/**
 * @file tarfs_tar.h
 *
 * Header file for tarfs_tar.c
 * Contains functions needed for parsing tar
 * This interface is aimed for interoperability with VFS
 *
 * @author Jaroslav Drazan <jaroslavdrazan@seznam.cz>
 * @author Petr Cermak <xgxg@seznam.cz>
 */

/* ************************************************************************* *
 *                                                                           *
 *   This program is free software; you can redistribute it and/or modify    *
 *   it under the terms of the GNU General Public License as published by    *
 *   the Free Software Foundation; either version 2 of the License, or       *
 *   (at your option) any later version.                                     *
 *                                                                           *
 * ************************************************************************* */

#ifndef __TARFS_TAR_H__
#define __TARFS_TAR_H__

// super_block
#include <linux/fs.h>

/**
 * @brief Performs quick valiadtion of tar
 *
 * This function controls only the first block
 *
 * @param s Super block structure needed to perform i/o operations
 * @return 1 - OK, 0 - is not tar, or other error
 */
int tar_quick_validation(struct super_block* s);

/**
 * @brief Returns number of root inode
 *
 * @param s Super block structure needed to perform i/o operations
 * @return Number of root inode, TARFS_EVAL - error
 */
unsigned long tar_get_root_ino(struct super_block* s);

/**
 * @breif Returns number of blocks in tar
 *
 * @param s Super block structure needed to perform i/o operations
 * @return Number of blocks, 0 - error (or empty)
 */
unsigned long tar_length(struct super_block* s);

/**
 * @brief Reads inode from tar
 *
 * Fills inode data like times, acces rights, size of file
 *
 * @param s Super block structure needed to perform i/o operations
 * @param inode Inode structure to be filled
 * @param rdev [out] If inode type is device, this parameter is filled with value
 * kdev_t_to_nr(major, minor)
 * @return Type of inode, as defined in stat.h (S_IFREG, S_IFLNK, S_IFCHR, S_IFBLK, S_IFIFO, S_IFDIR), 0 in case of error
 */
int tar_fill_inode(struct super_block* s, struct inode* inode, int* rdev);

/**
 * @brief Reads directory entries
 *
 * Reads directory entries, until stopped by returning <0 from filldir function,
 * after that, it stores last entry id read into filp->f_pos. When called again,
 * it continues from the last f_pos stored.
 *
 * @param s Super block structure needed to perform i/o operations
 * @param filp A file structure representing directory being read
 * @param dirent Falls through this function to the filldir call
 * @param filldir Pointer to a function called to add new dir entry
 * @return Count of directory entries read, TARFS_EVAL otherwise
 */
unsigned long tar_readdir(struct file* filp, void* dirent, filldir_t filldir);

/**
 * @brief Searches for file in given directory
 *
 * @param s Super block structure needed to perform i/o operations
 * @param ino Inode of directory to be searched in
 * @param fname Name of desired file
 * @param fsize Size of fname
 * @return Inode number of file if found, @a TARFS_EVAL otherwise
 */
unsigned long tar_lookup(struct super_block* s, unsigned long ino,const char* fname, unsigned int fsize);

/**
 * @brief Fills buffer with data from given inode
 *
 * Reads data from inode with given offset to the end of file or end of buffer (max PAGE_SIZE bytes)
 *
 * @param s Super block structure needed to perform i/o operations
 * @param inode Inode with data to be read
 * @param offset Offset of desired data
 * @param buffer Alredy allocated buffer of size PAGE_SIZE  (PAGE_SIZE should be multiple of 512)
 * @return 0 - EOF, 1 - OK, 2 - Symlink, TARFS_EVAL otherwise
 */
unsigned long tar_read_page(struct super_block* s, struct inode* inode, loff_t offset, void* buffer);

#endif //__TARFS_TAR_H__