FileManager: Remove clicked breadcrumbs for non-existing directories

This fixes #8204.

In the case that we just navigated up from a directory because it was
deleted, we can detect that easily by checking if the child directory
exists, and then remove the relevant breadcrumbs immediately.

However, it's harder to notice if a child directory for a breadcrumb
is deleted at another time. Previously, clicking that breadcrumb would
crash, but now we check to see if the directory it points to actually
exists. If it doesn't, we pop that breadcrumb and any after it, off
of the breadcrumbbar.

This may not be the ideal solution - maybe it should detect that the
directory is gone automatically - but it works and doesn't involve
managing additional directory watchers.

Userland/Applications/FileManager/main.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, Sam Atkins <atkinssj@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -922,16 +923,18 @@ int run_in_windowed_mode(RefPtr<Core::ConfigFile> config, String initial_locatio
         {
             LexicalPath lexical_path(new_path);
 
-            auto segment_index_of_new_path_in_breadcrumbbar = [&]() -> Optional<size_t> {
-                for (size_t i = 0; i < breadcrumbbar.segment_count(); ++i) {
-                    if (breadcrumbbar.segment_data(i) == new_path)
-                        return i;
-                }
-                return {};
-            }();
+            auto segment_index_of_new_path_in_breadcrumbbar = breadcrumbbar.find_segment_with_data(new_path);
 
             if (segment_index_of_new_path_in_breadcrumbbar.has_value()) {
-                breadcrumbbar.set_selected_segment(segment_index_of_new_path_in_breadcrumbbar.value());
+                auto new_segment_index = segment_index_of_new_path_in_breadcrumbbar.value();
+                breadcrumbbar.set_selected_segment(new_segment_index);
+
+                // If the path change was because the directory we were in was deleted,
+                // remove the breadcrumbs for it.
+                if ((new_segment_index + 1 < breadcrumbbar.segment_count())
+                    && !Core::File::is_directory(breadcrumbbar.segment_data(new_segment_index + 1))) {
+                    breadcrumbbar.remove_end_segments(new_segment_index + 1);
+                }
             } else {
                 breadcrumbbar.clear_segments();
 
@@ -949,7 +952,15 @@ int run_in_windowed_mode(RefPtr<Core::ConfigFile> config, String initial_locatio
                 breadcrumbbar.set_selected_segment(breadcrumbbar.segment_count() - 1);
 
                 breadcrumbbar.on_segment_click = [&](size_t segment_index) {
-                    directory_view.open(breadcrumbbar.segment_data(segment_index));
+                    auto selected_path = breadcrumbbar.segment_data(segment_index);
+                    if (Core::File::is_directory(selected_path)) {
+                        directory_view.open(selected_path);
+                    } else {
+                        dbgln("Breadcrumb path '{}' doesn't exist", selected_path);
+                        breadcrumbbar.remove_end_segments(segment_index);
+                        auto existing_path_segment = breadcrumbbar.find_segment_with_data(directory_view.path());
+                        breadcrumbbar.set_selected_segment(existing_path_segment.value());
+                    }
                 };
             }
         }

Userland/Libraries/LibGUI/FileSystemModel.cpp

@@ -272,11 +272,11 @@ FileSystemModel::FileSystemModel(String root_path, Mode mode)
             auto canonical_event_path = LexicalPath::canonicalized_path(event.event_path);
             if (m_root_path.starts_with(canonical_event_path)) {
                 // Deleted directory contains our root, so navigate to our nearest parent.
-                auto new_path = LexicalPath(m_root_path).dirname();
-                while (!Core::File::is_directory(new_path))
-                    new_path = LexicalPath(new_path).dirname();
+                auto new_path = LexicalPath(m_root_path).parent();
+                while (!Core::File::is_directory(new_path.string()))
+                    new_path = new_path.parent();
 
-                set_root_path(new_path);
+                set_root_path(new_path.string());
             } else if (node.parent) {
                 refresh_node(*node.parent);
             }