OS_LAB/getdents.c

#define __LIBRARY__
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <fcntl.h>

#include <linux/kernel.h>
#include <linux/sched.h>
#include <asm/segment.h>
#include <sys/stat.h>

#define BUF_MAX  128
#define	DIRBUF  8192
#define NAME_MAX  14

struct dirent {                            /* Ŀ¼<C4BF><C2BC>ṹ<EFBFBD><E1B9B9> */
	long           d_ino;                  /* i<>ڵ<EFBFBD> */
	off_t          d_off;                  /* λ<><CEBB> */
	unsigned short d_reclen;               /* <20>ļ<EFBFBD><C4BC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> */
	char           d_name[NAME_MAX + 1];   /* <20>ļ<EFBFBD><C4BC><EFBFBD> */
};

int sys_getdents(unsigned int fd, struct dirent* dirp, unsigned int count) {
	struct file* file;
	struct m_inode* inode;
	struct buffer_head* head;
	struct dir_entry* de_tmp;
	struct dirent* self_tmp;                       /* ָ<><D6B8><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Զ<EFBFBD><D4B6><EFBFBD>ṹ<EFBFBD><E1B9B9><EFBFBD><EFBFBD><EFBFBD>ʱָ<CAB1><D6B8> */
	char* buf;
	int dir_size, dire_size, read_bytes, addr_off, i;

	dir_size = sizeof(struct dirent);              /* <20><>ǰĿ¼<C4BF>ṹ<EFBFBD><E1B9B9>Ĵ<EFBFBD>С */
	dire_size = sizeof(struct dir_entry);          /*  Ŀ¼<C4BF><C2BC>ṹ<EFBFBD><E1B9B9>Ĵ<EFBFBD>С  */

	self_tmp = (struct dirent*)malloc(dir_size);       /* <20>ȷ<EFBFBD><C8B7><EFBFBD><EFBFBD>ʼ<EFBFBD>ռ<EFBFBD> */
	buf = (char*)malloc(dir_size);

	file = current->filp[fd];                      /* <20><>ȡ<EFBFBD><C8A1>ǰĿ¼<C4BF><C2BC><EFBFBD><EFBFBD>Ϣ */
	inode = file->f_inode;
	head = bread(inode->i_dev, inode->i_zone[0]);

	/* <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ѭ<EFBFBD><D1AD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>dirpΪ<70><CEAA><EFBFBD><EFBFBD><EFBFBD>ڴ<EFBFBD>洢<EFBFBD><E6B4A2><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ŀ¼<C4BF><C2BC><EFBFBD><EFBFBD>Ϣ<EFBFBD><CFA2>read_bytes<65>洢<EFBFBD><E6B4A2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֽ<EFBFBD><D6BD><EFBFBD> */
	read_bytes = 0;
	for (addr_off = 0; addr_off < inode->i_size; addr_off += dire_size) {   /* <20>ӵ<EFBFBD>ǰĿ¼<C4BF><C2BC><EFBFBD><EFBFBD>ڿ<EFBFBD>ʼ<EFBFBD><CABC><EFBFBD><EFBFBD>ȡÿһ<C3BF><D2BB>Ŀ¼<C4BF><C2BC>Ļ<EFBFBD><C4BB><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> */
		if (read_bytes >= count - dir_size)                                 /* <20><><EFBFBD><EFBFBD><EFBFBD>ȡ<EFBFBD><C8A1><EFBFBD>ֽ<EFBFBD><D6BD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ƣ<EFBFBD>ֱ<EFBFBD><D6B1><EFBFBD>˳<EFBFBD>ѭ<EFBFBD><D1AD> */
			break;
		de_tmp = (struct dir_entry*)(head->b_data + addr_off);              /* deָ<65><D6B8>Ŀ¼<C4BF><EFBFBD><EEBBBA><EFBFBD><EFBFBD><EFBFBD>Ľṹ<C4BD><E1B9B9> */
		if (!de_tmp->inode)                                                 /* <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ŀ¼<C4BF><EFBFBD><EEA3AC><EFBFBD><EFBFBD> */
			continue;
		self_tmp->d_ino = de_tmp->inode;                                    /* Ŀ¼<C4BF><C2BC><EFBFBD><EFBFBD><EFBFBD>Ϣ<EFBFBD><CFA2><EFBFBD><EFBFBD>deָ<65><D6B8>Ľṹ<C4BD><E1B9B9><EFBFBD>У<EFBFBD><D0A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ǿ<EFBFBD><C7BF><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʱָ<CAB1><D6B8>self_tmpָ<70><D6B8>Ľṹ<C4BD><E1B9B9><EFBFBD><EFBFBD> */
		self_tmp->d_off = 0;
		self_tmp->d_reclen = dir_size;
		strcpy(self_tmp->d_name, de_tmp->name);
		memcpy(buf, self_tmp, dir_size);                                    /* <20>Ѹն<D1B8><D5B6><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ݿ<EFBFBD><DDBF><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>buf<75><66><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ڴ<EFBFBD><DAB4><EFBFBD> */
		for (i = 0; i < dir_size; i++)                                      /* <20><><EFBFBD>ڴ<EFBFBD><DAB4><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB><EFBFBD>ֽ<EFBFBD>һ<EFBFBD><D2BB><EFBFBD>ֽڵؿ<DAB5><D8BF><EFBFBD><EFBFBD><EFBFBD>dirp<72><70><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>û<EFBFBD>һ<EFBFBD><D2BB><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֵ */
			put_fs_byte(*(buf + i), ((char*)dirp) + i + read_bytes);
		read_bytes += dir_size;
	}
	return read_bytes;
}