namei.c

来自「基于组件方式开发操作系统的OSKIT源代码」· C语言 代码 · 共 1,292 行 · 第 1/2 页

	int i;
	const unsigned char *ip;
	char *op;
	int fill;
	unsigned char c1, c2, c3;

	if (utf8) {
		*outlen = utf8_mbstowcs((__u16 *) outname, name, PAGE_SIZE);
		if (name[len-1] == '.')
			*outlen-=2;
		op = &outname[*outlen * sizeof(__u16)];
	} else {
		if (name[len-1] == '.') 
			len--;
		op = outname;
		if (nls) {
			for (i = 0, ip = name, op = outname, *outlen = 0;
			     i < len && *outlen <= 260; i++, *outlen += 1)
			{
				if (escape && (*ip == ':')) {
					if (i > len - 4) return -EINVAL;
					c1 = fat_esc2uni[ip[1]];
					c2 = fat_esc2uni[ip[2]];
					c3 = fat_esc2uni[ip[3]];
					if (c1 == 255 || c2 == 255 || c3 == 255)
						return -EINVAL;
					*op++ = (c1 << 4) + (c2 >> 2);
					*op++ = ((c2 & 0x3) << 6) + c3;
					ip += 4;
				} else {
					*op++ = nls->charset2uni[*ip].uni1;
					*op++ = nls->charset2uni[*ip].uni2;
					ip++;
				}
			}
		} else {
			for (i = 0, ip = name, op = outname, *outlen = 0;
			     i < len && *outlen <= 260; i++, *outlen += 1)
			{
				*op++ = *ip++;
				*op++ = 0;
			}
		}
	}
	if (*outlen > 260)
		return -ENAMETOOLONG;

	if (*outlen % 13) {
		*op++ = 0;
		*op++ = 0;
		*outlen += 1;
		if (*outlen % 13) {
			fill = 13 - (*outlen % 13);
			for (i = 0; i < fill; i++) {
				*op++ = 0xff;
				*op++ = 0xff;
			}
			*outlen += fill;
		}
	}

	return 0;
}

static int
vfat_fill_long_slots(struct msdos_dir_slot *ds, const char *name, int len,
		     char *msdos_name, int *slots,
		     int uni_xlate, int utf8, struct nls_table *nls)
{
	struct msdos_dir_slot *ps;
	struct msdos_dir_entry *de;
	int res;
	int slot;
	unsigned char cksum;
	char *uniname;
	const char *ip;
	unsigned long page;
	int unilen;
	int i;
	loff_t offset;

	if (name[len-1] == '.') len--;
	if(!(page = __get_free_page(GFP_KERNEL)))
		return -ENOMEM;
	uniname = (char *) page;
	res = xlate_to_uni(name, len, uniname, &unilen, uni_xlate, utf8, nls);
	if (res < 0) {
		free_page(page);
		return res;
	}

	*slots = unilen / 13;
	for (cksum = i = 0; i < 11; i++) {
		cksum = (((cksum&1)<<7)|((cksum&0xfe)>>1)) + msdos_name[i];
	}
	PRINTK3(("vfat_fill_long_slots 3: slots=%d\n",*slots));

	for (ps = ds, slot = *slots; slot > 0; slot--, ps++) {
		ps->id = slot;
		ps->attr = ATTR_EXT;
		ps->reserved = 0;
		ps->alias_checksum = cksum;
		ps->start = 0;
		offset = (slot - 1) * 26;
		ip = &uniname[offset];
		memcpy(ps->name0_4, ip, 10);
		memcpy(ps->name5_10, ip+10, 12);
		memcpy(ps->name11_12, ip+22, 4);
	}
	ds[0].id |= 0x40;

	de = (struct msdos_dir_entry *) ps;
	PRINTK3(("vfat_fill_long_slots 9\n"));
	strncpy(de->name, msdos_name, MSDOS_NAME);
	(*slots)++;

	free_page(page);
	return 0;
}

/* We can't get "." or ".." here - VFS takes care of those cases */

static int vfat_build_slots(struct inode *dir,const char *name,int len,
     struct msdos_dir_slot *ds, int *slots)
{
	struct msdos_dir_entry *de;
	char msdos_name[MSDOS_NAME];
	int res, xlate, utf8;
	struct nls_table *nls;

	de = (struct msdos_dir_entry *) ds;
	xlate = MSDOS_SB(dir->i_sb)->options.unicode_xlate;
	utf8 = MSDOS_SB(dir->i_sb)->options.utf8;
	nls = MSDOS_SB(dir->i_sb)->nls_io;

