4 files changed, 145 insertions, 0 deletions
diff --git a/kernel/src/filesystem/rootfs/filesystem.cpp b/kernel/src/filesystem/rootfs/filesystem.cpp
new file mode 100644
index 0000000..7fe5c1e
--- /dev/null
+++ b/kernel/src/filesystem/rootfs/filesystem.cpp
@@ -0,0 +1,47 @@
+#include <kernel/filesystem/rootfs/filesystem.hpp>
+
+#include <kernel/filesystem/filesystem.hpp>
+#include <kernel/filesystem/inode.hpp>
+#include <kernel/filesystem/rootfs/inode.hpp>
+#include <kernel/filesystem/type.hpp>
+
+#include <kstd/memory>
+
+#include <string_view>
+
+namespace kernel::filesystem::rootfs
+{
+
+  struct type final : kernel::filesystem::type
+  {
+    [[nodiscard]] auto name() const noexcept -> std::string_view override
+    {
+      return "rootfs";
+    }
+
+    [[nodiscard]] auto requires_device() const noexcept -> bool override
+    {
+      return true;
+    }
+
+    [[nodiscard]] auto make_instance() const -> kstd::shared_ptr<kernel::filesystem::filesystem> override
+    {
+      return kstd::make_shared<filesystem>();
+    }
+  };
+
+  [[gnu::used]]
+  constexpr auto registration = type_registration<type>{};
+
+  auto filesystem::mount(kstd::shared_ptr<kernel::filesystem::inode> const &) -> operation_result
+  {
+    m_root_inode = kstd::make_shared<inode>();
+    return operation_result::success;
+  }
+
+  auto filesystem::lookup(kstd::shared_ptr<kernel::filesystem::inode> const &, std::string_view) const
+      -> kstd::shared_ptr<kernel::filesystem::inode>
+  {
+    return nullptr;
+  }
+}  // namespace kernel::filesystem::rootfs
diff --git a/kernel/src/filesystem/rootfs/filesystem.tests.cpp b/kernel/src/filesystem/rootfs/filesystem.tests.cpp
new file mode 100644
index 0000000..ae320e9
--- /dev/null
+++ b/kernel/src/filesystem/rootfs/filesystem.tests.cpp
@@ -0,0 +1,38 @@
+#include <kernel/filesystem/rootfs/filesystem.hpp>
+
+#include <kernel/filesystem/filesystem.hpp>
+
+#include <kstd/memory>
+#include <kstd/print>
+#include <kstd/vector>
+
+#include <catch2/catch_test_macros.hpp>
+
+SCENARIO("Rootfs filesystem mount and lookup", "[filesystem][rootfs][filesystem]")
+{
+  GIVEN("a mounted rootfs filesystem")
+  {
+    auto fs = kernel::filesystem::rootfs::filesystem{};
+    auto result = fs.mount(nullptr);
+
+    THEN("the filesystem can be mounted successfully")
+    {
+      REQUIRE(result == kernel::filesystem::filesystem::operation_result::success);
+      REQUIRE(fs.root_inode() != nullptr);
+    }
+
+    THEN("looking up a non-existent directory returns null")
+    {
+      auto non_existent_inode_1 = fs.lookup(fs.root_inode(), "");
+      REQUIRE(non_existent_inode_1 == nullptr);
+      auto non_existent_inode_2 = fs.lookup(fs.root_inode(), "nonexistent");
+      REQUIRE(non_existent_inode_2 == nullptr);
+    }
+
+    THEN("looking up with a null parent inode returns null")
+    {
+      auto result = fs.lookup(nullptr, "dev");
+      REQUIRE(result == nullptr);
+    }
+  }
+}
diff --git a/kernel/src/filesystem/rootfs/inode.cpp b/kernel/src/filesystem/rootfs/inode.cpp
new file mode 100644
index 0000000..f64fb87
--- /dev/null
+++ b/kernel/src/filesystem/rootfs/inode.cpp
@@ -0,0 +1,23 @@
+#include <kernel/filesystem/inode.hpp>
+
+#include <kernel/filesystem/rootfs/inode.hpp>
+
+#include <cstddef>
+
+namespace kernel::filesystem::rootfs
+{
+  auto inode::read(void *, size_t, size_t) const -> size_t
+  {
+    return 0;
+  }
+
+  auto inode::write(void const *, size_t, size_t) -> size_t
+  {
+    return 0;
+  }
+
+  auto inode::is_directory() const -> bool
+  {
+    return true;
+  }
+}  // namespace kernel::filesystem::rootfs
diff --git a/kernel/src/filesystem/rootfs/inode.tests.cpp b/kernel/src/filesystem/rootfs/inode.tests.cpp
new file mode 100644
index 0000000..f4b634f
--- /dev/null
+++ b/kernel/src/filesystem/rootfs/inode.tests.cpp
@@ -0,0 +1,37 @@
+#include <kernel/filesystem/rootfs/inode.hpp>
+
+#include <kstd/memory>
+#include <kstd/print>
+#include <kstd/vector>
+
+#include <catch2/catch_test_macros.hpp>
+
+SCENARIO("Rootfs inode read/write", "[filesystem][rootfs][inode]")
+{
+  GIVEN("a rootfs inode")
+  {
+    auto inode = kernel::filesystem::rootfs::inode{};
+
+    WHEN("reading from the inode")
+    {
+      kstd::vector<char> buffer(10);
+      auto bytes_read = inode.read(buffer.data(), 0, buffer.size());
+
+      THEN("no bytes are read")
+      {
+        REQUIRE(bytes_read == 0);
+      }
+    }
+
+    WHEN("writing to the inode")
+    {
+      kstd::vector<char> buffer(10, 'x');
+      auto bytes_written = inode.write(buffer.data(), 0, buffer.size());
+
+      THEN("no bytes are written")
+      {
+        REQUIRE(bytes_written == 0);
+      }
+    }
+  }
+}