first draft of an devfs implementation

9 files changed, 146 insertions, 49 deletions

diff --git a/kernel/CMakeLists.txt b/kernel/CMakeLists.txt
index 406ac54..eb762ac 100644
--- a/kernel/CMakeLists.txt
+++ b/kernel/CMakeLists.txt
@@ -21,6 +21,8 @@ add_executable("kernel"
     "src/devices/storage/storage_management.cpp"
     "src/devices/storage/ram_disk/ram_disk_controller.cpp"
     "src/devices/storage/ram_disk/ram_disk_device.cpp"
+    "src/filesystem/devfs/devfs_filesystem.cpp"
+    "src/filesystem/devfs/devfs_root_inode.cpp"
     "src/filesystem/ext2/ext2_file.cpp"
     "src/filesystem/ext2/ext2_filesystem.cpp"
     "src/filesystem/ext2/ext2_inode.cpp"
diff --git a/kernel/include/kernel/filesystem/devfs/devfs_filesystem.hpp b/kernel/include/kernel/filesystem/devfs/devfs_filesystem.hpp
new file mode 100644
index 0000000..5559c2a
--- /dev/null
+++ b/kernel/include/kernel/filesystem/devfs/devfs_filesystem.hpp
@@ -0,0 +1,25 @@
+#ifndef TEACH_OS_KERNEL_FILESYSTEM_DEVFS_DEVFS_FILESYSTEM_HPP
+#define TEACH_OS_KERNEL_FILESYSTEM_DEVFS_DEVFS_FILESYSTEM_HPP
+
+#include "kernel/devices/device.hpp"
+#include "kernel/filesystem/filesystem.hpp"
+#include "kernel/filesystem/inode.hpp"
+
+#include <kstd/memory>
+#include <kstd/vector>
+
+#include <string_view>
+
+namespace filesystem::devfs
+{
+  struct devfs_filesystem : filesystem
+  {
+    auto mount(kstd::shared_ptr<devices::device> const & device) -> int override;
+    auto lookup(kstd::shared_ptr<inode> const & parent, std::string_view name) -> kstd::shared_ptr<inode> override;
+
+  private:
+    auto build_device_inode_table() -> void;
+  };
+}  // namespace filesystem::devfs
+
+#endif
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/devfs/devfs_root_inode.hpp b/kernel/include/kernel/filesystem/devfs/devfs_root_inode.hpp
new file mode 100644
index 0000000..b1d37ab
--- /dev/null
+++ b/kernel/include/kernel/filesystem/devfs/devfs_root_inode.hpp
@@ -0,0 +1,19 @@
+#ifndef TEACH_OS_KERNEL_FILESYSTEM_DEVFS_DEVFS_ROOT_INODE_HPP
+#define TEACH_OS_KERNEL_FILESYSTEM_DEVFS_DEVFS_ROOT_INODE_HPP
+
+#include "kernel/filesystem/inode.hpp"
+
+#include <cstddef>
+
+namespace filesystem::devfs
+{
+  struct devfs_root_inode : inode
+  {
+    devfs_root_inode();
+
+    auto read(void * buffer, size_t offset, size_t size) const -> size_t override;
+    auto write(void const * buffer, size_t offset, size_t size) -> size_t override;
+  };
+}  // namespace filesystem::devfs
+
+#endif
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/device_inode.hpp b/kernel/include/kernel/filesystem/device_inode.hpp
index ce0f91c..1cf08d4 100644
--- a/kernel/include/kernel/filesystem/device_inode.hpp
+++ b/kernel/include/kernel/filesystem/device_inode.hpp
@@ -18,6 +18,8 @@ namespace filesystem
     auto read(void * buffer, size_t offset, size_t size) const -> size_t override;
     auto write(void const * buffer, size_t offset, size_t size) -> size_t override;
 
