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|
#!/bin/sh
set -e
root_disk() {
diskutil info -plist /
}
# i.e., "disk1"
root_disk_identifier() {
diskutil info -plist / | xmllint --xpath "/plist/dict/key[text()='ParentWholeDisk']/following-sibling::string[1]/text()" -
}
find_nix_volume() {
diskutil apfs list -plist "$1" | xmllint --xpath "(/plist/dict/array/dict/key[text()='Volumes']/following-sibling::array/dict/key[text()='Name']/following-sibling::string[starts-with(translate(text(),'N','n'),'nix')]/text())[1]" - 2>/dev/null || true
}
test_fstab() {
grep -q "/nix apfs rw" /etc/fstab 2>/dev/null
}
test_nix_symlink() {
[ -L "/nix" ] || grep -q "^nix." /etc/synthetic.conf 2>/dev/null
}
test_synthetic_conf() {
grep -q "^nix$" /etc/synthetic.conf 2>/dev/null
}
# Create the paths defined in synthetic.conf, saving us a reboot.
create_synthetic_objects(){
# Big Sur takes away the -B flag we were using and replaces it
# with a -t flag that appears to do the same thing (but they
# don't behave exactly the same way in terms of return values).
# This feels a little dirty, but as far as I can tell the
# simplest way to get the right one is to just throw away stderr
# and call both... :]
{
/System/Library/Filesystems/apfs.fs/Contents/Resources/apfs.util -t || true # Big Sur
/System/Library/Filesystems/apfs.fs/Contents/Resources/apfs.util -B || true # Catalina
} >/dev/null 2>&1
}
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() {
fdesetup isactive >/dev/null
}
# 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 -> $(readlink "/nix")" >&2
exit 2
fi
if ! test_synthetic_conf; then
echo "Configuring /etc/synthetic.conf..." >&2
echo nix | sudo tee -a /etc/synthetic.conf
if ! test_synthetic_conf; then
echo "error: failed to configure synthetic.conf;" >&2
suggest_report_error
exit 1
fi
fi
if ! test_nix; then
echo "Creating mountpoint for /nix..." >&2
create_synthetic_objects # the ones we defined in synthetic.conf
if ! test_nix; then
sudo mkdir -p /nix 2>/dev/null || true
fi
if ! test_nix; then
echo "error: failed to bootstrap /nix; if a reboot doesn't help," >&2
suggest_report_error
exit 1
fi
fi
disk="$(root_disk_identifier)"
volume=$(find_nix_volume "$disk")
if [ -z "$volume" ]; then
echo "Creating a Nix Store volume..." >&2
if test_filevault_in_use; then
# TODO: Not sure if it's in-scope now, but `diskutil apfs list`
# shows both filevault and encrypted at rest status, and it
# may be the more semantic way to test for this? It'll show
# `FileVault: No (Encrypted at rest)`
# `FileVault: No`
# `FileVault: Yes (Unlocked)`
# and so on.
if test_t2_chip_present; then
echo "warning: boot volume is FileVault-encrypted, but the Nix store volume" >&2
echo " is only encrypted at rest." >&2
echo " See https://nixos.org/nix/manual/#sect-macos-installation" >&2
else
echo "error: refusing to create Nix store volume because the boot volume is" >&2
echo " FileVault encrypted, but encryption-at-rest is not available." >&2
echo " Manually create a volume for the store and re-run this script." >&2
echo " See https://nixos.org/nix/manual/#sect-macos-installation" >&2
exit 1
fi
fi
sudo diskutil apfs addVolume "$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 "$volume" | sed 's/ /\\040/g')
# shellcheck disable=SC2209
printf "\$a\nLABEL=%s /nix apfs rw,nobrowse\n.\nwq\n" "$label" | EDITOR=ed sudo vifs
fi
}
main "$@"
|
