Introduce path Clean/Join helper functions (#23495)

Since #23493 has conflicts with latest commits, this PR is my proposal
for fixing #23371

Details are in the comments

And refactor the `modules/options` module, to make it always use
"filepath" to access local files.

Benefits:

* No need to do `util.CleanPath(strings.ReplaceAll(p, "\\", "/"))),
"/")` any more (not only one before)
* The function behaviors are clearly defined

3 files changed, 21 insertions, 18 deletions

diff --git a/modules/storage/local.go b/modules/storage/local.go
index 15f5761e8f..d22974a65a 100644
--- a/modules/storage/local.go
+++ b/modules/storage/local.go
@@ -5,11 +5,11 @@ package storage
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"net/url"
 	"os"
 	"path/filepath"
-	"strings"
 
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/util"
@@ -41,13 +41,19 @@ func NewLocalStorage(ctx context.Context, cfg interface{}) (ObjectStorage, error
 	}
 	config := configInterface.(LocalStorageConfig)
 
+	if !filepath.IsAbs(config.Path) {
+		return nil, fmt.Errorf("LocalStorageConfig.Path should have been prepared by setting/storage.go and should be an absolute path, but not: %q", config.Path)
+	}
 	log.Info("Creating new Local Storage at %s", config.Path)
 	if err := os.MkdirAll(config.Path, os.ModePerm); err != nil {
 		return nil, err
 	}
 
 	if config.TemporaryPath == "" {
-		config.TemporaryPath = config.Path + "/tmp"
+		config.TemporaryPath = filepath.Join(config.Path, "tmp")
+	}
+	if !filepath.IsAbs(config.TemporaryPath) {
+		return nil, fmt.Errorf("LocalStorageConfig.TemporaryPath should be an absolute path, but not: %q", config.TemporaryPath)
 	}
 
 	return &LocalStorage{
@@ -58,7 +64,7 @@ func NewLocalStorage(ctx context.Context, cfg interface{}) (ObjectStorage, error
 }
 
 func (l *LocalStorage) buildLocalPath(p string) string {
-	return filepath.Join(l.dir, util.CleanPath(strings.ReplaceAll(p, "\\", "/")))
+	return util.FilePathJoinAbs(l.dir, p)
 }
 
 // Open a file
@@ -128,10 +134,7 @@ func (l *LocalStorage) URL(path, name string) (*url.URL, error) {
 
 // IterateObjects iterates across the objects in the local storage
 func (l *LocalStorage) IterateObjects(prefix string, fn func(path string, obj Object) error) error {
-	dir := l.dir
-	if prefix != "" {
-		dir = filepath.Join(l.dir, util.CleanPath(prefix))
-	}
+	dir := l.buildLocalPath(prefix)
 	return filepath.WalkDir(dir, func(path string, d os.DirEntry, err error) error {
 		if err != nil {
 			return err
diff --git a/modules/storage/local_test.go b/modules/storage/local_test.go
index 2b112df8f1..9649761a0f 100644
--- a/modules/storage/local_test.go
+++ b/modules/storage/local_test.go
@@ -20,29 +20,29 @@ func TestBuildLocalPath(t *testing.T) {
 		expected string
 	}{
 		{
-			"a",
+			"/a",
 			"0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
-			"a/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
+			"/a/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
 		},
 		{
-			"a",
+			"/a",
 			"../0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
-			"a/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
+			"/a/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
 		},
 		{
-			"a",
+			"/a",
 			"0\\a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
-			"a/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
+			"/a/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
 		},
 		{
-			"b",
+			"/b",
 			"a/../0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
-			"b/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
+			"/b/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
 		},
 		{
-			"b",
+			"/b",
 			"a\\..\\0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
-			"b/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
+			"/b/0/a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a14",
 		},
 	}
 
diff --git a/modules/storage/minio.go b/modules/storage/minio.go
index 8cc06bcdd3..5c67dbf26a 100644
--- a/modules/storage/minio.go
+++ b/modules/storage/minio.go
@@ -121,7 +121,7 @@ func NewMinioStorage(ctx context.Context, cfg interface{}) (ObjectStorage, error
 }
 
 func (m *MinioStorage) buildMinioPath(p string) string {
-	return strings.TrimPrefix(path.Join(m.basePath, util.CleanPath(strings.ReplaceAll(p, "\\", "/"))), "/")
+	return util.PathJoinRelX(m.basePath, p)
 }
 
 // Open open a file