fix: use FS with OS-specific path separator for loading docuemnts

Signed-off-by: nikpivkin <[email protected]>

Author: nikpivkin

pkg/iac/rego/store.go

@@ -2,21 +2,41 @@ package rego
 
 import (
 	"fmt"
+	"io"
 	"io/fs"
 	"os"
 	"path/filepath"
 	"slices"
 	"strings"
 
+	"github.com/liamg/memoryfs"
 	"github.com/open-policy-agent/opa/v1/loader"
 	"github.com/open-policy-agent/opa/v1/storage"
 )
 
 // initialize a store populated with OPA data files found in dataPaths
 func initStore(dataFS fs.FS, dataPaths, namespaces []string) (storage.Store, error) {
+	fsys := memoryfs.New()
+	// The virtual file system uses a slash ('/') as a path separator,
+	// but OPA uses the filepath package, which is OS-dependent.
+	// So we need to create a copy of the filesystem where the paths use the an OS-specific separator.
+	if err := fs.WalkDir(dataFS, ".", func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return fsys.MkdirAll(path, d.Type().Perm())
+		}
+		return fsys.WriteLazyFile(filepath.FromSlash(path), func() (io.Reader, error) {
+			return fsys.Open(path)
+		}, d.Type().Perm())
+	}); err != nil {
+		return nil, fmt.Errorf("walk dir: %w", err)
+	}
+
 	// FilteredPaths will recursively find all file paths that contain a valid document
 	// extension from the given list of data paths.
-	allDocumentPaths, _ := loader.FilteredPathsFS(dataFS, dataPaths,
+	allDocumentPaths, _ := loader.FilteredPathsFS(fsys, dataPaths,
 		func(abspath string, info os.FileInfo, depth int) bool {
 			return !info.IsDir() && !isDataFile(info)
 		},