RE: filexfer-07

["Richard Whalen" <Whalenr%process.com@localhost>]

> -----Original Message-----
> From: ietf-ssh-owner%NetBSD.org@localhost [mailto:ietf-ssh-owner%NetBSD.org@localhost]On
> Behalf Of Joseph Galbraith
> Sent: Friday, April 01, 2005 4:59 PM
> To: der Mouse
> Cc: ietf-ssh%NetBSD.org@localhost
> Subject: Re: filexfer-07
> 
> > 7.1.1.3, describing SSH_FXF_ACCESS_READ_LOCK: s/gaurantee/guarantee/
> > (twice).  Also, it's not clear whether "the exclusive reader" means
> > with respect to other sftp clients or with respect to all other OS
> > activity; and, an exclusive read lock is a very peculiar 
> thing, and not
> > at all what a "read lock" normally does.
> 
> All right; I renamed it to SSH_FXF_ACCESS_EXCLUSIVE_READ,
> and changed it to say:
> 
>    The server MUST guarantee that no other handle has been
>    opened with ACE4_READ_DATA access, and that no other
>    handle will be opened with ACE4_READ_DATA access until
>    the client closes the handle.  (This MUST apply both
>    to other clients and to other processes on the server.)
> 
>    If there is a conflicting lock the server MUST return
>    SSH_FX_LOCK_CONFLICT.  If the server cannot make the locking
>    guarantee, it MUST return SSH_FX_OP_UNSUPPORTED.
> 
>    Other handles MAY be opened for ACE4_WRITE_DATA or any other
>    access, as long as it does not include ACE4_READ_DATA.
> 
> Is this better?
> 

I think that the lock described is still pretty unusual for a file.  When accessing a file the usual methods of locking are:

None - I don't care if there is other current access, I'll take my chances if something modifies it while I'm writing/reading it.

Read - I don't want anyone to modify the file (or its attributes) while I'm reading it.  I don't care about other readers.

Write - I don't want anyone else to be accessing the file while I access it for write. I don't want to risk others getting a corrupt file while I'm changing it.