try writeStringSafe as solution to save issues

Author: Cvolton

loader/include/Geode/utils/file.hpp

@@ -49,6 +49,7 @@ namespace geode::utils::file {
     }
 
     GEODE_DLL Result<> writeString(std::filesystem::path const& path, std::string const& data);
+    GEODE_DLL Result<> writeStringSafe(std::filesystem::path const& path, std::string const& data);
     GEODE_DLL Result<> writeBinary(std::filesystem::path const& path, ByteVector const& data);
 
     template <class T>

loader/src/loader/ModImpl.cpp

@@ -218,11 +218,11 @@ Result<> Mod::Impl::saveData() {
     // saveData is expected to be synchronous, and always called from GD thread
     ModStateEvent(m_self, ModEventType::DataSaved).post();
 
-    auto res = utils::file::writeString(m_saveDirPath / "settings.json", json.dump());
+    auto res = utils::file::writeStringSafe(m_saveDirPath / "settings.json", json.dump());
     if (!res) {
         log::error("Unable to save settings: {}", res.unwrapErr());
     }
-    auto res2 = utils::file::writeString(m_saveDirPath / "saved.json", m_saved.dump());
+    auto res2 = utils::file::writeStringSafe(m_saveDirPath / "saved.json", m_saved.dump());
     if (!res2) {
         log::error("Unable to save values: {}", res2.unwrapErr());
     }

loader/src/utils/file.cpp

@@ -81,7 +81,43 @@ Result<> utils::file::writeString(std::filesystem::path const& path, std::string
     }
 
     file << data;
+    if (file.fail()) {
+        file.close();
+        return Err("Failed to write to file");
+    }
+
     file.close();
+
+    return Ok();
+}
+
+Result<> utils::file::writeStringSafe(std::filesystem::path const& path, std::string const& data) {
+    std::error_code ec;
+
+    auto tmpPath = path;
+    tmpPath += ".tmp";
+
+    auto res = utils::file::writeString(tmpPath, data);
+    if (!res) {
+        if (std::filesystem::exists(tmpPath, ec)) {
+            std::filesystem::remove(tmpPath, ec);
+        }
+        return res;
+    }
+
+    if (std::filesystem::exists(path, ec)) {
+        std::filesystem::remove(path, ec);
+    }
+
+    if (ec) {
+        return Err("Unable to remove old file: " + ec.message());
+    }
+
+    std::filesystem::rename(tmpPath, path, ec);
+    if (ec) {
+        return Err("Unable to rename temporary file: " + ec.message());
+    }
+
     return Ok();
 }