Linux Certif

Toute la documentation sur la certification Linux LPI

emgrip

NAME

emgrip - converts a .deb to Emdebian Grip on-the-fly

Synopsis

  DEB_BUILD_OPTIONS='usegrip' emgrip [-v|--verbose] [-q|--quiet] [-o|--outdir DIRECTORY] FILENAME
 
 

where FILENAME is a .dsc, a .changes or a .deb

  emgrip -?|-h|--help|--version
 
 

Description

Converts a .deb package to Emdebian Grip by unpacking, pruning particular classes of files (determined by DEB_BUILD_OPTIONS) and repacking with a shortened description and the em1 version suffix.

When creating a public Emdebian Grip repository, it is strongly recommended to specify .changes or .dsc files to allow the generation of Emdebian TDebs from the source package as well as including the source package itself in the repository.

If a file exists with the same name in the output directory, it will be overwritten.

Copyright and Licence

  Copyright (C) 1997-2000  Roman Hodek <roman@hodek.net>
  Copyright (C) 2000-2002  Colin Watson <cjwatson@debian.org>
  Copyright (C) 2002-2004  David Schleef <ds@schleef.org>
  Copyright (C) 2004  Nikita Youshchenko <yoush@cs.msu.su>
  Copyright (C) 2004  Raphael Bossek <bossekr@debian.org>
  Copyright (C) 2007-2008  Neil Williams <codehelp@debian.org>
 
  This package is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 3 of the License, or
  (at your option) any later version.
 
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 

Emdebian Grip

The idea here is based on dpkg-cross:

  1. receive .deb or .changes as a command-line option
  2. parse DEB_BUILD_OPTIONS
  3. unpack the .deb as dpkg-cross does
  4. remove files as per DEB_BUILD_OPTIONS
  5. repack the .deb with an Emdebian version suffix.
  6. build new .deb and revise .changes so that the
      original source can be retained.
  7. Include the gripped packages into a local mirror
      to reduce the size of Packages.gz and the size of
      the mirror itself.
 
 

As few dependencies as possible - this script should become a new package and have a new set of lintian checks to allow perl etc.

  NO FUNCTIONAL CHANGES IN THE FINAL .DEB !
 
 

Conversion of Debian TDebs to Emdebian TDebs needs to be done inside the source package so a .changes file is needed for this step. If the .changes file references a Debian TDeb, emgrip will run 'em_installtdeb -a $arch --no-sign' inside the source package (where $arch is determined from the contents of the .changes file).

Individual packages containing translation files will have the translation files removed and Debian TDebs are skipped.

Future versions will also have to understand Dpkg Classes but until those are implemented, this uses brute force.

The new package also needs dh_grip which can be added to all debian/rules files just before dpkg-build .. or dh_builddeb and which does nothing in the normal circumstance but does the same as emgrip *if* the DEB_BUILD_OPTIONS ``usegrip'' is set or if the other DEB_BUILD_OPTIONS are set, like ``nodocs'', ``nohelp'' or ``noessential''.

DEB_BUILD_OPTIONS

If none of these options are set, emgrip does nothing.

  nodocs
 Remove all content in /usr/share/doc/*/ except the copyright
 file and compress the copyright file itself. Remove manpages
 and info pages (translated or not). Also remove doc-base files
 that describe the documentation that no longer exists.
 
  nohelp
 Remove even help files from all packages, including -doc packages.
 Includes removing /usr/share/gtk-doc/html and
 /usr/share/gnome/help/\$package
 Despite removing the help files, dependencies on help file utilities
 like scrollkeeper will remain, at least for Lenny.
 
  noessential
 Remove the 'Essential: yes' tag from DEBIAN/control - this
 is a brute force removal, no additional dependencies are to
 be generated (no patches) so care is needed here.
 
  nolintian
 Remove all files from /usr/share/lintian/overrides and
 /usr/share/linda/overrides - saves up to 1Mb.
 
  usegrip
 Combination flag that sets all DEB_BUILD_OPTIONS for Emdebian
 Grip - noessential, nohelp, nodocs, nolintian
 
  nosymbols
 Currently being tested - the idea is to drop DEBIAN/symbols files
 but this could have unpredictable effects on packages built on a
 system lacking these symbols. The space saved by dropping these files
 might not be worth the cost, so 'usegrip' does not yet activate
 'nosymbols'. This might be suitable for Crush, maybe not Grip.
 
  noperl
 Remove any file that is found to be a perl script text executable
 by 'file' - used by Crush.
 
  usecrush
 Combination flag that adds nosymbols and noperl to usegrip.
 
 

Field removal

Functional control fields are retained but the question arises:
 Who defines functional?

Well, for the current purposes of Emdebian Grip, functional includes only the following control fields:

  Package
  Source
  Version
  Architecture
  Maintainer
  Installed-Size
  Depends
  Pre-Depends
  Conflicts
  Replaces
  Section
  Priority
  Description
  Task
 
 

Recommends is explicitly rejected, as is Suggests - the expectation is that Emdebian Grip will disable Install-Recommends in apt anyway, so that Gripped packages can be mixed with Debian or locally-built packages.

Note also that 'Essential' is not.

Homepage, VCS* and all X- control fields are dropped.

The net result is a (potentially) much cleaner dpkg database.

The description is trimmed to four lines (or three if the fourth line is empty with a comment appended:
 This is an Emdebian Grip package.

Automation

Relatively simple, but a few checks are needed in case your list of possible packages includes packages already processed by dpkg-cross.

  #!/bin/sh
  set -e
 
  DIR=/tmp/myrepo/
  for deb in `ls /var/cache/apt/archives/*.deb`; do
     cross=`echo $deb | grep "\-.*-cross" || true`
     if [ ! -z "$cross" ]; then
         echo "skipping dpkg-cross package: $deb"
         continue
     fi
     DEB_BUILD_OPTIONS="nodocs nohelp usegrip" ./emgrip -o $DIR $deb
  done
 
 

A similar script should be able to cope with obtaining .changes files to retain the source packages.

Despite using dcut internally, emgrip isn't set up to obtain the .changes files directly from http://incoming.debian.org, a wrapper script would be needed.

An additional wrapper is likely to be needed to allow an Emdebian Grip repository to ``catch-up'' with the existing Debian mirrors, e.g. if the first upload to the Grip repository is a binary-only upload without a referenced .orig.tar.gz.

emgrip does ensure that the .tar.gz is copied into the output directory and reprepro can locate the relevant files if the --ignore=missingfile option is passed. Sadly, this functionality is not preserved in the reprepro processincoming mode.

To ease the process of gripping an existing mirror, the emdebian-grip package depends on 'reprepro' to create a filtered Debian mirror that can be kept up to date, generates meta-data for Emdebian Grip, builds gripped packages in an 'incoming/' directory and includes the packages into the final Emdebian Grip repository.

Once a package has been ``gripped'', the binary packages could be removed from the filtered mirror - the source packages (particularly the .orig.tar.gz) are probably best retained in the filtered mirror.

Pruning empty directories

A subroutine to prune directories has been tested in emgrip and it is possible to identify directories that were intentionally empty in the Debian package. However, aggressively removing directories that end up as empty after removal of unsupported scripts and files is likely to be a step too far. Some packages may expect a directory to exist merely because a file was originally packaged into that directory, so we need Dpkg Classes to tell the difference.

emgrip therefore leaves empty directories in place.