+    [[nodiscard]] auto device() const -> kstd::shared_ptr<devices::device> const &;
+
   private:
     using block_op = void (*)(size_t idx, size_t off, size_t len, size_t done, devices::block_device * device,
                               std::byte * scratch, void * buffer);
diff --git a/kernel/include/kernel/filesystem/vfs.hpp b/kernel/include/kernel/filesystem/vfs.hpp
index cf268a3..f301b7a 100644
--- a/kernel/include/kernel/filesystem/vfs.hpp
+++ b/kernel/include/kernel/filesystem/vfs.hpp
@@ -1,17 +1,13 @@
 #ifndef TEACH_OS_KERNEL_FILESYSTEM_VFS_HPP
 #define TEACH_OS_KERNEL_FILESYSTEM_VFS_HPP
 
-#include "kernel/devices/device.hpp"
 #include "kernel/filesystem/dentry.hpp"
 #include "kernel/filesystem/filesystem.hpp"
-#include "kernel/filesystem/inode.hpp"
 #include "kernel/filesystem/mount_table.hpp"
 #include "kernel/filesystem/open_file_description.hpp"
 
 #include <kstd/memory>
-#include <kstd/vector>
 
-#include <optional>
 #include <string_view>
 
 namespace filesystem
@@ -27,18 +23,9 @@ namespace filesystem
     auto do_mount(std::string_view path, kstd::shared_ptr<filesystem> const & filesystem) -> int;
 
   private:
-    // TODO BA-FS26 remove again and use devtempfs
-    struct device_node_entry
-    {
-      std::string_view name;
-      kstd::shared_ptr<inode> node;
-    };
-    kstd::vector<std::optional<device_node_entry>> m_device_nodes;  // TODO BA-FS26 remove again, use devtempfs
-
     vfs() = default;
     auto init_internal() -> void;
 
-    auto make_device_node(kstd::shared_ptr<devices::device> const & device) -> void;
     [[nodiscard]] auto resolve_path(std::string_view path) -> kstd::shared_ptr<dentry>;
 
     mount_table m_mount_table;
diff --git a/kernel/src/filesystem/devfs/devfs_filesystem.cpp b/kernel/src/filesystem/devfs/devfs_filesystem.cpp
new file mode 100644
index 0000000..cfd2d88
--- /dev/null
+++ b/kernel/src/filesystem/devfs/devfs_filesystem.cpp
@@ -0,0 +1,57 @@
+#include "kernel/filesystem/devfs/devfs_filesystem.hpp"
+
+#include "kernel/devices/device.hpp"
+#include "kernel/devices/storage/storage_management.hpp"
+#include "kernel/filesystem/devfs/devfs_root_inode.hpp"
+#include "kernel/filesystem/device_inode.hpp"
+#include "kernel/filesystem/inode.hpp"
+
+#include <kstd/memory>
+
+#include <algorithm>
+#include <string_view>
+
+namespace filesystem::devfs
+{
+  auto devfs_filesystem::mount(kstd::shared_ptr<devices::device> const & /*device*/) -> int
+  {
+    m_root_inode = kstd::make_shared<devfs_root_inode>();
+    build_device_inode_table();
+    return 0;
+  }
+
+  auto devfs_filesystem::lookup(kstd::shared_ptr<inode> const & parent, std::string_view name)
+      -> kstd::shared_ptr<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) {
+      auto device_inode_ptr = static_cast<device_inode *>(dev_node.get());
+      if (!device_inode_ptr)
+      {
+        return false;
+      }
+      return device_inode_ptr->device()->name() == name;
+    });
+    return (it != m_inodes.end()) ? *it : nullptr;
+  }
+
+  auto devfs_filesystem::build_device_inode_table() -> void
+  {
+    m_inodes.clear();
+
+    auto storage_mgmt = devices::storage::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 filesystem::devfs
\ No newline at end of file
diff --git a/kernel/src/filesystem/devfs/devfs_root_inode.cpp b/kernel/src/filesystem/devfs/devfs_root_inode.cpp
new file mode 100644
index 0000000..53441b0
--- /dev/null
+++ b/kernel/src/filesystem/devfs/devfs_root_inode.cpp
@@ -0,0 +1,22 @@
+#include "kernel/filesystem/devfs/devfs_root_inode.hpp"
+
+#include "kernel/filesystem/inode.hpp"
+
+#include <cstddef>
+
+namespace filesystem::devfs
+{
+  devfs_root_inode::devfs_root_inode()
+      : inode(inode_kind::directory)
+  {}
+
+  auto devfs_root_inode::read(void * /*buffer*/, size_t /*offset*/, size_t /*size*/) const -> size_t
+  {
+    return 0;
+  }
+
+  auto devfs_root_inode::write(void const * /*buffer*/, size_t /*offset*/, size_t /*size*/) -> size_t
+  {
+    return 0;
+  }
+}  // namespace filesystem::devfs
\ No newline at end of file
diff --git a/kernel/src/filesystem/device_inode.cpp b/kernel/src/filesystem/device_inode.cpp
index 812b43a..64cd6e9 100644
--- a/kernel/src/filesystem/device_inode.cpp
+++ b/kernel/src/filesystem/device_inode.cpp
@@ -76,6 +76,11 @@ namespace filesystem
     }
   }
 
