Invalidate less-node file cache if modified (#3219)

Author: matthew-dean

lib/less-node/file-manager.js

@@ -108,18 +108,32 @@ FileManager.prototype.loadFile = function(filename, currentDirectory, options, e
                             }
                         }
 
+                        var modified = false;
+
                         if (self.contents[fullFilename]) {
-                            fulfill({ contents: self.contents[fullFilename], filename: fullFilename});
+                            try {
+                                var stat = fs.statSync.apply(this, [fullFilename]);
+                                if (stat.mtime.getTime() === self.contents[fullFilename].mtime.getTime()) {
+                                    fulfill({ contents: self.contents[fullFilename].data, filename: fullFilename});
+                                }
+                                else {
+                                    modified = true;
+                                }
+                            }
+                            catch (e) {
+                                modified = true;
+                            }
                         }
-                        else {
+                        if (modified || !self.contents[fullFilename]) {
                             var readFileArgs = [fullFilename];
                             if (!options.rawBuffer) {
                                 readFileArgs.push('utf-8');
                             }
                             if (options.syncImport) {
                                 try {
                                     var data = fs.readFileSync.apply(this, readFileArgs);
-                                    self.contents[fullFilename] = data;
+                                    var stat = fs.statSync.apply(this, [fullFilename]);
+                                    self.contents[fullFilename] = { data: data, mtime: stat.mtime };
                                     fulfill({ contents: data, filename: fullFilename});
                                 }
                                 catch (e) {
@@ -133,7 +147,8 @@ FileManager.prototype.loadFile = function(filename, currentDirectory, options, e
                                         filenamesTried.push(isNodeModule ? npmPrefix + fullFilename : fullFilename);
                                         return tryPrefix(j + 1);
                                     }
-                                    self.contents[fullFilename] = data;
+                                    var stat = fs.statSync.apply(this, [fullFilename]);
+                                    self.contents[fullFilename] = { data: data, mtime: stat.mtime };      
                                     fulfill({ contents: data, filename: fullFilename});
                                 });
                                 fs.readFile.apply(this, readFileArgs);