build: fix cross-platform build support and add macOS CI

.github/workflows/ci.yml

@@ -195,6 +195,30 @@ jobs:
         run: |
           docker run --rm --volume $(pwd):/note-c/ --workdir /note-c/ --entrypoint ./scripts/run_cppcheck.sh ghcr.io/blues/note_c_ci:latest
 
+  run_macos_unit_tests:
+    runs-on: macos-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Configure
+        run: cmake -B build -DNOTE_C_BUILD_TESTS=ON
+
+      - name: Build
+        run: cmake --build build --parallel $(sysctl -n hw.ncpu)
+
+      # NOTE: ctest is not run here. A subset of tests that rely on FFF
+      # symbol interposition fail on macOS due to two-level namespace
+      # linking. The build step above verifies that all sources and tests
+      # compile and link successfully.
+      #
+      # Even with -Wl,-flat_namespace, intra-library calls within the
+      # note_c dylib are resolved at link time as direct calls, so FFF
+      # fakes in the test executable cannot interpose them. Fully fixing
+      # this would require linking note-c as a static library for tests
+      # or using a different mocking approach on macOS.
+
   publish_ci_image:
     runs-on: ubuntu-latest
     # Make sure unit tests unit tests passed before publishing.

CMakeLists.txt

@@ -27,26 +27,48 @@ option(NOTE_C_SINGLE_PRECISION "Use single precision for JSON floating point num
 option(NOTE_C_HEARTBEAT_CALLBACK "Enable heartbeat callback support." OFF)
 
 set(NOTE_C_SRC_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+
+# Detect whether the system already provides strlcpy/strlcat (macOS, *BSD).
+# When present, we skip the bundled implementations in n_str.c and define
+# guards so note.h doesn't redeclare them (which collides with the platform's
+# fortified macros).
+include(CheckSymbolExists)
+check_symbol_exists(strlcpy "string.h" HAVE_STRLCPY)
+check_symbol_exists(strlcat "string.h" HAVE_STRLCAT)
+
 add_library(note_c SHARED)
-target_sources(
-    note_c
-    PRIVATE
-        ${NOTE_C_SRC_DIR}/n_atof.c
-        ${NOTE_C_SRC_DIR}/n_b64.c
-        ${NOTE_C_SRC_DIR}/n_cjson.c
-        ${NOTE_C_SRC_DIR}/n_cjson_helpers.c
-        ${NOTE_C_SRC_DIR}/n_cobs.c
-        ${NOTE_C_SRC_DIR}/n_const.c
-        ${NOTE_C_SRC_DIR}/n_ftoa.c
-        ${NOTE_C_SRC_DIR}/n_helpers.c
-        ${NOTE_C_SRC_DIR}/n_hooks.c
-        ${NOTE_C_SRC_DIR}/n_i2c.c
-        ${NOTE_C_SRC_DIR}/n_md5.c
-        ${NOTE_C_SRC_DIR}/n_printf.c
-        ${NOTE_C_SRC_DIR}/n_request.c
-        ${NOTE_C_SRC_DIR}/n_serial.c
-        ${NOTE_C_SRC_DIR}/n_str.c
+
+set(NOTE_C_SOURCES
+    ${NOTE_C_SRC_DIR}/n_atof.c
+    ${NOTE_C_SRC_DIR}/n_b64.c
+    ${NOTE_C_SRC_DIR}/n_cjson.c
+    ${NOTE_C_SRC_DIR}/n_cjson_helpers.c
+    ${NOTE_C_SRC_DIR}/n_cobs.c
+    ${NOTE_C_SRC_DIR}/n_const.c
+    ${NOTE_C_SRC_DIR}/n_ftoa.c
+    ${NOTE_C_SRC_DIR}/n_helpers.c
+    ${NOTE_C_SRC_DIR}/n_hooks.c
+    ${NOTE_C_SRC_DIR}/n_i2c.c
+    ${NOTE_C_SRC_DIR}/n_md5.c
+    ${NOTE_C_SRC_DIR}/n_printf.c
+    ${NOTE_C_SRC_DIR}/n_request.c
+    ${NOTE_C_SRC_DIR}/n_serial.c
 )
+# n_str.c provides weak strlcpy/strlcat. On systems that already have them
+# the file won't compile because the platform headers define these as
+# fortified macros that conflict with the function definitions.
+if(NOT HAVE_STRLCPY OR NOT HAVE_STRLCAT)
+    list(APPEND NOTE_C_SOURCES ${NOTE_C_SRC_DIR}/n_str.c)
+endif()
+target_sources(note_c PRIVATE ${NOTE_C_SOURCES})
+
+if(HAVE_STRLCPY)
+    target_compile_definitions(note_c PUBLIC HAVE_STRLCPY)
+endif()
+if(HAVE_STRLCAT)
+    target_compile_definitions(note_c PUBLIC HAVE_STRLCAT)
+endif()
+
 target_compile_options(
     note_c
     PRIVATE
@@ -56,28 +78,35 @@ target_compile_options(
         -Werror
         -Og
         -ggdb
-    PUBLIC
-        -m32
-        -mfpmath=sse
-        -msse2
 )
+# The Linux CI runs tests in 32-bit mode. These flags are x86-specific and
+# unavailable on Apple toolchains or non-x86 architectures.
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|i[3-6]86")
+    target_compile_options(note_c PUBLIC -m32 -mfpmath=sse -msse2)
+endif()
 target_include_directories(
     note_c
     PUBLIC ${NOTE_C_SRC_DIR}
 )
-target_link_directories(
-    note_c
-    PUBLIC
-        /lib32
-        /usr/lib32
-        /usr/lib/gcc/x86_64-linux-gnu/12/32
-)
-target_link_options(
-    note_c
-    PUBLIC
-        -m32
-        -Wl,-melf_i386
-)
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|i[3-6]86")
+    target_link_directories(
+        note_c
+        PUBLIC
+            /lib32
+            /usr/lib32
+            /usr/lib/gcc/x86_64-linux-gnu/12/32
+    )
+    target_link_options(
+        note_c
+        PUBLIC
+            -m32
+            -Wl,-melf_i386
+    )
+endif()
+if(APPLE)
+    # Use flat namespace so test fakes (FFF) can interpose library symbols
+    target_link_options(note_c PRIVATE -Wl,-flat_namespace)
+endif()
 
