Re: Resource Fork as Extended Attributes
Re: Resource Fork as Extended Attributes
- Subject: Re: Resource Fork as Extended Attributes
- From: mm w <email@hidden>
- Date: Wed, 22 Jul 2009 21:18:24 +0200
[ENOTSUP] The file system does not support extended
attributes or has the feature disabled.
listxattr
On Wed, Jul 22, 2009 at 7:27 PM, shailesh
jain<email@hidden> wrote:
> @Mark.
>
> Interestingly I tried creating several extended attributes with size > 4096
> bytes and it just works fine. I never enabled any flags to support extend
> based attributes. Is there a way you can check whether extend based
> attributes are enabled ?
>
> Shailesh Jain
>
>
> On Wed, Jul 22, 2009 at 9:19 AM, Mark Day <email@hidden> wrote:
>>
>> The extended attributes API is what you use to get at what TN1150 calls a
>> "named fork." So far, we only support what TN1150 refers to as inline
>> attributes (where the content of the attribute is stored directly in the
>> B-tree node). The APIs are the getxattr(2), setxattr(2), removexattr(2) and
>> listxattr(2) system calls.
>> As Chris Suter mentioned, there is an experimental implementation of
>> extent-based extended attributes. But that support is disabled by default.
>> I would suggest that you do not try enabling it yourself. If we do end up
>> shipping support for extent-based extended attributes, the implementation
>> could be different and incompatible with the one you currently see in the
>> sources.
>>
>> -Mark
>> On Jul 20, 2009, at 11:39 PM, shailesh jain wrote:
>>
>> @Terry:
>>
>> Except for Apple TN1150 (I haven't read in entirety), all places that I
>> have referred wikipedia, Mac OSX internals by amit singh and private
>> communications with other folks suggest that arbitrary number of forks are
>> supported. (with limitations on size ? ..
>> so still not as full fledged as named streams on NTFS)
>>
>> Ok, I failed to find on google. Is there a place where I can lookup API's
>> to access resource forks (any number of). ( I know that through extended
>> attribute interface, I can access resource fork) ?
>>
>>
>>
>> Shailesh Jain
>>
>>
>>
>> On Wed, Jul 15, 2009 at 8:15 PM, Terry Lambert <email@hidden> wrote:
>>>
>>> On Jul 15, 2009, at 6:00 PM, shailesh jain wrote:
>>>>
>>>> TN1150 says following:
>>>>
>>>> "HFS Plus has an attribute file, another B-tree, that can be used to
>>>> store additional information for a file or directory. Since it is part of
>>>> the volume format, this information can be kept with the file or directory
>>>> as is it moved or renamed, and can be deleted when the file or directory is
>>>> deleted. The contents of the attribute file's records have not been fully
>>>> defined yet, but the goal is to provide an arbitrary number of forks,
>>>> identified by Unicode names, for any file or directory."
>>>>
>>>> Does that mean HFS+ now supports arbitrary number of forks rather that
>>>> just 'data fork + resource fork' ? And arbitrary number of forks can be
>>>> accessed by getxattr and friends ?
>>>
>>> I think "The contents of the attribute file's records have not been fully
>>> defined yet" is pretty clear...
>>>
>>> -- Terry
>>
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