[syslinux] port syslinux isohybrid perl script to C

[H. Peter Anvin]

On 03/31/2010 09:47 AM, Thomas Schmitt wrote:
> Hi,
> 
>> Quite frankly, if we need such a program, then we already have it, and
>> any integration with xorriso is completely pointless.
>> If we can't eliminate a step and a user interface, then the whole
>> exercise is moot.
> 
> We can eliminate the step of post-processing.
> The MBR template could be created once and
> used many times.
> Its production fits better into the usual
> course of ISOLINUX preparation, which happens
> _before_ the result is copied to media.
> 
> A default MBR template that comes with syslinux
> would eliminate the need for user interaction
> in most cases.
> If the name of that default MBR is specified
> as syslinux standard, then libisofs could find
> it without help by the user.
> So we'd spare completely the isohybrid step
> in normal situations.
> 
> isohybrid would get added a bit of new user
> interface, though. For experts.
> 
> There is also a technical advantage:
> 
> isohybrid needs random read-write access
> to the finished ISO image.
> libisofs could write the image directly to a
> target that only provides sequential write
> access: E.g. a SSH pipe, or a CD-R.
> 

Let me be more explicit:

Either do it right or don't do it at all.  I WILL NOT consider
supporting a half-arsed farce with a far richer interface than is
necessary, and which doesn't even help me get rid of a utility.
Furthermore, you STILL need the parameters in order to generate the MBR,
properly pad the image, and so on, so you'd have to have intimate
knowledge of what they mean *anyway*.  This whole "MBR template" idea is
utter crap.

The MBR is a structural piece, that will remain stable, because it
doesn't have anything to do with isohybrid *per se* to do at all.  The
only thing in this whole bit which is isohybrid-specific is putting the
LBA of the boot file at offset 432..439, and as previously explained we
could get rid of that, too.

The reason your previous attempt was such a spectacular failure was you
embedded actual code into xorriso, rather than concentrating on the
structure.

	-hpa