makechrootpkg, arch-nspawn: Force-enable local '/repo/' repository.

The change in arch-nspawn is subtle:

  This was the source of "infamous" "it fails every other time" bug that
  took me over a year to solve.  <https://labs.parabola.nu/issues/435>

  By having a repository of local packages (rather than simply running
  `pacman -U`), we are inviting pacman to cache them in
  `/var/cache/pacman/pkg`.  Besides being needless disk writes, this
  actually causes a real issue.  If the package gets rebuilt, pacman
  will balk, as the file no longer matches the cached signature.

  So, how do we prevent pacman from caching these local packages?
  Simple: include the directory they are already in in the
  pacman.conf:CacheDir list.  This will prevent pacman from copying
  the files to one of the other cache directories.

2 files changed, 12 insertions, 0 deletions

diff --git a/arch-nspawn.in b/arch-nspawn.in
index ea6e5ea..85af8c5 100644
--- a/arch-nspawn.in
+++ b/arch-nspawn.in
@@ -106,6 +106,7 @@ elif [[ $(cat "$working_dir/.arch-chroot") != $CHROOT_VERSION ]]; then
 fi
 
 build_mount_args
+cache_dirs+=('/repo/')
 copy_hostconf
 
 eval $(grep '^CARCH=' "$working_dir/etc/makepkg.conf")
diff --git a/makechrootpkg.in b/makechrootpkg.in
index 878c663..3f4e009 100644
--- a/makechrootpkg.in
+++ b/makechrootpkg.in
@@ -308,6 +308,15 @@ EOF
 		chmod 440 "$copydir/etc/sudoers.d/builduser-pacman"
 	fi
 
+	if ! grep -q '^\[repo\]' "$copydir/etc/pacman.conf"; then
+		local line=$(grep -n '^\[' "$copydir/etc/pacman.conf" |grep -Fv ':[options]'|sed 's/:.*//;1q')
+		local ins='[repo]
+SigLevel = Optional TrustAll
+Server = file:///repo
+'
+		sed -i "${line}i${ins//$'\n'/\\n}" "$copydir/etc/pacman.conf"
+	fi
+
 	# This is a little gross, but this way the script is recreated every time in the
 	# working copy
 	{
@@ -399,6 +408,8 @@ _chrootprepare() {
 		exit 1
 	fi
 
+	# Sync deps now, as networking may be disabled during _chrootbuild
+	cp /repo/repo.db /var/lib/pacman/sync/repo.db
 	sudo -u builduser makepkg "$@" --nobuild
 }