[syslinux] SYSLINUX 3.81-pre10

[Thomas Schmitt]

Hi,

i am pondering over the license issue
and the problem of keeping libisofs up to
date with isohybrid development.
License situation and code quality would
be better if libisofs uses your scripts
directly. (Security will suffer a bit.)

This seems achievable by a new option
for isohybrid:

-piped  $ibsig  $de_lba  $imgsize

  If this option is given then isohybrid
  ignores argument isoimage.iso and
  it avoids any seeking and reading of the
  image file.
  (In 3.81-pre10: lines 128 to 180, 
   196 to 208, 256.)
  It writes the MBR to stdout rather than
  to image file.
  (Line 247)
  It does not pad up the image file to
  a fake cylinder boundary.
  (Lines 249 to 253)

  Parameter $ibsig is a 32 bit hex number which
  announces the signature of isolinux.bin
  for compatibility checking.
  Parameter $de_lba is a decimal number which
  sets the sector number of isolinux.bin.
  Parameter $imgsize is a decimal number which
  sets the total size of the image.

  If three parameters are inconvient then
  one could also prescribe three options
  which are mandatory with mode -piped.

This provides no back channel for $padding.
So the caller will have to compute it from
$h and $s. This will be unambigous if the
caller is forced to set options -h and -s
or if the default h=64, s=32 becomes part
of isohybrid specs.
The formula
  $cylsize = $h*$s*512;
  $frac = $imgsize % $cylsize;
  $padding = ($frac > 0) ? $cylsize - $frac : 0;
would become part of isohybrid specs.


It would be helpful if the isohybrid specs
would tell the absolute path where the script
can be found with a vanilla installation of
SYSLINUX. 
(It is a security risk to evaluate $PATH and
 it is cumbersome if the user of libisofs has
 to give the full path of isohybrid. A nice
 compromise would be a fixed default path
 in libisofs, overridable by a user provided path.)


Have a nice day :)

Thomas