From e5c5ec7c6bf8d0460b870b1dacc5c928326fb81b Mon Sep 17 00:00:00 2001
From: Luke Shumaker <LukeShu@sbcglobal.net>
Date: Mon, 12 Nov 2012 18:56:53 -0500
Subject: librechroot: learn how to sync copies with root

---
 src/chroot-tools/librechroot | 119 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 101 insertions(+), 18 deletions(-)

(limited to 'src')

diff --git a/src/chroot-tools/librechroot b/src/chroot-tools/librechroot
index d53448a..1c9700c 100755
--- a/src/chroot-tools/librechroot
+++ b/src/chroot-tools/librechroot
@@ -27,35 +27,107 @@
 
 cmd=${0##*/}
 
-clean_chroot() {  # Clean packages with pacman
-	msg "Cleaning chroot with pacman: ${chroot_path}"
+lock_open_write() {
+	local fd=$1
+	local path=$2
+	local msg=$3
+
+	# Only reopen the FD if it wasn't handed to us
+	if [[ $(readlink -f /dev/fd/$fd) != "${path}.lock" ]]; then
+		exec $fd>"${path}.lock"
+	fi
+
+	if ! flock -n $fd; then
+		stat_busy "$msg"
+		flock $fd
+		stat_done
+	fi
+}
+
+lock_open_read() {
+	local fd=$1
+	local path=$2
+	local msg=$3
+
+	# Only reopen the FD if it wasn't handed to us
+	if [[ $(readlink -f /dev/fd/$fd) != "${path}.lock" ]]; then
+		exec $fd>"${path}.lock"
+	fi
 
-	cp -a "$(dirname $0)/chcleanup"   "${chroot_path}/clean"
-	mkarchroot -r "cd /build; /clean" "${chroot_path}"
+	if ! flock -sn $fd; then
+		stat_busy "$msg"
+		flock -s $fd
+		stat_done
+	fi
+}
 
-	#mkarchroot "${chroot_path}" base base-devel sudo "${CHROOTEXTRAPKG[@]}"
+lock_close() {
+	local fd=$1
+	exec $fd>&-
+}
+
+clean_pacman() {
+	msg "Cleaning chroot with pacman: ${copydir}"
+
+	cp -a "$(dirname $0)/chcleanup"   "${copydir}/clean"
+	mkarchroot -r "cd /build; /clean" "${copydir}"
+
+	#mkarchroot "${copydir}" base base-devel sudo "${CHROOTEXTRAPKG[@]}"
 }
 
 clean_repo() {
-	msg "Cleaning repo for chroot: ${chroot_path}"
+	msg "Cleaning repo for chroot: ${copydir}"
+
+	if [ -d  "${copydir}/repo" ]; then
+		find "${copydir}/repo/" -mindepth 1 -delete
+	else
+		mkdir -p "${copydir}/repo"
+	fi
+	bsdtar -czf "${copydir}/repo/repo.db.tar.gz" -T /dev/null
+	ln -s "repo.db.tar.gz" "${copydir}/repo/repo.db"
+}
+
+##
+# This function is almost verbatim from makechrootpkg
+##
+sync() {
+	if [[ $CHROOTCOPY = root ]]; then
+		error "Cannot sync the root copy with itself"
+		exit 1
+	fi
+
+	# Note that '9' is the same FD number as in mkarchroot
+	lock_open_write 9 "$copydir" "Locking chroot copy '$copy'"
+	lock_open_read  8 "$rootdir" "Locking clean chroot"
 
-	if [ -d  "${chroot_path}/repo" ]; then
-		find "${chroot_path}/repo/" -mindepth 1 -delete
+	stat_busy 'Creating clean working copy'
+	local use_rsync=false
+	if type -P btrfs >/dev/null; then
+		[[ -d $copydir ]] && btrfs subvolume delete "$copydir" &>/dev/null
+		btrfs subvolume snapshot "$chrootdir/root" "$copydir" &>/dev/null ||
+			use_rsync=true
 	else
-		mkdir -p "${chroot_path}/repo"
+		use_rsync=true
 	fi
-	bsdtar -czf "${chroot_path}/repo/repo.db.tar.gz" -T /dev/null
-	ln -s "repo.db.tar.gz" "${chroot_path}/repo/repo.db"
+
+	if $use_rsync; then
+		mkdir -p "$copydir"
+		rsync -a --delete -q -W -x "$CHROOTDIR/$CHROOT/root/" "$copydir"
+	fi
+	stat_done
+
+	lock_close 8
+	lock_close 9
 }
 
 update() {
-	msg "Updating chroot: ${chroot_path}"
-	mkarchroot -u "${chroot_path}"
+	msg "Updating chroot: ${copydir}"
+	mkarchroot -u "${copydir}"
 }
 
 enter() {
-	msg "Entering chroot: ${chroot_path}"
-	mkarchroot -r "bash" "${chroot_path}"
+	msg "Entering chroot: ${copydir}"
+	mkarchroot -r "bash" "${copydir}"
 }
 
 usage() {
@@ -72,6 +144,7 @@ usage() {
 	echo ' Modes:'
 	echo ' -h              Show this message'
 	echo ' -c              Clean the chroot using pacman'
+	echo " -C              Clean the chroot by syncing it with 'root' copy"
 	echo ' -r              Clean /repo in the chroot'
 	echo ' -u              Update the chroot'
 }
@@ -88,7 +161,8 @@ main() {
 			d) CHROOTDIR=$OPTARG;;
 			l) CHROOTCOPY=$OPTARG;;
 
-			c) mode=clean_chroot;;
+			c) mode=clean_pacman;;
+			C) mode=sync;;
 			r) mode=clean_repo;;
 			u) mode=update;;
 
@@ -104,15 +178,24 @@ main() {
 	esac
 
 	# not local
-	chroot_path="${CHROOTDIR}/${CHROOT}/${CHROOTCOPY}"
+	rootdir="${CHROOTDIR}/${CHROOT}/root"
+	copydir="${CHROOTDIR}/${CHROOT}/${CHROOTCOPY}"
 
 	if (( EUID )); then
 		error "This script must be run as root."
 		exit 1
 	fi
 
+	if [[ ! -d $rootdir ]]; then
+		libremkchroot -d "$CHROOTDIR" "$CHROOT"
+	fi
+
+	if [[ ! -d $copydir ]] && [[ $mode != sync ]]; then
+		sync
+	fi
+
 	case "$mode" in
-		clean_chroot) clean_chroot; exit $?;;
+		clean_pacman) clean_pacman; exit $?;;
 		clean_repo) clean_repo; exit $?;;
 		update) update; exit $?;;
 		enter) enter; exit $?;;
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