@@ -0,0 +1,36 @@
+name: micro-ROS fork Update Checker
+on:
+  workflow_dispatch:
+    inputs:
+      name:
+        description: "Manual trigger"
+  schedule:
+    - cron:  '0 4 * * *'
+
+jobs:
+    micro_ros_fork_update_check:
+        runs-on: ubuntu-latest
+        container: ubuntu:24.04
+        strategy:
+          fail-fast: false
+          matrix:
+            branches: [humble, jazzy, kilted, master]
+        steps:
+          - name: Check
+            id: check
+            shell: bash
+            run: |
+              apt update; apt install -y git
+              REPO=$(echo ${{ github.repository }} | awk '{split($0,a,"/"); print a[2]}')
+              git clone -b ${{ matrix.branches }} https://github.com/micro-ros/$REPO
+              cd $REPO
+              git remote add ros2 https://github.com/ros2/$REPO
+              git fetch ros2
+              git fetch origin
+              echo "::set-output name=merge_required::true"
+              CMP=$(git rev-list --left-right --count ros2/${{ matrix.branches }}...origin/${{ matrix.branches }} | awk '{print $1}')
+              if [ $CMP = "0" ]; then echo "::set-output name=merge_required::false"; fi
+
+          - name: Alert
+            if: ${{ steps.check.outputs.merge_required  == 'true' }}
+            run: exit 1
@@ -0,0 +1,6 @@
+{
+    "files.associations": {
+        "*.uml": "plantuml",
+        "*.in": "c"
+    }
+}
@@ -2,6 +2,12 @@ cmake_minimum_required(VERSION 3.20)
 
 project(rcutils)
 
+option(RCUTILS_NO_THREAD_SUPPORT "Disable thread support." OFF)
+option(RCUTILS_NO_FILESYSTEM "Disable filesystem usage." OFF)
+option(RCUTILS_AVOID_DYNAMIC_ALLOCATION "Disable dynamic allocations." OFF)
+option(RCUTILS_NO_64_ATOMIC "Enable alternative support for 64 bits atomic operations in platforms with no native support." OFF)
+option(RCUTILS_MICROROS "Flag for building micro-ROS." ON)
+
 include(CheckLibraryExists)
 
 find_package(ament_cmake REQUIRED)
@@ -17,7 +23,7 @@ if(UNIX AND NOT APPLE)
   endif()
 endif()
 
-if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+if(NOT RCUTILS_MICROROS AND (CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang"))
   # enables building a static library but later link it into a dynamic library
   add_compile_options(-fPIC)
 endif()
@@ -66,6 +72,7 @@ set(rcutils_sources
   src/time.c
   ${time_impl_c}
   src/uint8_array.c
+  $<$<BOOL:${RCUTILS_NO_64_ATOMIC}>:src/atomic_64bits.c>
 )
 set_source_files_properties(
   ${rcutils_sources}
@@ -76,6 +83,7 @@ add_library(
   ${rcutils_sources})
 target_include_directories(${PROJECT_NAME} PUBLIC
   "$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>"
+  "$<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>"
   "$<INSTALL_INTERFACE:include/${PROJECT_NAME}>")
 
 # Causes the visibility macros to use dllexport rather than dllimport,
@@ -87,10 +95,18 @@ if(BUILD_TESTING AND NOT RCUTILS_DISABLE_FAULT_INJECTION)
 endif()
 
 target_link_libraries(${PROJECT_NAME}
-  ${CMAKE_DL_LIBS}
   ament_cmake_ros_core::ament_ros_defaults
 )
 
