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 937 行 · 第 1/2 页

	inode = ext2_new_inode (dir, S_IFDIR, &err);
	if (!inode)
		goto out;

	inode->i_op = &ext2_dir_inode_operations;
	inode->i_size = inode->i_sb->s_blocksize;
	inode->i_blocks = 0;	
	dir_block = ext2_bread (inode, 0, 1, &err);
	if (!dir_block) {
		inode->i_nlink--; /* is this nlink == 0? */
		mark_inode_dirty(inode);
		iput (inode);
		return err;
	}
	de = (struct ext2_dir_entry_2 *) dir_block->b_data;
	de->inode = cpu_to_le32(inode->i_ino);
	de->name_len = 1;
	de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(de->name_len));
	strcpy (de->name, ".");
	if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
				      EXT2_FEATURE_INCOMPAT_FILETYPE))
		de->file_type = EXT2_FT_DIR;
	de = (struct ext2_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
	de->inode = cpu_to_le32(dir->i_ino);
	de->rec_len = cpu_to_le16(inode->i_sb->s_blocksize - EXT2_DIR_REC_LEN(1));
	de->name_len = 2;
	strcpy (de->name, "..");
	if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
				      EXT2_FEATURE_INCOMPAT_FILETYPE))
		de->file_type = EXT2_FT_DIR;
	inode->i_nlink = 2;
	mark_buffer_dirty(dir_block, 1);
	brelse (dir_block);
	inode->i_mode = S_IFDIR | (mode & (S_IRWXUGO|S_ISVTX) & ~current->fs->umask);
	if (dir->i_mode & S_ISGID)
		inode->i_mode |= S_ISGID;
	mark_inode_dirty(inode);
	bh = ext2_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
	if (!bh)
		goto out_no_entry;
	de->inode = cpu_to_le32(inode->i_ino);
	if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
				      EXT2_FEATURE_INCOMPAT_FILETYPE))
		de->file_type = EXT2_FT_DIR;
	dir->i_version = ++event;
	mark_buffer_dirty(bh, 1);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	dir->i_nlink++;
	dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(dir);
	d_instantiate(dentry, inode);
	brelse (bh);
	err = 0;
out:
	return err;

out_no_entry:
	inode->i_nlink = 0;
	mark_inode_dirty(inode);
	iput (inode);
	goto out;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
static int empty_dir (struct inode * inode)
{
	unsigned long offset;
	struct buffer_head * bh;
	struct ext2_dir_entry_2 * de, * de1;
	struct super_block * sb;
	int err;

	sb = inode->i_sb;
	if (inode->i_size < EXT2_DIR_REC_LEN(1) + EXT2_DIR_REC_LEN(2) ||
	    !(bh = ext2_bread (inode, 0, 0, &err))) {
	    	ext2_warning (inode->i_sb, "empty_dir",
			      "bad directory (dir #%lu) - no data block",
			      inode->i_ino);
		return 1;
	}
	de = (struct ext2_dir_entry_2 *) bh->b_data;
	de1 = (struct ext2_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
	if (le32_to_cpu(de->inode) != inode->i_ino || !le32_to_cpu(de1->inode) || 
	    strcmp (".", de->name) || strcmp ("..", de1->name)) {
	    	ext2_warning (inode->i_sb, "empty_dir",
			      "bad directory (dir #%lu) - no `.' or `..'",
			      inode->i_ino);
		brelse (bh);
		return 1;
	}
	offset = le16_to_cpu(de->rec_len) + le16_to_cpu(de1->rec_len);
	de = (struct ext2_dir_entry_2 *) ((char *) de1 + le16_to_cpu(de1->rec_len));
	while (offset < inode->i_size ) {
		if (!bh || (void *) de >= (void *) (bh->b_data + sb->s_blocksize)) {
			brelse (bh);
			bh = ext2_bread (inode, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, &err);
			if (!bh) {
#if 0
				ext2_error (sb, "empty_dir",
					    "directory #%lu contains a hole at offset %lu",
					    inode->i_ino, offset);
#endif
				offset += sb->s_blocksize;
				continue;
			}
			de = (struct ext2_dir_entry_2 *) bh->b_data;
		}
		if (!ext2_check_dir_entry ("empty_dir", inode, de, bh,
					   offset)) {
			brelse (bh);
			return 1;
		}
		if (le32_to_cpu(de->inode)) {
			brelse (bh);
			return 0;
		}
		offset += le16_to_cpu(de->rec_len);
		de = (struct ext2_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
	}
	brelse (bh);
	return 1;
}

int ext2_rmdir (struct inode * dir, struct dentry *dentry)
{
	int retval;
	struct inode * inode;
	struct buffer_head * bh;
	struct ext2_dir_entry_2 * de;

