::Warning, GUI::MessageBox::InputType::YesNo);
+        auto main_window = create_dummy_child_window(window_server_client_id, parent_window_id);
+
+        auto result = GUI::MessageBox::show(main_window, String::formatted("Allow {} ({}) to {} \"{}\"?", exe_name, pid, access_string, path), "File Permissions Requested", GUI::MessageBox::Type::Warning, GUI::MessageBox::InputType::YesNo);
 
         approved = result == GUI::MessageBox::ExecYes;
 
@@ -80,40 +99,40 @@ Messages::FileSystemAccessServer::RequestFileResponse ClientConnection::request_
 
         if (file.is_error()) {
             dbgln("FileSystemAccessServer: Couldn't open {}, error {}", path, file.error());
-
-            return { errno, Optional<IPC::File> {} };
+            async_handle_prompt_end(errno, Optional<IPC::File> {}, path);
+        } else {
+            async_handle_prompt_end(0, IPC::File(file.value()->leak_fd(), IPC::File::CloseAfterSending), path);
         }
-
-        return { 0, IPC::File(file.value()->leak_fd(), IPC::File::CloseAfterSending) };
+    } else {
+        async_handle_prompt_end(-1, Optional<IPC::File> {}, path);
     }
-
-    return { -1, Optional<IPC::File> {} };
 }
 
-Messages::FileSystemAccessServer::PromptOpenFileResponse ClientConnection::prompt_open_file(String const& path_to_view, Core::OpenMode const& requested_access)
+void ClientConnection::prompt_open_file(i32 window_server_client_id, i32 parent_window_id, String const& path_to_view, Core::OpenMode const& requested_access)
 {
     auto relevant_permissions = requested_access & (Core::OpenMode::ReadOnly | Core::OpenMode::WriteOnly);
     VERIFY(relevant_permissions != Core::OpenMode::NotOpen);
 
-    auto main_window = GUI::Window::construct();
+    auto main_window = create_dummy_child_window(window_server_client_id, parent_window_id);
+
     auto user_picked_file = GUI::FilePicker::get_open_filepath(main_window, "Select file", path_to_view);
 
-    return prompt_helper<Messages::FileSystemAccessServer::PromptOpenFileResponse>(user_picked_file, requested_access);
+    prompt_helper(user_picked_file, requested_access);
 }
 
-Messages::FileSystemAccessServer::PromptSaveFileResponse ClientConnection::prompt_save_file(String const& name, String const& ext, String const& path_to_view, Core::OpenMode const& requested_access)
+void ClientConnection::prompt_save_file(i32 window_server_client_id, i32 parent_window_id, String const& name, String const& ext, String const& path_to_view, Core::OpenMode const& requested_access)
 {
     auto relevant_permissions = requested_access & (Core::OpenMode::ReadOnly | Core::OpenMode::WriteOnly);
     VERIFY(relevant_permissions != Core::OpenMode::NotOpen);
 
-    auto main_window = GUI::Window::construct();
+    auto main_window = create_dummy_child_window(window_server_client_id, parent_window_id);
+
     auto user_picked_file = GUI::FilePicker::get_save_filepath(main_window, name, ext, path_to_view);
 
-    return prompt_helper<Messages::FileSystemAccessServer::PromptSaveFileResponse>(user_picked_file, requested_access);
+    prompt_helper(user_picked_file, requested_access);
 }
 
-template<typename T>
-T ClientConnection::prompt_helper(Optional<String> const& user_picked_file, Core::OpenMode const& requested_access)
+void ClientConnection::prompt_helper(Optional<String> const& user_picked_file, Core::OpenMode const& requested_access)
 {
     if (user_picked_file.has_value()) {
         VERIFY(user_picked_file->starts_with("/"sv));
@@ -122,20 +141,20 @@ T ClientConnection::prompt_helper(Optional<String> const& user_picked_file, Core
         if (file.is_error()) {
             dbgln("FileSystemAccessServer: Couldn't open {}, error {}", user_picked_file.value(), file.error());
 
