read.c

#include "api.h"
/* Function to read a data from a file. If file_size not exceeds 4096 bytes then read only direct block */
int read_file(char *filePath)
{
	int i;
	int file_inode_index = get_inode(filePath, 0, strlen(filePath));
	//int file_inode_index = 2;
	inode * file_inode = &(inode_table_object->inode_index[file_inode_index]);
	int file_size = file_inode->size;

	char buff[4096];
	si_block * si_block_object ;
	si_block_object = (si_block *) buff;
	my_read(si_block_object, BS, file_inode->single_indirect_block_offset);
#ifdef DEBUG_BUILD
	printf("in read.c read_file: *** File_inode: %d  di_db_offset: %d  si_block_offset:%d  ***\n", file_inode_index, file_inode->direct_block_offset,file_inode->single_indirect_block_offset);

	printf("\n--------------------------------------\n");
	for(i = 0;i < (BS / sizeof(int *));i++){
		printf("in read.c read_file(): si_block(%d) -> db_offset[%d]:%d\n",file_inode->single_indirect_block_offset,i,si_block_object->db_index[i]);
	}
	printf("\n--------------------------------------\n");
#endif
	if(file_size < sizeof(data_block))
		print_data_block(file_size, file_inode->direct_block_offset);
	else
		print_data_block(sizeof(data_block), file_inode->direct_block_offset);


	if(file_size > BS){
		//file_size -= BS;
		read_file_from_indirect_block(file_size-BS, file_inode);
	}
	//putc('\n',stdout);
	return 0;
}
/* Function to read from a file from single indirect block */
int read_file_from_indirect_block(int file_size, inode * file_inode)
{
	int i,print_len;
	char buff[BS];
	si_block * si_block_object ;
	si_block_object = (si_block *) buff;

	my_read(si_block_object, BS, file_inode->single_indirect_block_offset);
	int remain_block = ceil((float) (file_size * 1.0)/ BS);

	print_len = BS;

	while(remain_block > 0){
		if(remain_block > BS / sizeof(int *)){
			for(i = 0;i < (BS / sizeof(int *)) - 1;i++ ){
				//printf("\n------------------- si_block[%d] at (%d)----------------------------\n",i,si_block_object->db_index[i]);
				print_data_block(print_len, si_block_object->db_index[i]);
				file_size -= BS;
			}
		}else{
			for(i = 0;i < remain_block ;i++ ){
				if(file_size < BS)
					print_len = file_size;
				//printf("\n------------------- si_block[%d] at (%d)----------------------------\n",i,si_block_object->db_index[i]);
				print_data_block(print_len, si_block_object->db_index[i]);
				file_size -= BS;
			}
		}
		my_read(si_block_object, BS, si_block_object->db_index[(BS / sizeof(int *)) - 1]);
		remain_block -= (BS / sizeof(int *)) - 1;
	}

	return 0;
}

int print_data_block(int count, unsigned int offset){
	int i;
	data_block data_block_object;
	my_read(&data_block_object, count, offset);
	for(i=0; i < count ; i++)
		putc(data_block_object.data[i],stdout);
	return 0;
}