Move demandDirectoryRoot into kyaml/filesys (#4677)

* Move demandDirectoryRoot into kyaml/filesys

* Make root directory platform-agnostic

Support windows root directory. Dogfood own error package.

* Use cleaner windows support implementation

* Address feedback

* Address feedback x2

* Re-apply go.sum changes to avoid CI errors

api/loader/errors.go

@@ -3,6 +3,9 @@
 
 package loader
 
-import "fmt"
+import "sigs.k8s.io/kustomize/kyaml/errors"
 
-var ErrorHTTP = fmt.Errorf("HTTP Error")
+var (
+	ErrHTTP     = errors.Errorf("HTTP Error")
+	ErrRtNotDir = errors.Errorf("must build at directory")
+)

api/loader/fileloader.go

@@ -4,7 +4,6 @@
 package loader
 
 import (
-	"errors"
 	"fmt"
 	"io/ioutil"
 	"log"
@@ -15,6 +14,7 @@ import (
 
 	"sigs.k8s.io/kustomize/api/ifc"
 	"sigs.k8s.io/kustomize/api/internal/git"
+	"sigs.k8s.io/kustomize/kyaml/errors"
 	"sigs.k8s.io/kustomize/kyaml/filesys"
 )
 
@@ -123,7 +123,7 @@ func (fl *fileLoader) Root() string {
 func newLoaderOrDie(
 	lr LoadRestrictorFunc,
 	fSys filesys.FileSystem, path string) *fileLoader {
-	root, err := demandDirectoryRoot(fSys, path)
+	root, err := filesys.ConfirmDir(fSys, path)
 	if err != nil {
 		log.Fatalf("unable to make loader at '%s'; %v", path, err)
 	}
@@ -146,30 +146,11 @@ func newLoaderAtConfirmedDir(
 	}
 }
 
-// Assure that the given path is in fact a directory.
-func demandDirectoryRoot(
-	fSys filesys.FileSystem, path string) (filesys.ConfirmedDir, error) {
-	if path == "" {
-		return "", fmt.Errorf(
-			"loader root cannot be empty")
-	}
-	d, f, err := fSys.CleanedAbs(path)
-	if err != nil {
-		return "", err
-	}
-	if f != "" {
-		return "", fmt.Errorf(
-			"'%s' must be a directory so that it can used as a build root",
-			path)
-	}
-	return d, nil
-}
-
 // New returns a new Loader, rooted relative to current loader,
 // or rooted in a temp directory holding a git repo clone.
 func (fl *fileLoader) New(path string) (ifc.Loader, error) {
 	if path == "" {
-		return nil, fmt.Errorf("new root cannot be empty")
+		return nil, errors.Errorf("new root cannot be empty")
 	}
 
 	repoSpec, err := git.NewRepoSpecFromURL(path)
@@ -185,9 +166,9 @@ func (fl *fileLoader) New(path string) (ifc.Loader, error) {
 	if filepath.IsAbs(path) {
 		return nil, fmt.Errorf("new root '%s' cannot be absolute", path)
 	}
-	root, err := demandDirectoryRoot(fl.fSys, fl.root.Join(path))
+	root, err := filesys.ConfirmDir(fl.fSys, fl.root.Join(path))
 	if err != nil {
-		return nil, err
+		return nil, errors.WrapPrefixf(err, ErrRtNotDir.Error())
 	}
 	if err = fl.errIfGitContainmentViolation(root); err != nil {
 		return nil, err
@@ -317,9 +298,9 @@ func (fl *fileLoader) Load(path string) ([]byte, error) {
 		if resp.StatusCode < 200 || resp.StatusCode > 299 {
 			_, err := git.NewRepoSpecFromURL(path)
 			if err == nil {
-				return nil, errors.New("URL is a git repository")
+				return nil, errors.Errorf("URL is a git repository")
 			}
-			return nil, fmt.Errorf("%w: status code %d (%s)", ErrorHTTP, resp.StatusCode, http.StatusText(resp.StatusCode))
+			return nil, fmt.Errorf("%w: status code %d (%s)", ErrHTTP, resp.StatusCode, http.StatusText(resp.StatusCode))
 		}
 		body, err := ioutil.ReadAll(resp.Body)
 		if err != nil {

api/loader/fileloader_test.go

@@ -15,7 +15,6 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/require"
-
 	"sigs.k8s.io/kustomize/api/ifc"
 	"sigs.k8s.io/kustomize/api/internal/git"
 	"sigs.k8s.io/kustomize/api/konfig"
@@ -408,11 +407,8 @@ func TestLocalLoaderReferencingGitBase(t *testing.T) {
 	fSys.MkdirAll(topDir)
 	fSys.MkdirAll(cloneRoot + "/foo/base")
 
-	root, err := demandDirectoryRoot(fSys, topDir)
-	require.NoError(err)
-
 	l1 := newLoaderAtConfirmedDir(
-		RestrictionRootOnly, root, fSys, nil,
+		RestrictionRootOnly, filesys.ConfirmedDir(topDir), fSys, nil,
 		git.DoNothingCloner(filesys.ConfirmedDir(cloneRoot)))
 	require.Equal(topDir, l1.Root())
 
@@ -430,11 +426,8 @@ func TestRepoDirectCycleDetection(t *testing.T) {
 	fSys.MkdirAll(topDir)
 	fSys.MkdirAll(cloneRoot)
 
-	root, err := demandDirectoryRoot(fSys, topDir)
-	require.NoError(err)
-
 	l1 := newLoaderAtConfirmedDir(
-		RestrictionRootOnly, root, fSys, nil,
+		RestrictionRootOnly, filesys.ConfirmedDir(topDir), fSys, nil,
 		git.DoNothingCloner(filesys.ConfirmedDir(cloneRoot)))
 	p1 := "github.com/someOrg/someRepo/foo"
 	rs1, err := git.NewRepoSpecFromURL(p1)
@@ -455,11 +448,8 @@ func TestRepoIndirectCycleDetection(t *testing.T) {
 	fSys.MkdirAll(topDir)
 	fSys.MkdirAll(cloneRoot)
 
-	root, err := demandDirectoryRoot(fSys, topDir)
-	require.NoError(err)
-
 	l0 := newLoaderAtConfirmedDir(
-		RestrictionRootOnly, root, fSys, nil,
+		RestrictionRootOnly, filesys.ConfirmedDir(topDir), fSys, nil,
 		git.DoNothingCloner(filesys.ConfirmedDir(cloneRoot)))
 
 	p1 := "github.com/someOrg/someRepo1"

api/loader/loader.go

@@ -7,6 +7,7 @@ package loader
 import (
 	"sigs.k8s.io/kustomize/api/ifc"
 	"sigs.k8s.io/kustomize/api/internal/git"
+	"sigs.k8s.io/kustomize/kyaml/errors"
 	"sigs.k8s.io/kustomize/kyaml/filesys"
 )
 
@@ -25,9 +26,9 @@ func NewLoader(
 		return newLoaderAtGitClone(
 			repoSpec, fSys, nil, git.ClonerUsingGitExec)
 	}
-	root, err := demandDirectoryRoot(fSys, target)
+	root, err := filesys.ConfirmDir(fSys, target)
 	if err != nil {
-		return nil, err
+		return nil, errors.WrapPrefixf(err, ErrRtNotDir.Error())
 	}
 	return newLoaderAtConfirmedDir(
 		lr, root, fSys, nil, git.ClonerUsingGitExec), nil