1 files changed, 123 insertions, 0 deletions
diff --git a/kernel/src/filesystem/vfs.cpp b/kernel/src/filesystem/vfs.cpp
new file mode 100644
index 0000000..2123fc7
--- /dev/null
+++ b/kernel/src/filesystem/vfs.cpp
@@ -0,0 +1,123 @@
+#include "kernel/filesystem/vfs.hpp"
+
+#include "kapi/system.hpp"
+
+#include "kernel/devices/device.hpp"
+#include "kernel/devices/storage/storage_management.hpp"
+#include "kernel/filesystem/custody.hpp"
+#include "kernel/filesystem/device_file.hpp"
+#include "kernel/filesystem/ext2/ext2_filesystem.hpp"
+#include "kernel/filesystem/inode.hpp"
+#include "kernel/filesystem/inode_file.hpp"
+#include "kernel/filesystem/mount.hpp"
+#include "kernel/filesystem/open_file_description.hpp"
+
+#include <kstd/cstring>
+#include <kstd/memory>
+
+#include <algorithm>
+#include <optional>
+#include <string_view>
+
+namespace filesystem
+{
+  namespace
+  {
+    constinit auto static active_vfs = std::optional<vfs>{};
+  }  // namespace
+
+  auto vfs::init() -> void
+  {
+    if (active_vfs)
+    {
+      kapi::system::panic("[FILESYSTEM] vfs has already been initialized.");
+    }
+
+    active_vfs.emplace(vfs{});
+
+    auto storage_mgmt = devices::storage::storage_management::get();
+    if (auto boot_device = storage_mgmt.determine_boot_device())
+    {
+      active_vfs->m_root_fs = kstd::make_shared<ext2::ext2_filesystem>();
+      if (active_vfs->m_root_fs->mount(boot_device) != 0)
+      {
+        kapi::system::panic("[FILESYSTEM] Failed to mount root filesystem.");
+      }
+
+      active_vfs->m_root_mount = mount{"/", active_vfs->m_root_fs};
+
+      std::ranges::for_each(storage_mgmt.all_controllers(), [&](auto controller) {
+        std::ranges::for_each(controller->all_devices(), [&](auto device) { active_vfs->make_device_node(device); });
+      });
+    }
+    else
+    {
+      // TODO BA-FS26 ?? what when no boot_device == no modules loaded??
+    }
+  }
+
+  auto vfs::get() -> vfs &
+  {
+    if (!active_vfs)
+    {
+      kapi::system::panic("[FILESYSTEM] vfs has not been initialized.");
+    }
+
+    return *active_vfs;
+  }
+
+  auto vfs::open(std::string_view path) -> std::optional<open_file_description>
+  {
+    if (auto custody = resolve_path(path))
+    {
+      auto node = custody->get_inode();
+      if (node->is_device())
+      {
+        auto current_device_file = kstd::make_shared<device_file>(node->backing_device());
+        current_device_file->open();
+        return open_file_description{current_device_file};
+      }
+
+      auto current_inode_file = kstd::make_shared<inode_file>(node);
+      current_inode_file->open();
+      return open_file_description{current_inode_file};
+    }
+
+    return std::nullopt;
+  }
+
+  auto vfs::make_device_node(kstd::shared_ptr<devices::device> const & device) -> void
+  {
+    if (!device)
+    {
+      kapi::system::panic("[FILESYSTEM] make_device_node called with null device.");
+    }
+
+    m_device_nodes.push_back(device_node_entry{device->name(), kstd::make_shared<inode>(device)});
+  }
+
+  auto vfs::resolve_path(std::string_view path) -> std::optional<custody>
+  {
+    // TODO BA-FS26 implement real path resolution with mounts and directories etc.
+    // For now, just support device nodes at /dev/<device_name>.
+
+    constexpr auto device_prefix = std::string_view{"/dev/"};
+    if (path.starts_with(device_prefix))
+    {
+      auto const device_name = path.substr(device_prefix.size());
+      auto entry = std::ranges::find_if(m_device_nodes, [&](auto const & device_entry) {
+        return device_entry.has_value() && device_entry->name == device_name;
+      });
+
+      if (entry != m_device_nodes.end())
+      {
+        return custody{nullptr, entry->value().node};
+      }
+
+      return std::nullopt;
+    }
+
+    return std::nullopt;
+  }
+
+}  // namespace filesystem
+\ No newline at end of file