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authorJose M. Guisado <jguisado@soleta.eu>2023-08-16 14:10:45 +0200
committerAlejandro Sirgo Rica <asirgo@soleta.eu>2024-03-04 11:33:10 +0100
commit4129256caf54ab61ff87fdd5c25eb08f1c2b0458 (patch)
treefb91ccb0bc55dbbb7d772c62b66171d70eebf634
parente3c375f8d7d449ede2848e13209e0ee4dd075fb4 (diff)
utils: add uefi.py
Add UEFI related utilities inside a new utility module: uefi.py _check_efibootmgr_json ====================== Check if the system efibootmgr executable supports JSON output. This is a private function used only by other functions from uefi.py. is_uefi_supported ================= Check if the system supports UEFI firmware. run_efibootmgr_json =================== Runs efibootmgr with json output support. Return the JSON output as a Python dict. efibootmgr_create_bootentry =========================== Create nvram boot entry. This bootentry is usually later set to boot next just once via "BootNext" nvram variable. efibootmgr_delete_bootentry =========================== Delete a nvram boot entry. Used to avoid duplicates when booting the same disk and partition from a given client. efibootmgr_bootnext =================== Set nvram "BootNext" variable to a given boot entry so after client reboot, PXE is not executed and the given boot entry takes precedence. Add dependency with efibootmgr version >= 18, and efibootmgr JSON output which is currently out of tree from util-linux repo.
-rw-r--r--src/utils/uefi.py97
1 files changed, 97 insertions, 0 deletions
diff --git a/src/utils/uefi.py b/src/utils/uefi.py
new file mode 100644
index 0000000..e0c41d1
--- /dev/null
+++ b/src/utils/uefi.py
@@ -0,0 +1,97 @@
+#
+# Copyright (C) 2023 Soleta Networks <info@soleta.eu>
+#
+# This program is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the
+# Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+import json
+import logging
+import os
+import shlex
+import subprocess
+
+import fdisk
+
+def _find_bootentry(entries, label):
+ for entry in entries:
+ if entry['description'] == label:
+ return entry
+ else:
+ raise NameError('Boot entry {label} not found')
+
+
+def _strip_boot_prefix(entry):
+ try:
+ num = entry['name'][4:]
+ except:
+ raise KeyError('Unable to strip "Boot" prefix from boot entry')
+ return num
+
+
+def _check_efibootmgr_json():
+ """
+ Checks if efibootmgr --json option is supported.
+ Returns True if supported, False otherwise.
+ """
+ supported = True
+ try:
+ subprocess.run(['efibootmgr-json', '--json'], stdout=subprocess.DEVNULL,
+ stderr=subprocess.DEVNULL, check=True)
+ except subprocess.CalledProcessError:
+ supported = False
+ return supported
+
+
+def is_uefi_supported():
+ return True if os.path.exists("/sys/firmware/efi") else False
+
+
+def run_efibootmgr_json():
+ if _check_efibootmgr_json() is False:
+ raise RuntimeError('efibootmgr-json not available')
+
+ proc = subprocess.run(['efibootmgr-json', '--json'], capture_output=True, text=True)
+ dict_json = json.loads(proc.stdout)
+
+ return dict_json
+
+
+def efibootmgr_bootnext(description):
+ logging.info(f'Setting BootNext to value from boot entry with label {description}')
+ bootnext_cmd = 'efibootmgr-json -n {bootnum}'
+ boot_entries = run_efibootmgr_json().get('vars', [])
+
+ entry = _find_bootentry(boot_entries, description)
+ num = _strip_boot_prefix(entry) # efibootmgr output uses BootXXXX for each entry, remove the "Boot" prefix.
+ bootnext_cmd = bootnext_cmd.format(bootnum=num)
+ subprocess.run(shlex.split(bootnext_cmd), check=True,
+ stdout=subprocess.DEVNULL)
+
+
+def efibootmgr_delete_bootentry(label):
+ dict_json = run_efibootmgr_json()
+ efibootmgr_cmd = 'efibootmgr-json -q -b {bootnum} -B'
+
+ for entry in dict_json.get('vars', []):
+ if entry['description'] == label:
+ num = entry['name'][4:] # Remove "Boot" prefix to extract num
+ efibootmgr_cmd = efibootmgr_cmd.format(bootnum=num)
+ subprocess.run(shlex.split(efibootmgr_cmd), check=True)
+ break
+ else:
+ logging.info(f'Cannot delete boot entry {label} because it was not found.')
+
+
+def efibootmgr_create_bootentry(disk, part, loader, label, add_to_bootorder=True):
+ entries = run_efibootmgr_json().get('vars', [])
+ create_opt = '-c' if add_to_bootorder else '-C'
+ index_opt = f'-I {len(entries)}' # Requires efibootmgr version 18
+ efibootmgr_cmd = f'efibootmgr-json {create_opt} {index_opt} -d {disk} -p {part} -L {label} -l {loader}'
+ logging.info(f'efibootmgr-json command creating boot entry: {efibootmgr_cmd}')
+ try:
+ proc = subprocess.run(shlex.split(efibootmgr_cmd), check=True, text=True)
+ except subprocess.CalledProcessError as e:
+ logging.error(f'Unexpected error adding boot entry to nvram. UEFI firmware might be buggy?.')
+ raise e