Merge branch 'fmorgner/develop-BA-FS26/dynamic-fs' into 'develop-BA-FS26'

Add support infrastructure for automatic file system registration

See merge request teachos/kernel!46

9 files changed, 243 insertions, 28 deletions

diff --git a/kernel/src/filesystem/dentry.cpp b/kernel/src/filesystem/dentry.cpp
index 14de875..3d8e01a 100644
--- a/kernel/src/filesystem/dentry.cpp
+++ b/kernel/src/filesystem/dentry.cpp
@@ -41,7 +41,7 @@ namespace kernel::filesystem
 
   auto dentry::name() const -> std::string_view
   {
-    return m_name.view();
+    return m_name;
   }
 
   auto dentry::absolute_path() const -> kstd::string
diff --git a/kernel/src/filesystem/devfs/filesystem.cpp b/kernel/src/filesystem/devfs/filesystem.cpp
index f0d8bf7..ce887ff 100644
--- a/kernel/src/filesystem/devfs/filesystem.cpp
+++ b/kernel/src/filesystem/devfs/filesystem.cpp
@@ -5,6 +5,7 @@
 #include <kernel/filesystem/devfs/inode.hpp>
 #include <kernel/filesystem/device_inode.hpp>
 #include <kernel/filesystem/inode.hpp>
+#include <kernel/filesystem/type.hpp>
 
 #include <kapi/devices/device.hpp>
 
@@ -15,6 +16,27 @@
 
 namespace kernel::filesystem::devfs
 {
+  struct type final : kernel::filesystem::type
+  {
+    [[nodiscard]] auto name() const noexcept -> std::string_view override
+    {
+      return "devfs";
+    }
+
+    [[nodiscard]] auto requires_device() const noexcept -> bool override
+    {
+      return false;
+    }
+
+    [[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>();
diff --git a/kernel/src/filesystem/ext2/filesystem.cpp b/kernel/src/filesystem/ext2/filesystem.cpp
index 12aeaaa..3180a19 100644
--- a/kernel/src/filesystem/ext2/filesystem.cpp
+++ b/kernel/src/filesystem/ext2/filesystem.cpp
@@ -6,6 +6,7 @@
 #include <kernel/filesystem/ext2/superblock.hpp>
 #include <kernel/filesystem/filesystem.hpp>
 #include <kernel/filesystem/inode.hpp>
+#include <kernel/filesystem/type.hpp>
 
 #include <kstd/memory>
 #include <kstd/unikstd.h>
@@ -18,6 +19,28 @@
 
 namespace kernel::filesystem::ext2
 {
+
+  struct type final : kernel::filesystem::type
+  {
+    [[nodiscard]] auto name() const noexcept -> std::string_view override
+    {
+      return "ext2";
+    }
+
+    [[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 & backing_inode) -> operation_result
   {
     kernel::filesystem::filesystem::mount(backing_inode);
diff --git a/kernel/src/filesystem/rootfs/filesystem.cpp b/kernel/src/filesystem/rootfs/filesystem.cpp
index 0ba2936..7fe5c1e 100644
--- a/kernel/src/filesystem/rootfs/filesystem.cpp
+++ b/kernel/src/filesystem/rootfs/filesystem.cpp
@@ -1,8 +1,9 @@
 #include <kernel/filesystem/rootfs/filesystem.hpp>
 
-#include "kernel/filesystem/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>
 
