From d027d60f364e4e6345d26bc5f90eaedcc7793fc7 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@ost.ch>
Date: Wed, 22 Jul 2026 16:02:50 +0200
Subject: kapi/fs: implement status and raw_device

---
 kernel/kapi/filesystem.cpp                         |  5 +++
 kernel/kernel/filesystem/device_inode.cpp          | 15 +++++++
 kernel/kernel/filesystem/device_inode.hpp          |  5 +++
 kernel/kernel/filesystem/device_inode.tests.cpp    | 51 ++++++++++++++++++++++
 kernel/kernel/filesystem/ext2/inode.cpp            | 32 ++++++++++++++
 kernel/kernel/filesystem/ext2/inode.hpp            |  7 +++
 kernel/kernel/filesystem/inode.cpp                 | 46 +++++++++++++++++++
 kernel/kernel/filesystem/inode.hpp                 | 14 ++++++
 kernel/kernel/filesystem/vfs.cpp                   | 11 +++++
 kernel/kernel/filesystem/vfs.hpp                   |  5 +++
 .../kernel/test_support/filesystem/filesystem.cpp  |  5 ++-
 .../kernel/test_support/filesystem/filesystem.hpp  |  5 ++-
 12 files changed, 197 insertions(+), 4 deletions(-)

(limited to 'kernel')

diff --git a/kernel/kapi/filesystem.cpp b/kernel/kapi/filesystem.cpp
index b2f94747..10c9835a 100644
--- a/kernel/kapi/filesystem.cpp
+++ b/kernel/kapi/filesystem.cpp
@@ -68,4 +68,9 @@ namespace kapi::filesystem
     return kernel::filesystem::vfs::get().create(path);
   }
 
+  auto status(std::string_view path) -> kstd::result<file_status>
+  {
+    return kernel::filesystem::vfs::get().status(path);
+  }
+
 }  // namespace kapi::filesystem
\ No newline at end of file
diff --git a/kernel/kernel/filesystem/device_inode.cpp b/kernel/kernel/filesystem/device_inode.cpp
index 464c5ea9..5ac18019 100644
--- a/kernel/kernel/filesystem/device_inode.cpp
+++ b/kernel/kernel/filesystem/device_inode.cpp
@@ -1,16 +1,21 @@
 #include <kernel/filesystem/device_inode.hpp>
 
 #include <kernel/devices/block_device_utils.hpp>
+#include <kernel/filesystem/device_number_registry.hpp>
 #include <kernel/filesystem/error.hpp>
+#include <kernel/filesystem/inode.hpp>
 
 #include <kapi/devices.hpp>
 #include <kapi/devices/device.hpp>
+#include <kapi/filesystem.hpp>
 #include <kapi/system.hpp>
 
 #include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 #include <kstd/units.hpp>
 
+#include <optional>
+
 namespace kernel::filesystem
 {
   device_inode::device_inode(kstd::shared_ptr<kapi::devices::device> const & device)
@@ -54,4 +59,14 @@ namespace kernel::filesystem
     return true;
   }
 
+  auto device_inode::raw_device() const -> std::optional<kapi::filesystem::device_number>
+  {
+    if (auto number = device_number_registry::get().number_of(*m_device))
+    {
+      return *number;
+    }
+
+    return std::nullopt;
+  }
+
 }  // namespace kernel::filesystem
\ No newline at end of file
diff --git a/kernel/kernel/filesystem/device_inode.hpp b/kernel/kernel/filesystem/device_inode.hpp
index be9fc577..698124f2 100644
--- a/kernel/kernel/filesystem/device_inode.hpp
+++ b/kernel/kernel/filesystem/device_inode.hpp
@@ -4,11 +4,14 @@
 #include <kernel/filesystem/inode.hpp>
 
 #include <kapi/devices/device.hpp>
+#include <kapi/filesystem.hpp>
 
 #include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 #include <kstd/units.hpp>
 
+#include <optional>
+
 namespace kernel::filesystem
 {
   /**
@@ -58,6 +61,8 @@ namespace kernel::filesystem
     */
     [[nodiscard]] auto is_block_device() const -> bool override;
 
+    [[nodiscard]] auto raw_device() const -> std::optional<kapi::filesystem::device_number> override;
+
   private:
     kstd::shared_ptr<kapi::devices::device> m_device;
   };
diff --git a/kernel/kernel/filesystem/device_inode.tests.cpp b/kernel/kernel/filesystem/device_inode.tests.cpp
index e821ce1d..4c6e0338 100644
--- a/kernel/kernel/filesystem/device_inode.tests.cpp
+++ b/kernel/kernel/filesystem/device_inode.tests.cpp
@@ -1,11 +1,18 @@
 #include <kernel/filesystem/device_inode.hpp>
 
