/
systemd-boot-builder.py
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/
systemd-boot-builder.py
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#! @python3@/bin/python3 -B
import argparse
import shutil
import os
import sys
import errno
import subprocess
import glob
import tempfile
import errno
import warnings
import ctypes
libc = ctypes.CDLL("libc.so.6")
import re
import datetime
import glob
import os.path
def copy_if_not_exists(source, dest):
if not os.path.exists(dest):
shutil.copyfile(source, dest)
def system_dir(profile, generation):
if profile:
return "/nix/var/nix/profiles/system-profiles/%s-%d-link" % (profile, generation)
else:
return "/nix/var/nix/profiles/system-%d-link" % (generation)
BOOT_ENTRY = """title NixOS{profile}
version Generation {generation} {description}
linux {kernel}
initrd {initrd}
options {kernel_params}
"""
def write_loader_conf(profile, generation):
with open("@efiSysMountPoint@/loader/loader.conf.tmp", 'w') as f:
if "@timeout@" != "":
f.write("timeout @timeout@\n")
if profile:
f.write("default nixos-%s-generation-%d\n" % (profile, generation))
else:
f.write("default nixos-generation-%d\n" % (generation))
if not @editor@:
f.write("editor 0");
os.rename("@efiSysMountPoint@/loader/loader.conf.tmp", "@efiSysMountPoint@/loader/loader.conf")
def profile_path(profile, generation, name):
return os.readlink("%s/%s" % (system_dir(profile, generation), name))
def copy_from_profile(profile, generation, name, dry_run=False):
store_file_path = profile_path(profile, generation, name)
suffix = os.path.basename(store_file_path)
store_dir = os.path.basename(os.path.dirname(store_file_path))
efi_file_path = "/efi/nixos/%s-%s.efi" % (store_dir, suffix)
if not dry_run:
copy_if_not_exists(store_file_path, "@efiSysMountPoint@%s" % (efi_file_path))
return efi_file_path
def describe_generation(generation_dir):
try:
with open("%s/nixos-version" % generation_dir) as f:
nixos_version = f.read()
except IOError:
nixos_version = "Unknown"
kernel_dir = os.path.dirname(os.path.realpath("%s/kernel" % generation_dir))
module_dir = glob.glob("%s/lib/modules/*" % kernel_dir)[0]
kernel_version = os.path.basename(module_dir)
build_time = int(os.path.getctime(generation_dir))
build_date = datetime.datetime.fromtimestamp(build_time).strftime('%F')
description = "NixOS {}, Linux Kernel {}, Built on {}".format(
nixos_version, kernel_version, build_date
)
return description
def write_entry(profile, generation, machine_id):
kernel = copy_from_profile(profile, generation, "kernel")
initrd = copy_from_profile(profile, generation, "initrd")
try:
append_initrd_secrets = profile_path(profile, generation, "append-initrd-secrets")
subprocess.check_call([append_initrd_secrets, "@efiSysMountPoint@%s" % (initrd)])
except FileNotFoundError:
pass
if profile:
entry_file = "@efiSysMountPoint@/loader/entries/nixos-%s-generation-%d.conf" % (profile, generation)
else:
entry_file = "@efiSysMountPoint@/loader/entries/nixos-generation-%d.conf" % (generation)
generation_dir = os.readlink(system_dir(profile, generation))
tmp_path = "%s.tmp" % (entry_file)
kernel_params = "systemConfig=%s init=%s/init " % (generation_dir, generation_dir)
with open("%s/kernel-params" % (generation_dir)) as params_file:
kernel_params = kernel_params + params_file.read()
with open(tmp_path, 'w') as f:
f.write(BOOT_ENTRY.format(profile=" [" + profile + "]" if profile else "",
generation=generation,
kernel=kernel,
initrd=initrd,
kernel_params=kernel_params,
description=describe_generation(generation_dir)))
if machine_id is not None:
f.write("machine-id %s\n" % machine_id)
os.rename(tmp_path, entry_file)