+configure_file(
+    "${PROJECT_SOURCE_DIR}/include/rcutils/configuration_flags.h.in"
+    "${PROJECT_BINARY_DIR}/include/rcutils/configuration_flags.h"
+)
+
+if(NOT RCUTILS_NO_FILESYSTEM)
+  target_link_libraries(${PROJECT_NAME} ${CMAKE_DL_LIBS})
+endif()
+
 check_library_exists(atomic __atomic_load_8 "" HAVE_LIBATOMICS)
 
 if(HAVE_LIBATOMICS AND NOT WIN32 AND NOT APPLE)
@@ -162,20 +178,22 @@ if(BUILD_TESTING)
     TIMEOUT 10
   )
 
-  ament_add_gmock(test_logging_macros test/test_logging_macros.cpp)
-  target_link_libraries(test_logging_macros
-    ${PROJECT_NAME}
-    ament_cmake_ros_core::ament_ros_defaults
-  )
+  if(NOT RCUTILS_MICROROS)
+    ament_add_gmock(test_logging_macros test/test_logging_macros.cpp)
+    target_link_libraries(test_logging_macros
+      ${PROJECT_NAME}
+      ament_cmake_ros_core::ament_ros_defaults
+    )
 
-  add_executable(test_logging_macros_c test/test_logging_macros.c)
-  target_link_libraries(test_logging_macros_c
-    ${PROJECT_NAME}
-    ament_cmake_ros_core::ament_ros_defaults
-  )
-  ament_add_test(test_logging_macros_c
-    COMMAND "$<TARGET_FILE:test_logging_macros_c>"
-    GENERATE_RESULT_FOR_RETURN_CODE_ZERO)
+    add_executable(test_logging_macros_c test/test_logging_macros.c)
+    target_link_libraries(test_logging_macros_c
+      ${PROJECT_NAME}
+      ament_cmake_ros_core::ament_ros_defaults
+    )
+    ament_add_test(test_logging_macros_c
+      COMMAND "$<TARGET_FILE:test_logging_macros_c>"
+      GENERATE_RESULT_FOR_RETURN_CODE_ZERO)
+  endif()
 
   set(SKIP_MEMORY_TOOLS_TEST "")
   if(NOT memory_tools_is_available)
@@ -637,15 +655,17 @@ if(BUILD_TESTING)
     )
   endif()
 
-  ament_add_gtest(test_logging_enable_for
-    test/test_logging_enable_for.cpp
-  )
-  if(TARGET test_logging_enable_for)
-    target_link_libraries(test_logging_enable_for
-      ${PROJECT_NAME}
-      osrf_testing_tools_cpp::memory_tools
-      ament_cmake_ros_core::ament_ros_defaults
+  if(NOT RCUTILS_MICROROS)
+    ament_add_gtest(test_logging_enable_for
+      test/test_logging_enable_for.cpp
     )
+    if(TARGET test_logging_enable_for)
+      target_link_libraries(test_logging_enable_for
+        ${PROJECT_NAME}
+        osrf_testing_tools_cpp::memory_tools
+        ament_cmake_ros_core::ament_ros_defaults
+      )
+    endif()
   endif()
 
   ament_add_gtest(test_logging_console_output_handler
@@ -696,5 +716,5 @@ ament_export_dependencies(ament_cmake ament_cmake_ros_core)
 ament_package()
 
 install(
-  DIRECTORY include/
+  DIRECTORY include/ ${CMAKE_CURRENT_BINARY_DIR}/include/
   DESTINATION include/${PROJECT_NAME})
@@ -85,6 +85,21 @@ RCUTILS_WARN_UNUSED
 rcutils_allocator_t
 rcutils_get_zero_initialized_allocator(void);
 
+/// Set rcutils default allocators.
+/**
+ * <hr>
+ * Attribute          | Adherence
+ * ------------------ | -------------
+ * Allocates Memory   | No
+ * Thread-Safe        | Yes
+ * Uses Atomics       | No
+ * Lock-Free          | Yes
+ */
+RCUTILS_PUBLIC
+RCUTILS_WARN_UNUSED
+bool
+rcutils_set_default_allocator(rcutils_allocator_t * allocator);
+
 /// Return a properly initialized rcutils_allocator_t with default values.
 /**
  * This defaults to:
 
