Re: Rock Ridge features in grub-mkrescue

[Thomas Schmitt]

Hi,

i meanwhile decided to let xorrisofs option --norock revoke the -find job
which might have been ordered by option -r.
  http://libburnia-project.org/changeset/5695


Now for the patches.

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My own proposal would need a different description:

> address@hidden --no-xorrisofs-r
> +Do not silently pass a -r flag to the @command{xorrisofs} program by
> +default.

The program executed by grub-mkrescue is actually xorriso, not the
link xorrisofs. This becomes important when --xorriso= is used. The
replacement program must accept "-as" "mkisofs" as first two arguments.
Like
  -as mkisofs -graft-points --modification-date=2016040709073100 ... 

How about this:

  Do not add option -r to the arguments of the @command{xorriso} run.


> + [...] Instead, allow the Rock Ridge features of the ISO image to
> +be determined entirely by user-specified arguments explictly passed to
> +the @command{xorrisofs} program on the command line.

One should rather explain that without -r, the default -R is enabled.
This default can be overridden by -r or --norock (the latter since
xorriso-1.2.4).

How about:

  Without this option, the file owner and group id numbers are preserved
  as well as the POSIX permissions. With -r, owner and group become 0.
  Permissions are set to read-only for all and to executable for all if
  executable for anybody.

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Not necessarily my personal favorite:

> address@hidden address@hidden
> + [...] Value
> +'basic' (the default) requests inclusion of simplified file ownership
> +and permission information by which all files share a single owner and
> +a limited set of permissions.

This is too rough a description of option -r. I'd propose the one
above. The full description in man xorrisofs is:

  -r
      Enable Rock Ridge and set user and group id of all files in  the
      ISO   image   to  0.   Grant  r-permissions  to  all.  Deny  all
      w-permissions.  If any x-permission is set,  grant  x-permission
      to all.  Remove s-bit and t-bit.


> + [...] Value 'full' requests inclusion of full
> +Unix-style ownership and permission information.

Probably "POSIX" would be better than "Unix-style".
After all it does not cover ACLs, which i would count as part of full
permission information.


> + [...] In some cases, the
> +selected Rock Ridge mode can be effectively over-ridden by flags
> +passed directly to the @command{xorriso} program.

Consider to omit this sentence.
I know what you mean. But the situation is complicated (released xorriso
versions can disable Rock Ridge but cannot convert -r to -R).
Any simplified statement can only increase confusion.

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Have a nice day :)

Thomas