fix(targets): compare the Info.plist bplist prefix without ASCII folding (#2100)

* fix(targets): compare the Info.plist bplist prefix without ASCII folding

The six-byte prefix check used an encoding that maps high-bit bytes onto bplist, so a non-binary property list could be sent to the binary decoder.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(targets): satisfy the strict index check in the plist prefix test

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: morluto <76467478+morluto@users.noreply.github.com>

src/application/AppBundleExecutable.test.ts

@@ -0,0 +1,34 @@
+import { mkdtemp, mkdir, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+
+import { describe, expect, it } from "vitest";
+
+import { resolveAppBundleExecutable } from "./AppBundleExecutable.js";
+
+describe("app bundle Info.plist magic", () => {
+  it("does not decode a high-bit fold of bplist as a binary Info.plist", async () => {
+    const root = await mkdtemp(join(tmpdir(), "rea-bplist-fold-"));
+    try {
+      const bundle = join(root, "Fixture.app");
+      const plistPath = join(bundle, "Contents", "Info.plist");
+      await mkdir(join(bundle, "Contents"), { recursive: true });
+      const plist = Buffer.from("bplist00");
+      plist[0] = (plist[0] ?? 0) | 0x80;
+      await writeFile(plistPath, plist);
+      let decoded = false;
+      const result = await resolveAppBundleExecutable(bundle, {
+        readFile: async () => plist,
+        realpath: async (path) => path,
+        decodeBinaryPlist: async () => {
+          decoded = true;
+          return "Fixture";
+        },
+      });
+      expect(decoded).toBe(false);
+      expect(result.ok).toBe(false);
+    } finally {
+      await rm(root, { recursive: true, force: true });
+    }
+  });
+});