Merge branch 'develop-BA-FS26' into 'develop'HEADdevelop

Merge of BA-FS26 branch into develop

See merge request teachos/kernel!49

4 files changed, 229 insertions, 0 deletions

diff --git a/kernel/src/filesystem/devfs/filesystem.cpp b/kernel/src/filesystem/devfs/filesystem.cpp
new file mode 100644
index 0000000..ce887ff
--- /dev/null
+++ b/kernel/src/filesystem/devfs/filesystem.cpp
@@ -0,0 +1,81 @@
+#include <kernel/filesystem/devfs/filesystem.hpp>
+
+#include "kernel/filesystem/filesystem.hpp"
+#include <kernel/devices/storage/management.hpp>
+#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>
+
+#include <kstd/memory>
+
+#include <algorithm>
+#include <string_view>
+
+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>();
+    build_device_inode_table();
+
+    return operation_result::success;
+  }
+
+  auto filesystem::lookup(kstd::shared_ptr<kernel::filesystem::inode> const & parent, std::string_view name) const
+      -> kstd::shared_ptr<kernel::filesystem::inode>
+  {
+    if (!parent || !parent->is_directory())
+    {
+      return nullptr;
+    }
+
+    if (parent.get() != m_root_inode.get())
+    {
+      return nullptr;
+    }
+
+    auto it = std::ranges::find_if(m_inodes, [&](auto const & dev_node) {
+      if (auto device_inode_ptr = static_cast<device_inode *>(dev_node.get()))
+      {
+        return device_inode_ptr->device()->name() == name;
+      }
+      return false;
+    });
+    return (it != m_inodes.end()) ? *it : nullptr;
+  }
+
+  auto filesystem::build_device_inode_table() -> void
+  {
+    m_inodes.clear();
+
+    auto storage_mgmt = devices::storage::management::get();
+    std::ranges::for_each(storage_mgmt.all_controllers(), [&](auto const & controller) {
+      std::ranges::for_each(controller->all_devices(),
+                            [&](auto const & device) { m_inodes.push_back(kstd::make_shared<device_inode>(device)); });
+    });
+  }
+}  // namespace kernel::filesystem::devfs
\ No newline at end of file
diff --git a/kernel/src/filesystem/devfs/filesystem.tests.cpp b/kernel/src/filesystem/devfs/filesystem.tests.cpp
new file mode 100644
index 0000000..36cb411
--- /dev/null
+++ b/kernel/src/filesystem/devfs/filesystem.tests.cpp
@@ -0,0 +1,72 @@
+#include <kernel/filesystem/devfs/filesystem.hpp>
+
+#include <kernel/filesystem/filesystem.hpp>
+#include <kernel/test_support/filesystem/storage_boot_module_fixture.hpp>
+
+#include <catch2/catch_test_macros.hpp>
+
+SCENARIO_METHOD(kernel::tests::filesystem::storage_boot_module_fixture,
+                "Devfs filesystem lookup uses storage management devices", "[filesystem][devfs][filesystem]")
+{
+  GIVEN("a boot module registry with one module")
+  {
+    setup_modules(1);
+
+    auto fs = kernel::filesystem::devfs::filesystem{};
+    auto result = fs.mount(nullptr);
+
+    THEN("mount succeeds")
+    {
+      REQUIRE(result == kernel::filesystem::filesystem::operation_result::success);
+      REQUIRE(fs.root_inode() != nullptr);
+    }
+
+    THEN("lookup on root finds ram0 device inode")
+    {
+      auto inode = fs.lookup(fs.root_inode(), "ram0");
+      REQUIRE(inode != nullptr);
+      REQUIRE(inode->is_device());
+    }
+
+    THEN("lookup of an unknown device returns null")
+    {
+      auto inode = fs.lookup(fs.root_inode(), "ram99");
+      REQUIRE(inode == nullptr);
+    }
+
+    THEN("lookup with wrong parent returns null")
+    {
+      auto other_fs = kernel::filesystem::devfs::filesystem{};
+      other_fs.mount(nullptr);
+
+      auto inode = fs.lookup(other_fs.root_inode(), "ram0");
+      REQUIRE(inode == nullptr);
+    }
+
+    THEN("lookup with a non-directory parent returns null")
+    {
+      auto non_directory_inode = fs.lookup(fs.root_inode(), "ram0");
+      REQUIRE(non_directory_inode != nullptr);
+      REQUIRE_FALSE(non_directory_inode->is_directory());
+
+      auto result = fs.lookup(non_directory_inode, "anything");
+      REQUIRE(result == nullptr);
+    }
+  }
+
+  GIVEN("a boot module registry with three modules")
+  {
+    setup_modules(3, 2048);
+
+    auto fs = kernel::filesystem::devfs::filesystem{};
+    auto result = fs.mount(nullptr);
+    REQUIRE(result == kernel::filesystem::filesystem::operation_result::success);
+
+    THEN("lookup finds all generated RAM devices")
+    {
+      REQUIRE(fs.lookup(fs.root_inode(), "ram0") != nullptr);
+      REQUIRE(fs.lookup(fs.root_inode(), "ram16") != nullptr);
+      REQUIRE(fs.lookup(fs.root_inode(), "ram32") != nullptr);
+    }
+  }
+}
diff --git a/kernel/src/filesystem/devfs/inode.cpp b/kernel/src/filesystem/devfs/inode.cpp
new file mode 100644
index 0000000..7bbfbbe
--- /dev/null
+++ b/kernel/src/filesystem/devfs/inode.cpp
@@ -0,0 +1,21 @@
+#include <kernel/filesystem/devfs/inode.hpp>
+
+#include <cstddef>
+
+namespace kernel::filesystem::devfs
+{
+  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::devfs
\ No newline at end of file
diff --git a/kernel/src/filesystem/devfs/inode.tests.cpp b/kernel/src/filesystem/devfs/inode.tests.cpp
new file mode 100644
index 0000000..ae26e74
--- /dev/null
+++ b/kernel/src/filesystem/devfs/inode.tests.cpp
@@ -0,0 +1,55 @@
+#include <kernel/filesystem/devfs/inode.hpp>
+
+#include <kstd/memory>
+#include <kstd/print>
+#include <kstd/vector>
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <cstdint>
+
+SCENARIO("Devfs inode creation", "[filesystem][devfs][inode]")
+{
+  GIVEN("a devfs inode")
+  {
+    auto inode = kernel::filesystem::devfs::inode{};
+
+    THEN("the inode has the correct kind")
+    {
+      REQUIRE(inode.is_directory());
+      REQUIRE_FALSE(inode.is_device());
+      REQUIRE_FALSE(inode.is_regular());
+      REQUIRE_FALSE(inode.is_symbolic_link());
+    }
+  }
+}
+
+SCENARIO("Devfs inode read/write", "[filesystem][devfs][inode]")
+{
+  GIVEN("a devfs inode")
+  {
+    auto inode = kernel::filesystem::devfs::inode{};
+
+    WHEN("attempting to read from the devfs inode")
+    {
+      kstd::vector<uint8_t> buffer(512);
+      auto bytes_read = inode.read(buffer.data(), 0, buffer.size());
+
+      THEN("no bytes are read")
+      {
+        REQUIRE(bytes_read == 0);
+      }
+    }
+
+    WHEN("attempting to write to the devfs inode")
+    {
+      kstd::vector<uint8_t> buffer(512);
+      auto bytes_written = inode.write(buffer.data(), 0, buffer.size());
+
+      THEN("no bytes are written")
+      {
+        REQUIRE(bytes_written == 0);
+      }
+    }
+  }
+}