Publish Vulpes Preview 15 sources for desktop, Android and Tundra

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tundra/droidian/backup-boot.py

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+#!/usr/bin/env python3
+# SPDX-License-Identifier: MPL-2.0
+"""Read the six inventoried Sargo boot partitions; never open a device for writing."""
+import datetime
+import fcntl
+import hashlib
+import json
+import os
+from pathlib import Path
+import pwd
+import stat
+import struct
+import subprocess
+import tempfile
+
+PARTITIONS = {
+    'boot_a': 67108864, 'boot_b': 67108864,
+    'dtbo_a': 8417280, 'dtbo_b': 8417280,
+    'vbmeta_a': 65536, 'vbmeta_b': 65536,
+}
+
+
+def copy_exact(source, destination, size):
+    digest = hashlib.sha256()
+    remaining = size
+    while remaining:
+        chunk = source.read(min(1024 * 1024, remaining))
+        if not chunk:
+            raise RuntimeError('Partition read ended before its declared size')
+        destination.write(chunk)
+        digest.update(chunk)
+        remaining -= len(chunk)
+    return digest.hexdigest()
+
+
+def main():
+    if os.geteuid() != 0:
+        raise RuntimeError('Partition reads require sudo in your own terminal')
+    account = pwd.getpwnam('droidian')
+    getprop = next((p for p in ('/usr/bin/getprop', '/bin/getprop') if Path(p).exists()), None)
+    if not getprop:
+        raise RuntimeError('Cannot establish Android device identity')
+    device = subprocess.check_output([getprop, 'ro.product.device'], text=True, timeout=10).strip()
+    compatible = Path('/proc/device-tree/compatible').read_bytes().split(b'\0')
+    if device != 'sargo' or b'google,b4s4-sdm670' not in compatible:
+        raise RuntimeError('This recipe only supports the inventoried Sargo adaptation')
+    os.umask(0o077)
+    folder = Path(tempfile.mkdtemp(prefix='vulpes-boot-backup-', dir='/var/tmp'))
+    report = {'recordedAt': datetime.datetime.now(datetime.timezone.utc).isoformat(),
+              'device': device, 'rawPartitions': True, 'restorationTested': False,
+              'scope': 'Boot, DTBO and vbmeta only; excludes userdata, vendor and system',
+              'files': {}}
+    for name, expected_size in PARTITIONS.items():
+        path = (Path('/dev/disk/by-partlabel') / name).resolve(strict=True)
+        fd = os.open(path, os.O_RDONLY | os.O_CLOEXEC | os.O_NOFOLLOW)
+        with os.fdopen(fd, 'rb') as source:
+            if not stat.S_ISBLK(os.fstat(source.fileno()).st_mode):
+                raise RuntimeError('Not a block device: ' + str(path))
+            size = struct.unpack('Q', fcntl.ioctl(source.fileno(), 0x80081272, bytes(8)))[0]
+            if size != expected_size:
+                raise RuntimeError('Partition layout differs from the inventory: ' + name)
+            target = folder / (name + '.img')
+            with target.open('xb') as output:
+                digest = copy_exact(source, output, size)
+                output.flush()
+                os.fsync(output.fileno())
+            with target.open('rb') as saved:
+                if hashlib.file_digest(saved, 'sha256').hexdigest() != digest:
+                    raise RuntimeError('Backup verification failed: ' + name)
+            report['files'][target.name] = {'source': str(path), 'bytes': size, 'sha256': digest}
+    (folder / 'manifest.json').write_text(json.dumps(report, indent=2) + '\n')
+    # Keep incomplete backups root-only; transfer ownership only after all six pass.
+    for child in folder.iterdir():
+        os.chown(child, account.pw_uid, account.pw_gid)
+    os.chown(folder, account.pw_uid, account.pw_gid)
+    print('Backup verified:', folder)
+
+
+if __name__ == '__main__':
+    main()