fix(files/cache): uniqueness guarantees in the file cache layer

Signed-off-by: Git'Fellow <12234510+solracsf@users.noreply.github.com>

lib/private/Files/Cache/Cache.php

@@ -1015,7 +1015,6 @@ class Cache implements ICache {
 	/**
 	 * inner function because we can't add new params to the public function without breaking any child classes
 	 *
-	 * @param string $path
 	 * @param array|null|ICacheEntry $entry (optional) meta data of the folder
 	 * @param bool $ignoreUnknown don't mark the folder size as unknown if any of it's children are unknown
 	 * @return int|float
@@ -1029,7 +1028,19 @@ class Cache implements ICache {
 			$id = $entry['fileid'];
 
 			$query = $this->getQueryBuilder();
-			$query->select('size', 'unencrypted_size')
+			$sizeCol = $query->getColumnName('size');
+			$unencryptedSizeCol = $query->getColumnName('unencrypted_size');
+			$query->selectAlias($query->func()->sum('size'), 'size_sum')
+				->selectAlias($query->func()->min('size'), 'size_min')
+				->selectAlias($query->func()->max('unencrypted_size'), 'unencrypted_max')
+				->selectAlias(
+					$query->createFunction("SUM(CASE WHEN $unencryptedSizeCol > 0 THEN $unencryptedSizeCol ELSE $sizeCol END)"),
+					'unencrypted_sum'
+				)
+				->selectAlias(
+					$query->createFunction("MIN(CASE WHEN $unencryptedSizeCol > 0 THEN $unencryptedSizeCol ELSE $sizeCol END)"),
+					'unencrypted_min'
+				)
 				->from('filecache')
 				->whereStorageId($this->getNumericStorageId())
 				->whereParent($id);
@@ -1038,34 +1049,24 @@ class Cache implements ICache {
 			}
 
 			$result = $query->executeQuery();
-			$rows = $result->fetchAll();
+			$agg = $result->fetch();
 			$result->closeCursor();
 
-			if ($rows) {
-				$sizes = array_map(function (array $row) {
-					return Util::numericToNumber($row['size']);
-				}, $rows);
-				$unencryptedOnlySizes = array_map(function (array $row) {
-					return Util::numericToNumber($row['unencrypted_size']);
-				}, $rows);
-				$unencryptedSizes = array_map(function (array $row) {
-					return Util::numericToNumber(($row['unencrypted_size'] > 0) ? $row['unencrypted_size'] : $row['size']);
-				}, $rows);
-
-				$sum = array_sum($sizes);
-				$min = min($sizes);
-
-				$unencryptedSum = array_sum($unencryptedSizes);
-				$unencryptedMin = min($unencryptedSizes);
-				$unencryptedMax = max($unencryptedOnlySizes);
+			// SUM() returns NULL on empty set
+			if ($agg && $agg['size_sum'] !== null) {
+				$sum = Util::numericToNumber($agg['size_sum']);
+				$min = Util::numericToNumber($agg['size_min']);
+				$unencryptedMax = Util::numericToNumber($agg['unencrypted_max'] ?? 0);
+				$unencryptedSum = Util::numericToNumber($agg['unencrypted_sum'] ?? 0);
+				$unencryptedMin = Util::numericToNumber($agg['unencrypted_min'] ?? 0);
 
 				$sum = 0 + $sum;
 				$min = 0 + $min;
-				if ($min === -1) {
-					$totalSize = $min;
-				} else {
-					$totalSize = $sum;
-				}
+				$unencryptedSum = 0 + $unencryptedSum;
+				$unencryptedMin = 0 + $unencryptedMin;
+
+				$totalSize = ($min === -1) ? $min : $sum;
+
 				if ($unencryptedMin === -1 || $min === -1) {
 					$unencryptedTotal = $unencryptedMin;
 				} else {
@@ -1077,15 +1078,16 @@ class Cache implements ICache {
 				$unencryptedMax = 0;
 			}
 
-			// only set unencrypted size for a folder if any child entries have it set, or the folder is empty
+			// only set unencrypted size for a folder if any child entries have it set
+			// or if the folder is empty
 			$shouldWriteUnEncryptedSize = $unencryptedMax > 0 || $totalSize === 0 || ($entry['unencrypted_size'] ?? 0) > 0;
 			if ($entry['size'] !== $totalSize || (($entry['unencrypted_size'] ?? 0) !== $unencryptedTotal && $shouldWriteUnEncryptedSize)) {
 				if ($shouldWriteUnEncryptedSize) {
-					// if all children have an unencrypted size of 0, just set the folder unencrypted size to 0 instead of summing the sizes
+					// if all children have an unencrypted size of 0
+					// just set the folder unencrypted size to 0 instead of summing the sizes
 					if ($unencryptedMax === 0) {
 						$unencryptedTotal = 0;
 					}
-
 					$this->update($id, [
 						'size' => $totalSize,
 						'unencrypted_size' => $unencryptedTotal,

lib/private/Files/Cache/Propagator.php

@@ -75,7 +75,7 @@ class Propagator implements IPropagator {
 
 		$parentHashes = array_map('md5', $parents);
 		sort($parentHashes); // Ensure rows are always locked in the same order
-		$etag = uniqid(); // since we give all folders the same etag we don't ask the storage for the etag
+		$etag = bin2hex(random_bytes(8)); // since we give all folders the same etag we don't ask the storage for the etag
 