	retval = -ENOENT;
	bh = ext2_find_entry (dir, dentry->d_name.name, dentry->d_name.len, &de);
	if (!bh)
		goto end_rmdir;

	inode = dentry->d_inode;
	DQUOT_INIT(inode);

	retval = -EIO;
	if (le32_to_cpu(de->inode) != inode->i_ino)
		goto end_rmdir;

	retval = -ENOTEMPTY;
	if (!empty_dir (inode))
		goto end_rmdir;

	retval = ext2_delete_entry (de, bh);
	dir->i_version = ++event;
	if (retval)
		goto end_rmdir;
	mark_buffer_dirty(bh, 1);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	if (inode->i_nlink != 2)
		ext2_warning (inode->i_sb, "ext2_rmdir",
			      "empty directory has nlink!=2 (%d)",
			      inode->i_nlink);
	inode->i_version = ++event;
	inode->i_nlink = 0;
	inode->i_size = 0;
	mark_inode_dirty(inode);
	dir->i_nlink--;
	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(dir);
	d_delete(dentry);

end_rmdir:
	brelse (bh);
	return retval;
}

int ext2_unlink(struct inode * dir, struct dentry *dentry)
{
	int retval;
	struct inode * inode;
	struct buffer_head * bh;
	struct ext2_dir_entry_2 * de;

	retval = -ENOENT;
	bh = ext2_find_entry (dir, dentry->d_name.name, dentry->d_name.len, &de);
	if (!bh)
		goto end_unlink;

	inode = dentry->d_inode;
	DQUOT_INIT(inode);

	retval = -EIO;
	if (le32_to_cpu(de->inode) != inode->i_ino)
		goto end_unlink;
	
	if (!inode->i_nlink) {
		ext2_warning (inode->i_sb, "ext2_unlink",
			      "Deleting nonexistent file (%lu), %d",
			      inode->i_ino, inode->i_nlink);
		inode->i_nlink = 1;
	}
	retval = ext2_delete_entry (de, bh);
	if (retval)
		goto end_unlink;
	dir->i_version = ++event;
	mark_buffer_dirty(bh, 1);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(dir);
	inode->i_nlink--;
	mark_inode_dirty(inode);
	inode->i_ctime = dir->i_ctime;
	retval = 0;
	d_delete(dentry);	/* This also frees the inode */

end_unlink:
	brelse (bh);
	return retval;
}

int ext2_symlink (struct inode * dir, struct dentry *dentry, const char * symname)
{
	struct ext2_dir_entry_2 * de;
	struct inode * inode;
	struct buffer_head * bh = NULL, * name_block = NULL;
	char * link;
	int i, l, err = -EIO;
	char c;

	if (!(inode = ext2_new_inode (dir, S_IFLNK, &err))) {
		return err;
	}
	inode->i_mode = S_IFLNK | S_IRWXUGO;
	inode->i_op = &ext2_symlink_inode_operations;
	for (l = 0; l < inode->i_sb->s_blocksize - 1 &&
	     symname [l]; l++)
		;
	if (l >= sizeof (inode->u.ext2_i.i_data)) {

		ext2_debug ("l=%d, normal symlink\n", l);

		name_block = ext2_bread (inode, 0, 1, &err);
		if (!name_block) {
			inode->i_nlink--;
			mark_inode_dirty(inode);
			iput (inode);
			return err;
		}
		link = name_block->b_data;
	} else {
		link = (char *) inode->u.ext2_i.i_data;

		ext2_debug ("l=%d, fast symlink\n", l);

	}
	i = 0;
	while (i < inode->i_sb->s_blocksize - 1 && (c = *(symname++)))
		link[i++] = c;
	link[i] = 0;
	if (name_block) {
		mark_buffer_dirty(name_block, 1);
		brelse (name_block);
	}
	inode->i_size = i;
	mark_inode_dirty(inode);

	bh = ext2_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
	if (!bh)
		goto out_no_entry;
	de->inode = cpu_to_le32(inode->i_ino);
	if (EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
				      EXT2_FEATURE_INCOMPAT_FILETYPE))
		de->file_type = EXT2_FT_SYMLINK;
	dir->i_version = ++event;
	mark_buffer_dirty(bh, 1);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	brelse (bh);
	d_instantiate(dentry, inode);
	err = 0;
out:
	return err;

out_no_entry:
	inode->i_nlink--;
	mark_inode_dirty(inode);
	iput (inode);
	goto out;
}

int ext2_link (struct dentry * old_dentry,
		struct inode * dir, struct dentry *dentry)
{
	struct inode *inode = old_dentry->d_inode;
	struct ext2_dir_entry_2 * de;
	struct buffer_head * bh;
	int err;