+#include <kernel/filesystem/device_number_registry.hpp>
+#include <kernel/filesystem/inode.hpp>
 #include <kernel/test_support/cpu.hpp>
 #include <kernel/test_support/devices/block_device.hpp>
 #include <kernel/test_support/devices/character_device.hpp>
+#include <kernel/test_support/filesystem/device_number_registry.hpp>
+
+#include <kapi/devices.hpp>
+#include <kapi/filesystem.hpp>
 
 #include <kstd/memory.hpp>
 #include <kstd/print.hpp>
+#include <kstd/result.hpp>
 #include <kstd/system_error.hpp>
 #include <kstd/units.hpp>
 #include <kstd/vector.hpp>
@@ -17,6 +24,17 @@
 
 using namespace kstd::units_literals;
 
+namespace
+{
+  struct registry_reset_guard
+  {
+    ~registry_reset_guard()
+    {
+      kernel::tests::filesystem::device_number_registry::deinit();
+    }
+  };
+}  // namespace
+
 SCENARIO("Device inode construction", "[filesystem][device_inode]")
 {
   GIVEN("a block device")
@@ -117,3 +135,36 @@ SCENARIO("Device inode read/write with a non-block device", "[filesystem][device
     }
   }
 }
+
+SCENARIO("Device inode raw_device()", "[filesystem][device-inode]")
+{
+  auto resetter = registry_reset_guard{};
+
+  GIVEN("A block device that has been published and numbered")
+  {
+    auto device = kstd::make_shared<kernel::tests::devices::block_device>("ram0", 512_B);
+    REQUIRE(kapi::devices::interface_registry::get().publish<kapi::devices::block_device>(device, "ram0"));
+
+    auto inode = kernel::filesystem::device_inode{device};
+
+    THEN("raw_device() return the number assigned to the device")
+    {
+      auto expected = kernel::filesystem::device_number_registry::get().number_of(*device);
+      REQUIRE(expected);
+
+      auto actual = inode.raw_device();
+      REQUIRE(actual == expected);
+    }
+  }
+
+  GIVEN("a block device that has never been published")
+  {
+    auto device = kstd::make_shared<kernel::tests::devices::block_device>("never_published", 512_B);
+    auto inode = kernel::filesystem::device_inode{device};
+
+    THEN("raw_device() is nullopt, not a stale or default number")
+    {
+      REQUIRE_FALSE(inode.raw_device());
+    }
+  }
+}
diff --git a/kernel/kernel/filesystem/ext2/inode.cpp b/kernel/kernel/filesystem/ext2/inode.cpp
index f42e2c0c..89e52232 100644
--- a/kernel/kernel/filesystem/ext2/inode.cpp
+++ b/kernel/kernel/filesystem/ext2/inode.cpp
@@ -3,6 +3,7 @@
 #include <kernel/filesystem/ext2/filesystem.hpp>
 #include <kernel/filesystem/inode.hpp>
 
+#include <kapi/filesystem.hpp>
 #include <kapi/system.hpp>
 
 #include <kstd/cstring.hpp>
@@ -12,6 +13,7 @@
 #include <algorithm>
 #include <cstddef>
 #include <cstdint>
+#include <optional>
 
 using namespace kstd::units_literals;
 
@@ -201,6 +203,36 @@ namespace kernel::filesystem::ext2
     return (m_data.mode & constants::mode_mask) == constants::mode_symbolic_link;
   }
 
+  auto inode::status() const -> kstd::result<kapi::filesystem::file_status>
+  {
+    auto result = kernel::filesystem::inode::status();
+    if (!result)
+    {
+      return result;
+    }
+
+    result->size = size();
+    result->inode_number = m_inode_number;
+    result->link_count = m_data.links_count;
+
+    return result;
+  }
+
+  auto inode::raw_device() const -> std::optional<kapi::filesystem::device_number>
+  {
+    if (!is_device())
+    {
+      return std::nullopt;
+    }
+
+    auto const raw_device_number = m_data.block[0];
+
+    return kapi::filesystem::device_number{
+      .major = static_cast<std::uint8_t>((raw_device_number >> 8) & 0xff),
+      .minor = static_cast<std::uint8_t>(raw_device_number & 0xff),
+    };
+  }
+
   auto inode::size() const -> kstd::units::bytes
   {
     uint64_t size = m_data.size;
diff --git a/kernel/kernel/filesystem/ext2/inode.hpp b/kernel/kernel/filesystem/ext2/inode.hpp
index 1d364a54..a15532b0 100644
--- a/kernel/kernel/filesystem/ext2/inode.hpp
+++ b/kernel/kernel/filesystem/ext2/inode.hpp
@@ -3,6 +3,8 @@
 
