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void-packages/common/chroot-style/ethereal.sh
2024-03-29 08:12:19 +01:00

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#!/bin/sh
#
# This chroot script uses symlinks to emulate being in a chroot using
# the host system as the masterdir
#
# It will damage your host system, only use it in disposable
# containers.
#
# 2 extra steps required when using this chroot-style:
# 1. Symlink / to masterdir inside the void-packages repo
# 2. write the arch of the host system, as dictated by xbps-uhelper arch
# into /.xbps_chroot_init
#
# The supported way to make use of thie chroot-style is to create
# a root filesystem that has base-chroot and git installed and
# have it inside a container engine like Docker.
#
# Docker example:
# $ mkdir -p /tmp/image
# $ xbps-install -y -r /tmp/image \
# -R http://mirrors.servercentral.com/voidlinux/current \
# -S base-chroot
# $ tar -pC /tmp/image -c . | sudo docker import - voidlinux/masterdir
# $ rm -rf /tmp/image
# # docker run --rm -it \
# -e XBPS_CHROOT_CMD=ethereal \
# -e XBPS_ALLOW_CHROOT_BREAKOUT=yes \
# -v $(pwd):/hostrepo voidlinux/masterdir \
# /bin/bash -c 'ln -s / /hostrepo/masterdir && /hostrepo/xbps-src pkg <pkgname>'
#
readonly MASTERDIR="$1"
readonly DISTDIR="$2"
readonly HOSTDIR="$3"
readonly EXTRA_ARGS="$4"
readonly CMD="$5"
shift 5
if [ -z "$MASTERDIR" -o -z "$DISTDIR" ]; then
echo "$0 MASTERDIR/DISTDIR not set"
exit 1
fi
msg_red() {
# error messages in bold/red
[ -n "$NOCOLORS" ] || printf >&2 "\033[1m\033[31m"
printf "=> ERROR: %s\\n" "$@" >&2
[ -n "$NOCOLORS" ] || printf >&2 "\033[m"
}
fake_mount() {
# If we already have a symlink from the desired place
# to the base location then just return 0
if [ -L "$2" -a "$(readlink "$2")" = "$1" ]; then
return 0
fi
if [ -d "$2" ] && ! rmdir "$2" >/dev/null 2>&1; then
msg_red "Failed to remove $2, not empty ?\n"
exit 1
fi
[ -f "$2" -o -L "$2" ] && rm -f "$2"
ln -s "$1" "$2"
echo "linked $2 -> $1"
}
if [ "${XBPS_ALLOW_CHROOT_BREAKOUT}" != "yes" ]; then
msg_red "chroot-style 'ethereal' requires XBPS_ALLOW_CHROOT_BREAKOUT=yes\n"
msg_red "This chroot-style is meant for disposable containers and will destroy your system\n"
exit 1
fi
if [ ! -L "$MASTERDIR" -o "$(readlink "$MASTERDIR")" != "/" ]; then
msg_red "$MASTERDIR isn't symlinked to /!\n"
exit 1
fi
fake_mount "$DISTDIR" "$MASTERDIR"/void-packages
# Do the same for hostdir
if [ -n "$HOSTDIR" ]; then
fake_mount "$HOSTDIR" "$MASTERDIR"/host
fi
# xbps-src may send some other binds, parse them here
while getopts 'b:' c -- "$EXTRA_ARGS"; do
# Skip everything that's not a bind
[ "$c" = "b" ] || continue
from="${OPTARG%:*}"
to="${OPTARG#*:}"
fake_mount "$from" "$to"
mounts="${mounts} $to"
done
# Store current directory for returning later
OLDPWD="$(pwd)"
# To give the illusion we entered the chroot, cd to /
cd / || {
msg_red "Failed to change directory to root!\n"
exit 1 ; }
# Tell xbps-src that we are "in the chroot"
# Start with `env` so our environment var's stay the same
env IN_CHROOT=1 $CMD $@
# Store return of the command we care about
ret="$?"
# Return to OLDPWD
cd "${OLDPWD}"
# Remove the symlink and restore an empty dir to simulate
# an umount operation.
if [ -n "$HOSTDIR" ]; then
rm -f "$MASTERDIR"/host
mkdir -p "$MASTERDIR"/host
fi
# Same as the operation above, do it all for all mountpoints
# that were passed to us.
for m in $mounts; do
rm -f "$m"
mkdir -p "$m"
done
rm -f "$MASTERDIR"/void-packages
mkdir -p "$MASTERDIR"/void-packages
exit $ret