Re: Invalid ACLS on windows file
>
> James Harper wrote:
> > Would you accept a patch which allowed the setting of raw data without any
> validation? The data stream generated by the BackupRead API under Windows
> contains DATA, ALTERNATE_DATA, EA_DATA, LINK, OBJECT_ID, PROPERTY_DATA,
> REPARSE_DATA, SECURITY_DATA, and SPARSE_BLOCK streams. You handle most of them
> already, but not OBJECT_ID which is one that I need. I can't see that it would
> add much value to ntfs-3g for anything other than backup and restore.
> >
>
> Doing that blindly is calling for problems.
>
> Examples :
>
> I guess "LINK" is defining alternate names for the file.
> Assuming the name space information is provided, setting
> a name is not just setting an attribute, the main purpose
> is to create an entry in the index of some directory. At
> least the information about the directory is needed.
> You must have solved that one, where did you get the
> directory from ?
> Do you have an example of backup data associated to
> a LINK attribute ?
No, I don't think I do. For the use I need this for I think that hardlinks are provided another way.
>
> The same problem goes with "OBJECT_ID". Its purpose
> is to define a unique id is some domain, so that the
> file can be located in the domain. For the OBJECT_ID
> to be meaningful, it has to be indexed in a special file,
> which means special processing for this attribute.
>
> Also with "SECURITY_DATA", as each ACL is indexed
> twice in a special file. This situation a currently dealt
> with, which gives indications to what has to be done
> for OBJECT_ID.
Hmmm... so, more complicated than I thought.
>
> As far as I understand, "SPARSE_BLOCK" is not an
> attribute of the file, but rather an information needed
> to decode DATA or ALTERNATE_DATA when the
> stream is sparse (to avoid backing up holes).
>
OK. I haven't seen one of these yet either.
> I do not know what PROPERTY_DATA is. It must be
> the "$PROPERTY_SET" mentioned in
> http://msdn.microsoft.com/en-us/library/bb470038(VS.85).aspx
> with the (user) comment "The associated data stream
> is undocumented. Its usage is not clear."
> Do you have an example ?
I might have seen one go flying by the restore logs. I'll know more once I get OBJECT_ID's working and the logs
are reduced to a more sensible size :)
>
> I would add that "EA_DATA" is considered obsolete,
> as the only known reference to it in Win32 are the
> backup and restore function. The EA_DATA were the
> extended attributes on OS2, and the ADS is now
> used for this purpose.
OK
> And in your list there is nothing about encrypted files
> which use the attribute "$LOGGED_UTILITY_STREAM"
> and have significant data beyond the advertised
> stream size.
I haven't yet looked into how BackupRead deals with encrypted streams.
>
> Finally, unless I get more information, only OBJECT_ID
> appears as eligible for extra support, with a specific
> processing.
>
> > Do the xattr namespaces have to be pre-registered with Linux, or can I
> create something like 'system.ntfs_raw_X' where X is the hex value that
> corresponds to the data stream?
> >
>
> I do not know of any registration process for the
> extended attributes in system name space. I consider
> that prefixing by "ntfs_" is enough to avoid conflicts.
> The attributes in system name space are not returned
> by listxattr(), consequently they cannot be wrongly
> processed by applications which do not know about
> them.
>
> For the OBJECT_ID, I acknowledge they can be
> needed in a networked environment and may have to
> be backed up. I can add support for them if you provide
> me with examples... (should take a few weeks).
> I can also merge the patches you would send me !
>
I haven't written any code yet, but in looking through your code I think I mostly just need to replicate a
similar code path as for existing attributes, eg:
. Create a ntfs_object_id entry
. Create a routine to read/write - call ntfs_attr_readall etc with AT_OBJECT_ID
. Create some validation for write's - your assistance is probably required here, although if I can find
some documentation on the structure I can probably put something together myself
Thanks for considering this.
James
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