Function serve

lib/core/index.js:229–344

(stat)

    function serve(stat) {
      // Do a MIME lookup, fall back to octet-stream and handle gzip
      // and brotli special case.
      const defaultType = opts.contentType || 'application/octet-stream';
      let contentType = mime.lookup(file, defaultType);
      const range = (req.headers && req.headers.range);
      const lastModified = (new Date(stat.mtime)).toUTCString();
      const etag = generateEtag(stat, weakEtags);
      let cacheControl = cache;
      let stream = null;
      if (contentType && isTextFile(contentType)) {
        if (stat.size < buffer.constants.MAX_LENGTH) {
          const bytes = fs.readFileSync(file);
          const sniffedEncoding = htmlEncodingSniffer(bytes, {
            defaultEncoding: 'UTF-8'
          });
          contentType += `; charset=${sniffedEncoding}`;
          stream = Readable.from(bytes)
        } else {
          // Assume text types are utf8
          contentType += '; charset=UTF-8';
        }
      }

      if (file === gzippedFile) { // is .gz picked up
        res.setHeader('Content-Encoding', 'gzip');
        // strip gz ending and lookup mime type
        contentType = mime.lookup(path.basename(file, '.gz'), defaultType);
      } else if (file === brotliFile) { // is .br picked up
        res.setHeader('Content-Encoding', 'br');
        // strip br ending and lookup mime type
        contentType = mime.lookup(path.basename(file, '.br'), defaultType);
      }

      if (typeof cacheControl === 'function') {
        cacheControl = cache(pathname);
      }
      if (typeof cacheControl === 'number') {
        cacheControl = `max-age=${cacheControl}`;
      }

      if (range) {
        const total = stat.size;
        const parts = range.trim().replace(/bytes=/, '').split('-');
        const partialstart = parts[0];
        const partialend = parts[1];
        const start = parseInt(partialstart, 10);
        const end = Math.min(
          total - 1,
          partialend ? parseInt(partialend, 10) : total - 1
        );
        const chunksize = (end - start) + 1;
        let fstream = null;

        if (start > end || isNaN(start) || isNaN(end)) {
          status['416'](res, next);
          return;
        }