nextcloud#17980 - Workaround SMB Storage Driver Bug when Deleting Fol…

…ders

For some reason, on SMBv3/Azure Files when there are more than 62 files in a folder, `RecursiveDirectoryIterator` cannot reliably iterate over the contents.

lib/private/Files/Storage/Local.php

@@ -91,32 +91,7 @@ public function rmdir($path) {
 			return false;
 		}
 		try {
-			$it = new \RecursiveIteratorIterator(
-				new \RecursiveDirectoryIterator($this->getSourcePath($path)),
-				\RecursiveIteratorIterator::CHILD_FIRST
-			);
-			/**
-			 * RecursiveDirectoryIterator on an NFS path isn't iterable with foreach
-			 * This bug is fixed in PHP 5.5.9 or before
-			 * See #8376
-			 */
-			$it->rewind();
-			while ($it->valid()) {
-				/**
-				 * @var \SplFileInfo $file
-				 */
-				$file = $it->current();
-				if (in_array($file->getBasename(), array('.', '..'))) {
-					$it->next();
-					continue;
-				} elseif ($file->isDir()) {
-					rmdir($file->getPathname());
-				} elseif ($file->isFile() || $file->isLink()) {
-					unlink($file->getPathname());
-				}
-				$it->next();
-			}
-			return rmdir($this->getSourcePath($path));
+			return $this->multipassRmdir($path);
 		} catch (\UnexpectedValueException $e) {
 			return false;
 		}
@@ -487,4 +462,90 @@ public function moveFromStorage(IStorage $sourceStorage, $sourceInternalPath, $t
 	public function writeStream(string $path, $stream, int $size = null): int {
 		return (int)file_put_contents($this->getSourcePath($path), $stream);
 	}
+
+	/**
+	 * Attempts to clear out and delete the specified folder.
+	 *
+	 * This method makes multiple passes over the contents of the folder until
+	 * either all the files inside are removed, or the contents cannot be
+	 * deleted. This is a workaround for bugs in an underlying storage driver
+	 * that might otherwise cause only some files within a folder to be deleted
+	 * while others are inexplicably left behind.
+	 *
+	 * See:
+	 * https://github.com/nextcloud/server/issues/17980
+	 *
+	 * @param string $path
+	 *   The path to the folder to remove.
+	 *
+	 * @return bool
+	 *   Whether or not the folder was successfully removed.
+	 *
+	 * @throws ForbiddenException
+	 * 	 If the specified path is not accessible.
+	 */
+	protected function multipassRmdir($path):bool {
+		$unlink_count = -1;
+
+		// Keep looping until we're no longer actually un-linking anything
+		// after two passes in a row.
+		do {
+			$previous_unlink_count = $unlink_count;
+			$unlink_count          = $this->unlinkDirContents($path);
+		} while (($previous_unlink_count != 0) || ($unlink_count != 0));
+
+		return rmdir($this->getSourcePath($path));
+	}
+
+	/**
+	 * Attempts to delete all of the files inside the given folder.
+	 *
+	 * @param string $path
+	 *   The path to the folder containing the files to remove.
+	 *
+	 * @return int
+	 *   The number of files successfully deleted.
+	 *
+	 * @throws ForbiddenException
+	 * 	 If the specified path is not accessible.
+	 */
+	protected function unlinkDirContents(string $path): int {
+		$total_unlink_count = 0;
+
+		$it = new \RecursiveIteratorIterator(
+			new \RecursiveDirectoryIterator(
+				$this->getSourcePath($path),
+				\FilesystemIterator::SKIP_DOTS
+			),
+			\RecursiveIteratorIterator::CHILD_FIRST
+		);
+
+		/**
+		 * RecursiveDirectoryIterator on an NFS path isn't iterable with foreach
+		 * This bug is fixed in PHP 5.5.9 or before
+		 * See #8376
+		 */
+		$it->rewind();
+
+		while ($it->valid()) {
+			/* @var \SplFileInfo $file */
+			$file = $it->current();
+
+			if ($file->isDir()) {
+				$successful_unlink = rmdir($file->getPathname());
+			} elseif ($file->isFile() || $file->isLink()) {
+				$successful_unlink = @unlink($file->getPathname());
+			} else {
+				$successful_unlink = FALSE;
+			}
+
+			if ($successful_unlink) {
+				++$total_unlink_count;
+			}
+
+			$it->next();
+		}
+
+		return $total_unlink_count;
+	}
 }