From 760752ef2045aaceb0393911a0919f9bc0104282 Mon Sep 17 00:00:00 2001
From: Lukas Oesch <lukasoesch20@gmail.com>
Date: Sun, 15 Mar 2026 20:37:14 +0100
Subject: implement first inode draft, fix make_device_node, implement first
 draft of resolve_path (currently with temp m_device_nodes in vfs -> has later
 to be deleted again, just for tests)

---
 kernel/filesystem/src/vfs.cpp | 77 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 64 insertions(+), 13 deletions(-)

(limited to 'kernel/filesystem/src/vfs.cpp')

diff --git a/kernel/filesystem/src/vfs.cpp b/kernel/filesystem/src/vfs.cpp
index 573994a..2ecf847 100644
--- a/kernel/filesystem/src/vfs.cpp
+++ b/kernel/filesystem/src/vfs.cpp
@@ -4,13 +4,17 @@
 
 #include "devices/device.hpp"
 #include "devices/storage/storage_management.hpp"
+#include "filesystem/custody.hpp"
+#include "filesystem/device_file.hpp"
 #include "filesystem/ext2/ext2_filesystem.hpp"
+#include "filesystem/inode.hpp"
+#include "filesystem/inode_file.hpp"
 #include "filesystem/mount.hpp"
+#include "filesystem/open_file_description.hpp"
 
 #include <kstd/cstring>
 
 #include <algorithm>
-#include <array>
 #include <optional>
 #include <string_view>
 
@@ -23,12 +27,11 @@ namespace filesystem
     // TODO BA-FS26 @Felix better solution? while dynamic memory not available?
     // TODO BA-FS26 remove when dynamic memory available;
     constinit auto static root_fs = std::optional<ext2::ext2_filesystem>{};
-    // TODO BA-FS26 use kstd::vector when available
-    constinit auto static filesystems = std::array<std::optional<ext2::ext2_filesystem>, 1>{};
 
-    // TODO BA-FS26 @Felix
-    // TODO BA-FS26 depends on the length of ram_disk_device name
-    constinit std::array<char, 10> device_mount_path = {'/', 'd', 'e', 'v', '/', 'x', 'x', 'x', 'x', '\0'};
+    // TODO BA-FS26 remove when dynamic memory available;
+    constinit auto static temp_device_file = std::optional<device_file>{};
+    // TODO BA-FS26 remove when dynamic memory available;
+    constinit auto static temp_inode_file = std::optional<inode_file>{};
   }  // namespace
 
   auto vfs::init() -> void
@@ -71,19 +74,67 @@ namespace filesystem
     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())
+      {
+        temp_device_file.emplace(node->backing_device());
+        temp_device_file->open();
+        return open_file_description{&*temp_device_file};
+      }
+
+      temp_inode_file.emplace(node);
+      temp_inode_file->open();
+      return open_file_description{&*temp_inode_file};
+    }
+
+    return std::nullopt;
+  }
+
   auto vfs::make_device_node(devices::device * device) -> void
   {
-    auto device_name = device->name();
-    kstd::libc::memcpy(&device_mount_path[5], device_name.data(), device_name.size());
+    if (!device)
+    {
+      kapi::system::panic("[FILESYSTEM] make_device_node called with null device.");
+    }
+
+    auto const device_name = device->name();
+
+    // TODO BA-FS26 this logic isn't needed anymore when kstd::vector available, just use push_back
+    auto const slot = std::ranges::find_if(m_device_nodes, [](auto const & entry) { return !entry.has_value(); });
+    if (slot == m_device_nodes.end())
+    {
+      kapi::system::panic("[FILESYSTEM] No free slot available for device nodes.");
+    }
+
+    slot->emplace(device_node_entry{device_name, 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>.
 
-    // TODO BA-FS26 use kstd::vector and push_back when available
-    filesystems[0].emplace(ext2::ext2_filesystem{});
-    if (filesystems[0]->mount(device) != 0)
+    constexpr auto device_prefix = std::string_view{"/dev/"};
+    if (path.starts_with(device_prefix))
     {
-      kapi::system::panic("[FILESYSTEM] Failed to mount device filesystem.");
+      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;
     }
 
-    m_mounts[0] = mount{std::string_view{device_mount_path.data()}, &*filesystems[0]};
+    return std::nullopt;
   }
 
 }  // namespace filesystem
\ No newline at end of file
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