Re: [PATCH] hfsplus: add missing osx prefix to FinderInfo attribute check

[Viacheslav Dubeyko <slava@dubeyko.com>]

On Tue, 2015-03-31 at 23:41 -0400, Thomas Hebb wrote:
> By the time we reach strcmp_xattr_finder_info(), hfsplus_osx_getxattr()
> has already prefixed the user-provided xattr name with "osx.", so the
> existing check for the special FinderInfo attribute will always fail,
> and ENODATA will be returned to userspace.
> 
> Since hfsplus_listxattr() reports the FinderInfo attribute, this
> behavior causes certain userspace utilities (e.g. patch) to fail, since
> the kernel lists an attribute that doesn't exist.
> 

Could you describe in more details how do you use userspace utilities
for extracting xattr? I suspect that you simply use it in incorrect way.

Thanks,
Vyacheslav Dubeyko.

> Cc: stable@vger.kernel.org
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
> Cc: Sergei Antonov <saproj@gmail.com>
> Cc: Anton Altaparmakov <anton@tuxera.com>
> Cc: Fabian Frederick <fabf@skynet.be>
> Cc: Christian Kujau <lists@nerdbynature.de>
> Signed-off-by: Thomas Hebb <tommyhebb@gmail.com>
> ---
>  fs/hfsplus/xattr.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
> index d98094a..da0664e 100644
> --- a/fs/hfsplus/xattr.c
> +++ b/fs/hfsplus/xattr.c
> @@ -28,8 +28,16 @@ const struct xattr_handler *hfsplus_xattr_handlers[] = {
>   static int strcmp_xattr_finder_info(const char *name)
>  {
> +	int err = 0;
> +
>  	if (name) {
> -		return strncmp(name, HFSPLUS_XATTR_FINDER_INFO_NAME,
> +		err = strncmp(name, XATTR_MAC_OSX_PREFIX,
> +				XATTR_MAC_OSX_PREFIX_LEN);
> +		if (err)
> +			return err;
> +
> +		return strncmp(name + XATTR_MAC_OSX_PREFIX_LEN,
> +				HFSPLUS_XATTR_FINDER_INFO_NAME,
>  				sizeof(HFSPLUS_XATTR_FINDER_INFO_NAME));
>  	}
>  	return -1;