diff options
Diffstat (limited to 'scripts/create-darwin-volume.sh')
| -rwxr-xr-x | scripts/create-darwin-volume.sh | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/scripts/create-darwin-volume.sh b/scripts/create-darwin-volume.sh new file mode 100755 index 000000000..dac30d72d --- /dev/null +++ b/scripts/create-darwin-volume.sh @@ -0,0 +1,185 @@ +#!/bin/sh +set -e + +root_disk() { + diskutil info -plist / +} + +apfs_volumes_for() { + disk=$1 + diskutil apfs list -plist "$disk" +} + +disk_identifier() { + xpath "/plist/dict/key[text()='ParentWholeDisk']/following-sibling::string[1]/text()" 2>/dev/null +} + +volume_list_true() { + key=$1 + xpath "/plist/dict/array/dict/key[text()='Volumes']/following-sibling::array/dict/key[text()='$key']/following-sibling::true[1]" 2> /dev/null +} + +volume_get_string() { + key=$1 i=$2 + xpath "/plist/dict/array/dict/key[text()='Volumes']/following-sibling::array/dict[$i]/key[text()='$key']/following-sibling::string[1]/text()" 2> /dev/null +} + +find_nix_volume() { + disk=$1 + i=1 + volumes=$(apfs_volumes_for "$disk") + while true; do + name=$(echo "$volumes" | volume_get_string "Name" "$i") + if [ -z "$name" ]; then + break + fi + case "$name" in + [Nn]ix*) + echo "$name" + break + ;; + esac + i=$((i+1)) + done +} + +test_fstab() { + grep -q "/nix apfs rw" /etc/fstab 2>/dev/null +} + +test_nix_symlink() { + [ -L "/nix" ] || grep -q "^nix." /etc/synthetic.conf 2>/dev/null +} + +test_synthetic_conf() { + grep -q "^nix$" /etc/synthetic.conf 2>/dev/null +} + +test_nix() { + test -d "/nix" +} + +test_t2_chip_present(){ + # Use xartutil to see if system has a t2 chip. + # + # This isn't well-documented on its own; until it is, + # let's keep track of knowledge/assumptions. + # + # Warnings: + # - Don't search "xart" if porn will cause you trouble :) + # - Other xartutil flags do dangerous things. Don't run them + # naively. If you must, search "xartutil" first. + # + # Assumptions: + # - the "xART session seeds recovery utility" + # appears to interact with xartstorageremoted + # - `sudo xartutil --list` lists xART sessions + # and their seeds and exits 0 if successful. If + # not, it exits 1 and prints an error such as: + # xartutil: ERROR: No supported link to the SEP present + # - xART sessions/seeds are present when a T2 chip is + # (and not, otherwise) + # - the presence of a T2 chip means a newly-created + # volume on the primary drive will be + # encrypted at rest + # - all together: `sudo xartutil --list` + # should exit 0 if a new Nix Store volume will + # be encrypted at rest, and exit 1 if not. + sudo xartutil --list >/dev/null 2>/dev/null +} + +test_filevault_in_use() { + disk=$1 + # list vols on disk | get value of Filevault key | value is true + apfs_volumes_for "$disk" | volume_list_true FileVault | grep -q true +} + +# use after error msg for conditions we don't understand +suggest_report_error(){ + # ex "error: something sad happened :(" >&2 + echo " please report this @ https://github.com/nixos/nix/issues" >&2 +} + +main() { + ( + echo "" + echo " ------------------------------------------------------------------ " + echo " | This installer will create a volume for the nix store and |" + echo " | configure it to mount at /nix. Follow these steps to uninstall. |" + echo " ------------------------------------------------------------------ " + echo "" + echo " 1. Remove the entry from fstab using 'sudo vifs'" + echo " 2. Destroy the data volume using 'diskutil apfs deleteVolume'" + echo " 3. Remove the 'nix' line from /etc/synthetic.conf or the file" + echo "" + ) >&2 + + if test_nix_symlink; then + echo "error: /nix is a symlink, please remove it and make sure it's not in synthetic.conf (in which case a reboot is required)" >&2 + echo " /nix -> $(readlink "/nix")" >&2 + exit 2 + fi + + if ! test_synthetic_conf; then + echo "Configuring /etc/synthetic.conf..." >&2 + echo nix | sudo tee -a /etc/synthetic.conf + if ! test_synthetic_conf; then + echo "error: failed to configure synthetic.conf;" >&2 + suggest_report_error + exit 1 + fi + fi + + if ! test_nix; then + echo "Creating mountpoint for /nix..." >&2 + /System/Library/Filesystems/apfs.fs/Contents/Resources/apfs.util -B || true + if ! test_nix; then + sudo mkdir -p /nix 2>/dev/null || true + fi + if ! test_nix; then + echo "error: failed to bootstrap /nix; if a reboot doesn't help," >&2 + suggest_report_error + exit 1 + fi + fi + + disk=$(root_disk | disk_identifier) + volume=$(find_nix_volume "$disk") + if [ -z "$volume" ]; then + echo "Creating a Nix Store volume..." >&2 + + if test_filevault_in_use "$disk"; then + # TODO: Not sure if it's in-scope now, but `diskutil apfs list` + # shows both filevault and encrypted at rest status, and it + # may be the more semantic way to test for this? It'll show + # `FileVault: No (Encrypted at rest)` + # `FileVault: No` + # `FileVault: Yes (Unlocked)` + # and so on. + if test_t2_chip_present; then + echo "warning: boot volume is FileVault-encrypted, but the Nix store volume" >&2 + echo " is only encrypted at rest." >&2 + echo " See https://nixos.org/nix/manual/#sect-macos-installation" >&2 + else + echo "error: refusing to create Nix store volume because the boot volume is" >&2 + echo " FileVault encrypted, but encryption-at-rest is not available." >&2 + echo " Manually create a volume for the store and re-run this script." >&2 + echo " See https://nixos.org/nix/manual/#sect-macos-installation" >&2 + exit 1 + fi + fi + + sudo diskutil apfs addVolume "$disk" APFS 'Nix Store' -mountpoint /nix + volume="Nix Store" + else + echo "Using existing '$volume' volume" >&2 + fi + + if ! test_fstab; then + echo "Configuring /etc/fstab..." >&2 + label=$(echo "$volume" | sed 's/ /\\040/g') + printf "\$a\nLABEL=%s /nix apfs rw,nobrowse\n.\nwq\n" "$label" | EDITOR=ed sudo vifs + fi +} + +main "$@" |