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Re: passive translators


From: Neal H. Walfield
Subject: Re: passive translators
Date: Thu, 21 Jun 2007 10:20:03 +0200
User-agent: Wanderlust/2.14.0 (Africa) SEMI/1.14.6 (Maruoka) FLIM/1.14.6 (Marutamachi) APEL/10.6 Emacs/21.4 (i386-pc-linux-gnu) MULE/5.0 (SAKAKI)

At Thu, 21 Jun 2007 15:37:49 +0800,
Wei Shen wrote:
> 
> Hi,
> 
> Could you please give some explanation on "PFINETSERVER=fd:3 myprog
> 3</path/to/pfinet"? What does "myprog 3<" mean, the naming closure?

From the bash manual:

  3.6.1 Redirecting Input

  Redirection of input causes the file whose name results from the
  expansion of word to be opened for reading on file descriptor n, or
  the standard input (file descriptor 0) if n is not specified.
  
  The general format for redirecting input is:
  
  [n]<word

  http://www.gnu.org/software/bash/manual/bashref.html#SEC38

So, as bash starts myprog, it opens /path/to/pfinet and inserts the
resulting file descriptor into the program as fd 3.

> (1) Assume a chroot process invokes "settrans -cp /foo /hurd/firmlink /".
> 
> (2) The fs server will associate node /*foo* (/chroot/foo) with translator *
> firmlink*. Since the fs server knows the quest is from a chroot process,
> it can save a chroot attribute "/chroot" (it is a string representation of
> the chroot path, but not a handle or other expressions of capability), in
> addition to the translator command "/hurd/firmlink /".

The translator does not necessarily know a symbolic representation for
the capability passed to file_reparent.

Neal




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