	if (S_ISDIR(inode->i_mode))
		return -EPERM;

	if (inode->i_nlink >= EXT2_LINK_MAX)
		return -EMLINK;

	bh = ext2_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
	if (!bh)
		return err;

	de->inode = cpu_to_le32(inode->i_ino);
	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb,
				      EXT2_FEATURE_INCOMPAT_FILETYPE)) {
		if (S_ISREG(inode->i_mode))
			de->file_type = EXT2_FT_REG_FILE;
		else if (S_ISDIR(inode->i_mode))
			de->file_type = EXT2_FT_DIR;
		else if (S_ISLNK(inode->i_mode))
			de->file_type = EXT2_FT_SYMLINK;
		else if (S_ISCHR(inode->i_mode))
			de->file_type = EXT2_FT_CHRDEV;
		else if (S_ISBLK(inode->i_mode))
			de->file_type = EXT2_FT_BLKDEV;
		else if (S_ISFIFO(inode->i_mode))  
			de->file_type = EXT2_FT_FIFO;
	}
	dir->i_version = ++event;
	mark_buffer_dirty(bh, 1);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	brelse (bh);
	inode->i_nlink++;
	inode->i_ctime = CURRENT_TIME;
	mark_inode_dirty(inode);
	inode->i_count++;
	d_instantiate(dentry, inode);
	return 0;
}

#define PARENT_INO(buffer) \
	((struct ext2_dir_entry_2 *) ((char *) buffer + \
	le16_to_cpu(((struct ext2_dir_entry_2 *) buffer)->rec_len)))->inode

/*
 * Anybody can rename anything with this: the permission checks are left to the
 * higher-level routines.
 */
int ext2_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 ext2_dir_entry_2 * old_de, * new_de;
	int retval;

	old_bh = new_bh = dir_bh = NULL;

	old_bh = ext2_find_entry (old_dir, old_dentry->d_name.name, old_dentry->d_name.len, &old_de);
	/*
	 *  Check for inode number is _not_ due to possible IO errors.
	 *  We might rmdir the source, keep it as pwd of some process
	 *  and merrily kill the link to whatever was created under the
	 *  same name. Goodbye sticky bit ;-<
	 */
	old_inode = old_dentry->d_inode;
	retval = -ENOENT;
	if (!old_bh || le32_to_cpu(old_de->inode) != old_inode->i_ino)
		goto end_rename;

	new_inode = new_dentry->d_inode;
	new_bh = ext2_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;
		} else {
			DQUOT_INIT(new_inode);
		}
	}
	if (S_ISDIR(old_inode->i_mode)) {
		if (new_inode) {
			retval = -ENOTEMPTY;
			if (!empty_dir (new_inode))
				goto end_rename;
		}
		retval = -EIO;
		dir_bh = ext2_bread (old_inode, 0, 0, &retval);
		if (!dir_bh)
			goto end_rename;
		if (le32_to_cpu(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 >= EXT2_LINK_MAX)
			goto end_rename;
	}
	if (!new_bh) {
		new_bh = ext2_add_entry (new_dir, new_dentry->d_name.name,
					new_dentry->d_name.len, &new_de,
					&retval);
		if (!new_bh)
			goto end_rename;
	}
	new_dir->i_version = ++event;

	/*
	 * ok, that's it
	 */
	new_de->inode = le32_to_cpu(old_inode->i_ino);
	if (EXT2_HAS_INCOMPAT_FEATURE(new_dir->i_sb,
				      EXT2_FEATURE_INCOMPAT_FILETYPE))
		new_de->file_type = old_de->file_type;
	
	ext2_delete_entry (old_de, old_bh);

	old_dir->i_version = ++event;
	if (new_inode) {
		new_inode->i_nlink--;
		new_inode->i_ctime = CURRENT_TIME;
		mark_inode_dirty(new_inode);
	}
	old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
	old_dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(old_dir);
	if (dir_bh) {
		PARENT_INO(dir_bh->b_data) = le32_to_cpu(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++;
			new_dir->u.ext2_i.i_flags &= ~EXT2_BTREE_FL;
			mark_inode_dirty(new_dir);
		}
	}
	mark_buffer_dirty(old_bh,  1);
	if (IS_SYNC(old_dir)) {
		ll_rw_block (WRITE, 1, &old_bh);
		wait_on_buffer (old_bh);
	}
	mark_buffer_dirty(new_bh, 1);
	if (IS_SYNC(new_dir)) {
		ll_rw_block (WRITE, 1, &new_bh);
		wait_on_buffer (new_bh);
	}

	retval = 0;

end_rename:
	brelse (dir_bh);
	brelse (old_bh);
	brelse (new_bh);
	return retval;
}