common: add chroot-style 'ethereal'

common/chroot-style/ethereal.sh

@@ -0,0 +1,135 @@
+#!/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" "$@"
+	[ -n "$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 $1 -> $2"
+}
+
+if [ "${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

common/xbps-src/shutils/chroot.sh

@@ -216,6 +216,7 @@ chroot_handler() {
         env -i -- PATH="/usr/bin:/usr/sbin:$PATH" SHELL=/bin/sh \
             HOME=/tmp IN_CHROOT=1 LC_COLLATE=C LANG=en_US.UTF-8 \
             SOURCE_DATE_EPOCH="$SOURCE_DATE_EPOCH" \
+            XBPS_ALLOW_CHROOT_BREAKOUT="$XBPS_ALLOW_CHROOT_BREAKOUT" \
             $XBPS_COMMONDIR/chroot-style/${XBPS_CHROOT_CMD:=uunshare}.sh \
             $XBPS_MASTERDIR $XBPS_DISTDIR "$XBPS_HOSTDIR" "$XBPS_CHROOT_CMD_ARGS" \
             /void-packages/xbps-src $action $pkg

etc/defaults.conf

@@ -114,6 +114,7 @@ XBPS_SUCMD="sudo /bin/sh -c"
 # 	- uchroot (uses xbps-uchroot(8), namespaces, setgid)
 # 	- proot (uses proot, external, does not need special permissions)
 # 	- bwrap (uses bwrap, external, does not need special permissions)
+#	- ethereal (uses root, needs no permissions, for disposable containers)
 #
 # The order is already set as shown above, but can be overriden below.
 # Additional arguments to the chroot style can be passed in via XBPS_CHROOT_CMD_ARGS.
@@ -126,3 +127,9 @@ XBPS_SUCMD="sudo /bin/sh -c"
 # the HEAD commit time.
 #
 #XBPS_USE_BUILD_MTIME=yes
+
+# [OPTIONAL]
+# When using the 'ethereal' chroot-style this switch must be activated, it is
+# meant as safeguard against users casually destroying their systems
+#
+#XBPS_ALLOW_CHROOT_BREAKOUT=yes

xbps-src

@@ -577,7 +577,7 @@ if [ -n "${NO_COLOR+x}" ]; then
 fi
 
 chroot_check() {
-    if [ -f $XBPS_MASTERDIR/.xbps_chroot_init ]; then
+    if [ -f $XBPS_MASTERDIR/.xbps_chroot_init -o "$XBPS_CHROOT_CMD" = "ethereal" ]; then
         export CHROOT_READY=1
     fi
 }