linux/stat.c

/*
 *  linux/fs/stat.c
 *
 *  (C) 1991  Linus Torvalds
 */

#include <errno.h>
#include <sys/stat.h>

#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <asm/segment.h>
#include <fcntl.h>

static void cp_stat(struct m_inode * inode, struct stat * statbuf)
{
	struct stat tmp;
	int i;

	verify_area(statbuf,sizeof (* statbuf));
	tmp.st_dev = inode->i_dev;
	tmp.st_ino = inode->i_num;
	tmp.st_mode = inode->i_mode;
	tmp.st_nlink = inode->i_nlinks;
	tmp.st_uid = inode->i_uid;
	tmp.st_gid = inode->i_gid;
	tmp.st_rdev = inode->i_zone[0];
	tmp.st_size = inode->i_size;
	tmp.st_atime = inode->i_atime;
	tmp.st_mtime = inode->i_mtime;
	tmp.st_ctime = inode->i_ctime;
	for (i=0 ; i<sizeof (tmp) ; i++)
		put_fs_byte(((char *) &tmp)[i],&((char *) statbuf)[i]);
}

static void new_cp_stat(struct m_inode * inode, struct stat * statbuf)
{
	struct stat tmp;
	int i;

	verify_area(statbuf,sizeof (* statbuf));
	tmp.st_dev = inode->i_dev;
	tmp.st_ino = inode->i_num;
	tmp.st_mode = inode->i_mode;
	tmp.st_nlink = inode->i_nlinks;
	tmp.st_uid = inode->i_uid;
	tmp.st_gid = inode->i_gid;
	tmp.st_rdev = inode->i_zone[0];
	tmp.st_size = inode->i_size;
	tmp.st_atime = inode->i_atime;
	tmp.st_mtime = inode->i_mtime;
	tmp.st_ctime = inode->i_ctime;
	for (i=0 ; i<sizeof (tmp) ; i++)
		//put_fs_byte(((char *) &tmp)[i],&((char *) statbuf)[i]);
		((char *)statbuf)[i]=((char *) &tmp)[i];
}


int sys_stat(char * filename, struct stat * statbuf)
{
	struct m_inode * inode;

	if (!(inode=namei(filename)))
		return -ENOENT;
	cp_stat(inode,statbuf);
	iput(inode);
	return 0;
}

int my_stat(char * filename, struct stat * statbuf)
{
	struct m_inode * inode;

	if (!(inode=namei(filename)))
		return -ENOENT;
	new_cp_stat(inode,statbuf);
	iput(inode);
	return 0;
}

int sys_lstat(char * filename, struct stat * statbuf)
{
	return sys_stat(filename, statbuf);
}

int sys_fstat(unsigned int fd, struct stat * statbuf)
{
	struct file * f;
	struct m_inode * inode;

	if (fd >= NR_OPEN || !(f=current->filp[fd]) || !(inode=f->f_inode))
		return -EBADF;
	cp_stat(inode,statbuf);
	return 0;
}

int sys_readlink()
{
	return -ENOSYS;
}

char *sys_getcwd(char *buf,size_t size)
{
	char path[128], cwd[128], name[16], res[128]; 
	int dirp; 
	struct stat sb, sb_d, sb_1; 
	dev_t dev; 
	ino_t ino; 
	int tmp = 0, i; 
	memset(res, 0, sizeof(res)); 
	while(1) 
	{ 
		//将当前目录的字符串"."存入buf中才能作为stat的参数传入使用
		put_fs_byte('.', &buf[0]); 
		put_fs_byte(0, &buf[1]); 

		//获取当前目录的文件信息
		my_stat(buf, &sb); 
		dev = sb.st_dev; 
		ino = sb.st_ino;

		//将父目录".."字符串写入buf中
		put_fs_byte('.', &buf[0]); 
		put_fs_byte('.', &buf[1]); 
		put_fs_byte(0, &buf[2]); 

		//获取父目录的对应的目录流
		dirp = sys_open(buf, O_RDONLY, 0); 
		//获取父目录的文件信息
		my_stat(buf, &sb_1); 

		//判断当前目录是否与父目录相同，相同则找到当前路径
		if(sb_1.st_dev == dev && sb_1.st_ino == ino)
		{ 
			break; 
		}

		//在父目录对应的目录流读取条目（与getdents类似）
		//遍历父目录下对应的所有目录与之前获取的当前目录想匹配，匹配成功的目录项对当前目录所在的目录项，即可保存名字后继续向前寻找
		while(my_read(dirp, name, 16) > 0 && name[0])
		{ 
			tmp = 0; 
			memset(path, 0, sizeof(path)); 
			path[0] = '.';path[1] = '.';path[2] = '/'; 
			while(name[tmp+2])
			{ 
				path[tmp+3] = name[tmp+2]; 
				tmp++; 
			}
			path[tmp+3] = 0; 
			for(i=0;i<size;i++)
				put_fs_byte(path[i], &buf[i]); 

		    //获取当前父目录下的目录项文件信息
			my_stat(buf, &sb_d); 
			if(dev == sb_d.st_dev && ino == sb_d.st_ino)
			{ 
				//若匹配成功，则写入文件路径
				memset(cwd, 0, sizeof(cwd)); 
				strcat(cwd, "/"); 
				strcat(cwd, name+2); 
				strcat(cwd, res); 
				strncpy(res, cwd, size); 
				break; 
			}
		}
		//关闭当前打开的父目录
		sys_close(dirp); 

		//将buf重新修改为父目录对应的字符串".."
		put_fs_byte('.', &buf[0]); 
		put_fs_byte('.', &buf[1]); 
		put_fs_byte(0, &buf[2]); 

		//改变当前目录到上一级，继续上述遍历寻找步骤直到父目录与当前目录相一致
		sys_chdir(buf);
	}
	//将得到的路径写入buf中
	for(i=0;i<size;i++) 
		put_fs_byte(res[i], &buf[i]); 
	sys_close(dirp); 
	sys_chdir(buf); 
	return buf;
}