A name a snapshot cannot hold gets a notification of its own

Reported apart from unreadable files, with example paths and the advice to rename
them, instead of advice about permissions. Start of the 1.1.0 plan in PLAN.md.

lib/Command/RunBackup.php

@@ -79,6 +79,9 @@ HELP);
 				if (($f['unreadable'] ?? 0) > 0) {
 					$output->writeln(sprintf('<comment>  warning: %d unreadable files or folders are missing from this backup (see the server log)</comment>', $f['unreadable']));
 				}
+				if (($f['badNames'] ?? 0) > 0) {
+					$output->writeln(sprintf('<comment>  warning: %d files or folders are missing from this backup because their name is not supported; rename them and the next backup includes them (see the server log)</comment>', $f['badNames']));
+				}
 				if (($f['changing'] ?? 0) > 0) {
 					$output->writeln(sprintf('<comment>  warning: %d files kept changing and were saved as read (see the server log)</comment>', $f['changing']));
 				}

lib/Job/BackupRun.php

@@ -64,7 +64,7 @@ final class BackupRun {
 					// such path must not make a backup fail, or the whole snapshot unreadable later.
 					// The cursor stays where it is: the state is JSON, which cannot hold such a name. A
 					// next step meets it again, and it is reported once.
-					self::recordUnreadable($state, $stats, mb_scrub($logical, 'UTF-8'));
+					self::recordBadName($state, $stats, $logical);
 					continue;
 				}
 				if (is_dir($path)) {
@@ -250,10 +250,26 @@ final class BackupRun {
 		$stats['unreadable'] = ($stats['unreadable'] ?? 0) + 1;
 	}
 
-	/** @return array{unreadable: list<string>, changing: list<string>} examples for the report (first 50 each) */
+	/**
+	 * A file or directory left out because of its name. Remembered like an unreadable one, in a form
+	 * that fits the JSON state and is safe to show: control characters and invalid bytes replaced.
+	 */
+	private static function recordBadName(array &$state, array &$stats, string $logical): void {
+		$shown = (string)preg_replace('/[\x00-\x1f\x7f]/', '?', mb_scrub($logical, 'UTF-8'));
+		if (isset($state['badNames'][$shown])) {
+			return;
+		}
+		if (count($state['badNames'] ?? []) < 1000) {
+			$state['badNames'][$shown] = true;
+		}
+		$stats['badNames'] = ($stats['badNames'] ?? 0) + 1;
+	}
+
+	/** @return array{unreadable: list<string>, badNames: list<string>, changing: list<string>} examples for the report (first 50 each) */
 	public static function warnings(array $state): array {
 		return [
 			'unreadable' => array_slice(array_map('strval', array_keys($state['unreadable'] ?? [])), 0, 50),
+			'badNames' => array_slice(array_map('strval', array_keys($state['badNames'] ?? [])), 0, 50),
 			'changing' => array_slice(array_map('strval', array_values($state['changing'] ?? [])), 0, 50),
 		];
 	}

lib/Notification/Notifier.php

@@ -46,6 +46,10 @@ final class Notifier implements INotifier {
 				$notification->setParsedSubject($l->t('Backup to %1$s finished with warnings: %2$s unreadable, %3$s changed while being read', [$p['target'], $p['unreadable'], $p['changing']]));
 				$notification->setParsedMessage($l->t('Unreadable files and folders are missing from this backup (check their permissions). Files that kept changing were saved as they were while being read. Examples: %s', [$p['examples'] ?? '']));
 				break;
+			case 'run_bad_names':
+				$notification->setParsedSubject($l->n('Backup to %s finished, but %n item is missing because of its name', 'Backup to %s finished, but %n items are missing because of their names', (int)$p['count'], [$p['target']]));
+				$notification->setParsedMessage($l->t('Names with a backslash or a control character, or that are not valid UTF-8, are not supported, so these files and folders are not in this backup. Rename them; the next backup includes them. Examples: %s', [$p['examples'] ?? '']));
+				break;
 			case 'quota_warning':
 				$notification->setParsedSubject($l->t('Backup location %1$s is at %2$s%% of its limit (%3$s of %4$s)', [$p['target'], $p['percent'], $p['used'], $p['limit']]));
 				$notification->setParsedMessage($l->t('Backups stop when the limit is reached. Raise the limit, or let the retention policy remove older backups.'));

lib/Service/AlertService.php

@@ -61,6 +61,16 @@ final class AlertService {
 			'examples' => mb_strimwidth(implode(', ', array_merge($examples['unreadable'], $examples['changing'])), 0, 300, '…')]);
 	}
 
+	/**
+	 * A backup that finished but left out files or folders because of their name.
+	 *
+	 * @param list<string> $examples
+	 */
+	public function runBadNames(Run $run, string $targetName, int $count, array $examples): void {
+		$this->notifyAdmins('run_bad_names', 'run-' . $run->getId(), ['target' => $targetName, 'count' => (string)$count,
+			'examples' => mb_strimwidth(implode(', ', $examples), 0, 300, '…')]);
+	}
+
 	/**
 	 * Remember how much is stored on a location (for the settings page) and warn administrators
 	 * once a day when it is at 80% of its limit or more.

lib/Service/BackupService.php

@@ -253,8 +253,13 @@ final class BackupService {
 					try {
 						$this->alerts->storedBytes($target, $repo->storedBytes());
 						$stats = $state['files']['stats'];
+						$warnings = BackupRun::warnings($state['files']);
+						if (($stats['badNames'] ?? 0) > 0) {
+							$this->logger->warning(sprintf('NG Backup run %d to %s: %d left out because their name is not supported (rename them): %s',
+								$run->getId(), $target->getName(), $stats['badNames'], implode(', ', $warnings['badNames'])));
+							$this->alerts->runBadNames($run, $target->getName(), (int)$stats['badNames'], $warnings['badNames']);
+						}
 						if (($stats['unreadable'] ?? 0) > 0 || ($stats['changing'] ?? 0) > 0) {
-							$warnings = BackupRun::warnings($state['files']);
 							$this->logger->warning(sprintf('NG Backup run %d to %s: %d unreadable (missing from the snapshot): %s; %d changed while being read: %s',
 								$run->getId(), $target->getName(), $stats['unreadable'] ?? 0, implode(', ', $warnings['unreadable']),
 								$stats['changing'] ?? 0, implode(', ', $warnings['changing'])));