stylelint/lib/vendor/writeFileAtomic.js

// This is a fork of https://github.com/npm/write-file-atomic v2.3.0
// with graceful-fs replaced with fs to avoid memory leak during testing
// See: https://github.com/stylelint/stylelint/pull/2992

"use strict";
module.exports = writeFile;
module.exports.sync = writeFileSync;
module.exports._getTmpname = getTmpname; // for testing
module.exports._cleanupOnExit = cleanupOnExit;

var fs = require("fs");
var MurmurHash3 = require("imurmurhash");
var onExit = require("signal-exit");
var path = require("path");
var activeFiles = {};

var invocations = 0;
function getTmpname(filename) {
  return (
    filename +
    "." +
    MurmurHash3(__filename)
      .hash(String(process.pid))
      .hash(String(++invocations))
      .result()
  );
}

function cleanupOnExit(tmpfile) {
  return function() {
    try {
      fs.unlinkSync(typeof tmpfile === "function" ? tmpfile() : tmpfile);
    } catch (_) {}
  };
}

function writeFile(filename, data, options, callback) {
  if (options instanceof Function) {
    callback = options;
    options = null;
  }
  if (!options) options = {};

  var Promise = options.Promise || global.Promise;
  var truename;
  var fd;
  var tmpfile;
  var removeOnExit = cleanupOnExit(() => tmpfile);
  var absoluteName = path.resolve(filename);

  new Promise(function serializeSameFile(resolve) {
    // make a queue if it doesn't already exist
    if (!activeFiles[absoluteName]) activeFiles[absoluteName] = [];

    activeFiles[absoluteName].push(resolve); // add this job to the queue
    if (activeFiles[absoluteName].length === 1) resolve(); // kick off the first one
  })
    .then(function getRealPath() {
      return new Promise(function(resolve) {
        fs.realpath(filename, function(_, realname) {
          truename = realname || filename;
          tmpfile = getTmpname(truename);
          resolve();
        });
      });
    })
    .then(function stat() {
      return new Promise(function stat(resolve) {
        if (options.mode && options.chown) resolve();
        else {
          // Either mode or chown is not explicitly set
          // Default behavior is to copy it from original file
          fs.stat(truename, function(err, stats) {
            if (err || !stats) resolve();
            else {
              options = Object.assign({}, options);

              if (!options.mode) {
                options.mode = stats.mode;
              }
              if (!options.chown && process.getuid) {
                options.chown = { uid: stats.uid, gid: stats.gid };
              }
              resolve();
            }
          });
        }
      });
    })
    .then(function thenWriteFile() {
      return new Promise(function(resolve, reject) {
        fs.open(tmpfile, "w", options.mode, function(err, _fd) {
          fd = _fd;
          if (err) reject(err);
          else resolve();
        });
      });
    })
    .then(function write() {
      return new Promise(function(resolve, reject) {
        if (Buffer.isBuffer(data)) {
          fs.write(fd, data, 0, data.length, 0, function(err) {
            if (err) reject(err);
            else resolve();
          });
        } else if (data != null) {
          fs.write(
            fd,
            String(data),
            0,
            String(options.encoding || "utf8"),
            function(err) {
              if (err) reject(err);
              else resolve();
            }
          );
        } else resolve();
      });
    })
    .then(function syncAndClose() {
      if (options.fsync !== false) {
        return new Promise(function(resolve, reject) {
          fs.fsync(fd, function(err) {
            if (err) reject(err);
            else fs.close(fd, resolve);
          });
        });
      }
    })
    .then(function chown() {
      if (options.chown) {
        return new Promise(function(resolve, reject) {
          fs.chown(tmpfile, options.chown.uid, options.chown.gid, function(
            err
          ) {
            if (err) reject(err);
            else resolve();
          });
        });
      }
    })
    .then(function chmod() {
      if (options.mode) {
        return new Promise(function(resolve, reject) {
          fs.chmod(tmpfile, options.mode, function(err) {
            if (err) reject(err);
            else resolve();
          });
        });
      }
    })
    .then(function rename() {
      return new Promise(function(resolve, reject) {
        fs.rename(tmpfile, truename, function(err) {
          if (err) reject(err);
          else resolve();
        });
      });
    })
    .then(function success() {
      removeOnExit();
      callback();
    })
    .catch(function fail(err) {
      removeOnExit();
      fs.unlink(tmpfile, function() {
        callback(err);
      });
    })
    .then(function checkQueue() {
      activeFiles[absoluteName].shift(); // remove the element added by serializeSameFile
      if (activeFiles[absoluteName].length > 0) {
        activeFiles[absoluteName][0](); // start next job if one is pending
      } else delete activeFiles[absoluteName];
    });
}

function writeFileSync(filename, data, options) {
  if (!options) options = {};
  try {
    filename = fs.realpathSync(filename);
  } catch (ex) {
    // it's ok, it'll happen on a not yet existing file
  }
  var tmpfile = getTmpname(filename);

  try {
    if (!options.mode || !options.chown) {
      // Either mode or chown is not explicitly set
      // Default behavior is to copy it from original file
      try {
        var stats = fs.statSync(filename);
        options = Object.assign({}, options);
        if (!options.mode) {
          options.mode = stats.mode;
        }
        if (!options.chown && process.getuid) {
          options.chown = { uid: stats.uid, gid: stats.gid };
        }
      } catch (ex) {
        // ignore stat errors
      }
    }

    var removeOnExit = onExit(cleanupOnExit(tmpfile));
    var fd = fs.openSync(tmpfile, "w", options.mode);
    if (Buffer.isBuffer(data)) {
      fs.writeSync(fd, data, 0, data.length, 0);
    } else if (data != null) {
      fs.writeSync(fd, String(data), 0, String(options.encoding || "utf8"));
    }
    if (options.fsync !== false) {
      fs.fsyncSync(fd);
    }
    fs.closeSync(fd);
    if (options.chown)
      fs.chownSync(tmpfile, options.chown.uid, options.chown.gid);
    if (options.mode) fs.chmodSync(tmpfile, options.mode);
    fs.renameSync(tmpfile, filename);
    removeOnExit();
  } catch (err) {
    removeOnExit();
    try {
      fs.unlinkSync(tmpfile);
    } catch (e) {}
    throw err;
  }
}