Function download

scripts/npm-shim.js:177–201

(url, dest, redirectsLeft)

// GET with manual redirect following (GitHub release URLs redirect to a CDN).
function download(url, dest, redirectsLeft) {
  return new Promise(function (resolve, reject) {
    var https = require('https');
    // timeout is an idle/inactivity timeout — it won't kill a slow-but-progressing
    // download, only a stalled connection (so a blocked mirror fails fast with
    // guidance instead of hanging the user's command forever).
    var req = https.get(url, { headers: { 'User-Agent': 'codegraph-npm-shim' }, timeout: 30000 }, function (res) {
      var status = res.statusCode;
      if (status >= 300 && status < 400 && res.headers.location) {
        res.resume();
        if (redirectsLeft <= 0) { reject(new Error('too many redirects')); return; }
        download(new URL(res.headers.location, url).toString(), dest, redirectsLeft - 1).then(resolve, reject);
        return;
      }
      if (status !== 200) { res.resume(); reject(new Error('HTTP ' + status)); return; }
      var file = fs.createWriteStream(dest);
      res.on('error', reject);
      res.pipe(file);
      file.on('error', reject);
      file.on('finish', function () { file.close(function () { resolve(); }); });
    });
    req.on('timeout', function () { req.destroy(new Error('connection timed out')); });
    req.on('error', reject);
  });
}

// Best-effort integrity check. When the release publishes a SHA256SUMS file, the
// downloaded archive MUST match its listed hash or we abort. When that file is