From 32ccaad00a2b678803e2be003945d177242dc952 Mon Sep 17 00:00:00 2001
From: Patrick Wuttke <p.wuttke@dsfishlabs.com>
Date: Mon, 22 Sep 2025 21:41:31 +0200
Subject: [PATCH] Added Stream::copyTo() and fixed read flag in
 FileStream::getFeatures(). Made throwOnError() throw Exception instead of
 std::runtime_error.

---
 source/mijin/io/stream.cpp | 25 ++++++++++++++++++++++++-
 source/mijin/io/stream.hpp |  6 ++++--
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/source/mijin/io/stream.cpp b/source/mijin/io/stream.cpp
index dc7856e..57148db 100644
--- a/source/mijin/io/stream.cpp
+++ b/source/mijin/io/stream.cpp
@@ -290,6 +290,29 @@ mijin::Task<StreamError> Stream::c_readLine(std::string& outString)
     co_return StreamError::SUCCESS;
 }
 
+StreamError Stream::copyTo(Stream& other)
+{
+    MIJIN_ASSERT(getFeatures().read, "Stream must support reading.");
+    MIJIN_ASSERT(other.getFeatures().write, "Other stream must support writing.");
+
+    static constexpr std::size_t CHUNK_SIZE = 4096;
+    std::array<std::byte, CHUNK_SIZE> chunk = {};
+
+    while (!isAtEnd())
+    {
+        std::size_t bytesRead = 0;
+        if (const StreamError error = readRaw(chunk, {.partial = true}, &bytesRead); error != StreamError::SUCCESS)
+        {
+            return error;
+        }
+        if (const StreamError error = other.writeRaw(chunk.data(), bytesRead); error != StreamError::SUCCESS)
+        {
+            return error;
+        }
+    }
+    return StreamError::SUCCESS;
+}
+
 FileStream::~FileStream()
 {
     if (handle) {
@@ -441,7 +464,7 @@ StreamFeatures FileStream::getFeatures()
     if (handle)
     {
         return {
-            .read = (mode == FileOpenMode::READ),
+            .read = (mode == FileOpenMode::READ || mode == FileOpenMode::READ_WRITE),
             .write = (mode == FileOpenMode::WRITE || mode == FileOpenMode::APPEND || mode == FileOpenMode::READ_WRITE),
             .tell = true,
             .seek = true,
diff --git a/source/mijin/io/stream.hpp b/source/mijin/io/stream.hpp
index 6ea23db..8893ba0 100644
--- a/source/mijin/io/stream.hpp
+++ b/source/mijin/io/stream.hpp
@@ -275,6 +275,8 @@ public:
 
     StreamError getTotalLength(std::size_t& outLength);
 
+    StreamError copyTo(Stream& otherStream);
+
     template<template<typename> typename TAllocator>
     StreamError readRest(BaseTypelessBuffer<TAllocator>& outBuffer);
 
@@ -544,7 +546,7 @@ inline void throwOnError(mijin::StreamError error)
     if (error == mijin::StreamError::SUCCESS) {
         return;
     }
-    throw std::runtime_error(errorName(error));
+    throw Exception(errorName(error));
 }
 
 inline void throwOnError(mijin::StreamError error, std::string message)
@@ -552,7 +554,7 @@ inline void throwOnError(mijin::StreamError error, std::string message)
     if (error == mijin::StreamError::SUCCESS) {
         return;
     }
-    throw std::runtime_error(message + ": " + errorName(error));
+    throw Exception(message + ": " + errorName(error));
 }
 
 template<typename TSuccess>