1 files changed, 32 insertions, 0 deletions
diff --git a/internal/ctlsocksrv/sanitize.go b/internal/ctlsocksrv/sanitize.go
new file mode 100644
index 0000000..4333872
--- /dev/null
+++ b/internal/ctlsocksrv/sanitize.go
@@ -0,0 +1,32 @@
+package ctlsocksrv
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+// SanitizePath adapts filepath.Clean for FUSE paths.
+// 1) Leading slash(es) are dropped
+// 2) It returns "" instead of "."
+// 3) If the cleaned path points above CWD (start with ".."), an empty string
+//    is returned
+// See the TestSanitizePath testcases for examples.
+func SanitizePath(path string) string {
+	// (1)
+	for len(path) > 0 && path[0] == '/' {
+		path = path[1:]
+	}
+	if len(path) == 0 {
+		return ""
+	}
+	clean := filepath.Clean(path)
+	// (2)
+	if clean == "." {
+		return ""
+	}
+	// (3)
+	if clean == ".." || strings.HasPrefix(clean, "../") {
+		return ""
+	}
+	return clean
+}