• Open Menu Close Menu
  • Apple
  • Shopping Bag
  • Apple
  • Mac
  • iPad
  • iPhone
  • Watch
  • TV
  • Music
  • Support
  • Search apple.com
  • Shopping Bag

Lists

Open Menu Close Menu
  • Terms and Conditions
  • Lists hosted on this site
  • Email the Postmaster
  • Tips for posting to public mailing lists
Re: Resource Fork as Extended Attributes
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Resource Fork as Extended Attributes


  • Subject: Re: Resource Fork as Extended Attributes
  • From: Sean Fagan <email@hidden>
  • Date: Wed, 15 Jul 2009 20:22:37 -0700

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 ?

No, it doesn't mean that.

The attributes btree file mentioned is used for extended attributes -- as you note, getxattr and friends. However, the difference between them and the resource fork is pretty large.

The Resource Fork can be opened up and treated as a normal file -- read, write, lseek, etc. You can read and write a portion of it -- currently, it's the only "extended attribute" that can take a positional argument to getxattr and setxattr.

The other EAs are manipulated solely through getxattr et al, and doing so is atomic: you write / read the entire EA, or you don't. You cannot use the read and write system calls on them. And so forth.

Sean.

_______________________________________________
Do not post admin requests to the list. They will be ignored.
Filesystem-dev mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden


  • Follow-Ups:
    • Re: Resource Fork as Extended Attributes
      • From: Paul Nelson <email@hidden>
References: 
 >Resource Fork as Extended Attributes (From: shailesh jain <email@hidden>)
 >Re: Resource Fork as Extended Attributes (From: Anton Altaparmakov <email@hidden>)
 >Re: Resource Fork as Extended Attributes (From: shailesh jain <email@hidden>)

  • Prev by Date: Re: Resource Fork as Extended Attributes
  • Next by Date: Re: Resource Fork as Extended Attributes
  • Previous by thread: Re: Resource Fork as Extended Attributes
  • Next by thread: Re: Resource Fork as Extended Attributes
  • Index(es):
    • Date
    • Thread