dillard
1839997972
Content-addressed repository on an IBackend (local implementation): 4 MiB blobs, deflate when it helps, each blob encrypted with its id as associated data, ~32 MiB packs with an encrypted header, one index file per pack, snapshots as encrypted JSON lines written last. Spike B: 390 MiB tree, peak 54 MiB; unchanged run reads nothing; a 1 MiB change in a 300 MiB file uploads one blob; full and partial restore are bit-identical; tampering is detected.
75 lines
2.5 KiB
PHP
75 lines
2.5 KiB
PHP
<?php
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declare(strict_types=1);
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// SPDX-FileCopyrightText: 2026 Dillard Blom
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// SPDX-License-Identifier: AGPL-3.0-or-later
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namespace OCA\NgBackup\Repository;
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use OCA\NgBackup\Backend\IBackend;
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use OCA\NgBackup\Crypto\StreamCipher;
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/**
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* Which blob lives in which pack. Every uploaded pack gets its own small encrypted index file
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* (index/<packId>), written right after the pack, so an interrupted run leaves a consistent
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* repository and the next run can reuse what was already uploaded.
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*
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* Phase 0 keeps the whole index in memory. For large repositories this becomes a table in the
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* Nextcloud database (a cache that can always be rebuilt from index/ and the pack headers).
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*/
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final class BlobIndex {
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/** @var array<string, array{0:string, 1:int, 2:int, 3:int, 4:int}> id => [pack, offset, length, raw, flags] */
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private array $blobs = [];
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/** @var array<string, true> blobs added in this run but whose pack is not uploaded yet */
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private array $pending = [];
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public function __construct(
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private IBackend $backend,
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private StreamCipher $cipher,
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) {
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}
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public function load(): void {
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foreach ($this->backend->list('index') as $path) {
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$packId = basename($path);
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$fh = $this->backend->get($path);
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$entries = json_decode($this->cipher->decryptString((string)stream_get_contents($fh), 'index:' . $packId), true, 512, JSON_THROW_ON_ERROR);
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fclose($fh);
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foreach ($entries as $e) {
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$this->blobs[$e['id']] = [$packId, $e['offset'], $e['length'], $e['raw'], $e['flags']];
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}
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}
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}
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public function has(string $id): bool {
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return isset($this->blobs[$id]) || isset($this->pending[$id]);
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}
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/** @return array{0:string, 1:int, 2:int, 3:int, 4:int} */
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public function get(string $id): array {
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return $this->blobs[$id] ?? throw new RepositoryException('Blob not in index: ' . $id);
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}
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public function addPending(string $id): void {
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$this->pending[$id] = true;
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}
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/** @param list<array{id:string, offset:int, length:int, raw:int, flags:int}> $entries */
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public function addPack(string $packId, array $entries): void {
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$stream = fopen('php://memory', 'w+b');
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fwrite($stream, $this->cipher->encryptString(json_encode($entries, JSON_THROW_ON_ERROR), 'index:' . $packId));
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rewind($stream);
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$this->backend->put('index/' . $packId, $stream);
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fclose($stream);
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foreach ($entries as $e) {
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$this->blobs[$e['id']] = [$packId, $e['offset'], $e['length'], $e['raw'], $e['flags']];
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unset($this->pending[$e['id']]);
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}
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}
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public function count(): int {
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return count($this->blobs);
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}
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}
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