@@ -10,6 +11,28 @@
 
 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>();
diff --git a/kernel/src/filesystem/type_registry.cpp b/kernel/src/filesystem/type_registry.cpp
new file mode 100644
index 0000000..d917c81
--- /dev/null
+++ b/kernel/src/filesystem/type_registry.cpp
@@ -0,0 +1,72 @@
+#include <kernel/filesystem/type_registry.hpp>
+
+#include <kapi/system.hpp>
+
+#include <kstd/memory>
+#include <kstd/print>
+
+#include <algorithm>
+#include <cstddef>
+#include <optional>
+#include <ranges>
+#include <span>
+
+namespace kernel::filesystem
+{
+
+  extern "C"
+  {
+    extern type_registry::pointer const __start_fs_types;
+    extern type_registry::pointer const __stop_fs_types;
+  }
+
+  namespace
+  {
+    auto constinit instance = std::optional<type_registry>{};
+  }
+
+  auto type_registry::init() -> void
+  {
+    if (instance)
+    {
+      kapi::system::panic("[FILESYSTEM] tried to initialize type registry more than once!");
+    }
+
+    instance.emplace();
+
+    auto type_descriptors = std::span{&__start_fs_types, &__stop_fs_types} |  //
+                            std::views::filter([](auto p) { return p != nullptr; });
+
+    std::ranges::for_each(type_descriptors, [](auto descriptor) {
+      kstd::println("[FILESYSTEM] registering '{}'", descriptor->name());
+      instance->add(descriptor);
+    });
+  }
+
+  auto type_registry::get() -> type_registry &
+  {
+    if (!instance)
+    {
+      kapi::system::panic("[FILESYSTEM] type registry has not been initialized!");
+    }
+
+    return *instance;
+  }
+
+  auto type_registry::add(pointer descriptor) -> bool
+  {
+    auto result = m_descriptors.emplace(descriptor->name(), descriptor);
+    return result.second;
+  }
+
+  auto type_registry::all() const noexcept -> std::span<pointer const>
+  {
+    return {m_descriptors.values().begin(), m_descriptors.values().end()};
+  }
+
+  auto type_registry::size() const noexcept -> std::size_t
+  {
+    return m_descriptors.size();
+  }
+
+}  // namespace kernel::filesystem
diff --git a/kernel/src/filesystem/type_registry.tests.cpp b/kernel/src/filesystem/type_registry.tests.cpp
new file mode 100644
index 0000000..8382579
--- /dev/null
+++ b/kernel/src/filesystem/type_registry.tests.cpp
@@ -0,0 +1,77 @@
+#include <kernel/filesystem/type_registry.hpp>
+
+#include <kernel/filesystem/filesystem.hpp>
+#include <kernel/filesystem/type.hpp>
+
+#include <kstd/memory>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <iterator>
+#include <string_view>
+
+struct test_type final : kernel::filesystem::type
+{
+  [[nodiscard]] auto name() const noexcept -> std::string_view override
+  {
+    return "bht_testfs";
+  }
+
+  [[nodiscard]] auto requires_device() const noexcept -> bool override
+  {
+    return false;
+  }
+
+  [[nodiscard]] auto make_instance() const -> kstd::shared_ptr<kernel::filesystem::filesystem> override
+  {
+    return nullptr;
+  }
+};
+
+SCENARIO("Filesystem type registry initialization and construction", "[filesystem]")
+{
+  GIVEN("A default constructed type_registry")
+  {
+    auto instance = kernel::filesystem::type_registry{};
+
+    WHEN("getting the span of filesystem descriptors")
+    {
+      auto descriptors = instance.all();
+
+      THEN("the span is empty")
+      {
+        REQUIRE(descriptors.empty());
+      }
+    }
+  }
+}
+
+SCENARIO("Filesystem type registry modifiers", "[filesystem]")
+{
+  GIVEN("A default constructed type_registry")
+  {
+    auto instance = kernel::filesystem::type_registry{};
+
+    WHEN("adding a type descriptor")
+    {
+      auto descriptor = test_type{};
+
+      instance.add(kstd::make_observer(&descriptor));
+
+      THEN("the size of the registry is one")
+      {
+        REQUIRE(instance.size() == 1);
+      }
+
+      THEN("the span is not empty")
+      {
+        REQUIRE_FALSE(instance.all().empty());
+      }
+
+      THEN("the span's size is equal to the registry size")
+      {
+        REQUIRE(std::size(instance.all()) == std::size(instance));
+      }
+    }
+  }
+}
diff --git a/kernel/src/filesystem/vfs.cpp b/kernel/src/filesystem/vfs.cpp
index ae85291..e5dff8c 100644
--- a/kernel/src/filesystem/vfs.cpp
+++ b/kernel/src/filesystem/vfs.cpp
@@ -12,7 +12,6 @@
 #include <kapi/system.hpp>
 
