fix path validation with sj:/bucket (#1543)

* Validates  before uplink attempts to download or upload

* Separate Validate function out to utils package and add tests

* Adds another test case

* Move proper URL Handling to FPath Package

* Add individual check notes and further test cases

* Fix Comment Spacing

internal/fpath/path.go

@@ -37,36 +37,37 @@ func New(p string) (FPath, error) {
 
 	var u *url.URL
 	var err error
+	// Loops to ensure URL is formatted correctly and does not get malformed during url.Parse()
 	for {
 		u, err = url.Parse(p)
 		if err != nil {
 			return fp, fmt.Errorf("malformed URL: %v, use format sj://bucket/", err)
 		}
-
+		// no scheme means local path
 		if u.Scheme == "" {
 			fp.local = true
 			return fp, nil
 		}
-
+		// not a valid scheme (s3, sj)
 		if _, validScheme := storjScheme[u.Scheme]; !validScheme {
 			return fp, fmt.Errorf("unsupported URL scheme: %s, use format sj://bucket/", u.Scheme)
 		}
-
+		// empty url
 		if u.Host == "" && u.Path == "" {
 			return fp, errors.New("no bucket specified, use format sj://bucket/")
 		}
-
+		// u.host equals the bucket name, if existing url is valid
 		if u.Host != "" {
 			break
 		}
-
-		p = strings.Replace(p, ":///", "://", 1)
+		// remove additional / if url.Parse() corrects from sj:/bucket to sj:///bucket
+		p = strings.Replace(u.String(), ":///", "://", 1)
 	}
-
+	// port was specified but is not necessary/allowed
 	if u.Port() != "" {
 		return fp, errors.New("port in Storj URL is not supported, use format sj://bucket/")
 	}
-
+	// set path information from url
 	fp.bucket = u.Host
 	if u.Path != "" {
 		fp.path = strings.TrimLeft(path.Clean(u.Path), "/")

internal/fpath/path_test.go

@@ -20,6 +20,27 @@ func TestStorjURL(t *testing.T) {
 		base   string
 		joint  string
 	}{
+		{
+			url:    "sj:/mybucket",
+			bucket: "mybucket",
+			path:   "",
+			base:   "",
+			joint:  "suffix",
+		},
+		{
+			url:    "sj:/mybucket/",
+			bucket: "mybucket",
+			path:   "",
+			base:   "",
+			joint:  "suffix",
+		},
+		{
+			url:    "sj:/mybucket/myfile",
+			bucket: "mybucket",
+			path:   "myfile",
+			base:   "myfile",
+			joint:  "suffix",
+		},
 		{
 			url:    "sj://mybucket",
 			bucket: "mybucket",
@@ -95,6 +116,7 @@ func TestStorjURL(t *testing.T) {
 func TestInvalidStorjURL(t *testing.T) {
 	for i, tt := range []string{
 		"://",
+		"sj:bucket",
 		"sj://",
 		"sj:///",
 		"sj://mybucket:8080/",