+  auto device_inode::device() const -> kstd::shared_ptr<devices::device> const &
+  {
+    return m_device;
+  }
+
   auto device_inode::process_blocks(size_t offset, size_t size, void * buffer, block_op op) const -> size_t
   {
     if (buffer == nullptr)
diff --git a/kernel/src/filesystem/vfs.cpp b/kernel/src/filesystem/vfs.cpp
index 483bae5..368d994 100644
--- a/kernel/src/filesystem/vfs.cpp
+++ b/kernel/src/filesystem/vfs.cpp
@@ -2,10 +2,9 @@
 
 #include "kapi/system.hpp"
 
-#include "kernel/devices/device.hpp"
 #include "kernel/devices/storage/storage_management.hpp"
 #include "kernel/filesystem/dentry.hpp"
-#include "kernel/filesystem/device_inode.hpp"
+#include "kernel/filesystem/devfs/devfs_filesystem.hpp"
 #include "kernel/filesystem/ext2/ext2_filesystem.hpp"
 #include "kernel/filesystem/filesystem.hpp"
 #include "kernel/filesystem/mount.hpp"
@@ -14,7 +13,6 @@
 
 #include <kstd/memory>
 
-#include <algorithm>
 #include <optional>
 #include <ranges>
 #include <string_view>
@@ -52,12 +50,18 @@ namespace filesystem
       auto boot_root_fs = kstd::make_shared<ext2::ext2_filesystem>();
       boot_root_fs->mount(boot_device);
 
-      do_mount("/", boot_root_fs);
+      if (do_mount("/", boot_root_fs) != 0)
+      {
+        kapi::system::panic("[FILESYSTEM] failed to mount root filesystem.");
+      }
+
+      auto device_fs = kstd::make_shared<devfs::devfs_filesystem>();
+      device_fs->mount(nullptr);
 
-      // TODO BA-FS26 use do_mount when tempdevfs is implemented -> just call /dev/ with all devices in devtempfs
-      std::ranges::for_each(storage_mgmt.all_controllers(), [&](auto controller) {
-        std::ranges::for_each(controller->all_devices(), [&](auto device) { make_device_node(device); });
-      });
+      if (do_mount("/dev", device_fs) != 0)
+      {
+        kapi::system::panic("[FILESYSTEM] failed to mount devfs at /dev.");
+      }
     }
     else
     {
@@ -118,39 +122,13 @@ namespace filesystem
     return -1;
   }
 
-  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().view(), kstd::make_shared<device_inode>(device)});
-  }
-
   auto vfs::resolve_path(std::string_view path) -> kstd::shared_ptr<dentry>
   {
-    // 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 implement full path resolution semantics.
     // TODO BA-FS26 better path validation
     // TODO BA-FS26 implement a path parser (maybe in libs?) and use it here and in do_mount
 
-    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 kstd::make_shared<dentry>(nullptr, entry->value().node);
-      }
-
-      return nullptr;
-    }
-    else if (!path.empty() && path.front() == '/')
+    if (!path.empty() && path.front() == '/')
     {
       auto root_mount = m_mount_table.get_root_mount();
       if (!root_mount)