 if(NOTE_C_LOW_MEM)
     target_compile_definitions(

n_helpers.c

@@ -2403,7 +2403,7 @@ uint32_t NoteMemAvailable(void)
     objHeader *lastObj = NULL;
     static long int maxsize = 35000;
     for (long int i=maxsize; i>=(long int)sizeof(objHeader); i=i-sizeof(objHeader)) {
-        for (long int j=0;; j++) {
+        for (;;) {
             objHeader *thisObj;
             thisObj = (objHeader *) _Malloc(i);
             if (thisObj == NULL) {
@@ -2416,16 +2416,8 @@ uint32_t NoteMemAvailable(void)
     }
 
     // Free the objects backwards
-    long int lastLength = 0;
-    long int lastLengthCount = 0;
     uint32_t total = 0;
     while (lastObj != NULL) {
-        if (lastObj->length != lastLength) {
-            lastLength = lastObj->length;
-            lastLengthCount = 1;
-        } else {
-            lastLengthCount++;
-        }
         objHeader *thisObj = lastObj;
         lastObj = lastObj->prev;
         total += thisObj->length;

n_ua.c

@@ -92,9 +92,9 @@ __attribute__((weak)) void NoteUserAgentUpdate(J *ua)
 */
 /**************************************************************************/
 #if defined(_MSC_VER)
-J *NoteUserAgent()
+J *NoteUserAgent(void)
 #else
-__attribute__((weak)) J *NoteUserAgent()
+__attribute__((weak)) J *NoteUserAgent(void)
 #endif
 {
 

scripts/check_libc_dependencies.sh

@@ -30,6 +30,8 @@ LIBC_WHITELIST=(
     "strchr"
     "strcmp"
     "strlen"
+    "strlcpy"   # bundled in n_str.c; also available in glibc 2.38+
+    "strlcat"   # bundled in n_str.c; also available in glibc 2.38+
     "strncmp"
     "strstr"
     "strtol"    # required by atoi in NoteGenEnvInt

test/CMakeLists.txt

@@ -16,8 +16,8 @@ FetchContent_Declare(
 )
 FetchContent_MakeAvailable(Catch2)
 
-# Add specific build flags for Catch2
-if(TARGET Catch2)
+# Add specific build flags for Catch2 (32-bit mode for Linux x86 CI only)
+if(TARGET Catch2 AND CMAKE_SYSTEM_NAME STREQUAL "Linux" AND CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|i[3-6]86")
     target_compile_options(Catch2
         PUBLIC
             -m32
@@ -47,6 +47,10 @@ macro(add_test TEST_NAME)
         PRIVATE -Og
         PRIVATE -ggdb
     )
+    if(APPLE)
+        # Allow test fakes (FFF) to interpose symbols from the note_c dylib
+        target_link_options(${TEST_NAME} PRIVATE -Wl,-flat_namespace)
+    endif()
 
     list(APPEND TEST_TARGETS ${TEST_NAME})
 
@@ -239,8 +243,12 @@ if(NOTE_C_COVERAGE)
     # ourselves, so we don't care about coverage for them.
     set(
         EXCLUDE_FROM_COVERAGE
-        "n_atof.c;n_b64.c;n_cjson.c;n_ftoa.c;n_md5.c;n_str.c"
+        "n_atof.c;n_b64.c;n_cjson.c;n_ftoa.c;n_md5.c"
     )
+    # n_str.c is only compiled when the system lacks strlcpy/strlcat.
+    if(NOT HAVE_STRLCPY OR NOT HAVE_STRLCAT)
+        list(APPEND EXCLUDE_FROM_COVERAGE "n_str.c")
+    endif()
     foreach(EXCLUDE_FILE ${EXCLUDE_FROM_COVERAGE})
         string(APPEND LCOV_EXCLUDE "--exclude '*/${EXCLUDE_FILE}' ")
     endforeach()