Added symlinks loop-filtering subroutine

Author: cmaglie

Diff for: internal/arduino/sketch/sketch.go

@@ -174,13 +174,26 @@ func (s *Sketch) supportedFiles() (paths.PathList, error) {
 		return err == nil
 	}
 
+	var loopErr error
+	explored := map[string]bool{}
+	filterLoops := func(p *paths.Path) bool {
+		dir := p.Canonical().String()
+		if explored[dir] {
+			loopErr = errors.New("directories symlink loop detected")
+			return false
+		}
+		explored[dir] = true
+		return true
+	}
+
 	files, err := s.FullPath.ReadDirRecursiveFiltered(
 		paths.AndFilter(
 			paths.OrFilter(
 				filterValidExtensions,
 				filterOutBrokenLinks,
 			),
 			filterOutBuildPaths,
+			filterLoops,
 		),
 		paths.AndFilter(
 			paths.FilterOutPrefixes("."),
@@ -191,6 +204,9 @@ func (s *Sketch) supportedFiles() (paths.PathList, error) {
 	if err != nil {
 		return nil, err
 	}
+	if loopErr != nil {
+		return nil, loopErr
+	}
 	return files, nil
 }