// $Id: ex3.c,v 1.5 2006/12/21 01:10:42 kaiya Exp kaiya $

/*
Spec
   Get dirent data in n'th block from standard input

Usage
   ./a.out block_number < filesystem_file

Output
    List of information of each file in the directory

Limit
   block_number: natural number and it should specify directory block. 
   0<=block_number<1440
   filesytem_file should be simple ext2 file system dump; 
   i.e. block size=1024B, number of blocks=1440.

Comple
   gcc thisfile.c using ext2_os2006.h

Platform
	gcc in PPC
 */

#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

// #include <linux/ext2_fs.h>
#include "ext2_os2006.h"

#define BLOCKSIZE 1024

/*
 Get dir_entry from byte array. 
 Arguments:
   *block ro: begin of byte array
   *de rw: begin address of gotten dir_entry. de->name is terminated.
   *resta rw: bytes still remained. 
 Return:
   pointer to the next dir entry.
 */
unsigned char* get_dir_entry(
	struct ext2_dir_entry_2* de, unsigned char* block, int* resta
){
	if(*resta<=0) return NULL;
	memcpy(de, block, sizeof(*de));
	de->name[de->name_len]='\0';
	*resta -= (int)rev16(de->rec_len);
	return block+(int)rev16(de->rec_len);
}

main(int argc, char* argv[]){
unsigned char block[BLOCKSIZE];
int nb, c;

	if(argc<2) exit(1);
	nb=atoi(argv[1]);
	if(nb<0 || nb>1440) exit(2);

	fprintf(stderr, "parse dir. block #\%d\n", nb);

	for(c=0; read(0, block, BLOCKSIZE)==BLOCKSIZE; c++){
		if(c==nb){
			struct ext2_dir_entry_2 dirent2;
			unsigned char* ptr=block;
			int rest=BLOCKSIZE;
			while((ptr=get_dir_entry(&dirent2, ptr, &rest))!=NULL){
				printf("inode = %d, file type = %d, file name =(%s) (lec_len = %d)\n",
					rev32(dirent2.inode), dirent2.file_type, dirent2.name, rev16(dirent2.rec_len)
				);
			}
			break;
		}
	}
}