access.c

基于UNIX6的文件系统模拟程序

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


unsigned int access(user_id,inode,mode)
unsigned int user_id;
struct inode *inode;
unsigned short mode;
{
	switch(mode%8)
	{
	case READ:
		if(inode->di_mode&ODIREAD) return 1;	
		if((inode->di_mode & GDIREAD)&&
			(user[user_id].u_gid == inode->di_gid))  return 1;
		if((inode->di_mode&UDIREAD)&&
			(user[user_id].u_uid == inode->di_uid))  return 1;
		return 0;
	case WRITE:
		if(inode->di_mode&ODIWRITE) return 1;	
		if((inode->di_mode & GDIWRITE)&&
			(user[user_id].u_gid == inode->di_gid))  return 1;
		if((inode->di_mode&UDIWRITE)&&
			(user[user_id].u_uid == inode->di_uid))  return 1;
		return 0;
	case EXICUTE:
		if(inode->di_mode&ODIEXICUTE) return 1;	
		if((inode->di_mode & GDIEXICUTE)&&
			(user[user_id].u_gid == inode->di_gid))  return 1;
		if((inode->di_mode&UDIEXICUTE)&&
			(user[user_id].u_uid == inode->di_uid))  return 1;
		return 0;
	case FAPPEND:
		if(inode->di_mode&ODIEXICUTE) return 1;	
		if((inode->di_mode & GDIEXICUTE)&&
			(user[user_id].u_gid == inode->di_gid))  return 1;
		if((inode->di_mode&UDIEXICUTE)&&
			(user[user_id].u_uid == inode->di_uid))  return 1;
		return 0;
	default:
		return 0;
	}
}