inodemanage.c

操作系统简单的登入程序

#include <stdio.h>
#include "filesys.h"
void updateinodemap(unsigned short order , char flag);
void updateinodetable(struct inode* ainode);
struct inode* posinode(unsigned short nid)
{
		struct inode* ainode=malloc(sizeof(struct inode));

		fd=fopen("filesystem","r+");

		fseek(fd,(3*BLOCKSIZE)+sizeof(struct inode)*nid,SEEK_SET);

		fread(ainode,sizeof(struct inode),1,fd);

		fclose(fd);

		return ainode;
	
}

/*
ialloc function write the ainode to the filesys.o(ainode's address  is already allocated).
change the super->s_pinode and ainode->i_ino.
*/
struct inode* ialloc(struct inode* ainode)
{

	unsigned short number=0;

	unsigned short i;
	
	struct inode* pinode;

	if(super->s_ninode==0)
	{
		printf("\n HAVE NO INODE LEFT!!!\n");

		return  NULL;
	}
        number=super->s_pinode;
		
		*(super->s_inode+number)='1';

	
	updateinodemap(number,'1');

	if(--super->s_ninode!=0)
	{
	
		for(i=0;i<INODENUMBER;i++)
		{
			
			if(*(super->s_inode +(super->s_pinode+i)%INODENUMBER)!='1')
			{
				super->s_pinode=(super->s_pinode+i)%INODENUMBER;	

				updatesys();
				
				break;	
			}

			
		}
		
	}



	
	ainode->i_ino=number;

	updateinodetable(ainode);

	return ainode;
	
	
}	


int ifree(unsigned short pos)

{
	if(super->s_ninode + 1 > BLOCKNUM)
	{
		printf("\nDisk Error!!!\n");

		return  DISKFULL;	
	}
	super->s_ninode++;

	*(super->s_inode+pos)='0';

	updateinodemap(pos,'0');
	
	super->s_pinode=pos;	

	updatesys();

	return DISKSUCCESS;
}
	
void updateinodemap(unsigned short order , char flag)
{	
		fd=fopen("filesystem","r+");
		
		fseek(fd,(2*BLOCKSIZE)+order,SEEK_SET);
		fwrite(&flag,sizeof(char),1,fd);

		fclose(fd);
		
}
void updateinodetable(struct inode* ainode)
{
		fd=fopen("filesystem","r+");
		fseek(fd,(3*BLOCKSIZE)+sizeof(struct inode)*(ainode->i_ino),SEEK_SET);
		fwrite(ainode,sizeof(struct inode),1,fd);
		fclose(fd);
		
}


void* fchmod(char* name,unsigned short mode)
{
	unsigned short nid;
	
	char* content;

	struct  inode* pinode;

	nid=map2inode(name);
	
	if(nid==MAPERR)
		return NULL;


	pinode=(struct inode*)posinode(nid);

	pinode->di_mode=mode;

		
	updateinodetable(pinode);

	return pinode;

}