 #include <kernel/filesystem/inode.hpp>
 
+#include <kapi/filesystem.hpp>
+
 #include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 #include <kstd/units.hpp>
@@ -10,6 +12,7 @@
 #include <array>
 #include <cstddef>
 #include <cstdint>
+#include <optional>
 
 namespace kernel::filesystem::ext2
 {
@@ -107,6 +110,10 @@ namespace kernel::filesystem::ext2
      */
     [[nodiscard]] auto is_symbolic_link() const -> bool override;
 
+    [[nodiscard]] auto status() const -> kstd::result<kapi::filesystem::file_status> override;
+
+    [[nodiscard]] auto raw_device() const -> std::optional<kapi::filesystem::device_number> override;
+
     /**
     @brief Get the size of the file represented by this inode.
     @return The size of the file in bytes.
diff --git a/kernel/kernel/filesystem/inode.cpp b/kernel/kernel/filesystem/inode.cpp
index e564ab38..d0762472 100644
--- a/kernel/kernel/filesystem/inode.cpp
+++ b/kernel/kernel/filesystem/inode.cpp
@@ -1,5 +1,12 @@
 #include <kernel/filesystem/inode.hpp>
 
+#include <kapi/filesystem.hpp>
+
+#include <kstd/result.hpp>
+
+#include <optional>
+#include <utility>
+
 namespace kernel::filesystem
 {
   auto inode::is_directory() const -> bool
@@ -31,4 +38,43 @@ namespace kernel::filesystem
   {
     return false;
   }
+
+  auto inode::status() const -> kstd::result<kapi::filesystem::file_status>
+  {
+    auto result = kapi::filesystem::file_status{};
+
+    if (is_directory())
+    {
+      result.mode = std::to_underlying(kapi::filesystem::file_type::directory);
+    }
+    else if (is_regular())
+    {
+      result.mode = std::to_underlying(kapi::filesystem::file_type::regular);
+    }
+    else if (is_block_device())
+    {
+      result.mode = std::to_underlying(kapi::filesystem::file_type::block_device);
+    }
+    else if (is_character_device())
+    {
+      result.mode = std::to_underlying(kapi::filesystem::file_type::character_device);
+    }
+    else if (is_symbolic_link())
+    {
+      result.mode = std::to_underlying(kapi::filesystem::file_type::symbolic_link);
+    }
+
+    if (auto const number = raw_device())
+    {
+      result.raw_device = *number;
+    }
+
+    return result;
+  }
+
+  auto inode::raw_device() const -> std::optional<kapi::filesystem::device_number>
+  {
+    return std::nullopt;
+  }
+
 }  // namespace kernel::filesystem
\ No newline at end of file
diff --git a/kernel/kernel/filesystem/inode.hpp b/kernel/kernel/filesystem/inode.hpp
index 005dc57b..25e5df31 100644
--- a/kernel/kernel/filesystem/inode.hpp
+++ b/kernel/kernel/filesystem/inode.hpp
@@ -1,9 +1,13 @@
 #ifndef TEACH_OS_KERNEL_FILESYSTEM_INODE_HPP
 #define TEACH_OS_KERNEL_FILESYSTEM_INODE_HPP
 
+#include <kapi/filesystem.hpp>
+
 #include <kstd/result.hpp>
 #include <kstd/units.hpp>
 
+#include <optional>
+
 namespace kernel::filesystem
 {
   //! Represents an inode in the filesystem.
@@ -62,6 +66,16 @@ namespace kernel::filesystem
     //!
     //! @return true iff. this inode is a symbolic link, false otherwise.
     [[nodiscard]] virtual auto is_symbolic_link() const -> bool;
+
+    //! Get POSIX status information for this inode.
+    //!
+    //! @return a populated status information object, or an error or failure.
+    [[nodiscard]] virtual auto status() const -> kstd::result<kapi::filesystem::file_status>;
+
+    //! Get the raw device, if any, this inode refers to.
+    //!
+    //! @return a device number if this inode refers to a device, an empty optional otherwise.
+    [[nodiscard]] virtual auto raw_device() const -> std::optional<kapi::filesystem::device_number>;
   };
 }  // namespace kernel::filesystem
 
diff --git a/kernel/kernel/filesystem/vfs.cpp b/kernel/kernel/filesystem/vfs.cpp
index 6533e027..c1a36856 100644
--- a/kernel/kernel/filesystem/vfs.cpp
+++ b/kernel/kernel/filesystem/vfs.cpp
@@ -186,6 +186,17 @@ namespace kernel::filesystem
     return create_inode(path, vfs_types::inode_type::regular);
   }
 