def mkdir_p(path):
try:
os.makedirs(path)
except OSError as e:
if e.errno != errno.EEXIST or not os.path.isdir(path):
raise
def get_generations(profile=None):
gen_list = subprocess.check_output([
"@nix@/bin/nix-env",
"--list-generations",
"-p",
"/nix/var/nix/profiles/%s" % ("system-profiles/" + profile if profile else "system"),
"--option", "build-users-group", ""],
universal_newlines=True)
gen_lines = gen_list.split('\n')
gen_lines.pop()
return [ (profile, int(line.split()[0])) for line in gen_lines ]
def remove_old_entries(gens):
rex_profile = re.compile("^@efiSysMountPoint@/loader/entries/nixos-(.*)-generation-.*\.conf$")
rex_generation = re.compile("^@efiSysMountPoint@/loader/entries/nixos.*-generation-(.*)\.conf$")
known_paths = []
for gen in gens:
known_paths.append(copy_from_profile(*gen, "kernel", True))
known_paths.append(copy_from_profile(*gen, "initrd", True))
for path in glob.iglob("@efiSysMountPoint@/loader/entries/nixos*-generation-[1-9]*.conf"):
try:
if rex_profile.match(path):
prof = rex_profile.sub(r"\1", path)
else:
prof = "system"
gen = int(rex_generation.sub(r"\1", path))
if not (prof, gen) in gens:
os.unlink(path)
except ValueError:
pass
for path in glob.iglob("@efiSysMountPoint@/efi/nixos/*"):
if not path in known_paths:
os.unlink(path)
def get_profiles():
if os.path.isdir("/nix/var/nix/profiles/system-profiles/"):
return [x
for x in os.listdir("/nix/var/nix/profiles/system-profiles/")
if not x.endswith("-link")]
else:
return []
def main():
parser = argparse.ArgumentParser(description='Update NixOS-related systemd-boot files')
parser.add_argument('default_config', metavar='DEFAULT-CONFIG', help='The default NixOS config to boot')
args = parser.parse_args()
try:
with open("/etc/machine-id") as machine_file:
machine_id = machine_file.readlines()[0]
except IOError as e:
if e.errno != errno.ENOENT:
raise
# Since systemd version 232 a machine ID is required and it might not
# be there on newly installed systems, so let's generate one so that
# bootctl can find it and we can also pass it to write_entry() later.
cmd = ["@systemd@/bin/systemd-machine-id-setup", "--print"]
machine_id = subprocess.check_output(cmd).rstrip()
if os.getenv("NIXOS_INSTALL_GRUB") == "1":
warnings.warn("NIXOS_INSTALL_GRUB env var deprecated, use NIXOS_INSTALL_BOOTLOADER", DeprecationWarning)
os.environ["NIXOS_INSTALL_BOOTLOADER"] = "1"
if os.getenv("NIXOS_INSTALL_BOOTLOADER") == "1":
# bootctl uses fopen() with modes "wxe" and fails if the file exists.
if os.path.exists("@efiSysMountPoint@/loader/loader.conf"):
os.unlink("@efiSysMountPoint@/loader/loader.conf")
if "@canTouchEfiVariables@" == "1":
subprocess.check_call(["@systemd@/bin/bootctl", "--path=@efiSysMountPoint@", "install"])
else:
subprocess.check_call(["@systemd@/bin/bootctl", "--path=@efiSysMountPoint@", "--no-variables", "install"])
mkdir_p("@efiSysMountPoint@/efi/nixos")
mkdir_p("@efiSysMountPoint@/loader/entries")
gens = get_generations()
for profile in get_profiles():
gens += get_generations(profile)
remove_old_entries(gens)
for gen in gens:
write_entry(*gen, machine_id)
if os.readlink(system_dir(*gen)) == args.default_config:
write_loader_conf(*gen)
# Since fat32 provides little recovery facilities after a crash,
# it can leave the system in an unbootable state, when a crash/outage
# happens shortly after an update. To decrease the likelihood of this
# event sync the efi filesystem after each update.
rc = libc.syncfs(os.open("@efiSysMountPoint@", os.O_RDONLY))
if rc != 0:
print("could not sync @efiSysMountPoint@: {}".format(os.strerror(rc)), file=sys.stderr)
if __name__ == '__main__':
main()