Storage limit per location

S3 has no bucket quota, so NG Backup enforces one: before a pack is
uploaded, the stored size plus the pack must stay under the location's
limit, otherwise the backup stops with an error (and administrators are
notified through the failed run). Repacking during prune is exempt, as it
is how space is freed. occ backup:target:limit NAME [SIZE|none].

Also ignore credential files in the repository.

lib/Repository/BlobIndex.php

@@ -139,6 +139,15 @@ final class BlobIndex {
 		}
 	}
 
+	/** Bytes of all blobs in the index (encrypted size, i.e. what is stored in packs). */
+	public function storedBytes(): int {
+		$total = 0;
+		foreach ($this->blobs as [, , $length]) {
+			$total += $length;
+		}
+		return $total;
+	}
+
 	public function count(): int {
 		return count($this->blobs);
 	}

lib/Repository/PackWriter.php

@@ -32,6 +32,7 @@ final class PackWriter {
 		private StreamCipher $cipher,
 		private BlobIndex $index,
 		private int $targetSize = 32 * 1048576,
+		private ?int $maxBytes = null,
 	) {
 		$this->reset();
 	}
@@ -64,6 +65,12 @@ final class PackWriter {
 		if ($this->entries === []) {
 			return;
 		}
+		if ($this->maxBytes !== null && $this->index->storedBytes() + $this->size > $this->maxBytes) {
+			$this->index->dropPending(array_column($this->entries, 'id'));
+			$this->reset();
+			throw new QuotaExceededException(sprintf('Storage limit of this location reached (%.1f GiB): backup stopped',
+				$this->maxBytes / 1073741824));
+		}
 		$packId = bin2hex(random_bytes(16));
 		$header = $this->cipher->encryptString(json_encode($this->entries, JSON_THROW_ON_ERROR), 'pack-header:' . $packId);
 		fwrite($this->buffer, $header . pack('N', strlen($header)));

lib/Repository/QuotaExceededException.php

@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+// SPDX-FileCopyrightText: 2026 Dillard Blom
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+namespace OCA\NgBackup\Repository;
+
+class QuotaExceededException extends RepositoryException {
+}

lib/Repository/Repository.php

@@ -32,6 +32,7 @@ final class Repository {
 	private StreamCipher $cipher;
 	private BlobIndex $index;
 	private ?PackWriter $runPacks = null;
+	private ?int $maxBytes = null;
 	private Catalog $catalog;
 
 	private function __construct(
@@ -93,6 +94,15 @@ final class Repository {
 			fn () => array_map('basename', $this->backend->list('trash/info')));
 	}
 
+	/** Refuse uploads that would make the stored data larger than this (null = no limit). */
+	public function setMaxBytes(?int $maxBytes): void {
+		$this->maxBytes = $maxBytes;
+	}
+
+	public function storedBytes(): int {
+		return $this->index->storedBytes();
+	}
+
 	/** Current catalog generation (for status and tests). */
 	public function catalogGeneration(): int {
 		return $this->catalog->gen;
@@ -145,7 +155,7 @@ final class Repository {
 	public function backupDirectory(string $source, ?string $parent = null, string $label = ''): array {
 		$source = rtrim($source, '/');
 		$previous = $parent !== null ? $this->loadEntries($parent) : [];
-		$packs = new PackWriter($this->backend, $this->cipher, $this->index);
+		$packs = new PackWriter($this->backend, $this->cipher, $this->index, 32 * 1048576, $this->maxBytes);
 		$stats = ['files' => 0, 'reused' => 0, 'read' => 0, 'newBlobs' => 0, 'dupBlobs' => 0, 'uploaded' => 0];
 
 		$tree = fopen('php://temp/maxmemory:' . (4 * 1048576), 'w+b');
@@ -226,7 +236,7 @@ final class Repository {
 	 * run is done, so the last pack is uploaded before anything references it.
 	 */
 	public function blobWriter(array &$stats): BlobWriter {
-		$this->runPacks ??= new PackWriter($this->backend, $this->cipher, $this->index);
+		$this->runPacks ??= new PackWriter($this->backend, $this->cipher, $this->index, 32 * 1048576, $this->maxBytes);
 		$packs = $this->runPacks;
 		return new BlobWriter(function (string $data) use ($packs, &$stats): string {
 			return $this->storeBlob($data, $packs, $stats);
@@ -258,7 +268,7 @@ final class Repository {
 
 	/** Store one blob of file data in the current run (deduplicated); returns its id. */
 	public function storeData(string $data, array &$stats): string {
-		$this->runPacks ??= new PackWriter($this->backend, $this->cipher, $this->index);
+		$this->runPacks ??= new PackWriter($this->backend, $this->cipher, $this->index, 32 * 1048576, $this->maxBytes);
 		return $this->storeBlob($data, $this->runPacks, $stats);
 	}
 
@@ -481,6 +491,7 @@ final class Repository {
 			} else {
 				$stats['repacked']++;
 				if (!$dryRun) {
+					// No size limit here: repacking is how space is freed.
 					$writer ??= new PackWriter($this->backend, $this->cipher, $this->index);
 					$path = 'packs/' . substr($packId, 0, 2) . '/' . $packId;
 					foreach ($blobs as $b) {