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#ifndef MERCURY_KERNEL_STORAGE_HPP
#define MERCURY_KERNEL_STORAGE_HPP
#include <mercury/kernel/utility.hpp>
#include <cstdint>
namespace mercury::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
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