feat: support bind mounting a tmpfs

A .cache can be bind mounted into the container to save the caches for
reuse, but sometimes we want to exclude specific caches (because they
don't work well, e.g. bazel's).

Component: makechrootpkg

1 files changed, 24 insertions, 20 deletions

diff --git a/src/makechrootpkg.in b/src/makechrootpkg.in
index 459f7ce..9df14e8 100644
--- a/src/makechrootpkg.in
+++ b/src/makechrootpkg.in
@@ -38,6 +38,7 @@ inspect=never
 
 bindmounts_ro=()
 bindmounts_rw=()
+bindmounts_tmpfs=()
 
 copy=$USER
 [[ -n ${SUDO_USER:-} ]] && copy=$SUDO_USER
@@ -65,23 +66,24 @@ usage() {
 	echo "Default makepkg args: ${default_makepkg_args[*]}"
 	echo ''
 	echo 'Flags:'
-	echo '-h         This help'
-	echo '-c         Clean the chroot before building'
-	echo '-d <dir>   Bind directory into build chroot as read-write'
-	echo '-D <dir>   Bind directory into build chroot as read-only'
-	echo '-u         Update the working copy of the chroot before building'
-	echo '           This is useful for rebuilds without dirtying the pristine'
-	echo '           chroot'
-	echo '-r <dir>   The chroot dir to use'
-	echo '-I <pkg>   Install a package into the working copy of the chroot'
-	echo '-l <copy>  The directory to use as the working copy of the chroot'
-	echo '           Useful for maintaining multiple copies'
-	echo "           Default: $copy"
-	echo '-n         Run namcap on the package'
-	echo '-C         Run checkpkg on the package'
-	echo '-T         Build in a temporary directory'
-	echo '-U         Run makepkg as a specified user'
-	echo '-x <when>  Inspect chroot after build (never, always, failure)'
+	echo '-h                This help'
+	echo '-c                Clean the chroot before building'
+	echo '-d <dir>          Bind directory into build chroot as read-write'
+	echo '-D <dir>          Bind directory into build chroot as read-only'
+	echo '-t <dir[:opts]>   Mount a tmpfs at directory'
+	echo '-u                Update the working copy of the chroot before building'
+	echo '                  This is useful for rebuilds without dirtying the pristine'
+	echo '                  chroot'
+	echo '-r <dir>          The chroot dir to use'
+	echo '-I <pkg>          Install a package into the working copy of the chroot'
+	echo '-l <copy>         The directory to use as the working copy of the chroot'
+	echo '                  Useful for maintaining multiple copies'
+	echo "                  Default: $copy"
+	echo '-n                Run namcap on the package'
+	echo '-C                Run checkpkg on the package'
+	echo '-T                Build in a temporary directory'
+	echo '-U                Run makepkg as a specified user'
+	echo '-x <when>         Inspect chroot after build (never, always, failure)'
 	exit 1
 }
 
@@ -148,7 +150,7 @@ install_packages() {
 	pkgnames=("${install_pkgs[@]##*/}")
 
 	cp -- "${install_pkgs[@]}" "$copydir/root/"
-	arch-nspawn "$copydir" "${bindmounts_ro[@]}" "${bindmounts_rw[@]}" \
+	arch-nspawn "$copydir" "${bindmounts_ro[@]}" "${bindmounts_rw[@]}" "${bindmounts_tmpfs[@]}" \
 		pacman -U --noconfirm --ask=4 -- "${pkgnames[@]/#//root/}"
 	ret=$?
 	rm -- "${pkgnames[@]/#/$copydir/root/}"
@@ -291,11 +293,12 @@ move_products() {
 }
 # }}}
 
-while getopts 'hcur:I:l:nCTD:d:U:x:' arg; do
+while getopts 'hcur:I:l:nCTD:d:U:x:t:' arg; do
 	case "$arg" in
 		c) clean_first=1 ;;
 		D) bindmounts_ro+=("--bind-ro=$OPTARG") ;;
 		d) bindmounts_rw+=("--bind=$OPTARG") ;;
+		t) bindmounts_tmpfs+=("--tmpfs=$OPTARG") ;;
 		u) update_first=1 ;;
 		r) passeddir="$OPTARG" ;;
 		I) install_pkgs+=("$OPTARG") ;;
@@ -365,7 +368,7 @@ if [[ ! -d $copydir ]] || (( clean_first )); then
 fi
 
 (( update_first )) && arch-nspawn "$copydir" \
-		"${bindmounts_ro[@]}" "${bindmounts_rw[@]}" \
+		"${bindmounts_ro[@]}" "${bindmounts_rw[@]}" "${bindmounts_tmpfs[@]}" \
 		pacman -Syuu --noconfirm
 
 if [[ -n ${install_pkgs[*]:-} ]]; then
@@ -390,6 +393,7 @@ nspawn_build_args=(
 	--tmpfs="/tmp:${tmp_opts}"
 	"${bindmounts_ro[@]}"
 	"${bindmounts_rw[@]}"
+	"${bindmounts_tmpfs[@]}"
 )
 
 if arch-nspawn "$copydir" \