+  auto vfs::status(std::string_view path) const -> kstd::result<kapi::filesystem::file_status>
+  {
+    auto resolved = resolve_path(path);
+    if (!resolved)
+    {
+      return kstd::failure(resolved.error());
+    }
+
+    return (*resolved)->get_inode()->status();
+  }
+
   auto vfs::create_inode(std::string_view path, vfs_types::inode_type type,
                          std::optional<kapi::filesystem::device_number> raw_device) -> kstd::result<void>
   {
diff --git a/kernel/kernel/filesystem/vfs.hpp b/kernel/kernel/filesystem/vfs.hpp
index b965e426..6ab67ef8 100644
--- a/kernel/kernel/filesystem/vfs.hpp
+++ b/kernel/kernel/filesystem/vfs.hpp
@@ -96,6 +96,11 @@ namespace kernel::filesystem
     // TODO remove again after the open method supports an optional create flag
     auto create(std::string_view path) -> kstd::result<void>;
 
+    //! Get the status of the file at a given path.
+    //!
+    //! @return A populated file status object on success, an error otherwise.
+    [[nodiscard]] auto status(std::string_view path) const -> kstd::result<kapi::filesystem::file_status>;
+
   private:
     /**
      * Note: Resolving a dentry requires traversing mount points; since the
diff --git a/kernel/kernel/test_support/filesystem/filesystem.cpp b/kernel/kernel/test_support/filesystem/filesystem.cpp
index 4dd69668..3acedd5f 100644
--- a/kernel/kernel/test_support/filesystem/filesystem.cpp
+++ b/kernel/kernel/test_support/filesystem/filesystem.cpp
@@ -1,10 +1,11 @@
 #include <kernel/test_support/filesystem/filesystem.hpp>
 
-#include <kernel/filesystem/device_number.hpp>
 #include <kernel/filesystem/inode.hpp>
 #include <kernel/filesystem/vfs_types.hpp>
 #include <kernel/test_support/filesystem/inode.hpp>
 
+#include <kapi/filesystem.hpp>
+
 #include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 #include <kstd/system_error.hpp>
@@ -22,7 +23,7 @@ namespace kernel::tests::filesystem
 
   auto filesystem::create_inode(kstd::shared_ptr<kernel::filesystem::inode> const &, std::string_view,
                                 kernel::filesystem::vfs_types::inode_type,
-                                std::optional<kernel::filesystem::device_number>)
+                                std::optional<kapi::filesystem::device_number>)
       -> kstd::result<kstd::shared_ptr<kernel::filesystem::inode>>
   {
     return kstd::make_shared<inode>();
diff --git a/kernel/kernel/test_support/filesystem/filesystem.hpp b/kernel/kernel/test_support/filesystem/filesystem.hpp
index 0f51499e..2b61aea3 100644
--- a/kernel/kernel/test_support/filesystem/filesystem.hpp
+++ b/kernel/kernel/test_support/filesystem/filesystem.hpp
@@ -1,11 +1,12 @@
 #ifndef TEACHOS_KERNEL_TEST_SUPPORT_FILESYSTEM_FILESYSTEM_HPP
 #define TEACHOS_KERNEL_TEST_SUPPORT_FILESYSTEM_FILESYSTEM_HPP
 
-#include <kernel/filesystem/device_number.hpp>
 #include <kernel/filesystem/filesystem.hpp>
 #include <kernel/filesystem/inode.hpp>
 #include <kernel/filesystem/vfs_types.hpp>
 
+#include <kapi/filesystem.hpp>
+
 #include <kstd/memory.hpp>
 #include <kstd/result.hpp>
 #include <kstd/system_error.hpp>
@@ -24,7 +25,7 @@ namespace kernel::tests::filesystem
 
     [[nodiscard]] auto create_inode(kstd::shared_ptr<kernel::filesystem::inode> const & parent, std::string_view name,
                                     kernel::filesystem::vfs_types::inode_type inode_type,
-                                    std::optional<kernel::filesystem::device_number> = std::nullopt)
+                                    std::optional<kapi::filesystem::device_number> = std::nullopt)
         -> kstd::result<kstd::shared_ptr<kernel::filesystem::inode>> override;
   };
 }  // namespace kernel::tests::filesystem
-- 
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