	*slots = 1;
	res = vfat_valid_longname(name, len, xlate);
	if (res < 0)
		return res;
	if (vfat_valid_shortname(name, len, utf8) >= 0) {
		vfat_format_name(name, len, de->name, utf8);
		return 0;
	}
	res = vfat_create_shortname(dir, name, len, msdos_name, utf8);
	if (res < 0)
		return res;
	return vfat_fill_long_slots(ds, name, len, msdos_name, slots, xlate,
					utf8, nls);
}

static int vfat_add_entry(struct inode *dir,struct qstr* qname,
	int is_dir,struct vfat_slot_info *sinfo_out,
	struct buffer_head **bh, struct msdos_dir_entry **de)
{
	struct super_block *sb = dir->i_sb;
	struct msdos_dir_slot *ps;
	loff_t offset;
	struct msdos_dir_slot *ds;
	int slots, slot;
	int res;
	struct msdos_dir_entry *de1;
	struct buffer_head *bh1;
	int ino;
	int len;
	loff_t dummy;

	ds = (struct msdos_dir_slot *)
	    kmalloc(sizeof(struct msdos_dir_slot)*MSDOS_SLOTS, GFP_KERNEL);
	if (ds == NULL) return -ENOMEM;

	len = qname->len;
	while (len && qname->name[len-1] == '.')
		len--;
	res = fat_search_long(dir, qname->name, len,
			(MSDOS_SB(sb)->options.name_check != 's') ||
			!MSDOS_SB(sb)->options.posixfs,
			&dummy, &dummy);
	if (res > 0) /* found */
		res = -EEXIST;
	if (res)
		goto cleanup;

	res = vfat_build_slots(dir, qname->name, len, ds, &slots);
	if (res < 0) goto cleanup;

	offset = fat_add_entries(dir, slots, &bh1, &de1, &ino);
	if (offset < 0) {
		res = offset;
		goto cleanup;
	}
	fat_brelse(sb, bh1);

	/* Now create the new entry */
	*bh = NULL;
	for (slot = 0, ps = ds; slot < slots; slot++, ps++) {
		if (fat_get_entry(dir,&offset,bh,de, &sinfo_out->ino) < 0) {
			res = -EIO;
			goto cleanup;
		}
		memcpy(*de, ps, sizeof(struct msdos_dir_slot));
		fat_mark_buffer_dirty(sb, *bh, 1);
	}

	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
	mark_inode_dirty(dir);

	fat_date_unix2dos(dir->i_mtime,&(*de)->time,&(*de)->date);
	(*de)->ctime_ms = 0;
	(*de)->ctime = (*de)->time;
	(*de)->adate = (*de)->cdate = (*de)->date;
	(*de)->start = 0;
	(*de)->starthi = 0;
	(*de)->size = 0;
	(*de)->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
	(*de)->lcase = CASE_LOWER_BASE | CASE_LOWER_EXT;


	fat_mark_buffer_dirty(sb, *bh, 1);

	/* slots can't be less than 1 */
	sinfo_out->long_slots = slots - 1;
	sinfo_out->longname_offset = offset - sizeof(struct msdos_dir_slot) * slots;
	res = 0;

cleanup:
	kfree(ds);
	return res;
}

static int vfat_find(struct inode *dir,struct qstr* qname,
	struct vfat_slot_info *sinfo, struct buffer_head **last_bh,
	struct msdos_dir_entry **last_de)
{
	struct super_block *sb = dir->i_sb;
	loff_t offset;
	int res,len;

	len = qname->len;
	while (len && qname->name[len-1] == '.') 
		len--;
	res = fat_search_long(dir, qname->name, len,
			(MSDOS_SB(sb)->options.name_check != 's'),
			&offset,&sinfo->longname_offset);
	if (res>0) {
		sinfo->long_slots = res-1;
		if (fat_get_entry(dir,&offset,last_bh,last_de,&sinfo->ino)>=0)
			return 0;
		res = -EIO;
	} 
	return res ? res : -ENOENT;
}