@@ -0,0 +1,19 @@
+
+#ifndef RCUTILS__CONFIGURATION_FLAGS_H_
+#define RCUTILS__CONFIGURATION_FLAGS_H_
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#cmakedefine RCUTILS_NO_FILESYSTEM
+#cmakedefine RCUTILS_AVOID_DYNAMIC_ALLOCATION
+#cmakedefine RCUTILS_NO_THREAD_SUPPORT
+#cmakedefine RCUTILS_MICROROS
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // RCUTILS__CONFIGURATION_FLAGS_H_
@@ -37,14 +37,19 @@ extern "C"
 #include "rcutils/testing/fault_injection.h"
 #include "rcutils/types/rcutils_ret.h"
 #include "rcutils/visibility_control.h"
+#include "rcutils/configuration_flags.h"
 
+#if !defined(RCUTILS_NO_FILESYSTEM)
 /// Write the given msg out to stderr, limiting the buffer size in the `fwrite`.
 /**
  * This ensures that there is an upper bound to a buffer overrun if `msg` is
  * non-null terminated.
  */
 #define RCUTILS_SAFE_FWRITE_TO_STDERR(msg) \
   do {fwrite(msg, sizeof(char), rcutils_strnlen(msg, 4096), stderr);} while (0)
+#else
+  #define RCUTILS_SAFE_FWRITE_TO_STDERR(msg)
+#endif
 
 /// Set the error message to stderr using a format string and format arguments.
 /**
@@ -55,6 +60,8 @@ extern "C"
  * \param[in] format_string The string to be used as the format of the error message.
  * \param[in] ... Arguments for the format string.
  */
+
+#if !defined(RCUTILS_AVOID_DYNAMIC_ALLOCATION)
 #define RCUTILS_SAFE_FWRITE_TO_STDERR_WITH_FORMAT_STRING(format_string, ...) \
   do { \
     char output_msg[RCUTILS_ERROR_MESSAGE_MAX_LENGTH]; \
@@ -66,7 +73,11 @@ extern "C"
       RCUTILS_SAFE_FWRITE_TO_STDERR(output_msg); \
     } \
   } while (0)
+#else
+#define RCUTILS_SAFE_FWRITE_TO_STDERR_WITH_FORMAT_STRING(format_string, ...)
+#endif
 
+#if !defined(RCUTILS_AVOID_DYNAMIC_ALLOCATION)
 /// The maximum length a formatted number is allowed to have.
 #define RCUTILS_ERROR_STATE_LINE_NUMBER_STR_MAX_LENGTH 20  // "18446744073709551615"
 
@@ -93,6 +104,13 @@ extern "C"
     RCUTILS_ERROR_STATE_LINE_NUMBER_STR_MAX_LENGTH - \
     RCUTILS_ERROR_FORMATTING_CHARACTERS - \
     1)
+#else
+#define RCUTILS_ERROR_STATE_LINE_NUMBER_STR_MAX_LENGTH 1
+#define RCUTILS_ERROR_FORMATTING_CHARACTERS 1
+#define RCUTILS_ERROR_MESSAGE_MAX_LENGTH 1
+#define RCUTILS_ERROR_STATE_MESSAGE_MAX_LENGTH 1
+#define RCUTILS_ERROR_STATE_FILE_MAX_LENGTH 1
+#endif  // RCUTILS_AVOID_DYNAMIC_ALLOCATION
 
 /// Struct wrapping a fixed-size c string used for returning the formatted error string.
 typedef struct rcutils_error_string_s
@@ -114,7 +132,7 @@ typedef struct rcutils_error_state_s
 } rcutils_error_state_t;
 
