esptool-wrapper/index.js

Super minimal wrapper around esptool.py write_flash

const async = require("async");
const args = require("minimist")(process.argv);
const debug = require("debug")("esptool-wrapper");
const fs = require("fs");
const spawn = require("child_process").spawn;

const EXEC = "esptool.py";

module.exports = function(config, cb) {
  async.waterfall([
    function versionCheck(next) {
      debug("creating results and starting");

      var results = {
        args: config.args || []
      };

      // run `esptoo.py version` to ensure it is; in PATH, executable, maybe version check?
      esptoolVersion(function(err, version) {
        if(err) {
          return cb(new Error("Unable to determine esptool.py version. Ensure it is available in $PATH"));
        }

        results.version = version;

        next(null, results);
      });
    },

    function(results, next) {
      if(!config.files) {
        return next(new Error("No files to flash! Not sure what to do. Giving up."));
      }

      debug("verifying files");

      async.each(config.files, function(file, done) {
        fs.access(file, fs.constants.R_OK, done);
      }, function(err) {
        next(err, results);
      });
    },

    function(results, next) {
      var args = results.args;

      debug("building command args");

      config.chip && args.push("--chip", config.chip);
      config.port && args.push("--port", config.port);
      config.baud && args.push("--baud", config.baud);

      args.push("write_flash");

      if(config.cmdArgs && Array.isArray(config.cmdArgs)) {
        args = args.concat(config.cmdArgs);
      }

      for(var addr in config.files) {
        let file = config.files[addr];

        args.push(addr, file);
      }

      results.args = args;

      next(null, results);
    },

    function(results, next) {
      debug("flashing");

      if(process.env.DRY) {
        console.log("%s %s", EXEC, results.args.join(" "));
        return next(null);
      }

      var cp = spawn(EXEC, results.args);
      
      var err = "";
      cp.stderr.on("data", function(c) {
        err += c.toString();
      });

      cp.on("close", function(code) {
        if(code > 0) {
          process.stderr.write(err);

          return next(new Error("esptool exited with: " + code));
        }

        next(null, results);
      });
    }
  ], cb);

  function esptoolVersion(cb) {
    debug("spawning esptool to check version");

    var sp = spawn(EXEC, [ "version" ]);
    var buf = "";

    sp.stdout.on("data", function(c) {
      buf += c.toString();
    });

    sp.on("close", function(code) {
      if(code !== 0) {
        return cb(code);
      }

      var parts = buf.split("\n");
      // shed last new line
      parts.pop();

      // return version (hopefully)
      cb(null, parts.pop());
    });
  }
}