/* Find a hashed dentry for inode; NULL if there are none */
static struct dentry *find_alias(struct inode *inode)
{
	struct list_head *head, *next, *tmp;
	struct dentry *alias;

	head = &inode->i_dentry;
	next = inode->i_dentry.next;
	while (next != head) {
		tmp = next;
		next = tmp->next;
		alias = list_entry(tmp, struct dentry, d_alias);
		if (!list_empty(&alias->d_hash))
			return dget(alias);
	}
	return NULL;
}

struct dentry *vfat_lookup(struct inode *dir,struct dentry *dentry)
{
	int res;
	struct vfat_slot_info sinfo;
	struct inode *inode;
	struct dentry *alias;
	struct buffer_head *bh = NULL;
	struct msdos_dir_entry *de;
	int table;
	
	PRINTK2(("vfat_lookup: name=%s, len=%d\n", 
		 dentry->d_name.name, dentry->d_name.len));

	table = (MSDOS_SB(dir->i_sb)->options.name_check == 's') ? 2 : 0;
	dentry->d_op = &vfat_dentry_ops[table];

	inode = NULL;
	res = vfat_find(dir,&dentry->d_name,&sinfo,&bh,&de);
	if (res < 0) {
		table++;
		goto error;
	}
	inode = fat_build_inode(dir->i_sb, de, sinfo.ino, &res);
	fat_brelse(dir->i_sb, bh);
	if (res)
		return ERR_PTR(res);
	alias = find_alias(inode);
	if (alias) {
		if (d_invalidate(alias)==0)
			dput(alias);
		else {
			iput(inode);
			return alias;
		}
		
	}
error:
	dentry->d_op = &vfat_dentry_ops[table];
	dentry->d_time = dentry->d_parent->d_inode->i_version;
	d_add(dentry,inode);
	return NULL;
}

int vfat_create(struct inode *dir,struct dentry* dentry,int mode)
{
	struct super_block *sb = dir->i_sb;
	struct inode *inode = NULL;
	struct buffer_head *bh = NULL;
	struct msdos_dir_entry *de;
	struct vfat_slot_info sinfo;
	int res;

	res = vfat_add_entry(dir, &dentry->d_name, 0, &sinfo, &bh, &de);
	if (res < 0)
		return res;
	inode = fat_build_inode(sb, de, sinfo.ino, &res);
	fat_brelse(sb, bh);
	if (!inode)
		return res;
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	mark_inode_dirty(inode);
	inode->i_version = ++event;
	dir->i_version = event;
	MSDOS_I(dir)->i_last_pos = 0;
	dentry->d_time = dentry->d_parent->d_inode->i_version;
	d_instantiate(dentry,inode);
	return 0;
}

static int vfat_create_dotdirs(struct inode *dir, struct inode *parent)
{
	struct super_block *sb = dir->i_sb;
	struct buffer_head *bh;
	struct msdos_dir_entry *de;
	__u16 date, time;

	if ((bh = fat_add_cluster1(dir)) == NULL) return -ENOSPC;
	/* zeroed out, so... */
	fat_date_unix2dos(dir->i_mtime,&time,&date);
	de = (struct msdos_dir_entry*)&bh->b_data[0];
	memcpy(de[0].name,MSDOS_DOT,MSDOS_NAME);
	memcpy(de[1].name,MSDOS_DOTDOT,MSDOS_NAME);
	de[0].attr = de[1].attr = ATTR_DIR;
	de[0].ctime = de[0].time = de[1].ctime = de[1].time = CT_LE_W(time);
	de[0].adate = de[0].cdate = de[0].date = de[1].adate =
		de[1].cdate = de[1].date = CT_LE_W(date);
	de[0].start = CT_LE_W(MSDOS_I(dir)->i_logstart);
	de[0].starthi = CT_LE_W(MSDOS_I(dir)->i_logstart>>16);
	de[1].start = CT_LE_W(MSDOS_I(parent)->i_logstart);
	de[1].starthi = CT_LE_W(MSDOS_I(parent)->i_logstart>>16);
	fat_mark_buffer_dirty(sb, bh, 1);
	fat_brelse(sb, bh);
	dir->i_atime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	mark_inode_dirty(dir);

	return 0;
}

static void vfat_remove_entry(struct inode *dir,struct vfat_slot_info *sinfo,
     struct buffer_head *bh, struct msdos_dir_entry *de)
{
	struct super_block *sb = dir->i_sb;
	loff_t offset;
	int i,ino;

