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

implement basic vfs

See merge request teachos/kernel!16

50 files changed, 1977 insertions, 491 deletions

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 05bba19..2231956 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -27,18 +27,28 @@ bht:
   image: registry.gitlab.ost.ch:45023/teachos/devcontainers/x86-64:15.2.0-4
   before_script:
     - apt update
-    - apt install -y build-essential cmake ninja-build lcov libcatch2-dev
+    - apt install -y build-essential cmake ninja-build lcov libcatch2-dev gcovr
   script:
     - cmake --preset bht
     - cmake --build --preset bht-dbg
     - ctest --preset bht-dbg
     - lcov --config-file .lcovrc --capture --directory $(pwd) --output-file coverage.info
     - lcov --config-file .lcovrc --list coverage.info
+    - genhtml --prefix $(pwd) --output-directory coverage coverage.info
+    - gcovr --root . --cobertura-pretty --output coverage/cobertura-coverage.xml
+  after_script:
+    - echo "CoverageReport public URL - https://teachos.pages.ost.ch/-/kernel/-/jobs/$CI_JOB_ID/artifacts/coverage/index.html"
   coverage: '/Total:\|\s*(\d+(\.\d+)?)\%/'
   artifacts:
     paths:
       - coverage.info
+      - coverage/
     expire_in: 24 hours
+    when: always
+    reports:
+      coverage_report:
+        coverage_format: cobertura
+        path: coverage/cobertura-coverage.xml
 
 license_check:
   stage: .pre
diff --git a/kernel/CMakeLists.txt b/kernel/CMakeLists.txt
index 398022c..eb762ac 100644
--- a/kernel/CMakeLists.txt
+++ b/kernel/CMakeLists.txt
@@ -21,15 +21,21 @@ 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/custody.cpp"
-    "src/filesystem/device_file.cpp"
+    "src/filesystem/ext2/ext2_inode.cpp"
+    "src/filesystem/dentry.cpp"
+    "src/filesystem/device_inode.cpp"
     "src/filesystem/file_descriptor_table.cpp"
     "src/filesystem/filesystem.cpp"
-    "src/filesystem/inode_file.cpp"
     "src/filesystem/inode.cpp"
+    "src/filesystem/mount_table.cpp"
     "src/filesystem/mount.cpp"
     "src/filesystem/open_file_description.cpp"
+    "src/filesystem/rootfs/rootfs_filesystem.cpp"
+    "src/filesystem/rootfs/rootfs_inode.cpp"
     "src/filesystem/vfs.cpp"
 )
 
diff --git a/kernel/include/kernel/devices/block_device.hpp b/kernel/include/kernel/devices/block_device.hpp
index fb7d104..e2026dd 100644
--- a/kernel/include/kernel/devices/block_device.hpp
+++ b/kernel/include/kernel/devices/block_device.hpp
@@ -3,8 +3,9 @@
 
 #include "kernel/devices/device.hpp"
 
+#include <kstd/string>
+
 #include <cstddef>
-#include <string_view>
 
 namespace devices
 {
@@ -20,7 +21,7 @@ namespace devices
      * @param name Device name.
      * @param block_size Size of one logical block in bytes.
      */
-    block_device(size_t major, size_t minor, std::string_view name, size_t block_size);
+    block_device(size_t major, size_t minor, kstd::string const & name, size_t block_size);
 
     /**
      * @brief Read data from the block at @p block_index into @p buffer.
diff --git a/kernel/include/kernel/devices/device.hpp b/kernel/include/kernel/devices/device.hpp
index d6f520f..66cb7f8 100644
--- a/kernel/include/kernel/devices/device.hpp
+++ b/kernel/include/kernel/devices/device.hpp
@@ -1,8 +1,9 @@
 #ifndef TEACH_OS_KERNEL_DEVICES_DEVICE_HPP
 #define TEACH_OS_KERNEL_DEVICES_DEVICE_HPP
 
+#include <kstd/string>
+
 #include <cstddef>
-#include <string_view>
 
 namespace devices
 {
@@ -17,7 +18,7 @@ namespace devices
      * @param minor Device minor number.
      * @param name Device name.
      */
-    device(size_t major, size_t minor, std::string_view name);
+    device(size_t major, size_t minor, kstd::string const & name);
 