 #include <kstd/memory>
-#include <kstd/string>
 #include <kstd/vector>
 
 #include <algorithm>
@@ -36,11 +35,10 @@ namespace kernel::filesystem
       kapi::system::panic("[FILESYSTEM] vfs has already been initialized.");
     }
 
-    active_vfs.emplace(vfs{});
-    active_vfs->init_internal();
+    active_vfs.emplace();
   }
 
-  auto vfs::init_internal() -> void
+  vfs::vfs()
   {
     // mount rootfs at /
     auto root_fs = kstd::make_shared<rootfs::filesystem>();
@@ -226,22 +224,22 @@ namespace kernel::filesystem
         continue;
       }
 
-      auto next_dentry = current_dentry->find_child(part.view());
+      auto next_dentry = current_dentry->find_child(part);
       if (!next_dentry)
       {
         auto current_fs = current_mount->get_filesystem();
-        auto found_inode = current_fs->lookup(current_dentry->get_inode(), part.view());
+        auto found_inode = current_fs->lookup(current_dentry->get_inode(), part);
         if (!found_inode)
         {
           return {nullptr, nullptr};
         }
 
-        next_dentry = kstd::make_shared<dentry>(current_dentry, found_inode, part.view());
+        next_dentry = kstd::make_shared<dentry>(current_dentry, found_inode, part);
         current_dentry->add_child(next_dentry);
       }
       else if (next_dentry->has_flag(dentry::dentry_flags::is_mount_point))
       {
-        current_mount = m_mount_table.find_mount(next_dentry->absolute_path().view());
+        current_mount = m_mount_table.find_mount(next_dentry->absolute_path());
         if (!current_mount)
         {
           kapi::system::panic("[FILESYSTEM] mount for dentry with mounted flag not found.");
diff --git a/kernel/src/filesystem/vfs.tests.cpp b/kernel/src/filesystem/vfs.tests.cpp
index 962e067..f1d0df0 100644
--- a/kernel/src/filesystem/vfs.tests.cpp
+++ b/kernel/src/filesystem/vfs.tests.cpp
@@ -106,8 +106,7 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
 
       auto mounted_monkey_1 = vfs.open("/information/monkey_house/monkey_1.txt");
       REQUIRE(mounted_monkey_1 != nullptr);
-      REQUIRE(vfs.close(mounted_monkey_1->absolute_path().view()) ==
-              kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(mounted_monkey_1->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
       auto unmounted_monkey_1 = vfs.open("/information/monkey_house/monkey_1.txt");
@@ -129,9 +128,8 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
       REQUIRE(mounted_monkey_1 != nullptr);
       REQUIRE(mounted_fish1 != nullptr);
 
-      REQUIRE(vfs.close(mounted_monkey_1->absolute_path().view()) ==
-              kernel::filesystem::vfs::operation_result::success);
-      REQUIRE(vfs.close(mounted_fish1->absolute_path().view()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(mounted_monkey_1->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(mounted_fish1->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::unmount_failed);
       REQUIRE(vfs.unmount("/information/monkey_house/infrastructure") ==
@@ -148,8 +146,7 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
 
       REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::unmount_failed);
 
-      REQUIRE(vfs.close(mounted_monkey_1->absolute_path().view()) ==
-              kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(mounted_monkey_1->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
     }
@@ -165,8 +162,8 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
       auto info_1 = vfs.open("/information/info_1.txt");
       REQUIRE(info_1 != nullptr);
 
-      REQUIRE(vfs.close(info_1->absolute_path().view()) == kernel::filesystem::vfs::operation_result::success);
-      REQUIRE_THROWS_AS(vfs.close(info_1->absolute_path().view()), std::runtime_error);
+      REQUIRE(vfs.close(info_1->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE_THROWS_AS(vfs.close(info_1->absolute_path()), std::runtime_error);
     }
 
