session: Do not cancel on None answer

greetd/src/context.rs

@@ -65,7 +65,7 @@ impl Context {
         loop {
             match scheduled_session.get_state().await {
                 Ok(SessionState::Ready) => break,
-                Ok(SessionState::Question(_, _)) => scheduled_session.post_response(Some("".to_string())).await?,
+                Ok(SessionState::Question(_, _)) => scheduled_session.post_response(None).await?,
                 Err(err) => return Err(format!("session start failed: {}", err).into()),
             }
         }

greetd/src/session/conv.rs

@@ -8,7 +8,7 @@ pub struct SessionConv<'a> {
 }
 
 impl<'a> SessionConv<'a> {
-    fn question(&self, msg: &str, style: AuthMessageType) -> Result<String, ()> {
+    fn question(&self, msg: &str, style: AuthMessageType) -> Result<Option<String>, ()> {
         let msg = SessionChildToParent::PamMessage {
             style,
             msg: msg.to_string(),
@@ -34,15 +34,27 @@ impl<'a> SessionConv<'a> {
 
 impl<'a> Converse for SessionConv<'a> {
     fn prompt_echo(&self, msg: &str) -> Result<String, ()> {
-        self.question(msg, AuthMessageType::Visible)
+        match self.question(msg, AuthMessageType::Visible) {
+            Ok(Some(response)) => Ok(response),
+            _ => Err(()),
+        }
     }
     fn prompt_blind(&self, msg: &str) -> Result<String, ()> {
-        self.question(msg, AuthMessageType::Secret)
+        match self.question(msg, AuthMessageType::Secret) {
+            Ok(Some(response)) => Ok(response),
+            _ => Err(()),
+        }
     }
     fn info(&self, msg: &str) -> Result<(), ()> {
-        self.question(msg, AuthMessageType::Info).map(|_| ())
+        match self.question(msg, AuthMessageType::Info) {
+            Ok(None) => Ok(()),
+            _ => Err(()),
+        }
     }
     fn error(&self, msg: &str) -> Result<(), ()> {
-        self.question(msg, AuthMessageType::Error).map(|_| ())
+        match self.question(msg, AuthMessageType::Error) {
+            Ok(None) => Ok(()),
+            _ => Err(()),
+        }
     }
 }

greetd/src/session/interface.rs

@@ -179,11 +179,7 @@ impl Session {
     /// authentication attempt.
     pub async fn post_response(&mut self, answer: Option<String>) -> Result<(), Error> {
         self.last_msg = None;
-        let msg = match answer {
-            Some(resp) => ParentToSessionChild::PamResponse { resp },
-            None => ParentToSessionChild::Cancel,
-        };
-        msg.send(&mut self.sock).await?;
+        ParentToSessionChild::PamResponse { resp: answer }.send(&mut self.sock).await?;
         Ok(())
     }
 
@@ -221,7 +217,7 @@ impl Session {
                 SessionChildToParent::FinalChildPid(raw_pid) => break Pid::from_raw(raw_pid as i32),
                 SessionChildToParent::PamMessage { style, msg } => {
                     eprintln!("pam_conv after start: {:?}, {}", style, msg);
-                    ParentToSessionChild::PamResponse{resp: "".to_string()}.send(&mut self.sock).await?;
+                    ParentToSessionChild::PamResponse{resp: None}.send(&mut self.sock).await?;
                     continue;
                 }
                 msg => panic!("expected Error or FinalChildPid from session worker, got: {:?}", msg),

greetd/src/session/worker.rs

@@ -32,7 +32,7 @@ pub enum ParentToSessionChild {
         vt: usize,
     },
     PamResponse {
-        resp: String,
+        resp: Option<String>,
     },
     Args {
         cmd: Vec<String>,