     /**
      * @brief Virtual destructor for device.
@@ -40,7 +41,7 @@ namespace devices
      * @brief Returns the name of the device.
      * @return Device name.
      */
-    [[nodiscard]] auto name() const -> std::string_view;
+    [[nodiscard]] auto name() const -> kstd::string const &;
 
     /**
      * @brief Check if the device is a block device.
@@ -54,7 +55,7 @@ namespace devices
   private:
     size_t m_major;
     size_t m_minor;
-    std::string_view m_name;
+    kstd::string m_name;
   };
 }  // namespace devices
 
diff --git a/kernel/include/kernel/filesystem/custody.hpp b/kernel/include/kernel/filesystem/custody.hpp
deleted file mode 100644
index 8a0e09a..0000000
--- a/kernel/include/kernel/filesystem/custody.hpp
+++ /dev/null
@@ -1,23 +0,0 @@
-#ifndef TEACH_OS_KERNEL_CUSTODY_HPP
-#define TEACH_OS_KERNEL_CUSTODY_HPP
-
-#include "kernel/filesystem/inode.hpp"
-
-#include <kstd/memory>
-
-namespace filesystem
-{
-  struct custody
-  {
-    custody(kstd::shared_ptr<custody> const & parent, kstd::shared_ptr<inode> const & node);
-
-    [[nodiscard]] auto get_inode() const -> kstd::shared_ptr<inode> const &;
-    [[nodiscard]] auto get_parent() const -> kstd::shared_ptr<custody> const &;
-
-  private:
-    kstd::shared_ptr<custody> m_parent;
-    kstd::shared_ptr<inode> m_inode;
-  };
-}  // namespace filesystem
-
-#endif
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/dentry.hpp b/kernel/include/kernel/filesystem/dentry.hpp
new file mode 100644
index 0000000..c28246f
--- /dev/null
+++ b/kernel/include/kernel/filesystem/dentry.hpp
@@ -0,0 +1,43 @@
+#ifndef TEACH_OS_KERNEL_FILESYSTEM_DENTRY_HPP
+#define TEACH_OS_KERNEL_FILESYSTEM_DENTRY_HPP
+
+#include "kernel/filesystem/inode.hpp"
+
+#include <kstd/memory>
+#include <kstd/string>
+#include <kstd/vector>
+
+#include <cstdint>
+#include <string_view>
+
+namespace filesystem
+{
+  struct dentry
+  {
+    enum class dentry_flags : uint32_t
+    {
+      dcache_mounted = 1 << 15
+    };
+
+    dentry(kstd::shared_ptr<dentry> const & parent, kstd::shared_ptr<inode> const & node, std::string_view name = {});
+
+    [[nodiscard]] auto get_inode() const -> kstd::shared_ptr<inode> const &;
+    [[nodiscard]] auto get_parent() const -> kstd::shared_ptr<dentry> const &;
+
+    auto add_child(kstd::shared_ptr<dentry> const & child) -> void;
+    [[nodiscard]] auto find_child(std::string_view name) const -> kstd::shared_ptr<dentry>;
+
+    auto set_flag(dentry_flags flag) -> void;
+    auto unset_flag(dentry_flags flag) -> void;
+    [[nodiscard]] auto has_flag(dentry_flags flag) const -> bool;
+
+  private:
+    kstd::string m_name;
+    kstd::shared_ptr<dentry> m_parent;
+    kstd::vector<kstd::shared_ptr<dentry>> m_children;
+    kstd::shared_ptr<inode> m_inode;
+    uint32_t m_flags{0};
+  };
+}  // namespace filesystem
+
+#endif
\ No newline at end of file
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_file.hpp b/kernel/include/kernel/filesystem/device_inode.hpp
index 06aa9b2..1cf08d4 100644
--- a/kernel/include/kernel/filesystem/device_file.hpp
+++ b/kernel/include/kernel/filesystem/device_inode.hpp
@@ -1,9 +1,9 @@
-#ifndef TEACH_OS_KERNEL_FILESYSTEM_DEVICE_FILE_HPP
-#define TEACH_OS_KERNEL_FILESYSTEM_DEVICE_FILE_HPP
+#ifndef TEACH_OS_KERNEL_FILESYSTEM_DEVICE_INODE_HPP
+#define TEACH_OS_KERNEL_FILESYSTEM_DEVICE_INODE_HPP
 
