Adding upstream version 3.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

error.go

@@ -0,0 +1,27 @@
+package archiver
+
+import (
+	"fmt"
+	"strings"
+)
+
+// IllegalPathError is an error returned when an illegal
+// path is detected during the archival process.
+//
+// By default, only the Filename is showed on error, but you might
+// also get the absolute value of the invalid path on the AbsolutePath
+// field.
+type IllegalPathError struct {
+	AbsolutePath string
+	Filename     string
+}
+
+func (err *IllegalPathError) Error() string {
+	return fmt.Sprintf("illegal file path: %s", err.Filename)
+}
+
+// IsIllegalPathError returns true if the provided error is of
+// the type IllegalPathError.
+func IsIllegalPathError(err error) bool {
+	return err != nil && strings.Contains(err.Error(), "illegal file path: ")
+}