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systemd/tools/list-discoverable-partitions.py
2022-11-21 12:26:35 +01:00

194 lines
9.1 KiB
Python

#!/usr/bin/env python3
# SPDX-License-Identifier: LGPL-2.1-or-later
import re
import sys
import uuid
HEADER = f'''\
| Name | Partition Type UUID | Allowed File Systems | Explanation |
|------|---------------------|----------------------|-------------|
'''
ARCHITECTURES = {
'ALPHA': 'Alpha',
'ARC': 'ARC',
'ARM': '32-bit ARM',
'ARM64': '64-bit ARM/AArch64',
'IA64': 'Itanium/IA-64',
'LOONGARCH64': 'LoongArch 64-bit',
'MIPS_LE': '32-bit MIPS LittleEndian (mipsel)',
'MIPS64_LE': '64-bit MIPS LittleEndian (mips64el)',
'PARISC': 'HPPA/PARISC',
'PPC': '32-bit PowerPC',
'PPC64': '64-bit PowerPC BigEndian',
'PPC64_LE': '64-bit PowerPC LittleEndian',
'RISCV32': 'RISC-V 32-bit',
'RISCV64': 'RISC-V 64-bit',
'S390': 's390',
'S390X': 's390x',
'TILEGX': 'TILE-Gx',
'X86': 'x86',
'X86_64': 'amd64/x86_64',
}
TYPES = {
'ROOT' : 'Root Partition',
'ROOT_VERITY' : 'Root Verity Partition',
'ROOT_VERITY_SIG' : 'Root Verity Signature Partition',
'USR' : '`/usr/` Partition',
'USR_VERITY' : '`/usr/` Verity Partition',
'USR_VERITY_SIG' : '`/usr/` Verity Signature Partition',
'ESP': 'EFI System Partition',
'SRV': 'Server Data Partition',
'VAR': 'Variable Data Partition',
'TMP': 'Temporary Data Partition',
'SWAP': 'Swap',
'HOME': 'Home Partition',
'USER_HOME': 'Per-user Home Partition',
'LINUX_GENERIC': 'Generic Linux Data Partition',
'XBOOTLDR': 'Extended Boot Loader Partition',
}
DESCRIPTIONS = {
'ROOT': (
'Any native, optionally in LUKS',
'On systems with matching architecture, the first partition with this type UUID on the disk '
'containing the active EFI ESP is automatically mounted to the root directory `/`. '
'If the partition is encrypted with LUKS or has dm-verity integrity data (see below), the '
'device mapper file will be named `/dev/mapper/root`.'),
'USR': (
'Any native, optionally in LUKS',
'Similar semantics to root partition, but just the `/usr/` partition.'),
'ROOT_VERITY': (
'A dm-verity superblock followed by hash data',
'Contains dm-verity integrity hash data for the matching root partition. If this feature is '
'used the partition UUID of the root partition should be the first 128 bits of the root hash '
'of the dm-verity hash data, and the partition UUID of this dm-verity partition should be the '
'final 128 bits of it, so that the root partition and its Verity partition can be discovered '
'easily, simply by specifying the root hash.'),
'USR_VERITY': (
'A dm-verity superblock followed by hash data',
'Similar semantics to root Verity partition, but just for the `/usr/` partition.'),
'ROOT_VERITY_SIG': (
'A serialized JSON object, see below',
'Contains a root hash and a PKCS#7 signature for it, permitting signed dm-verity GPT images.'),
'USR_VERITY_SIG': (
'A serialized JSON object, see below',
'Similar semantics to root Verity signature partition, but just for the `/usr/` partition.'),
'ESP': (
'VFAT',
'The ESP used for the current boot is automatically mounted to `/efi/` (or `/boot/` as '
'fallback), unless a different partition is mounted there (possibly via `/etc/fstab`, or '
'because the Extended Boot Loader Partition — see below — exists) or the directory is '
'non-empty on the root disk. This partition type is defined by the '
'[UEFI Specification](http://www.uefi.org/specifications).'),
'XBOOTLDR': (
'Typically VFAT',
'The Extended Boot Loader Partition (XBOOTLDR) used for the current boot is automatically '
'mounted to `/boot/`, unless a different partition is mounted there (possibly via '
'`/etc/fstab`) or the directory is non-empty on the root disk. This partition type '
'is defined by the [Boot Loader '
'Specification](https://uapi-group.org/specifications/specs/boot_loader_specification).'),
'SWAP': (
'Swap, optionally in LUKS',
'All swap partitions on the disk containing the root partition are automatically enabled. '
'If the partition is encrypted with LUKS, the device mapper file will be named '
