fix: Resolve dependency issues on Node.js 20 (#62)

* fix: Resolve dependency issues on Node.js 20

We drop the requirement for a native module, and make use of fs.statfs where available (Node.js >=18)

* fix: Fix incorrect checkSync implementation

Rewrites the checkSync implementation under Node 18+

Author: jduncanator

fallback.js

@@ -0,0 +1,29 @@
+var native = require("./build/Release/diskusage.node");
+var promise = typeof Promise !== "undefined" ? Promise : require("es6-promise").Promise;
+
+exports.check = function(path, callback) {
+  if (callback) {
+    return check(path, callback);
+  }
+
+  return new promise(function (resolve, reject) {
+    check(path, function (err, result) {
+      err ? reject(err) : resolve(result);
+    });
+  });
+};
+
+exports.checkSync = native.getDiskUsage;
+
+function check(path, callback) {
+  var result = undefined;
+  var error = undefined;
+
+  try {
+    result = native.getDiskUsage(path);
+  } catch (error_) {
+    error = error_;
+  }
+
+  callback(error, result);
+}

index.js

@@ -1,29 +1,47 @@
-var native = require("./build/Release/diskusage.node");
-var promise = typeof Promise !== "undefined" ? Promise : require("es6-promise").Promise;
+var fs = require('fs');
 
-exports.check = function(path, callback) {
-  if (callback) {
-    return check(path, callback);
-  }
+// Detect presence of fs.statfs
+if(typeof fs.statfs === 'function') {
+  exports.check = function(path, callback) {
+    if (callback) {
+      return check(path, callback);
+    }
 
-  return new promise(function (resolve, reject) {
-    check(path, function (err, result) {
-      err ? reject(err) : resolve(result);
+    return new Promise(function (resolve, reject) {
+      check(path, function (err, result) {
+        err ? reject(err) : resolve(result);
+      });
     });
-  });
-};
+  }
+
+  function check(path, callback) {
+    fs.statfs(path, function (err, result_) {
+      var result = undefined;
 
-exports.checkSync = native.getDiskUsage;
+      if (!err) {
+        result = {
+          available: result_.bavail * result_.bsize,
+          free: result_.bfree * result_.bsize,
+          total: result_.blocks * result_.bsize
+        };
+      }
+
+      callback(err, result);
+    });
+  }
 
-function check(path, callback) {
-  var result = undefined;
-  var error = undefined;
+  exports.checkSync = function(path) {
+    var result = fs.statfsSync(path);
 
-  try {
-    result = native.getDiskUsage(path);
-  } catch (error_) {
-    error = error_;
+    return {
+      available: result.bavail * result.bsize,
+      free: result.bfree * result.bsize,
+      total: result.blocks * result.bsize
+    }
   }
+} else {
+  var diskusage = require('./fallback.js');
 
-  callback(error, result);
-}
+  exports.check = diskusage.check;
+  exports.checkSync = diskusage.checkSync;
+}

package.json

@@ -6,11 +6,11 @@
   "typings": "index.d.ts",
   "gypfile": true,
   "dependencies": {
-    "es6-promise": "^4.2.5",
-    "nan": "^2.14.0"
+    "es6-promise": "^4.2.8",
+    "nan": "^2.18.0"
   },
   "devDependencies": {
-    "eslint": "^6.0.1"
+    "eslint": "^8.49.0"
   },
   "repository": {
     "type": "git",