	/* remove the shortname */
	dir->i_mtime = CURRENT_TIME;
	dir->i_atime = CURRENT_TIME;
	dir->i_version = ++event;
	MSDOS_I(dir)->i_last_pos = 0;
	mark_inode_dirty(dir);
	de->name[0] = DELETED_FLAG;
	fat_mark_buffer_dirty(sb, bh, 1);
	/* remove the longname */
	offset = sinfo->longname_offset; de = NULL;
	for (i = sinfo->long_slots; i > 0; --i) {
		if (fat_get_entry(dir, &offset, &bh, &de, &ino) < 0)
			continue;
		de->name[0] = DELETED_FLAG;
		de->attr = 0;
		fat_mark_buffer_dirty(sb, bh, 1);
	}
	if (bh) fat_brelse(sb, bh);
}

int vfat_rmdir(struct inode *dir,struct dentry* dentry)
{
	int res;
	struct vfat_slot_info sinfo;
	struct buffer_head *bh = NULL;
	struct msdos_dir_entry *de;

	if (!list_empty(&dentry->d_hash))
		return -EBUSY;

	res = fat_dir_empty(dentry->d_inode);
	if (res)
		return res;

	res = vfat_find(dir,&dentry->d_name,&sinfo, &bh, &de);
	if (res<0)
		return res;
	dentry->d_inode->i_nlink = 0;
	dentry->d_inode->i_mtime = CURRENT_TIME;
	dentry->d_inode->i_atime = CURRENT_TIME;
	fat_detach(dentry->d_inode);
	mark_inode_dirty(dentry->d_inode);
	/* releases bh */
	vfat_remove_entry(dir,&sinfo,bh,de);
	dir->i_nlink--;
	return 0;
}

int vfat_unlink(struct inode *dir, struct dentry* dentry)
{
	int res;
	struct vfat_slot_info sinfo;
	struct buffer_head *bh = NULL;
	struct msdos_dir_entry *de;

	PRINTK1(("vfat_unlink: %s\n", dentry->d_name.name));
	res = vfat_find(dir,&dentry->d_name,&sinfo,&bh,&de);
	if (res < 0)
		return res;
	dentry->d_inode->i_nlink = 0;
	dentry->d_inode->i_mtime = CURRENT_TIME;
	dentry->d_inode->i_atime = CURRENT_TIME;
	fat_detach(dentry->d_inode);
	mark_inode_dirty(dentry->d_inode);
	/* releases bh */
	vfat_remove_entry(dir,&sinfo,bh,de);
	d_delete(dentry);

	return res;
}


int vfat_mkdir(struct inode *dir,struct dentry* dentry,int mode)
{
	struct super_block *sb = dir->i_sb;
	struct inode *inode = NULL;
	struct vfat_slot_info sinfo;
	struct buffer_head *bh = NULL;
	struct msdos_dir_entry *de;
	int res;

	res = vfat_add_entry(dir, &dentry->d_name, 1, &sinfo, &bh, &de);
	if (res < 0)
		return res;
	inode = fat_build_inode(sb, de, sinfo.ino, &res);
	if (!inode)
		goto out;
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	mark_inode_dirty(inode);
	inode->i_version = ++event;
	dir->i_version = event;
	MSDOS_I(dir)->i_last_pos = 0;
	dir->i_nlink++;
	inode->i_nlink = 2; /* no need to mark them dirty */

	res = vfat_create_dotdirs(inode, dir);
	if (res < 0)
		goto mkdir_failed;
	dentry->d_time = dentry->d_parent->d_inode->i_version;
	d_instantiate(dentry,inode);
out:
	fat_brelse(sb, bh);
	return res;

mkdir_failed:
	inode->i_nlink = 0;
	inode->i_mtime = CURRENT_TIME;
	inode->i_atime = CURRENT_TIME;
	fat_detach(inode);
	mark_inode_dirty(inode);
	/* releases bh */
	vfat_remove_entry(dir,&sinfo,bh,de);
	iput(inode);
	dir->i_nlink--;
	return res;
}
 
int vfat_rename(struct inode *old_dir,struct dentry *old_dentry,
		struct inode *new_dir,struct dentry *new_dentry)
{
	struct super_block *sb = old_dir->i_sb;
	struct buffer_head *old_bh,*new_bh,*dotdot_bh;
	struct msdos_dir_entry *old_de,*new_de,*dotdot_de;
	int dotdot_ino;
	struct inode *old_inode, *new_inode;
	int res, is_dir;
	struct vfat_slot_info old_sinfo,sinfo;

	old_bh = new_bh = dotdot_bh = NULL;
	old_inode = old_dentry->d_inode;
	new_inode = new_dentry->d_inode;
	res = vfat_find(old_dir,&old_dentry->d_name,&old_sinfo,&old_bh,&old_de);
	PRINTK3(("vfat_rename 2\n"));
	if (res < 0) goto rename_done;

