myblog/node_modules/hexo-renderer-less/index.js

var less = require('less'),
  path = require('path');

hexo.extend.renderer.register('less', 'css', function(data, options, callback){
  var themeConfig = hexo.theme.config.less || {};
  var cwd = process.cwd();
  var paths = (themeConfig.paths || []).map(function(filepath){
    return path.join(cwd, filepath);    // assuming paths are relative from the root of the project
  });

  var parser = less.render(data.text, {
    paths: paths.concat(path.dirname(data.path)),
    filename: path.basename(data.path),
    compress: themeConfig.compress || false
  })
  .then(function(output) {
    callback(null, output.css);
  },
  function(error){
    callback(error);
  });
});