[Gluster-devel] Problems about acl_get_file used in posix_pacl_get

[Kinglong Mee]

Hi Niels,

On 2018/8/17 17:13, Niels de Vos wrote:
> On Fri, Aug 17, 2018 at 03:04:43PM +0800, Kinglong Mee wrote:
>> Hello folks,
>>
>> nfs-ganesha using the new gfapi named glfs_h_acl_set/glfs_h_acl_get,
>> at xlator posix, glusterfsd calls acl_get_file/acl_set_file (libacl functions) to process xattrs.
>>
>> By default, sys_lsetxattr/sys_llistxattr/sys_lgetxattr/sys_lremovexattr are used to process xattrs.
>> But, unfortunately, those two functions do syscall by getxattr/setxattr.
>> I don't think that is we want.
>>
>> Is it a known problem ?
> 
> There should not be a problem for libacl to use syscalls directly. The
> Gluster sources use sys_<syscall> so that there can be wrappers for the
> differences between OS's. In the end, these sys_<syscall> functions will
> mostly call the <syscall> with (adapted) arguments.
> 
> I do not know what problem you are facing, but I can imagine that there
> is a 'getxattr' symbol in the executable image that gets called by
> libacl, instead of the 'getxattr' syscall. This will likely result in
> very strange behaviour, if not segfaults.

Sorry for my unclear description.
The real problem here is libacl gets/sets xattrs by getxattr/setxattr which follow symbolic links,
but, posix xlator get/set xattrs by sys_l*xattr which do not follow symbolic links.

thanks,
Kinglong Mee