From 79b3dba1ed4b6870c4e989ada88e33b1ce0ddc21 Mon Sep 17 00:00:00 2001
From: Alexey Rusakov <Kitsune-Ral@users.sf.net>
Date: Mon, 16 May 2022 10:41:54 +0200
Subject: QOlmExpected and associated refactoring

As mentioned in the commit introducing `Expected`, `QOlmExpected` is
simply an alias for `Expected<T, QOlmError>`. This simplifies quite
a few function signatures in `QOlm*` classes and collapses unwieldy
`std::holds_alternative<>`/`std::get<>` constructs into a neat
contextual bool cast and an invocation of `operator*` or
`value()`/`error()` accessors that don't need to specify the type.

While refactoring the code, I found a couple of cases of mismatching
`uint32_t` and `qint32_t` in return values; a couple of cases where
`decrypt()` returns `QString` which is in fact `QByteArray` (e.g., in
`QOlmSession::decrypt()`); there's a repetitive algorithm in
`Connection::Private::sessionDecryptPrekey()` and
`sessionDecryptGeneral()`
---
 lib/e2ee/qolminboundsession.h | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

(limited to 'lib/e2ee/qolminboundsession.h')

diff --git a/lib/e2ee/qolminboundsession.h b/lib/e2ee/qolminboundsession.h
index 13515434..1a9b4415 100644
--- a/lib/e2ee/qolminboundsession.h
+++ b/lib/e2ee/qolminboundsession.h
@@ -5,11 +5,8 @@
 #pragma once
 
 #include "e2ee/e2ee.h"
-#include "e2ee/qolmerrors.h"
-#include "olm/olm.h"
 
-#include <memory>
-#include <variant>
+#include <olm/olm.h>
 
 namespace Quotient {
 
@@ -27,14 +24,13 @@ public:
     QByteArray pickle(const PicklingMode &mode) const;
     //! Deserialises from encrypted Base64 that was previously obtained by pickling
     //! an `OlmInboundGroupSession`.
-    static std::variant<std::unique_ptr<QOlmInboundGroupSession>, QOlmError>
-    unpickle(const QByteArray& picked, const PicklingMode& mode);
+    static QOlmExpected<QOlmInboundGroupSessionPtr> unpickle(
+        const QByteArray& pickled, const PicklingMode& mode);
     //! Decrypts ciphertext received for this group session.
-    std::variant<std::pair<QString, uint32_t>, QOlmError> decrypt(
-        const QByteArray& message);
+    QOlmExpected<std::pair<QByteArray, uint32_t> > decrypt(const QByteArray& message);
     //! Export the base64-encoded ratchet key for this session, at the given index,
     //! in a format which can be used by import.
-    std::variant<QByteArray, QOlmError> exportSession(uint32_t messageIndex);
+    QOlmExpected<QByteArray> exportSession(uint32_t messageIndex);
     //! Get the first message index we know how to decrypt.
     uint32_t firstKnownIndex() const;
     //! Get a base64-encoded identifier for this session.
-- 
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