Userland: Use Core::DirIterator::next_full_path()

Simplify some code by using this instead of concatenating the full path
ourselves at the call site.

Userland/Applications/SystemMonitor/DevicesModel.cpp

@@ -171,8 +171,7 @@ void DevicesModel::update()
     auto fill_in_paths_from_dir = [this](const String& dir) {
         Core::DirIterator dir_iter { dir, Core::DirIterator::Flags::SkipDots };
         while (dir_iter.has_next()) {
-            auto name = dir_iter.next_path();
+            auto path = dir_iter.next_full_path();
-            auto path = String::formatted("{}/{}", dir, name);
             struct stat statbuf;
             if (lstat(path.characters(), &statbuf) != 0) {
                 VERIFY_NOT_REACHED();

Userland/Demos/WidgetGallery/GalleryModels.h

@@ -78,16 +78,13 @@ public:
         Core::DirIterator iterator("/res/cursors", Core::DirIterator::Flags::SkipDots);
 
         while (iterator.has_next()) {
-            auto path = iterator.next_path();
+            auto path = iterator.next_full_path();
             if (path.contains("2x"))
                 continue;
             Cursor cursor;
-            StringBuilder full_path;
+            cursor.path = move(path);
-            full_path.append("/res/cursors/");
-            full_path.append(path);
-            cursor.path = full_path.to_string();
             cursor.bitmap = Gfx::Bitmap::load_from_file(cursor.path);
-            auto filename_split = path.split('.');
+            auto filename_split = cursor.path.split('.');
             cursor.name = filename_split[0];
             m_cursors.append(move(cursor));
         }
@@ -161,14 +158,11 @@ public:
         Core::DirIterator big_iterator("/res/icons/32x32", Core::DirIterator::Flags::SkipDots);
 
         while (big_iterator.has_next()) {
-            auto path = big_iterator.next_path();
+            auto path = big_iterator.next_full_path();
             if (!path.contains("filetype-") && !path.contains("app-"))
                 continue;
             IconSet icon_set;
-            StringBuilder full_path;
+            icon_set.big_icon = Gfx::Bitmap::load_from_file(path);
-            full_path.append("/res/icons/32x32/");
-            full_path.append(path);
-            icon_set.big_icon = Gfx::Bitmap::load_from_file(full_path.to_string());
             auto filename_split = path.split('.');
             icon_set.name = filename_split[0];
             m_icon_sets.append(move(icon_set));
@@ -179,14 +173,11 @@ public:
         Core::DirIterator little_iterator("/res/icons/16x16", Core::DirIterator::Flags::SkipDots);
 
         while (little_iterator.has_next()) {
-            auto path = little_iterator.next_path();
+            auto path = little_iterator.next_full_path();
             if (!path.contains("filetype-") && !path.contains("app-"))
                 continue;
             IconSet icon_set;
-            StringBuilder full_path;
+            icon_set.little_icon = Gfx::Bitmap::load_from_file(path);
-            full_path.append("/res/icons/16x16/");
-            full_path.append(path);
-            icon_set.little_icon = Gfx::Bitmap::load_from_file(full_path.to_string());
             auto filename_split = path.split('.');
             icon_set.name = filename_split[0];
             for (size_t i = 0; i < big_icons_found; i++) {

Userland/DevTools/HackStudio/Editor.cpp

@@ -142,7 +142,7 @@ static HashMap<String, String>& man_paths()
         // FIXME: This should also search man3, possibly other places..
         Core::DirIterator it("/usr/share/man/man2", Core::DirIterator::Flags::SkipDots);
         while (it.has_next()) {
-            auto path = String::formatted("/usr/share/man/man2/{}", it.next_path());
+            auto path = it.next_full_path();
             auto title = LexicalPath(path).title();
             paths.set(title, path);
         }

Userland/Libraries/LibCore/FileWatcher.cpp

@@ -55,10 +55,10 @@ static String get_child_path_from_inode_index(const String& path, unsigned child
     }
 
     while (iterator.has_next()) {
-        auto child_full_path = String::formatted("{}/{}", path, iterator.next_path());
+        auto child_full_path = iterator.next_full_path();
-        struct stat st;
 
-        if (lstat(child_full_path.characters(), &st)) {
+        struct stat st = {};
+        if (lstat(child_full_path.characters(), &st) < 0) {
             return {};
         }
 

Userland/Utilities/test-js.cpp

@@ -197,7 +197,7 @@ static void iterate_directory_recursively(const String& directory_path, Callback
     Core::DirIterator directory_iterator(directory_path, Core::DirIterator::Flags::SkipDots);
 
     while (directory_iterator.has_next()) {
-        auto file_path = String::formatted("{}/{}", directory_path, directory_iterator.next_path());
+        auto file_path = directory_iterator.next_full_path();
         if (Core::File::is_directory(file_path)) {
             iterate_directory_recursively(file_path, callback);
         } else {

Userland/Utilities/test-web.cpp

@@ -168,7 +168,7 @@ void iterate_directory_recursively(const String& directory_path, Callback callba
     Core::DirIterator directory_iterator(directory_path, Core::DirIterator::Flags::SkipDots);
 
     while (directory_iterator.has_next()) {
-        auto file_path = String::format("%s/%s", directory_path.characters(), directory_iterator.next_path().characters());
+        auto file_path = directory_iterator.next_full_path();
         if (Core::File::is_directory(file_path)) {
             iterate_directory_recursively(file_path, callback);
         } else {