 #include "kernel/devices/block_device.hpp"
 #include "kernel/devices/device.hpp"
-#include "kernel/filesystem/file.hpp"
+#include "kernel/filesystem/inode.hpp"
 
 #include <kstd/memory>
 
@@ -11,15 +11,15 @@
 
 namespace filesystem
 {
-  struct device_file : file
+  struct device_inode : inode
   {
-    explicit device_file(kstd::shared_ptr<devices::device> const & device);
-
-    auto open() -> void override;
+    explicit device_inode(kstd::shared_ptr<devices::device> const & device);
 
     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);
@@ -29,4 +29,4 @@ namespace filesystem
   };
 }  // namespace filesystem
 
-#endif
+#endif
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/ext2/ext2_file.hpp b/kernel/include/kernel/filesystem/ext2/ext2_file.hpp
new file mode 100644
index 0000000..e5357e3
--- /dev/null
+++ b/kernel/include/kernel/filesystem/ext2/ext2_file.hpp
@@ -0,0 +1,15 @@
+#ifndef TEACH_OS_KERNEL_FILESYSTEM_EXT2_FILE_HPP
+#define TEACH_OS_KERNEL_FILESYSTEM_EXT2_FILE_HPP
+
+#include <cstddef>
+
+namespace filesystem::ext2
+{
+  struct ext2_file
+  {
+    auto read(void * buffer, size_t offset, size_t size) const -> size_t;
+    auto write(void const * buffer, size_t offset, size_t size) -> size_t;
+  };
+}  // namespace filesystem::ext2
+
+#endif
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/ext2/ext2_filesystem.hpp b/kernel/include/kernel/filesystem/ext2/ext2_filesystem.hpp
index d6f69c8..1445e5a 100644
--- a/kernel/include/kernel/filesystem/ext2/ext2_filesystem.hpp
+++ b/kernel/include/kernel/filesystem/ext2/ext2_filesystem.hpp
@@ -14,10 +14,9 @@ namespace filesystem::ext2
   struct ext2_filesystem : filesystem
   {
     auto mount(kstd::shared_ptr<devices::device> const & device) -> int override;
-    auto lookup(inode const & parent, std::string_view name) -> inode * override;
+    auto lookup(kstd::shared_ptr<inode> const & parent, std::string_view name) -> kstd::shared_ptr<inode> override;
 
   private:
-    kstd::shared_ptr<devices::device> m_device{};
   };
 }  // namespace filesystem::ext2
 
diff --git a/kernel/include/kernel/filesystem/ext2/ext2_inode.hpp b/kernel/include/kernel/filesystem/ext2/ext2_inode.hpp
new file mode 100644
index 0000000..5f4d16a
--- /dev/null
+++ b/kernel/include/kernel/filesystem/ext2/ext2_inode.hpp
@@ -0,0 +1,25 @@
+#ifndef TEACH_OS_KERNEL_FILESYSTEM_EXT2_INODE_HPP
+#define TEACH_OS_KERNEL_FILESYSTEM_EXT2_INODE_HPP
+
+#include "kernel/filesystem/ext2/ext2_file.hpp"
+#include "kernel/filesystem/inode.hpp"
+
+#include <kstd/memory>
+
+#include <cstddef>
+
+namespace filesystem::ext2
+{
+  struct ext2_inode : inode
+  {
+    explicit ext2_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;
+
+  private:
+    kstd::shared_ptr<ext2_file> m_file;
+  };
+}  // namespace filesystem::ext2
+
+#endif
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/file.hpp b/kernel/include/kernel/filesystem/file.hpp
deleted file mode 100644
index e7e1b12..0000000
--- a/kernel/include/kernel/filesystem/file.hpp
+++ /dev/null
@@ -1,19 +0,0 @@
-#ifndef TEACH_OS_KERNEL_FILESYSTEM_FILE_HPP
-#define TEACH_OS_KERNEL_FILESYSTEM_FILE_HPP
-
-#include <cstddef>
-
-namespace filesystem
-{
-  struct file
-  {
-    virtual ~file() = default;
-
-    virtual auto open() -> void = 0;
-
-    virtual auto read(void * buffer, size_t offset, size_t size) const -> size_t = 0;
-    virtual auto write(void const * buffer, size_t offset, size_t size) -> size_t = 0;
-  };
-}  // namespace filesystem
-
-#endif
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/file_descriptor_table.hpp b/kernel/include/kernel/filesystem/file_descriptor_table.hpp
index 6d78532..bc6fb24 100644
--- a/kernel/include/kernel/filesystem/file_descriptor_table.hpp
+++ b/kernel/include/kernel/filesystem/file_descriptor_table.hpp
@@ -3,10 +3,9 @@
 