'`/dev/mapper/swap`. This partition type predates the Discoverable Partitions Specification.'),
'HOME': (
'Any native, optionally in LUKS',
'The first partition with this type UUID on the disk containing the root partition is '
'automatically mounted to `/home/`. If the partition is encrypted with LUKS, the device '
'mapper file will be named `/dev/mapper/home`.'),
'SRV': (
'Any native, optionally in LUKS',
'The first partition with this type UUID on the disk containing the root partition is '
'automatically mounted to `/srv/`. If the partition is encrypted with LUKS, the device '
'mapper file will be named `/dev/mapper/srv`.'),
'VAR': (
'Any native, optionally in LUKS',
'The first partition with this type UUID on the disk containing the root partition is '
'automatically mounted to `/var/` — under the condition that its partition UUID matches '
'the first 128 bits of `HMAC-SHA256(machine-id, 0x4d21b016b53445c2a9fb5c16e091fd2d)` '
'(i.e. the SHA256 HMAC hash of the binary type UUID keyed by the machine ID as read from '
'[`/etc/machine-id`](https://www.freedesktop.org/software/systemd/man/machine-id.html). '
'This special requirement is made because `/var/` (unlike the other partition types '
'listed here) is inherently private to a specific installation and cannot possibly be '
'shared between multiple OS installations on the same disk, and thus should be bound to '
'a specific instance of the OS, identified by its machine ID. If the partition is '
'encrypted with LUKS, the device mapper file will be named `/dev/mapper/var`.'),
'TMP': (
'Any native, optionally in LUKS',
'The first partition with this type UUID on the disk containing the root partition is '
'automatically mounted to `/var/tmp/`. If the partition is encrypted with LUKS, the '
'device mapper file will be named `/dev/mapper/tmp`. Note that the intended mount point '
'is indeed `/var/tmp/`, not `/tmp/`. The latter is typically maintained in memory via '
'`tmpfs` and does not require a partition on disk. In some cases it might be '
'desirable to make `/tmp/` persistent too, in which case it is recommended to make it '
'a symlink or bind mount to `/var/tmp/`, thus not requiring its own partition type UUID.'),
'USER_HOME': (
'Any native, optionally in LUKS',
'A home partition of a user, managed by '
'[`systemd-homed`](https://www.freedesktop.org/software/systemd/man/systemd-homed.html).'),
'LINUX_GENERIC': (
'Any native, optionally in LUKS',
'No automatic mounting takes place for other Linux data partitions. This partition type '
'should be used for all partitions that carry Linux file systems. The installer needs '
'to mount them explicitly via entries in `/etc/fstab`. Optionally, these partitions may '
'be encrypted with LUKS. This partition type predates the Discoverable Partitions Specification.'),
}
def extract(file):
for line in file:
# print(line)
m = re.match(r'^#define\s+SD_GPT_(.*SD_ID128_MAKE\(.*\))', line)
if not m:
continue
name = line.split()[1]
if m2 := re.match(r'^(ROOT|USR)_([A-Z0-9]+|X86_64|PPC64_LE|MIPS_LE|MIPS64_LE)(|_VERITY|_VERITY_SIG)\s+SD_ID128_MAKE\((.*)\)', m.group(1)):
type, arch, suffix, u = m2.groups()
u = uuid.UUID(u.replace(',', ''))
assert arch in ARCHITECTURES, f'{arch} not in f{ARCHITECTURES}'
type = f'{type}{suffix}'
assert type in TYPES
yield name, type, arch, u
elif m2 := re.match(r'(\w+)\s+SD_ID128_MAKE\((.*)\)', m.group(1)):
type, u = m2.groups()
u = uuid.UUID(u.replace(',', ''))
yield name, type, None, u
else:
raise Exception(f'Failed to match: {m.group(1)}')
def generate(defines):
prevtype = None
print(HEADER, end='')
uuids = set()
for name, type, arch, uuid in defines:
tdesc = TYPES[type]
adesc = '' if arch is None else f' ({ARCHITECTURES[arch]})'
# Let's make sure that we didn't select&paste the same value twice
assert uuid not in uuids
uuids.add(uuid)
if type != prevtype:
prevtype = type
morea, moreb = DESCRIPTIONS[type]
else:
morea = moreb = 'ditto'
print(f'| _{tdesc}{adesc}_ | `{uuid}` `{name}` | {morea} | {moreb} |')
if __name__ == '__main__':
known = extract(sys.stdin)
generate(known)