-            return { errno, Optional<IPC::File> {}, user_picked_file.value() };
+            async_handle_prompt_end(errno, Optional<IPC::File> {}, user_picked_file);
+        } else {
+            auto maybe_permissions = m_approved_files.get(user_picked_file.value());
+            auto new_permissions = requested_access & (Core::OpenMode::ReadOnly | Core::OpenMode::WriteOnly);
+            if (maybe_permissions.has_value())
+                new_permissions |= maybe_permissions.value();
+
+            m_approved_files.set(user_picked_file.value(), new_permissions);
+
+            async_handle_prompt_end(0, IPC::File(file.value()->leak_fd(), IPC::File::CloseAfterSending), user_picked_file);
         }
-
-        auto maybe_permissions = m_approved_files.get(user_picked_file.value());
-        auto new_permissions = requested_access & (Core::OpenMode::ReadOnly | Core::OpenMode::WriteOnly);
-        if (maybe_permissions.has_value())
-            new_permissions |= maybe_permissions.value();
-
-        m_approved_files.set(user_picked_file.value(), new_permissions);
-
-        return { 0, IPC::File(file.value()->leak_fd(), IPC::File::CloseAfterSending), user_picked_file.value() };
+    } else {
+        async_handle_prompt_end(-1, Optional<IPC::File> {}, Optional<String> {});
     }
-
-    return { -1, Optional<IPC::File> {}, Optional<String> {} };
 }
 
 }

Userland/Services/FileSystemAccessServer/ClientConnection.h

@@ -10,6 +10,7 @@
 #include <FileSystemAccessServer/FileSystemAccessClientEndpoint.h>
 #include <FileSystemAccessServer/FileSystemAccessServerEndpoint.h>
 #include <LibCore/Forward.h>
+#include <LibGUI/Forward.h>
 #include <LibIPC/ClientConnection.h>
 
 namespace FileSystemAccessServer {
@@ -25,12 +26,12 @@ public:
     virtual void die() override;
 
 private:
-    virtual Messages::FileSystemAccessServer::RequestFileResponse request_file(String const&, Core::OpenMode const&) override;
-    virtual Messages::FileSystemAccessServer::PromptOpenFileResponse prompt_open_file(String const&, Core::OpenMode const&) override;
-    virtual Messages::FileSystemAccessServer::PromptSaveFileResponse prompt_save_file(String const&, String const&, String const&, Core::OpenMode const&) override;
+    virtual void request_file(i32, i32, String const&, Core::OpenMode const&) override;
+    virtual void prompt_open_file(i32, i32, String const&, Core::OpenMode const&) override;
+    virtual void prompt_save_file(i32, i32, String const&, String const&, String const&, Core::OpenMode const&) override;
 
-    template<typename T>
-    T prompt_helper(Optional<String> const&, Core::OpenMode const&);
+    void prompt_helper(Optional<String> const&, Core::OpenMode const&);
+    RefPtr<GUI::Window> create_dummy_child_window(i32, i32);
 
     HashMap<String, Core::OpenMode> m_approved_files;
 };

Userland/Services/FileSystemAccessServer/FileSystemAccessClient.ipc

@@ -1,3 +1,4 @@
 endpoint FileSystemAccessClient
 {
+    handle_prompt_end(i32 error, Optional<IPC::File> fd, Optional<String> chosen_file) =|
 }

Userland/Services/FileSystemAccessServer/FileSystemAccessServer.ipc

@@ -3,7 +3,7 @@
 
 endpoint FileSystemAccessServer
 {
-    request_file(String path, Core::OpenMode requested_access) => (i32 error, Optional<IPC::File> fd)
-    prompt_open_file(String path_to_view, Core::OpenMode requested_access) => (i32 error, Optional<IPC::File> fd, Optional<String> chosen_file)
-    prompt_save_file(String title, String ext, String path_to_view, Core::OpenMode requested_access) => (i32 error, Optional<IPC::File> fd, Optional<String> chosen_file)
+    request_file(i32 window_server_client_id, i32 window_id, String path, Core::OpenMode requested_access) =|
+    prompt_open_file(i32 window_server_client_id, i32 window_id, String path_to_view, Core::OpenMode requested_access) =|
+    prompt_save_file(i32 window_server_client_id, i32 window_id,String title, String ext, String path_to_view, Core::OpenMode requested_access) =|
 }