 #include "open_file_description.hpp"
 
+#include <kstd/memory>
 #include <kstd/vector>
 
-#include <optional>
-
 namespace filesystem
 {
   struct file_descriptor_table
@@ -16,15 +15,14 @@ namespace filesystem
 
     ~file_descriptor_table() = default;
 
-    auto add_file(open_file_description & f) -> int;
-    [[nodiscard]] auto get_file(int fd) const -> std::optional<open_file_description>;
+    auto add_file(kstd::shared_ptr<open_file_description> const & f) -> int;
+    [[nodiscard]] auto get_file(int fd) const -> kstd::shared_ptr<open_file_description>;
     auto remove_file(int fd) -> void;
 
   private:
     file_descriptor_table() = default;
 
-    // TODO BA-FS26 use kstd::shared_ptr when available
-    kstd::vector<std::optional<open_file_description>> m_open_files{};
+    kstd::vector<kstd::shared_ptr<open_file_description>> m_open_files{};
   };
 }  // namespace filesystem
 
diff --git a/kernel/include/kernel/filesystem/filesystem.hpp b/kernel/include/kernel/filesystem/filesystem.hpp
index 23924c4..e069ced 100644
--- a/kernel/include/kernel/filesystem/filesystem.hpp
+++ b/kernel/include/kernel/filesystem/filesystem.hpp
@@ -5,6 +5,7 @@
 #include "kernel/filesystem/inode.hpp"
 
 #include <kstd/memory>
+#include <kstd/vector>
 
 #include <string_view>
 
@@ -14,13 +15,15 @@ namespace filesystem
   {
     virtual ~filesystem() = default;
 
-    virtual auto mount(kstd::shared_ptr<devices::device> const & device) -> int = 0;
-    virtual auto lookup(inode const & parent, std::string_view name) -> inode * = 0;
+    virtual auto mount(kstd::shared_ptr<devices::device> const & device) -> int;
+    virtual auto lookup(kstd::shared_ptr<inode> const & parent, std::string_view name) -> kstd::shared_ptr<inode> = 0;
 
-    [[nodiscard]] auto root_inode() const -> inode const &;
+    [[nodiscard]] auto root_inode() const -> kstd::shared_ptr<inode> const &;
 
   protected:
-    inode m_root_inode{};  // TODO BA-FS26 set during mount?
+    kstd::shared_ptr<inode> m_root_inode{};
+    kstd::shared_ptr<devices::device> m_device{};
+    kstd::vector<kstd::shared_ptr<inode>> m_inodes{};
   };
 
 }  // namespace filesystem
diff --git a/kernel/include/kernel/filesystem/inode.hpp b/kernel/include/kernel/filesystem/inode.hpp
index a2955f9..6d8f0d4 100644
--- a/kernel/include/kernel/filesystem/inode.hpp
+++ b/kernel/include/kernel/filesystem/inode.hpp
@@ -1,37 +1,32 @@
 #ifndef TEACH_OS_KERNEL_FILESYSTEM_INODE_HPP
 #define TEACH_OS_KERNEL_FILESYSTEM_INODE_HPP
 