 // make sure our math is right...
-#if __STDC_VERSION__ >= 201112L
+#if __STDC_VERSION__ >= 201112L && !defined(RCUTILS_AVOID_DYNAMIC_ALLOCATION)
 static_assert(
   sizeof(rcutils_error_string_t) == (
     RCUTILS_ERROR_STATE_MESSAGE_MAX_LENGTH +
@@ -226,8 +244,12 @@ rcutils_set_error_state(const char * error_string, const char * file, size_t lin
  *
  * \param[in] msg The error message to be set.
  */
+#ifdef RCUTILS_AVOID_DYNAMIC_ALLOCATION
+  #define RCUTILS_SET_ERROR_MSG(msg)
+#else
 #define RCUTILS_SET_ERROR_MSG(msg) \
   do {rcutils_set_error_state(msg, __FILE__, __LINE__);} while (0)
+#endif  // RCUTILS_AVOID_DYNAMIC_ALLOCATION
 
 /// Set the error message using a format string and format arguments.
 /**
@@ -238,6 +260,9 @@ rcutils_set_error_state(const char * error_string, const char * file, size_t lin
  * \param[in] format_string The string to be used as the format of the error message.
  * \param[in] ... Arguments for the format string.
  */
+#ifdef RCUTILS_AVOID_DYNAMIC_ALLOCATION
+  #define RCUTILS_SET_ERROR_MSG_WITH_FORMAT_STRING(format_string, ...)
+#else
 #define RCUTILS_SET_ERROR_MSG_WITH_FORMAT_STRING(format_string, ...) \
   do { \
     char output_msg[RCUTILS_ERROR_MESSAGE_MAX_LENGTH]; \
@@ -249,6 +274,8 @@ rcutils_set_error_state(const char * error_string, const char * file, size_t lin
       RCUTILS_SET_ERROR_MSG(output_msg); \
     } \
   } while (0)
+#endif  // RCUTILS_AVOID_DYNAMIC_ALLOCATION
+
 
 /// Indicate that the function intends to set an error message and return an error value.
 /**
 
@@ -41,7 +41,7 @@ extern "C"
  * \def RCUTILS_DEFAULT_LOGGER_DEFAULT_LEVEL
  * \brief The default severity level of the default logger.
  */
-#define RCUTILS_DEFAULT_LOGGER_DEFAULT_LEVEL RCUTILS_LOG_SEVERITY_INFO
+#define RCUTILS_DEFAULT_LOGGER_DEFAULT_LEVEL RCUTILS_LOG_SEVERITY_UNSET
 
 /// The flag if the logging system has been initialized.
 RCUTILS_PUBLIC
 
@@ -39,7 +39,7 @@ extern "C"
  * Use RCUTILS_LOG_MIN_SEVERITY_NONE to compile out all macros.
  */
 #ifndef RCUTILS_LOG_MIN_SEVERITY
-#define RCUTILS_LOG_MIN_SEVERITY RCUTILS_LOG_MIN_SEVERITY_DEBUG
+#define RCUTILS_LOG_MIN_SEVERITY RCUTILS_LOG_MIN_SEVERITY_NONE
 #endif
 
 /**
 
@@ -22,6 +22,8 @@ extern "C"
 {
 #endif
 
+#include "rcutils/configuration_flags.h"
+
 #ifndef _MSC_VER
 /// A macro to make the compiler warn when the return value of a function is not used.
 #define RCUTILS_WARN_UNUSED __attribute__((warn_unused_result))
@@ -32,7 +34,9 @@ extern "C"
 
 /// \cond Doxygen_Suppress
 // This block either sets RCUTILS_THREAD_LOCAL or RCUTILS_THREAD_LOCAL_PTHREAD.
-#if defined _WIN32 || defined __CYGWIN__
+#if defined(RCUTILS_NO_THREAD_SUPPORT)
+    #define RCUTILS_THREAD_LOCAL
+#elif defined _WIN32 || defined __CYGWIN__
 // Windows or Cygwin
   #define RCUTILS_THREAD_LOCAL __declspec(thread)
 #elif defined __APPLE__