Kernel: Make KLexicalPath::basename() more compliant

This removes some assertions from KLexicalPath::basename() by supporting
paths with trailing slashes, empty paths, paths consisting of only
slashes and paths with ending "." and ".." segments.

Kernel/KLexicalPath.cpp

@@ -8,6 +8,8 @@
 
 namespace Kernel::KLexicalPath {
 
+static StringView const s_single_dot = "."sv;
+
 bool is_absolute(StringView const& path)
 {
  return !path.is_empty() && path[0] == '/';
@@ -29,15 +31,20 @@ bool is_canonical(StringView const& path)
  return true;
 }
 
-StringView basename(StringView const& path)
+StringView basename(StringView const& a_path)
 {
+ if (a_path == "/"sv)
+ return a_path;
+ if (a_path.is_empty())
+ return s_single_dot;
+ auto path = a_path.trim("/"sv, TrimMode::Right);
+ // NOTE: If it's empty now, it means the path was just a series of slashes.
+ if (path.is_empty())
+ return a_path.substring_view(0, 1);
  auto slash_index = path.find_last('/');
- if (!slash_index.has_value()) {
- VERIFY(!path.is_empty());
+ if (!slash_index.has_value())
  return path;
- }
  auto basename = path.substring_view(*slash_index + 1);
- VERIFY(!basename.is_empty() && basename != "."sv && basename != ".."sv);
  return basename;
 }