app/instance: wrap internal implementation

This reduces the scope of the fst package, which was growing questionably large.

Signed-off-by: Ophestra <cat@gensokyo.uk>

1 files changed, 11 insertions, 0 deletions

diff --git a/internal/app/instance/common/path.go b/internal/app/instance/common/path.go
new file mode 100644
index 00000000..ce40f4f1
--- /dev/null
+++ b/internal/app/instance/common/path.go
@@ -0,0 +1,11 @@
+package common
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+func deepContainsH(basepath, targpath string) (bool, error) {
+	rel, err := filepath.Rel(basepath, targpath)
+	return err == nil && rel != ".." && !strings.HasPrefix(rel, string([]byte{'.', '.', filepath.Separator})), err
+}