Add the stdio backend

This patch adds the stdio backend which acts as a fallback backend and
uses standard input and output.  For password queries, the rpassword
crate is used to suppress output.  Also, default_backend is changed to
return Stdio if Dialog is not available.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/backends/mod.rs b/src/backends/mod.rs
index f5af7ef..5ae3cef 100644
--- a/src/backends/mod.rs
+++ b/src/backends/mod.rs
@@ -2,9 +2,11 @@
 // SPDX-License-Identifier: MIT
 
 mod dialog;
+mod stdio;
 mod zenity;
 
 pub use crate::backends::dialog::Dialog;
+pub use crate::backends::stdio::Stdio;
 pub use crate::backends::zenity::Zenity;
 
 use std::env;
@@ -49,6 +51,7 @@ pub(crate) fn is_available(name: &str) -> bool {
 pub(crate) fn from_str(s: &str) -> Option<Box<dyn Backend>> {
     match s.to_lowercase().as_ref() {
         "dialog" => Some(Box::new(Dialog::new())),
+        "stdio" => Some(Box::new(Stdio::new())),
         "zenity" => Some(Box::new(Zenity::new())),
         _ => None,
     }