#!/bin/sh # # mmdebstrap does have a --merged-usr option but only as a no-op for # debootstrap compatibility # # Using this hook script, you can emulate what debootstrap does to set up # merged /usr via directory symlinks, even using the exact same shell function # that debootstrap uses by running mmdebstrap with: # # --setup-hook=/usr/share/mmdebstrap/hooks/merged-usr/setup00.sh # # Alternatively, you can setup merged-/usr by installing the usrmerge package: # # --include=usrmerge # # mmdebstrap will not include this functionality via a --merged-usr option # because there are many reasons against implementing merged-/usr that way: # # https://wiki.debian.org/Teams/Dpkg/MergedUsr # https://wiki.debian.org/Teams/Dpkg/FAQ#Q:_Does_dpkg_support_merged-.2Fusr-via-aliased-dirs.3F # https://lists.debian.org/20190219044924.GB21901@gaara.hadrons.org # https://lists.debian.org/YAkLOMIocggdprSQ@thunder.hadrons.org # https://lists.debian.org/20181223030614.GA8788@gaara.hadrons.org # # In addition, the merged-/usr-via-aliased-dirs approach violates an important # principle of component based software engineering one of the core design # ideas/goals of mmdebstrap: All the information to create a chroot of a Debian # based distribution should be included in its packages and their metadata. # Using directory symlinks as used by debootstrap contradicts this principle. # The information whether a distribution uses this approach to merged-/usr or # not is not anymore contained in its packages but in a tool from the outside. # # Example real world problem: I'm using debbisect to bisect Debian unstable # between 2015 and today. For which snapshot.d.o timestamp should a merged-/usr # chroot be created and for which ones not? # # The problem is not the idea of merged-/usr but the problem is the way how it # got implemented in debootstrap via directory symlinks. That way of rolling # out merged-/usr is bad from the dpkg point-of-view and completely opposite of # the vision with which in mind I wrote mmdebstrap. set -eu if [ "${MMDEBSTRAP_VERBOSITY:-1}" -ge 3 ]; then set -x fi TARGET="$1" ARCH=$(dpkg --print-architecture) eval "$(APT_CONFIG="$MMDEBSTRAP_APT_CONFIG" apt-config shell ARCH Apt::Architecture)" if [ -e /usr/share/debootstrap/functions ]; then # shellcheck disable=SC1091 . /usr/share/debootstrap/functions doing_variant () { [ "$1" != "buildd" ]; } # shellcheck disable=SC2034 MERGED_USR="yes" setup_merged_usr else link_dir="" case $ARCH in hurd-*) exit 0;; amd64) link_dir="lib32 lib64 libx32" ;; i386) link_dir="lib64 libx32" ;; mips|mipsel) link_dir="lib32 lib64" ;; mips64*|mipsn32*) link_dir="lib32 lib64 libo32" ;; powerpc) link_dir="lib64" ;; ppc64) link_dir="lib32 lib64" ;; ppc64el) link_dir="lib64" ;; s390x) link_dir="lib32" ;; sparc) link_dir="lib64" ;; sparc64) link_dir="lib32 lib64" ;; x32) link_dir="lib32 lib64 libx32" ;; esac link_dir="bin sbin lib $link_dir" for dir in $link_dir; do ln -s usr/"$dir" "$TARGET/$dir" mkdir -p "$TARGET/usr/$dir" done fi # now install an empty "usr-is-merged" package to avoid installing the # usrmerge package on this system even after init-system-helpers starts # depending on "usrmerge | usr-is-merged". # # This package will not end up in the final chroot because the essential # hook replaces it with the actual usr-is-merged package from src:usrmerge. tmpdir=$(mktemp --directory --tmpdir="$TARGET/tmp") mkdir -p "$tmpdir/usr-is-merged/DEBIAN" cat << END > "$tmpdir/usr-is-merged/DEBIAN/control" Package: usr-is-merged Priority: optional Section: oldlibs Maintainer: Johannes Schauer Marin Rodrigues <josch@debian.org> Architecture: all Multi-Arch: foreign Source: mmdebstrap-dummy-usr-is-merged Version: 1 Description: dummy package created by mmdebstrap merged-usr setup hook This package was generated and installed by the mmdebstrap merged-usr setup hook at /usr/share/mmdebstrap/hooks/merged-usr. . If this package is installed in the final chroot, then this is a bug in mmdebstrap. Please report: https://gitlab.mister-muffin.de/josch/mmdebstrap END dpkg-deb --build "$tmpdir/usr-is-merged" "$tmpdir/usr-is-merged.deb" dpkg --root="$TARGET" --log="$TARGET/var/log/dpkg.log" --install "$tmpdir/usr-is-merged.deb" rm "$tmpdir/usr-is-merged.deb" "$tmpdir/usr-is-merged/DEBIAN/control" rmdir "$tmpdir/usr-is-merged/DEBIAN" "$tmpdir/usr-is-merged" "$tmpdir"