detect size of remote files - fixes misskey-dev#494

without this, remote files are assumed to have size 0 (even if we just
downloaded them!) and the range-related code won't run

packages/backend/src/server/FileServerService.ts

@@ -262,7 +262,6 @@ export class FileServerService {
 					const parts = range.replace(/bytes=/, '').split('-');
 					const start = parseInt(parts[0], 10);
 					let end = parts[1] ? parseInt(parts[1], 10) : file.file.size - 1;
-					console.log(end);
 					if (end > file.file.size) {
 						end = file.file.size - 1;
 					}
@@ -529,6 +528,9 @@ export class FileServerService {
 		if (!file.storedInternal) {
 			if (!(file.isLink && file.uri)) return '204';
 			const result = await this.downloadAndDetectTypeFromUrl(file.uri);
+			if (!file.size) {
+				file.size = (await fs.promises.stat(result.path)).size;
+			}
 			return {
 				...result,
 				url: file.uri,