From 42594eecd4bc181f196408679397f247df84f66e Mon Sep 17 00:00:00 2001
From: Darko Gjorgjijoski <dg@darkog.com>
Date: Mon, 28 Sep 2026 00:25:42 +0200
Subject: [PATCH] fix(relinker): report buffered output write failures

---
 core/relinker/CMakeLists.txt               | 13 +++++++
 core/relinker/io/src/FileWriter.cpp        |  2 +
 core/relinker/io/tests/FileWriterTests.cpp | 43 ++++++++++++++++++++++
 3 files changed, 58 insertions(+)
 create mode 100644 core/relinker/io/tests/FileWriterTests.cpp

diff --git a/core/relinker/CMakeLists.txt b/core/relinker/CMakeLists.txt
index 42ebb17ba..ee8aa80fc 100644
--- a/core/relinker/CMakeLists.txt
+++ b/core/relinker/CMakeLists.txt
@@ -106,6 +106,19 @@ endif()
 
 
 if(BUILD_TESTING)
+    if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+        add_executable(file_writer_tests
+            ${CMAKE_CURRENT_SOURCE_DIR}/io/tests/FileWriterTests.cpp
+            ${CMAKE_CURRENT_SOURCE_DIR}/io/src/FileWriter.cpp
+        )
+        target_include_directories(file_writer_tests PRIVATE
+            ${CMAKE_CURRENT_SOURCE_DIR}/domain/include
+            ${CMAKE_CURRENT_SOURCE_DIR}/io/include
+        )
+        add_test(NAME file_writer_binary COMMAND file_writer_tests binary)
+        add_test(NAME file_writer_text COMMAND file_writer_tests text)
+    endif()
+
     add_executable(amd64_only_converter_tests
         ${CMAKE_CURRENT_SOURCE_DIR}/codegen/tests/Amd64OnlyConverterTests.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/codegen/src/Amd64OnlyConverter.cpp
diff --git a/core/relinker/io/src/FileWriter.cpp b/core/relinker/io/src/FileWriter.cpp
index f30fdae52..a8c65fd63 100644
--- a/core/relinker/io/src/FileWriter.cpp
+++ b/core/relinker/io/src/FileWriter.cpp
@@ -9,6 +9,7 @@ void FileWriter::Write(const std::string& path, const std::vector<std::uint8_t>&
     if (!f)
         throw Domain::RelinkerException("Cannot open output file: " + path);
     f.write(reinterpret_cast<const char*>(data.data()), static_cast<std::streamsize>(data.size()));
+    f.close();
     if (!f)
         throw Domain::RelinkerException("Failed to write file: " + path);
 }
@@ -18,6 +19,7 @@ void FileWriter::Write(const std::string& path, const std::string& content) {
     if (!f)
         throw Domain::RelinkerException("Cannot open output file: " + path);
     f << content;
+    f.close();
     if (!f)
         throw Domain::RelinkerException("Failed to write file: " + path);
 }
diff --git a/core/relinker/io/tests/FileWriterTests.cpp b/core/relinker/io/tests/FileWriterTests.cpp
new file mode 100644
index 000000000..8edc710d5
--- /dev/null
+++ b/core/relinker/io/tests/FileWriterTests.cpp
@@ -0,0 +1,43 @@
+#include <io/FileWriter.hpp>
+#include <domain/Types.hpp>
+#include <iostream>
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+namespace {
+
+template<typename TValue>
+void requireWriteFailure(const TValue& data) {
+    Io::FileWriter writer;
+    writer.Write("/dev/null", data);
+    try {
+        writer.Write("/dev/full", data);
+    } catch (const Domain::RelinkerException& e) {
+        if (std::string(e.what()) != "Failed to write file: /dev/full")
+            throw std::runtime_error("Unexpected write failure: " + std::string(e.what()));
+        return;
+    }
+    throw std::runtime_error("Write to /dev/full reported success");
+}
+
+}
+
+int main(int argc, char* argv[]) {
+    try {
+        if (argc != 2) throw std::runtime_error("Expected binary or text");
+        const std::string mode = argv[1];
+        for (const std::size_t size : {std::size_t{3}, std::size_t{65536}}) {
+            if (mode == "binary")
+                requireWriteFailure(std::vector<std::uint8_t>(size, 0x41));
+            else if (mode == "text")
+                requireWriteFailure(std::string(size, 'A'));
+            else
+                throw std::runtime_error("Unknown test mode: " + mode);
+        }
+    } catch (const std::exception& e) {
+        std::cerr << e.what() << '\n';
+        return 1;
+    }
+    return 0;
+}