Function executeUpgrade

packages/cli/src/util/upgrade.ts:106–205

(targetVersion?: string)

 * reported without relying on whichever binary happens to be on `PATH`.
 */
export async function executeUpgrade(targetVersion?: string): Promise<number> {
  const totalSteps = targetVersion ? 2 : 3;
  renderUpgradeProgress(0, totalSteps, 'Resolving installer…');

  const { command: updateCommand, global } = await getUpdateCommandInfo().catch(
    error => {
      output.stopSpinner();
      throw error;
    }
  );
  const [command, ...args] = updateCommand.split(' ');

  const cwd = global ? tmpdir() : process.cwd();

  // The version currently running, captured before the install overwrites it.
  // This is what `vc --version` reports, for both Node.js and native binary.
  const versionBefore = pkg.version;

  let resolvedTargetVersion = targetVersion;
  if (!resolvedTargetVersion) {
    renderUpgradeProgress(1, totalSteps, 'Checking for updates…');
    resolvedTargetVersion = await getLatestPackageVersion(command, args);
  }

  if (
    resolvedTargetVersion &&
    isVersionCurrent(versionBefore, resolvedTargetVersion)
  ) {
    renderUpgradeProgress(totalSteps, totalSteps);
    output.stopSpinner();
    output.log(
      `No upgrade available. Vercel CLI is already up to date (v${versionBefore}).`
    );
    return 0;
  }

  output.debug(`Executing: ${updateCommand} (cwd: ${cwd})`);
  renderUpgradeProgress(targetVersion ? 1 : 2, totalSteps, 'Installing…');

  return new Promise<number>(resolve => {
    const stdout: Uint8Array[] = [];
    const stderr: Uint8Array[] = [];

    const upgradeProcess = spawn(command, args, {
      cwd,
      stdio: ['inherit', 'pipe', 'pipe'],
      shell: false,
    });

    upgradeProcess.stdout?.on('data', (data: Buffer) => {
      stdout.push(Uint8Array.from(data));
    });

    upgradeProcess.stderr?.on('data', (data: Buffer) => {
      stderr.push(Uint8Array.from(data));
    });

    upgradeProcess.on('error', (err: Error) => {