Re: What should listxattr() return if there are no xattrs?

["Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>]

On Mon, 20 Dec 2010 08:26:53 -0500, "Theodore Ts'o" <tytso@mit.edu> wrote:
> 
> Wang Sheng-Hui has sent some patches that change listxattr for the extN
> file systems to return ENODATA when an inode has no extended attributes
> (instead of zero).
> 
> I've noted that neither btrfs nor XFS do this, and would have rejected
> the patches on that basis. However, I'll note the man page for the
> listxattr(2) syscall is ambiguous:
> 
>     On  success,  a  positive number is returned indicating the size of the
>     extended attribute name list.  On failure, -1 is returned and errno  is
>     set appropriately.
> 
> It states that on success a _positive_ number is returned.  I've looked
> and this wordining is in SGI's man page as well.  I suspect the man page
> should be corrected to sate that "non-negative" number is returned?

I agree that man page needs update. Note that getfattr code does

	length = do_listxattr(path, NULL, 0);
	if (length < 0) {
		fprintf(stderr, "%s: %s: %s\n", progname, xquote(path, "\n\r"),
			strerror_ea(errno));
		had_errors++;
		return 1;
	} else if (length == 0)
		return 0;
		

-aneesh