 		$builder = $this->connection->getQueryBuilder();
 		$hashParams = array_map(static fn (string $hash): ILiteral => $builder->expr()->literal($hash), $parentHashes);
@@ -218,29 +218,32 @@ class Propagator implements IPropagator {
 					$query = $this->connection->getQueryBuilder();
 					$query->update('filecache')
 						->set('mtime', $query->func()->greatest('mtime', $query->createParameter('time')))
-						->set('etag', $query->expr()->literal(uniqid()))
+						->set('etag', $query->createParameter('etag'))
 						->where($query->expr()->eq('storage', $query->createNamedParameter($storageId, IQueryBuilder::PARAM_INT)))
 						->andWhere($query->expr()->eq('fileid', $query->createParameter('fileid')));
 
 					$queryWithSize = $this->connection->getQueryBuilder();
 					$queryWithSize->update('filecache')
 						->set('mtime', $queryWithSize->func()->greatest('mtime', $queryWithSize->createParameter('time')))
-						->set('etag', $queryWithSize->expr()->literal(uniqid()))
+						->set('etag', $queryWithSize->createParameter('etag'))
 						->set('size', $queryWithSize->func()->add('size', $queryWithSize->createParameter('size')))
 						->where($queryWithSize->expr()->eq('storage', $queryWithSize->createNamedParameter($storageId, IQueryBuilder::PARAM_INT)))
 						->andWhere($queryWithSize->expr()->eq('fileid', $queryWithSize->createParameter('fileid')));
 
 					while ($row = $result->fetchAssociative()) {
 						$item = $this->batch[$row['path']];
+						$newEtag = bin2hex(random_bytes(8));
 						if ($item['size'] && $row['size'] > -1) {
 							$queryWithSize->setParameter('fileid', $row['fileid'], IQueryBuilder::PARAM_INT)
 								->setParameter('size', $item['size'], IQueryBuilder::PARAM_INT)
 								->setParameter('time', $item['time'], IQueryBuilder::PARAM_INT)
-								->executeStatement();
+								->setParameter('etag', $newEtag, IQueryBuilder::PARAM_STR);
+							$queryWithSize->executeStatement();
 						} else {
 							$query->setParameter('fileid', $row['fileid'], IQueryBuilder::PARAM_INT)
 								->setParameter('time', $item['time'], IQueryBuilder::PARAM_INT)
-								->executeStatement();
+								->setParameter('etag', $newEtag, IQueryBuilder::PARAM_STR);
+							$query->executeStatement();
 						}
 					}
 				}
@@ -249,28 +252,31 @@ class Propagator implements IPropagator {
 				$query = $this->connection->getQueryBuilder();
 				$query->update('filecache')
 					->set('mtime', $query->func()->greatest('mtime', $query->createParameter('time')))
-					->set('etag', $query->expr()->literal(uniqid()))
+					->set('etag', $query->createParameter('etag'))
 					->where($query->expr()->eq('storage', $query->createNamedParameter($storageId, IQueryBuilder::PARAM_INT)))
 					->andWhere($query->expr()->eq('path_hash', $query->createParameter('hash')));
 
 				$queryWithSize = $this->connection->getQueryBuilder();
 				$queryWithSize->update('filecache')
 					->set('mtime', $queryWithSize->func()->greatest('mtime', $queryWithSize->createParameter('time')))
-					->set('etag', $queryWithSize->expr()->literal(uniqid()))
+					->set('etag', $queryWithSize->createParameter('etag'))
 					->set('size', $queryWithSize->func()->add('size', $queryWithSize->createParameter('size')))
 					->where($queryWithSize->expr()->eq('storage', $queryWithSize->createNamedParameter($storageId, IQueryBuilder::PARAM_INT)))
 					->andWhere($queryWithSize->expr()->eq('path_hash', $queryWithSize->createParameter('hash')));
 
 				foreach ($this->batch as $item) {
+					$newEtag = bin2hex(random_bytes(8));
 					if ($item['size']) {
 						$queryWithSize->setParameter('hash', $item['hash'], IQueryBuilder::PARAM_STR)
 							->setParameter('time', $item['time'], IQueryBuilder::PARAM_INT)
 							->setParameter('size', $item['size'], IQueryBuilder::PARAM_INT)
-							->executeStatement();
+							->setParameter('etag', $newEtag, IQueryBuilder::PARAM_STR);
+						$queryWithSize->executeStatement();
 					} else {
 						$query->setParameter('hash', $item['hash'], IQueryBuilder::PARAM_STR)
 							->setParameter('time', $item['time'], IQueryBuilder::PARAM_INT)
-							->executeStatement();
+							->setParameter('etag', $newEtag, IQueryBuilder::PARAM_STR);
+						$query->executeStatement();
 					}
 				}
 			}

lib/private/Files/Cache/Scanner.php

@@ -423,7 +423,7 @@ class Scanner extends BasicEmitter implements IScanner {
 					$updatedData['size'] = $size;
 				}
 				if ($etagChanged) {
-					$updatedData['etag'] = uniqid();
+					$updatedData['etag'] = bin2hex(random_bytes(8));
 				}
 				if ($updatedData) {
 					$this->cache->update($folderId, $updatedData);