Re: How to extend struct stat?

Jesse Pollard (pollard@tomcat.admin.navo.hpc.mil)
Tue, 5 Oct 1999 08:41:59 -0500 (CDT)


>I'm implementing ACLs. Project location:
><http://major.rithus.co.at/acl/>.
>
>For utilities like `ls', I need a flag `has extended access
>control information' in `struct stat'. Also, some operations
>in the VFS can be optimized with such a flag. An ioctl() call
>is inappropriate; this really belongs in the VFS.

Perhaps it is time to see about expanding the mode bits to include
several more fields (most unused at this time, but I can think of
several -a online/offline flag (file migration), a compressed flag
(file is compressed, may be used with the online flag. (More future
development...)

>
>Here is what I want ls to do. (This is also how Solaris
>implements it):
>
> andy@snowball:/acl/test > ls -l
> -rw-rw---- 1 andy toolies 5 Oct 5 13:27 file1
> -rw-rw----+ 1 andy toolies 5 Oct 5 13:27 file2
>
>I simply would have added a bit to the st_mode field in struct stat;
>that would have done the job. Unfortunately on i386 systems, st_mode
>is 16 bits wide, all bits used.

The display looks fine to me.
- perhaps it is time to see about expanding
the mode bits to include several more fields.
>
>I know this will break some scripts. The scripts need to be changed,
>simply.

I don't think it will hurt very many scripts - the mode field is not
as usefull as others (byte length, file name, owner). Since it is
still part of the first field there shouldn't too much of a problem.

-------------------------------------------------------------------------
Jesse I Pollard, II
Email: pollard@navo.hpc.mil

Any opinions expressed are solely my own.

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