creat.c

基于UNIX6的文件系统模拟程序

#include <stdio.h>
#include "filesys.h"


creat(u_id,filename,mode)
unsigned int u_id;
char *filename;
unsigned short mode;
{
	unsigned int di_ith,di_ino;
	struct inode *inode;
	int i,j;

	int user_id = getid(u_id);
	di_ino=namei(filename);
	if(di_ino != NULL) /* already existed */
	{
		inode=iget(di_ino);
		if(access(user_id,inode,mode)==0)
		{
			iput(inode);
			printf("\ncreat accessnot allowed\n");
			return;
		}
		/* free all the block of the old file */
		for(i=0;i<inode->di_size/BLOCKSIZ+1;i++)
		{
			bfree(inode->di_addr[i]);
		}
		/* to do :add code here to update the pointer of the sys_file */
		for(i=0;i<SYSOPENFILE;i++)
			if(sys_ofile[i].f_inode==inode)
			{
				sys_ofile[i].f_off=0;
			}
		for(i=0;i<NOFILE;i++)
			if(user[user_id].u_ofile[i]==SYSOPENFILE+1)
			{
				user[user_id].u_uid=inode->di_uid;
				user[user_id].u_gid=inode->di_gid;
				for(j=0;j<SYSOPENFILE;j++)
					if(sys_ofile[j].f_count=0)
					{
						user[user_id].u_ofile[i]=j;
						sys_ofile[j].f_flag=mode;
					}
				return i;
			}
	}
	else /*not existed before */
	{
		inode = ialloc();
		di_ith = iname(filename);

		dir.size++;


//		printf("dir.size:%d",dir.size);

		dir.direct[di_ith].d_ino=inode->i_ino;
		inode->di_mode=mode;//user[user_id].u_default_mode;

//		printf("mode:%d",mode);
		inode->di_uid=user[user_id].u_uid;
		inode->di_gid=user[user_id].u_gid;
		inode->di_size=0;
		inode->di_number=1;//0 I think 1 will be right here,so I got it changed

		for(i=0;i<SYSOPENFILE;i++)
			if(sys_ofile[i].f_count==0)
				break;
		for(j=0;j<NOFILE;j++)
			if(user[user_id].u_ofile[j]==SYSOPENFILE+1)
				break;

		user[user_id].u_ofile[j]=i;
		sys_ofile[i].f_flag=mode;
		sys_ofile[i].f_count=0;
		sys_ofile[i].f_off=0;
		sys_ofile[i].f_inode=inode;

		return j;
	}
}