	is_dir = S_ISDIR(old_inode->i_mode);

	if (is_dir && (res = fat_scan(old_inode,MSDOS_DOTDOT,&dotdot_bh,
				&dotdot_de,&dotdot_ino)) < 0)
		goto rename_done;

	if (new_dentry->d_inode) {
		res = vfat_find(new_dir,&new_dentry->d_name,&sinfo,&new_bh,
				&new_de);
		if (res < 0 || MSDOS_I(new_inode)->i_location != sinfo.ino) {
			/* WTF??? Cry and fail. */
			printk(KERN_WARNING "vfat_rename: fs corrupted\n");
			goto rename_done;
		}

		if (is_dir) {
			res = fat_dir_empty(new_inode);
			if (res)
				goto rename_done;
		}
		fat_detach(new_inode);
	} else {
		res = vfat_add_entry(new_dir,&new_dentry->d_name,is_dir,&sinfo,
					&new_bh,&new_de);
		if (res < 0) goto rename_done;
	}

	new_dir->i_version = ++event;
	MSDOS_I(new_dir)->i_last_pos = 0;

	/* releases old_bh */
	vfat_remove_entry(old_dir,&old_sinfo,old_bh,old_de);
	old_bh=NULL;
	fat_detach(old_inode);
	fat_attach(old_inode, sinfo.ino);
	mark_inode_dirty(old_inode);

	old_dir->i_version = ++event;
	old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
	mark_inode_dirty(old_dir);
	if (new_inode) {
		new_inode->i_nlink--;
		new_inode->i_ctime=CURRENT_TIME;
	}

	if (is_dir) {
		int start = MSDOS_I(new_dir)->i_logstart;
		dotdot_de->start = CT_LE_W(start);
		dotdot_de->starthi = CT_LE_W(start>>16);
		fat_mark_buffer_dirty(sb, dotdot_bh, 1);
		old_dir->i_nlink--;
		if (new_inode) {
			new_inode->i_nlink--;
		} else {
			new_dir->i_nlink++;
			mark_inode_dirty(new_dir);
		}
	}

rename_done:
	fat_brelse(sb, dotdot_bh);
	fat_brelse(sb, old_bh);
	fat_brelse(sb, new_bh);
	return res;

}


/* Public inode operations for the VFAT fs */
struct inode_operations vfat_dir_inode_operations = {
	&fat_dir_operations,	/* default directory file-ops */
	vfat_create,		/* create */
	vfat_lookup,		/* lookup */
	NULL,			/* link */
	vfat_unlink,		/* unlink */
	NULL,			/* symlink */
	vfat_mkdir,		/* mkdir */
	vfat_rmdir,		/* rmdir */
	NULL,			/* mknod */
	vfat_rename,		/* rename */
	NULL,			/* readlink */
	NULL,			/* followlink */
	NULL,			/* readpage */
	NULL,			/* writepage */
	NULL,			/* bmap */
	NULL,			/* truncate */
	NULL			/* permission */
};

struct super_block *vfat_read_super(struct super_block *sb,void *data,
				    int silent)
{
	struct super_block *res;
  
	MOD_INC_USE_COUNT;
	
	MSDOS_SB(sb)->options.isvfat = 1;

	res = fat_read_super(sb, data, silent, &vfat_dir_inode_operations);
	if (res == NULL) {
		sb->s_dev = 0;
		MOD_DEC_USE_COUNT;
		return NULL;
	}

	if (!parse_options((char *) data, &(MSDOS_SB(sb)->options))) {
		MOD_DEC_USE_COUNT;
	} else {
		MSDOS_SB(sb)->put_super_callback=vfat_put_super_callback;
		MSDOS_SB(sb)->options.dotsOK = 0;
		if (MSDOS_SB(sb)->options.posixfs) {
			MSDOS_SB(sb)->options.name_check = 's';
		}
		if (MSDOS_SB(sb)->options.name_check != 's') {
			sb->s_root->d_op = &vfat_dentry_ops[0];
		} else {
			sb->s_root->d_op = &vfat_dentry_ops[2];
		}
	}

	return res;
}

#ifdef MODULE
int init_module(void)
{
	return init_vfat_fs();
}

void cleanup_module(void)
{
	unregister_filesystem(&vfat_fs_type);
}

#endif /* ifdef MODULE */