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 634 行 · 第 1/2 页

	dir->i_nlink++;
	mark_inode_dirty(dir);
	brelse(bh);
        d_instantiate(dentry, inode);
 	return 0;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
static int empty_dir(struct inode * inode)
{
	struct super_block * sb;
	unsigned long pos, block, offset; /* pos = block * block_size + offset */
	struct buffer_head * bh;
	struct sysv_dir_entry * de;

	block = 0;
	bh = NULL;
	pos = offset = 2*SYSV_DIRSIZE;
	if (inode->i_size % SYSV_DIRSIZE)
		goto bad_dir;
	if (inode->i_size < pos)
		goto bad_dir;
	bh = sysv_file_bread(inode, 0, 0);
	if (!bh)
		goto bad_dir;
	de = (struct sysv_dir_entry *) (bh->b_data + 0*SYSV_DIRSIZE);
	if (!de->inode || strcmp(de->name,"."))
		goto bad_dir;
	de = (struct sysv_dir_entry *) (bh->b_data + 1*SYSV_DIRSIZE);
	if (!de->inode || strcmp(de->name,".."))
		goto bad_dir;
	sb = inode->i_sb;
	while (pos < inode->i_size) {
		if (!bh) {
			bh = sysv_file_bread(inode, block, 0);
			if (!bh) {
				/* offset = 0; */ block++;
				pos += sb->sv_block_size;
				continue;
			}
		}
		de = (struct sysv_dir_entry *) (bh->b_data + offset);
		pos += SYSV_DIRSIZE;
		offset += SYSV_DIRSIZE;
		if (de->inode) {
			brelse(bh);
			return 0;
		}
		if (offset < sb->sv_block_size)
			continue;
		brelse(bh);
		bh = NULL;
		offset = 0; block++;
	}
	brelse(bh);
	return 1;
bad_dir:
	brelse(bh);
	printk("Bad directory on device %s\n",
	       kdevname(inode->i_dev));
	return 1;
}

int sysv_rmdir(struct inode * dir, struct dentry * dentry)
{
	int retval;
	struct inode * inode;
	struct buffer_head * bh;
	struct sysv_dir_entry * de;

	inode = dentry->d_inode;
	bh = sysv_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
	retval = -ENOENT;
	if (!bh || de->inode != inode->i_ino)
		goto end_rmdir;

	if (!empty_dir(inode)) {
		retval = -ENOTEMPTY;
		goto end_rmdir;
	}
	if (!list_empty(&dentry->d_hash)) {
		retval = -EBUSY;
		goto end_rmdir;
	}
	if (inode->i_nlink != 2)
		printk("empty directory has nlink!=2 (%d)\n", inode->i_nlink);
	de->inode = 0;
	mark_buffer_dirty(bh, 1);
	inode->i_nlink=0;
	dir->i_nlink--;
	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	mark_inode_dirty(inode);
	mark_inode_dirty(dir);
	d_delete(dentry);
	retval = 0;
end_rmdir:
	brelse(bh);
	return retval;
}

int sysv_unlink(struct inode * dir, struct dentry * dentry)
{
	int retval;
	struct inode * inode;
	struct buffer_head * bh;
	struct sysv_dir_entry * de;

	retval = -ENOENT;
	inode = dentry->d_inode;
	bh = sysv_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
	if (!bh || de->inode != inode->i_ino)
		goto end_unlink;
	if (!inode->i_nlink) {
		printk("Deleting nonexistent file (%s:%lu), %d\n",
		        kdevname(inode->i_dev), inode->i_ino, inode->i_nlink);
		inode->i_nlink=1;
	}
	de->inode = 0;
	mark_buffer_dirty(bh, 1);
	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	mark_inode_dirty(dir);
	inode->i_nlink--;
	inode->i_ctime = dir->i_ctime;
	mark_inode_dirty(inode);
	d_delete(dentry);
	retval = 0;
end_unlink:
	brelse(bh);
	return retval;
}

int sysv_symlink(struct inode * dir, struct dentry * dentry, 
		 const char * symname)
{
	struct sysv_dir_entry * de;
	struct inode * inode;
	struct buffer_head * name_block;
	char * name_block_data;
	struct super_block * sb;
	int i;
	char c;
	struct buffer_head * bh;

	if (!(inode = sysv_new_inode(dir)))
		return -ENOSPC;

