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)

7 files changed, 156 insertions, 17 deletions

diff --git a/kernel/filesystem/include/filesystem/filesystem.hpp b/kernel/filesystem/include/filesystem/filesystem.hpp
index a5a1047..2077ed6 100644
--- a/kernel/filesystem/include/filesystem/filesystem.hpp
+++ b/kernel/filesystem/include/filesystem/filesystem.hpp
@@ -12,10 +12,10 @@ namespace filesystem
 
     virtual auto mount(devices::device * device) -> int = 0;
 
-    [[nodiscard]] auto root_inode() const -> inode *;
+    [[nodiscard]] auto root_inode() const -> inode const &;
 
   protected:
-    inode * m_root_inode{};  // TODO BA-FS26 set during mount?
+    inode m_root_inode{};  // TODO BA-FS26 set during mount?
   };
 
 }  // namespace filesystem
diff --git a/kernel/filesystem/include/filesystem/inode.hpp b/kernel/filesystem/include/filesystem/inode.hpp
index 44ec09a..eb8440f 100644
--- a/kernel/filesystem/include/filesystem/inode.hpp
+++ b/kernel/filesystem/include/filesystem/inode.hpp
@@ -1,13 +1,28 @@
 #ifndef TEACH_OS_KERNEL_FILESYSTEM_INODE_HPP
 #define TEACH_OS_KERNEL_FILESYSTEM_INODE_HPP
 
+#include "devices/device.hpp"
+
 #include <cstddef>
+
 namespace filesystem
 {
   struct inode
   {
+    inode() = default;
+    explicit inode(devices::device * device);
+
+    [[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 -> devices::device *;
+
     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:
+    devices::device * m_device{};
   };
 }  // namespace filesystem
 
diff --git a/kernel/filesystem/include/filesystem/vfs.hpp b/kernel/filesystem/include/filesystem/vfs.hpp
index 182666d..a881241 100644
--- a/kernel/filesystem/include/filesystem/vfs.hpp
+++ b/kernel/filesystem/include/filesystem/vfs.hpp
@@ -2,10 +2,14 @@
 #define TEACH_OS_KERNEL_FILESYSTEM_VFS_HPP
 
 #include "devices/device.hpp"
+#include "filesystem/custody.hpp"
+#include "filesystem/inode.hpp"
 #include "filesystem/mount.hpp"
+#include "filesystem/open_file_description.hpp"
 
 #include <array>
 #include <optional>
+#include <string_view>
 
 namespace filesystem
 {
@@ -16,13 +20,22 @@ namespace filesystem
 
     ~vfs() = default;
 
-    auto make_device_node(devices::device * device) -> void;
+    auto open(std::string_view path) -> std::optional<open_file_description>;
 
   private:
+    struct device_node_entry
+    {
+      std::string_view name;
+      inode node;
+    };
+
     vfs() = default;
+    auto make_device_node(devices::device * device) -> void;
+    [[nodiscard]] auto resolve_path(std::string_view path) -> std::optional<custody>;
 
     std::optional<mount> m_root_mount;
     std::array<mount, 10> m_mounts;  // TODO BA-FS26 remove when kstd::vector is available and used
+    std::array<std::optional<device_node_entry>, 10> m_device_nodes;  // TODO BA-FS26 use kstd::vector
   };
 }  // namespace filesystem
 
diff --git a/kernel/filesystem/src/ext2/ext2_filesystem.cpp b/kernel/filesystem/src/ext2/ext2_filesystem.cpp
index 7111d13..97257a2 100644
--- a/kernel/filesystem/src/ext2/ext2_filesystem.cpp
+++ b/kernel/filesystem/src/ext2/ext2_filesystem.cpp
@@ -1,6 +1,7 @@
 #include "filesystem/ext2/ext2_filesystem.hpp"
 
 #include "devices/device.hpp"
+#include "filesystem/inode.hpp"
 
 namespace filesystem::ext2
 {
@@ -10,6 +11,9 @@ namespace filesystem::ext2
     {
       return -1;  // TODO BA-FS26 panic or errorcode?
     }
+
+    m_root_inode = inode{};  // TODO BA-FS26 set properly during mount?
+
     // TODO BA-FS26 implement
     return 0;
   }
diff --git a/kernel/filesystem/src/filesystem.cpp b/kernel/filesystem/src/filesystem.cpp
index 2c63766..cdfe7f8 100644
--- a/kernel/filesystem/src/filesystem.cpp
+++ b/kernel/filesystem/src/filesystem.cpp
@@ -4,7 +4,7 @@
 
 namespace filesystem
 {
-  auto filesystem::root_inode() const -> inode *
+  auto filesystem::root_inode() const -> inode const &
   {
     return m_root_inode;
   }
diff --git a/kernel/filesystem/src/inode.cpp b/kernel/filesystem/src/inode.cpp
index 7bca507..a1427e2 100644
--- a/kernel/filesystem/src/inode.cpp
+++ b/kernel/filesystem/src/inode.cpp
@@ -2,18 +2,74 @@
 
 #include "kapi/system.hpp"
 
+#include "devices/device.hpp"
+
 #include <cstddef>
 
 namespace filesystem
 {
+  inode::inode(devices::device * device)
+      : m_device(device)
+  {
+    if (!m_device)
+    {
+      kapi::system::panic("[FILESYSTEM] inode constructed with null device.");
+    }
+  }
+
+  auto inode::is_device() const -> bool
+  {
+    return m_device != nullptr;
+  }
+
+  auto inode::is_block_device() const -> bool
+  {
+    return is_device() && m_device->is_block_device();
+  }
+
+  auto inode::major_device() const -> size_t
+  {
+    if (!is_device())
+    {
+      kapi::system::panic("[FILESYSTEM] inode::major_device called on non-device inode.");
+    }
+
+    return m_device->major();
+  }
+
+  auto inode::minor_device() const -> size_t
+  {
+    if (!is_device())
+    {
+      kapi::system::panic("[FILESYSTEM] inode::minor_device called on non-device inode.");
+    }
+
+    return m_device->minor();
+  }
+
+  auto inode::backing_device() const -> devices::device *
+  {
+    return m_device;
+  }
+
   auto inode::read(void * /*buffer*/, size_t /*offset*/, size_t /*size*/) const -> size_t
   {
+    if (is_device())
+    {
+      kapi::system::panic("[FILESYSTEM] inode::read called on device inode. Open it as a device file first.");
+    }
+
     // TODO BA-FS26
     return 0;
   }
 
   auto inode::write(void const *, size_t, size_t) -> size_t
   {
+    if (is_device())
+    {
+      kapi::system::panic("[FILESYSTEM] inode::write called on device inode. Open it as a device file first.");
+    }
+
     kapi::system::panic("[FILESYSTEM] inode::write is not implemented yet");
     return 0;
   }
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