Put and Read: content on the socket, for clients that share no files

The system daemon runs as its own user behind ProtectHome, so it can
neither read a file a desktop app wrote for Add nor write one back for
Materialize - redoal on the system varde failed every get with EACCES.
Put imports base64 bytes carried in the request and Read returns a raw
blob's bytes in the reply, both up to MAX_INLINE_BYTES (16 MiB).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

varde-daemon/tests/store_ops.rs

@@ -276,3 +276,45 @@ fn reflink_when_supported() {
     drop(daemon);
     let _ = std::fs::remove_dir_all(&base);
 }
+
+/// Put and Read carry the bytes on the socket: a client that shares no
+/// filesystem with the daemon (a desktop app and the system daemon, which
+/// runs as its own user behind ProtectHome) stores and reads back without
+/// a path either side must reach. A Put blob reads back by Materialize too.
+#[test]
+fn bytes_round_trip_inline() {
+    use base64::Engine as _;
+    let b64 = base64::engine::general_purpose::STANDARD;
+    let daemon = support::spawn_daemon();
+    let mut client = support::Client::connect(&daemon.socket);
+    let payload: Vec<u8> = (0..50_000u32).flat_map(|i| i.to_le_bytes()).collect();
+
+    let reply = client.request(&Request::Put { data: b64.encode(&payload) });
+    assert!(reply.ok, "put failed: {:?}", reply.error);
+    let hash = match reply.data {
+        Some(ResponseData::Added { hash, bytes }) => {
+            assert_eq!(bytes, payload.len() as u64);
+            hash
+        }
+        other => panic!("unexpected put reply: {other:?}"),
+    };
+
+    let reply = client.request(&Request::Read { hash: hash.clone() });
+    assert!(reply.ok, "read failed: {:?}", reply.error);
+    match reply.data {
+        Some(ResponseData::Bytes { data }) => assert_eq!(b64.decode(data).unwrap(), payload),
+        other => panic!("unexpected read reply: {other:?}"),
+    }
+
+    let dir = tempfile::tempdir().unwrap();
+    let dest = dir.path().join("out.bin");
+    materialize(&mut client, &hash, &dest, MaterializeMode::Copy).unwrap();
+    assert_eq!(std::fs::read(&dest).unwrap(), payload);
+
+    // Not base64: refused, not stored.
+    let reply = client.request(&Request::Put { data: "not base64!".into() });
+    assert_eq!(reply.error.expect("error body").code, ErrorCode::InvalidArgument);
+    // Unknown hash: not found.
+    let reply = client.request(&Request::Read { hash: "0".repeat(64) });
+    assert!(!reply.ok);
+}