-#include "kernel/devices/device.hpp"
-#include "kernel/filesystem/inode_metadata.hpp"
-
-#include <kstd/memory>
-
 #include <cstddef>
 
 namespace filesystem
 {
   struct inode
   {
-    inode() = default;
+    enum class inode_kind
+    {
+      regular,
+      directory,
+      device
+    };
+
     explicit inode(inode_kind kind);
-    explicit inode(kstd::shared_ptr<devices::device> const & device);
 
-    [[nodiscard]] auto metadata() const -> inode_metadata;
+    virtual ~inode() = default;
+
+    virtual auto read(void * buffer, size_t offset, size_t size) const -> size_t = 0;
+    virtual auto write(void const * buffer, size_t offset, size_t size) -> size_t = 0;
 
     [[nodiscard]] auto is_directory() const -> bool;
     [[nodiscard]] auto is_regular() const -> bool;
     [[nodiscard]] auto is_device() const -> bool;
-    [[nodiscard]] auto is_block_device() const -> bool;
-    [[nodiscard]] auto major_device() const -> size_t;
-    [[nodiscard]] auto minor_device() const -> size_t;
-    [[nodiscard]] auto backing_device() const -> kstd::shared_ptr<devices::device> const &;
-
-    auto read(void * buffer, size_t offset, size_t size) const -> size_t;
-    auto write(void const * buffer, size_t offset, size_t size) -> size_t;
 
   private:
     inode_kind m_kind{inode_kind::regular};
-    kstd::shared_ptr<devices::device> m_device{};
   };
 }  // namespace filesystem
 
diff --git a/kernel/include/kernel/filesystem/inode_file.hpp b/kernel/include/kernel/filesystem/inode_file.hpp
deleted file mode 100644
index ee84eee..0000000
--- a/kernel/include/kernel/filesystem/inode_file.hpp
+++ /dev/null
@@ -1,27 +0,0 @@
-#ifndef TEACH_OS_KERNEL_FILESYSTEM_INODE_FILE_HPP
-#define TEACH_OS_KERNEL_FILESYSTEM_INODE_FILE_HPP
-
-#include "kernel/filesystem/file.hpp"
-#include "kernel/filesystem/inode.hpp"
-
-#include <kstd/memory>
-
-#include <cstddef>
-
-namespace filesystem
-{
-  struct inode_file : file
-  {
-    explicit inode_file(kstd::shared_ptr<inode> const & inode);
-
-    auto open() -> void override;
-
-    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;
-
-  private:
-    kstd::shared_ptr<inode> m_inode;
-  };
-}  // namespace filesystem
-
-#endif
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/inode_metadata.hpp b/kernel/include/kernel/filesystem/inode_metadata.hpp
deleted file mode 100644
index ed5a09d..0000000
--- a/kernel/include/kernel/filesystem/inode_metadata.hpp
+++ /dev/null
@@ -1,24 +0,0 @@
-#ifndef TEACH_OS_KERNEL_FILESYSTEM_INODE_METADATA_HPP
-#define TEACH_OS_KERNEL_FILESYSTEM_INODE_METADATA_HPP
-
-#include <cstddef>
-#include <optional>
-
-namespace filesystem
-{
-  enum class inode_kind
-  {
-    regular,
-    directory,
-    device
-  };
-
-  struct inode_metadata
-  {
-    inode_kind kind{inode_kind::regular};
-    std::optional<size_t> major{};
-    std::optional<size_t> minor{};
-  };
-}  // namespace filesystem
-
-#endif  // TEACH_OS_KERNEL_FILESYSTEM_INODE_METADATA_HPP
\ No newline at end of file
diff --git a/kernel/include/kernel/filesystem/mount.hpp b/kernel/include/kernel/filesystem/mount.hpp
index 232a9be..0f37687 100644
--- a/kernel/include/kernel/filesystem/mount.hpp
+++ b/kernel/include/kernel/filesystem/mount.hpp
@@ -1,9 +1,11 @@
 #ifndef TEACH_OS_KERNEL_FILESYSTEM_MOUNT_HPP
 #define T