1 files changed, 104 insertions, 0 deletions
diff --git a/include/hilbert/kernel/storage.hpp b/include/hilbert/kernel/storage.hpp
new file mode 100644
index 0000000..ea40d86
--- /dev/null
+++ b/include/hilbert/kernel/storage.hpp
@@ -0,0 +1,104 @@
+#ifndef HILBERT_KERNEL_STORAGE_HPP
+#define HILBERT_KERNEL_STORAGE_HPP
+
+#include <hilbert/kernel/utility.hpp>
+#include <cstdint>
+
+namespace hilbert::kernel::storage {
+
+  typedef uint64_t node_id_t;
+  typedef uint64_t directory_iter_t;
+
+  enum class file_type {
+    regular_file,
+    directory,
+    symlink
+  };
+
+  enum class bd_result {
+    success,
+    out_of_bounds,
+    device_error
+  };
+
+  enum class fs_result {
+    success,
+    device_error,
+    fs_corrupt
+  };
+
+  struct dir_entry {
+    utility::string name;
+    node_id_t node;
+    file_type type;
+    //only used if type is regular_file.
+    uint64_t length;
+    //only used if type is symlink.
+    utility::string target;
+  };
+
+  class file_system_instance {
+
+  public:
+    virtual ~file_system_instance() {}
+
+    virtual fs_result get_root_node(node_id_t &out) = 0;
+
+    //it is assumed that this is a directory. sets iter_out
+    //to a value that can be passed to subsequent calls
+    //to get_next_child with the same argument for node.
+    virtual fs_result get_first_child(node_id_t node, std::optional<dir_entry> &out, directory_iter_t &iter_out) = 0;
+
+    //it is assumed that this is a directory. sets iter_out
+    //to a value that can be passed to subsequent calls
+    //to get_next_child with the same argument for node.
+    virtual fs_result get_next_child(node_id_t node, std::optional<dir_entry> &out, directory_iter_t &iter) = 0;
+
+    //it is assumed that this is a regular file and that
+    //the region requested is within the bounds of the file.
+    virtual fs_result read_bytes_from_file(node_id_t node, uint64_t start, uint64_t count, void *into) = 0;
+
+  };
+
+  class block_device {
+
+  private:
+    uint8_t *block_cache;
+    uint64_t block_cache_i;
+
+    //it is assumed that this block is within the bounds of the device.
+    bd_result load_cache_block(uint64_t i);
+
+  protected:
+    //implemented in driver. it is assumed that the
+    //blocks are within the bounds of the device.
+    virtual bd_result read_blocks_no_cache(uint64_t start, uint64_t count, void *into) = 0;
+
+    //it is assumed that this is only called once, by the driver, after
+    //block_size and block_count have been set, and before read_bytes or
+    //write_bytes can be called (e.g. in the derived class's constructor).
+    void allocate_block_cache();
+
+  public:
+    //set by storage component
+    file_system_instance *mounted_as;
+    //set by storage component
+    utility::uuid id;
+
+    //set by driver
+    uint64_t block_size;
+    //set by driver
+    uint64_t block_count;
+
+    virtual ~block_device() {
+      if (block_cache)
+        delete block_cache;
+    }
+
+    bd_result read_bytes(uint64_t start, uint64_t count, void *into);
+
+  };
+
+}
+
+#endif