Stream LocalGames Windows games at their projector's stage size

The session manager treats a LocalGames .exe as streamable when the file
exists, sizing the display from the Director projector's config chunk.

streaming/session-manager/src/games.ts

@@ -4,8 +4,11 @@ import { buffer } from 'node:stream/consumers';
 import { DatabaseSync } from 'node:sqlite';
 import yauzl from 'yauzl';
 
-/** Launch applications fp-launch can stream, lowercased. */
-const STREAMABLE_APPS = new Set(['fpsoftware\\startjava.bat', 'fpsoftware\\startjavainbrowser.bat']);
+/** Java launch applications fp-launch can stream, lowercased. */
+const JAVA_APPS = new Set(['fpsoftware\\startjava.bat', 'fpsoftware\\startjavainbrowser.bat']);
+
+/** Windows games installed under LocalGames, which fp-launch runs under Wine. */
+const LOCAL_EXE = /^localgames\\.+\.exe$/i;
 
 const DEFAULT_SIZE: Size = { width: 800, height: 600 };
 
@@ -41,7 +44,11 @@ export class GameCatalog {
          where g.id = ?`,
       )
       .get(gameId) as unknown as LaunchRow | undefined;
-    if (!row || !STREAMABLE_APPS.has(row.app.toLowerCase())) {
+    if (row && LOCAL_EXE.test(row.app)) {
+      const exe = await readFile(path.join(this.root, ...row.app.split('\\'))).catch(() => null);
+      return exe && (projectorStageSize(exe) ?? DEFAULT_SIZE);
+    }
+    if (!row || !JAVA_APPS.has(row.app.toLowerCase())) {
       return null;
     }
     const page = await this.readLaunchPage(gameId, row).catch(() => null);
@@ -72,6 +79,31 @@ export function appletSize(html: string): Size | null {
   return width > 0 && height > 0 ? { width, height } : null;
 }
 
+/**
+ * Reads the stage size of the movie in a Director projector from its config
+ * chunk: DRCF in big-endian movies, FCRD in little-endian ones. The chunk body
+ * starts with its own length, the file version, then the stage rect as
+ * big-endian top, left, bottom, right.
+ */
+export function projectorStageSize(exe: Buffer): Size | null {
+  for (const [tag, littleEndian] of [['FCRD', true], ['DRCF', false]] as const) {
+    for (let i = exe.indexOf(tag); i >= 0 && i + 8 <= exe.length; i = exe.indexOf(tag, i + 1)) {
+      const size = littleEndian ? exe.readUInt32LE(i + 4) : exe.readUInt32BE(i + 4);
+      const body = i + 8;
+      if (size < 12 || body + size > exe.length || exe.readUInt16BE(body) !== size) {
+        continue;
+      }
+      const [top, left, bottom, right] = [4, 6, 8, 10].map((offset) => exe.readInt16BE(body + offset));
+      const width = right - left;
+      const height = bottom - top;
+      if (width > 0 && height > 0 && width <= 4096 && height <= 4096) {
+        return { width, height };
+      }
+    }
+  }
+  return null;
+}
+
 /** Reads one entry from a zip, matching its name case-insensitively. */
 function readZipEntry(zipPath: string, name: string): Promise<Buffer | null> {
   const wanted = name.toLowerCase();

streaming/session-manager/test/games.test.ts

@@ -6,7 +6,21 @@ import { finished } from 'node:stream/promises';
 import { test } from 'node:test';
 import { DatabaseSync } from 'node:sqlite';
 import yazl from 'yazl';
-import { appletSize, GameCatalog } from '../src/games.ts';
+import { appletSize, GameCatalog, projectorStageSize } from '../src/games.ts';
+
+/** A fake projector holding a Director config chunk with the given stage rect. */
+function projector(tag: 'FCRD' | 'DRCF', rect: [number, number, number, number]): Buffer {
+  const body = Buffer.alloc(84);
+  body.writeUInt16BE(84, 0);
+  body.writeUInt16BE(0x163c, 2);
+  rect.forEach((value, i) => body.writeInt16BE(value, 4 + i * 2));
+  const header = Buffer.alloc(8);
+  header.write(tag, 0, 'latin1');
+  if (tag === 'FCRD') header.writeUInt32LE(84, 4);
+  else header.writeUInt32BE(84, 4);
+  // A stray tag with a nonsense size must be skipped
+  return Buffer.concat([Buffer.from('MZ junk FCRD\xff\xff\xff\xff junk', 'latin1'), header, body]);
+}
 
 test('appletSize reads the first applet tag', () => {
   assert.deepEqual(appletSize('<APPLET code="a.class" WIDTH=472 height="354" mayscript>'), { width: 472, height: 354 });
@@ -15,10 +29,19 @@ test('appletSize reads the first applet tag', () => {
   assert.equal(appletSize('<embed src="game.swf" width="550" height="400">'), null);
 });
 
+test('projectorStageSize reads the stage rect from either byte order', () => {
+  assert.deepEqual(projectorStageSize(projector('FCRD', [108, 112, 708, 912])), { width: 800, height: 600 });
+  assert.deepEqual(projectorStageSize(projector('DRCF', [0, 0, 480, 640])), { width: 640, height: 480 });
+  assert.equal(projectorStageSize(Buffer.from('MZ no config here')), null);
+  assert.equal(projectorStageSize(Buffer.from('MZ truncated FCRD\x54')), null);
+});
+
 test('GameCatalog sizes streamable games from their GameZIP or htdocs', async () => {
   const root = mkdtempSync(path.join(tmpdir(), 'fp-'));
   mkdirSync(path.join(root, 'Data', 'Games'), { recursive: true });
   mkdirSync(path.join(root, 'Legacy', 'htdocs', 'example.com', 'my game'), { recursive: true });
+  mkdirSync(path.join(root, 'LocalGames', 'aus'), { recursive: true });
+  writeFileSync(path.join(root, 'LocalGames', 'aus', 'Game.exe'), projector('FCRD', [108, 112, 708, 912]));
   writeFileSync(path.join(root, 'Legacy', 'htdocs', 'example.com', 'my game', 'index.html'), '<applet width=300 height=200>');
 
   const zip = new yazl.ZipFile();
@@ -35,6 +58,8 @@ test('GameCatalog sizes streamable games from their GameZIP or htdocs', async ()
     insert into game values ('legacy', 'FPSoftware\\startJava.bat', 'http://example.com/my%20game/', null);
     insert into game values ('missing', 'FPSoftware\\startJava.bat', 'http://example.com/none.html', null);
     insert into game values ('flash', 'FPSoftware\\Flash\\flashplayer_32_sa.exe', 'http://example.com/a.swf', null);
+    insert into game values ('exe', 'LocalGames\\aus\\Game.exe', '', null);
+    insert into game values ('missing-exe', 'LocalGames\\gone\\Game.exe', '', null);
   `);
   db.close();
 
@@ -43,5 +68,7 @@ test('GameCatalog sizes streamable games from their GameZIP or htdocs', async ()
   assert.deepEqual(await catalog.streamSize('legacy'), { width: 300, height: 200 });
   assert.deepEqual(await catalog.streamSize('missing'), { width: 800, height: 600 });
   assert.equal(await catalog.streamSize('flash'), null);
+  assert.deepEqual(await catalog.streamSize('exe'), { width: 800, height: 600 });
+  assert.equal(await catalog.streamSize('missing-exe'), null);
   assert.equal(await catalog.streamSize('unknown'), null);
 });