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Commit ad4d0532 authored by Jan Kara's avatar Jan Kara
Browse files

udf: Make stat on symlink report symlink length as st_size 



UDF encodes symlinks in a more complex fashion and thus i_size of a
symlink does not match the lenght of a string returned by readlink(2).
This confuses some applications (see bug 191241) and may be considered a
violation of POSIX. Fix the problem by reading the link into page cache
in response to stat(2) call and report the length of the decoded path.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent a17f0cb5

fs/udf/inode.c

+1 −1
Original line number Diff line number Diff line
@@ -1547,7 +1547,7 @@ static int udf_read_inode(struct inode *inode, bool hidden_inode) 
		break;

	case ICBTAG_FILE_TYPE_SYMLINK:

		inode->i_data.a_ops = &udf_symlink_aops;

		inode->i_op = &page_symlink_inode_operations;

		inode->i_op = &udf_symlink_inode_operations;

		inode_nohighmem(inode);

		inode->i_mode = S_IFLNK | S_IRWXUGO;

		break;

fs/udf/namei.c

+1 −1
Original line number Diff line number Diff line
@@ -931,7 +931,7 @@ static int udf_symlink(struct inode *dir, struct dentry *dentry, 
	}



	inode->i_data.a_ops = &udf_symlink_aops;

	inode->i_op = &page_symlink_inode_operations;

	inode->i_op = &udf_symlink_inode_operations;

	inode_nohighmem(inode);



	if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {

fs/udf/symlink.c

+30 −0
Original line number Diff line number Diff line
@@ -152,9 +152,39 @@ static int udf_symlink_filler(struct file *file, struct page *page) 
	return err;

}



static int udf_symlink_getattr(struct vfsmount *mnt, struct dentry *dentry,

			       struct kstat *stat)

{

	struct inode *inode = d_backing_inode(dentry);

	struct page *page;



	generic_fillattr(inode, stat);

	page = read_mapping_page(inode->i_mapping, 0, NULL);

	if (IS_ERR(page))

		return PTR_ERR(page);

	/*

	 * UDF uses non-trivial encoding of symlinks so i_size does not match

	 * number of characters reported by readlink(2) which apparently some

	 * applications expect. Also POSIX says that "The value returned in the

	 * st_size field shall be the length of the contents of the symbolic

	 * link, and shall not count a trailing null if one is present." So

	 * let's report the length of string returned by readlink(2) for

	 * st_size.

	 */

	stat->size = strlen(page_address(page));

	put_page(page);



	return 0;

}



/*

 * symlinks can't do much...

 */

const struct address_space_operations udf_symlink_aops = {

	.readpage		= udf_symlink_filler,

};



const struct inode_operations udf_symlink_inode_operations = {

	.get_link	= page_get_link,

	.getattr	= udf_symlink_getattr,

};

fs/udf/udfdecl.h

+1 −0
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ extern const struct inode_operations udf_dir_inode_operations; 
extern const struct file_operations udf_dir_operations;

extern const struct inode_operations udf_file_inode_operations;

extern const struct file_operations udf_file_operations;

extern const struct inode_operations udf_symlink_inode_operations;

extern const struct address_space_operations udf_aops;

extern const struct address_space_operations udf_adinicb_aops;

extern const struct address_space_operations udf_symlink_aops;