Use a local Walk function

arduino/builder/sketch.go

@@ -17,6 +17,7 @@ package builder
 
 import (
 	"bytes"
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -58,6 +59,44 @@ func SketchSaveItemCpp(item *sketch.Item, destPath string) error {
 	return nil
 }
 
+func simpleLocalWalkRecursive(root string, maxDepth int, walkFn func(path string, info os.FileInfo, err error) error) error {
+
+	info, err := os.Stat(root)
+
+	if err != nil {
+		return walkFn(root, nil, err)
+	}
+
+	err = walkFn(root, info, err)
+	if err == filepath.SkipDir {
+		return nil
+	}
+
+	if info.IsDir() {
+		if maxDepth <= 0 {
+			return walkFn(root, info, errors.New("Filesystem bottom is too deep (directory recursion or filesystem really deep): "+root))
+		}
+		maxDepth--
+		files, err := ioutil.ReadDir(root)
+		if err == nil {
+			for _, file := range files {
+				err = simpleLocalWalkRecursive(root+string(os.PathSeparator)+file.Name(), maxDepth, walkFn)
+				if err == filepath.SkipDir {
+					return nil
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
+// SimpleLocalWalk locally replaces filepath.Walk and/but goes through symlinks
+func SimpleLocalWalk(root string, walkFn func(path string, info os.FileInfo, err error) error) error {
+	// see discussion in https://github.com/arduino/arduino-cli/pull/421
+	return simpleLocalWalkRecursive(root, 40, walkFn)
+}
+
 // SketchLoad collects all the files composing a sketch.
 // The parameter `sketchPath` holds a path pointing to a single sketch file or a sketch folder,
 // the path must be absolute.
@@ -79,14 +118,28 @@ func SketchLoad(sketchPath, buildPath string) (*sketch.Sketch, error) {
 			return nil, errors.Wrap(err, "unable to find the main sketch file")
 		}
 		f.Close()
+		// ensure it is not a directory
+		info, err := os.Stat(mainSketchFile)
+		if err != nil {
+			return nil, errors.Wrap(err, "unable to check the main sketch file")
+		}
+		if info.IsDir() {
+			return nil, errors.Wrap(errors.New(mainSketchFile), "sketch must not be a directory")
+		}
 	} else {
 		sketchFolder = filepath.Dir(sketchPath)
 		mainSketchFile = sketchPath
 	}
 
 	// collect all the sketch files
 	var files []string
-	err = filepath.Walk(sketchFolder, func(path string, info os.FileInfo, err error) error {
+	err = SimpleLocalWalk(sketchFolder, func(path string, info os.FileInfo, err error) error {
+
+		if err != nil {
+			fmt.Printf("\nerror: %+v\n\n", err)
+			return filepath.SkipDir
+		}
+
 		// ignore hidden files and skip hidden directories
 		if strings.HasPrefix(info.Name(), ".") {
 			if info.IsDir() {