fix pkexec lookup for privilege escalation

electron/main/backend/superuser.ts

@@ -0,0 +1,49 @@
+import { spawn } from "node:child_process";
+import fs from "node:fs";
+import path from "node:path";
+
+export const SUPER_USER_COMMAND_CANDIDATES = [
+  "/usr/bin/pkexec",
+  "/run/wrappers/bin/pkexec",
+];
+
+const WHICH_TIMEOUT_MS = 5000;
+
+export const findExecutable = async (command: string): Promise<string> => {
+  if (path.isAbsolute(command)) {
+    try {
+      await fs.promises.access(command, fs.constants.X_OK);
+      return command;
+    } catch {
+      return "";
+    }
+  }
+
+  return await new Promise<string>((resolve) => {
+    const child = spawn("which", [command]);
+    let stdout = "";
+    let settled = false;
+
+    const timer = setTimeout(() => {
+      child.kill();
+      finish("");
+    }, WHICH_TIMEOUT_MS);
+
+    function finish(result: string) {
+      if (settled) return;
+      settled = true;
+      clearTimeout(timer);
+      resolve(result);
+    }
+
+    child.stdout?.on("data", (data) => {
+      stdout += data.toString();
+    });
+    child.on("close", (code) => {
+      finish(code === 0 ? stdout.trim() : "");
+    });
+    child.on("error", () => {
+      finish("");
+    });
+  });
+};