	inode->i_mode = S_IFLNK | 0777;
	inode->i_op = &sysv_symlink_inode_operations;
	name_block = sysv_file_bread(inode, 0, 1);
	if (!name_block) {
		inode->i_nlink--;
		mark_inode_dirty(inode);
		iput(inode);
		return -ENOSPC;
	}
	sb = inode->i_sb;
	name_block_data = name_block->b_data;
	i = 0;
	while (i < sb->sv_block_size_1 && (c = *(symname++)))
		name_block_data[i++] = c;
	name_block_data[i] = 0;
	mark_buffer_dirty(name_block, 1);
	brelse(name_block);
	inode->i_size = i;
	mark_inode_dirty(inode);
	bh = sysv_find_entry(dir, dentry->d_name.name,
                             dentry->d_name.len, &de);
	if (bh) {
		inode->i_nlink--;
		mark_inode_dirty(inode);
		iput(inode);
		brelse(bh);
		return -EEXIST;
	}
	i = sysv_add_entry(dir, dentry->d_name.name,
                           dentry->d_name.len, &bh, &de);
	if (i) {
		inode->i_nlink--;
		mark_inode_dirty(inode);
		iput(inode);
		return i;
	}
	de->inode = inode->i_ino;
	mark_buffer_dirty(bh, 1);
	brelse(bh);
        d_instantiate(dentry, inode);
	return 0;
}

int sysv_link(struct dentry * old_dentry, struct inode * dir, 
	      struct dentry * dentry)
{
	struct inode *oldinode = old_dentry->d_inode;
	int error;
	struct sysv_dir_entry * de;
	struct buffer_head * bh;

	if (S_ISDIR(oldinode->i_mode)) {
		return -EPERM;
	}
	if (oldinode->i_nlink >= oldinode->i_sb->sv_link_max) {
		return -EMLINK;
	}
	bh = sysv_find_entry(dir, dentry->d_name.name,
                             dentry->d_name.len, &de);
	if (bh) {
		brelse(bh);
		return -EEXIST;
	}
	error = sysv_add_entry(dir, dentry->d_name.name,
                               dentry->d_name.len, &bh, &de);
	if (error) {
		brelse(bh);
		return error;
	}
	de->inode = oldinode->i_ino;
	mark_buffer_dirty(bh, 1);
	brelse(bh);
	oldinode->i_nlink++;
	oldinode->i_ctime = CURRENT_TIME;
	mark_inode_dirty(oldinode);
	oldinode->i_count++;
        d_instantiate(dentry, oldinode);
	return 0;
}

#define PARENT_INO(buffer) \
(((struct sysv_dir_entry *) ((buffer) + 1*SYSV_DIRSIZE))->inode)

/*
 * Anybody can rename anything with this: the permission checks are left to the
 * higher-level routines.
 */
int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
		  struct inode * new_dir, struct dentry * new_dentry)
{
	struct inode * old_inode, * new_inode;
	struct buffer_head * old_bh, * new_bh, * dir_bh;
	struct sysv_dir_entry * old_de, * new_de;
	int retval;

	old_inode = old_dentry->d_inode;
	new_inode = new_dentry->d_inode;
	new_bh = dir_bh = NULL;
	old_bh = sysv_find_entry(old_dir, old_dentry->d_name.name,
				old_dentry->d_name.len, &old_de);
	retval = -ENOENT;
	if (!old_bh || old_de->inode != old_inode->i_ino)
		goto end_rename;
	retval = -EPERM;
	new_bh = sysv_find_entry(new_dir, new_dentry->d_name.name,
				new_dentry->d_name.len, &new_de);
	if (new_bh) {
		if (!new_inode) {
			brelse(new_bh);
			new_bh = NULL;
		}
	}
	if (S_ISDIR(old_inode->i_mode)) {
		if (new_inode) {
			retval = -ENOTEMPTY;
			if (!empty_dir(new_inode))
				goto end_rename;
		}
		retval = -EIO;
		dir_bh = sysv_file_bread(old_inode, 0, 0);
		if (!dir_bh)
			goto end_rename;
		if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
			goto end_rename;
		retval = -EMLINK;
		if (!new_inode && new_dir != old_dir &&
				new_dir->i_nlink >= new_dir->i_sb->sv_link_max)
			goto end_rename;
	}
	if (!new_bh) {
		retval = sysv_add_entry(new_dir, new_dentry->d_name.name,
					new_dentry->d_name.len, &new_bh, &new_de);
		if (retval)
			goto end_rename;
	}
	new_de->inode = old_inode->i_ino;
	old_de->inode = 0;
	old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
	mark_inode_dirty(old_dir);
	new_dir->i_ctime = new_dir->i_mtime = CURRENT_TIME;
	mark_inode_dirty(new_dir);
	if (new_inode) {
		new_inode->i_nlink--;
		new_inode->i_ctime = CURRENT_TIME;
		mark_inode_dirty(new_inode);
	}
	mark_buffer_dirty(old_bh, 1);
	mark_buffer_dirty(new_bh, 1);
	if (dir_bh) {
		PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
		mark_buffer_dirty(dir_bh, 1);
		old_dir->i_nlink--;
		mark_inode_dirty(old_dir);
		if (new_inode) {
			new_inode->i_nlink--;
			mark_inode_dirty(new_inode);
		} else {
			new_dir->i_nlink++;
			mark_inode_dirty(new_dir);
		}
	}
	retval = 0;
end_rename:
	brelse(dir_bh);
	brelse(old_bh);
	brelse(new_bh);
	return retval;
}