Syslinux - Sep 2012 - utils/isohybrid.c #inclusion of <uuid/uuid.h>

Good day, Matthew.

I recently got stuck while building Syslinux as <uuid/uuid.h> doesn't
exist
on my system.  The #inclusion was introduced in commit
2c3a24e5f4b807ec31595227afa59a818c060ca9.  Whence does this file come, if
you please?  I'm assuming it is the Linux kernel's, but can't seem
to
understand the directory prefix, in that case.

- Shao

On Sun, Sep 23, 2012 at 03:31:45PM -0400, Shao Miller
wrote:
> Good day, Matthew.
> 
> I recently got stuck while building Syslinux as <uuid/uuid.h>
doesn't exist
> on my system.  The #inclusion was introduced in commit
> 2c3a24e5f4b807ec31595227afa59a818c060ca9.  Whence does this file come, if
> you please?  I'm assuming it is the Linux kernel's, but can't
seem to
> understand the directory prefix, in that case.
With `locate uuid.h` did I found among others
  /usr/include/uuid/uuid.h

Doing `dpkg -S /usr/include/uuid/uuid.h` my Debian system give:
  uuid-dev: /usr/include/uuid/uuid.h
Meaning that the package "uuid-dev" provides the header file.


Groeten
Geert Stappers
-- 
> And is there a policy on top-posting vs. bottom-posting?
Yes.

Good day, Geert.

Thanks for the response.

I wonder which is better, if either:

1. Document that building Syslinux now depends on uuid-dev
2. Remove this dependence and use a Syslinux-internal uuid.h

What do you think?

- Shao Miller

It's from libuuid, which is part of util-linux but shouldn't be 
Linux-specific.

-- 
Matthew Garrett | mjg59 at srcf.ucam.org

Hi,
> > +"utils/isohybrid" needs the header file,
> > +
> > +     /usr/include/uuid/uuid.h
> It is not just the header file... it depends on the *library*.
I had some iportability troubles with that when i implemented
the --efi functionality in libisofs. After implementing a fallback
by own code, i decided to omit the library for now.

The self-made UUID generator is far from perfect.
But it passed collision tests with millions of tries and in theory
it should provide at least 50 bits of entropy per day.
See
 
http://bazaar.launchpad.net/~libburnia-team/libisofs/scdbackup/view/head:/libisofs/system_area.c
  void iso_random_uuid(Ecma119Image *t, uint8_t uuid[16])
in the case when Libisofs_with_uuid_generatE is not defined.

The idea is to use a hardcoded UUID as seed that was obtained from
the library and to then manipulate the seed by easily obtainable
weak pseudo-random data.

Surely one can improve the randomness by choosing more and better
sources of pseudo-random.
(One source of entropy is a CRC of the master object Ecma119Image t,
 that governs libisofs image generation. At least this one needs
 to be substituted in a standalone implementation.)


Have a nice day :)

Thomas

On 10/15/2012 11:25 PM, Thomas Schmitt wrote:
> 
> I had some iportability troubles with that when i implemented
> the --efi functionality in libisofs. After implementing a fallback
> by own code, i decided to omit the library for now.
> 
On most Unix platforms you can just open /dev/urandom, extract 16 bytes,
and overwrite six bits in the middle.

	-hpa

On Mon, 2012-10-15 at 16:25 -0700, H. Peter Anvin wrote:
> On 10/15/2012 12:52 AM, Matt Fleming wrote:
> > 
> > From 1ece228d9f133791b3d63d6996e475a1ad695af3 Mon Sep 17 00:00:00 2001
> > From: Geert Stappers <stappers at stappers.nl>
> > Date: Fri, 12 Oct 2012 21:36:50 +0200
> > Subject: [PATCH] README: document the need for
/usr/include/uuid/uuid.h
> > 
> > utils/isohybrid build depends on /usr/include/uuid/uuid.h The package
> > name varies between distribution families.
> > ---
> >  README | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/README b/README
> > index 08a82e4..1b7c2d3 100644
> > --- a/README
> > +++ b/README
> > @@ -20,6 +20,13 @@ SYSLINUX now builds in a Linux environment, using
nasm.  You need nasm
> >  version 2.03 or later (2.07 or later recommended) to build SYSLINUX
> >  from source.  See http://www.nasm.us/ for information about nasm.
> >  
> > +"utils/isohybrid" needs the header file,
> > +
> > +	/usr/include/uuid/uuid.h
> > +
> > +You can get it from the "uuid-dev" package on Debian based
systems or
> > +from the "libuuid-devel" package on RPM based
distributions.
> > +
> >  There is now a mailing list for SYSLINUX.  See the end of
syslinux.txt
> >  for details.
> >  
> 
> It is not just the header file... it depends on the *library*.
Should we update the documentation to reflect this? Do you have any
suggestions?

-- 
Matt Fleming, Intel Open Source Technology Center