     THEN("images can be stacked mounted and correct file system is unmounted again")
@@ -177,7 +174,7 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
       auto mounted_tickets = vfs.open("/information/entrance/tickets.txt");
       REQUIRE(mounted_tickets != nullptr);
 
-      REQUIRE(vfs.close(mounted_tickets->absolute_path().view()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(mounted_tickets->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
       mounted_tickets = vfs.open("/information/entrance/tickets.txt");
@@ -200,7 +197,7 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
       auto water = vfs.open("/monkey_house/infrastructure/water.txt");
       REQUIRE(water != nullptr);
 
-      REQUIRE(vfs.close(water->absolute_path().view()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(water->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       REQUIRE(vfs.unmount("/") == kernel::filesystem::vfs::operation_result::success);
 
@@ -221,7 +218,7 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
       auto water = vfs.open("/monkey_house/infrastructure/water.txt");
       REQUIRE(water != nullptr);
 
-      REQUIRE(vfs.close(water->absolute_path().view()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(water->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       auto dev_ram_16 = vfs.open("/dev/ram16");
       REQUIRE(dev_ram_16 == nullptr);
@@ -239,7 +236,7 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
       auto info_1 = vfs.open("/information/info_1.txt");
       REQUIRE(info_1 != nullptr);
 
-      REQUIRE(vfs.close(info_1->absolute_path().view()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(info_1->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       REQUIRE(vfs.unmount("/dev") == kernel::filesystem::vfs::operation_result::success);
       REQUIRE(vfs.unmount("/") == kernel::filesystem::vfs::operation_result::success);
@@ -362,7 +359,7 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
       std::string_view buffer_as_str{reinterpret_cast<char *>(buffer.data()), bytes_read};
       REQUIRE(buffer_as_str == "sheep_1");
 
-      REQUIRE(vfs.close(dentry->absolute_path().view()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(dentry->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
       auto unmounted_sheep_1 = vfs.open("/information/sheep_1.txt");
@@ -395,8 +392,8 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
       buffer_as_str = std::string_view{reinterpret_cast<char *>(goat_buffer.data()), bytes_read};
       REQUIRE(buffer_as_str == "goat_1");
 
-      REQUIRE(vfs.close(sheep_1->absolute_path().view()) == kernel::filesystem::vfs::operation_result::success);
-      REQUIRE(vfs.close(goat_1->absolute_path().view()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(sheep_1->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(goat_1->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::unmount_failed);
 
@@ -407,8 +404,7 @@ SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_vfs_fixture, "VFS
       auto still_mounted_sheep_1 = vfs.open("/information/sheep_1.txt");
       REQUIRE(still_mounted_sheep_1 != nullptr);
 
-      REQUIRE(vfs.close(still_mounted_sheep_1->absolute_path().view()) ==
-              kernel::filesystem::vfs::operation_result::success);
+      REQUIRE(vfs.close(still_mounted_sheep_1->absolute_path()) == kernel::filesystem::vfs::operation_result::success);
 
       REQUIRE(vfs.unmount("/information") == kernel::filesystem::vfs::operation_result::success);
       auto unmounted_sheep_1 = vfs.open("/information/sheep_1.txt");
diff --git a/kernel/src/main.cpp b/kernel/src/main.cpp
index 6985e94..8dc1349 100644
--- a/kernel/src/main.cpp
+++ b/kernel/src/main.cpp
@@ -1,3 +1,4 @@
+#include "kernel/filesystem/type_registry.hpp"
 #include <kernel/devices/storage/management.hpp>
 #include <kernel/filesystem/open_file_table.hpp>
 #include <kernel/filesystem/vfs.hpp>
@@ -138,6 +139,9 @@ auto main() -> int
   kernel::filesystem::open_file_table::init();
   kstd::println("[OS] Global open file table initialized.");
 
+  kernel::filesystem::type_registry::init();
+  kstd::println("[OS] Builtin filesystems registered.");
+
   kernel::filesystem::vfs::init();
   kstd::println("[OS] Virtual filesystem initialized.");