Function buffer

test/parallel/test-fs-readfile-buffer-option.js:78–81

(fileSize)

    let size;
    const data = fs.readFileSync(file, {
      buffer(fileSize) {
        size = fileSize;
        return Buffer.alloc(fileSize + 8);
      },
    });
    assert.strictEqual(size, content.length);
    assert.deepStrictEqual(data, content);