Added atomic support

CHANGELOG.md

@@ -5,6 +5,15 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.2.3] - 2026-05-19
+
+### Added
+- Atomic file saving: Implemented a safe save mechanism using temporary `-journal` files to prevent data loss or corruption during writes.
+- Explicit `flush()` and `close()` checks for improved reliability during file operations.
+
+### Changed
+- Incremented version to 0.2.3.
+
 ## [0.2.2] - 2026-05-15
 
 ### Added

README.md

@@ -2,11 +2,12 @@
 
 [![CI](https://github.com/FFMG/TinyJSON/actions/workflows/c-cpp.yml/badge.svg)](https://github.com/FFMG/TinyJSON/actions/workflows/c-cpp.yml)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](LICENSE)
-[![Version](https://img.shields.io/badge/version-0.2.2-blue.svg)](src/TinyJSON.h)
+[![Version](https://img.shields.io/badge/version-0.2.3-blue.svg)](src/TinyJSON.h)
 
 A lightweight and lightning-fast C++ JSON & JSON5 parser designed for high performance and minimal footprint.
 
 * Zero-dependency: Easy to integrate into any C++ project.
+* Atomic file saving: Guarantees data integrity by using a temporary file before overwriting.
 * Minimal memory overhead: Ideal for resource-constrained environments.
 * High-performance parsing: Benchmarked for speed against other leading parsers.
 * Simple API: Intuitive and easy to use.
@@ -129,8 +130,8 @@ The version is set in the `TinyJSON.h` file.
 ```cpp
 static const short TJ_VERSION_MAJOR = 0;
 static const short TJ_VERSION_MINOR = 2;
-static const short TJ_VERSION_PATCH = 0;
-static const char TJ_VERSION_STRING[] = "0.2.0";
+static const short TJ_VERSION_PATCH = 3;
+static const char TJ_VERSION_STRING[] = "0.2.3";
 ```
 
 ## Options

src/TinyJSON.cpp

@@ -28,6 +28,7 @@
 #include <fstream>
 #include <iostream>
 #include <cctype>
+#include <cstdio>
 
 static constexpr short TJ_MAX_NUMBER_OF_DIGGITS = 19;
 static constexpr short TJ_DEFAULT_STRING_READ_SIZE = 10;
@@ -4188,11 +4189,21 @@ namespace TinyJSON
       return false;
     }
 
-    //  try and optn the file...
-    std::ofstream outFile(file_path, std::ios::out | std::ios::binary);
+    // Allocate temporary file path
+    auto file_path_length = TJHelper::string_length(file_path);
+    auto journal_suffix = TJCHARPREFIX("-journal");
+    auto journal_length = TJHelper::string_length(journal_suffix);
+    TJCHAR* tmp_file_path = new TJCHAR[file_path_length + journal_length + 1];
+    TJHelper::copy_string(file_path, tmp_file_path, file_path_length);
+    TJHelper::copy_string(journal_suffix, tmp_file_path + file_path_length, journal_length);
+    tmp_file_path[file_path_length + journal_length] = TJ_NULL_TERMINATOR;
+
+    //  try and open the temporary file...
+    std::ofstream outFile((const char*)tmp_file_path, std::ios::out | std::ios::binary);
     if (!outFile)
     {
       write_result.assign_exception_message("Unable to open file for writing.");
+      delete[] tmp_file_path;
       write_result.throw_if_exception();
       return false;
     }
@@ -4204,6 +4215,7 @@ namespace TinyJSON
       if (!outFile)
       {
         write_result.assign_exception_message("Unable to write UTF-8 BOM.");
+        delete[] tmp_file_path;
         write_result.throw_if_exception();
         return false;
       }
@@ -4215,6 +4227,16 @@ namespace TinyJSON
     if (!outFile)
     {
       write_result.assign_exception_message("Unable to write to file.");
+      delete[] tmp_file_path;
+      write_result.throw_if_exception();
+      return false;
+    }
+
+    outFile.flush();
+    if (!outFile)
+    {
+      write_result.assign_exception_message("Unable to flush the file to disk.");
+      delete[] tmp_file_path;
       write_result.throw_if_exception();
       return false;
     }
@@ -4224,9 +4246,22 @@ namespace TinyJSON
     if (!outFile)
     {
       write_result.assign_exception_message("Unable to close the file.");
+      delete[] tmp_file_path;
       write_result.throw_if_exception();
       return false;
     }
+
+    // Atomic replace
+    std::remove((const char*)file_path);
+    if (std::rename((const char*)tmp_file_path, (const char*)file_path) != 0)
+    {
+      write_result.assign_exception_message("Unable to atomically rename the temporary file to the target file path.");
+      delete[] tmp_file_path;
+      write_result.throw_if_exception();
+      return false;
+    }
+
+    delete[] tmp_file_path;
     return true;
   }
 

src/TinyJSON.h

@@ -44,10 +44,11 @@
 // v0.2.0 - Breaking change: get_* methods no longer take throw parameters, use parse_options::strict instead.
 // v0.2.1 - added remove_at to TJValueArray.
 // v0.2.2 - added support for Json5 https://github.com/json5/
+// v0.2.3 - added atomic file saving
 static const short TJ_VERSION_MAJOR = 0;
 static const short TJ_VERSION_MINOR = 2;
-static const short TJ_VERSION_PATCH = 2;
-static const char TJ_VERSION_STRING[] = "0.2.2";
+static const short TJ_VERSION_PATCH = 3;
+static const char TJ_VERSION_STRING[] = "0.2.3";
 
 #ifndef TJ_USE_CHAR
 #  define TJ_USE_CHAR 1

tests/testtinyjsonversion.cpp

@@ -14,9 +14,9 @@ TEST(TestVersion, CheckVersionMinor) {
 }
 
 TEST(TestVersion, CheckVersionPatch) {
-  ASSERT_EQ(2, TJ_VERSION_PATCH);
+  ASSERT_EQ(3, TJ_VERSION_PATCH);
 }
 
 TEST(TestVersion, CheckVersionString) {
-  ASSERT_STREQ("0.2.2", TJ_VERSION_STRING);
+  ASSERT_STREQ("0.2.3", TJ_VERSION_STRING);
 }