build: add Darwin/macOS support

Adds platform handling for macOS:
 - Guard GCC-only -Wno-stringop-truncation behind a compiler check and
   silence Clang warnings promoted to errors by -Werror.  Probe each
   Clang flag with check_c_compiler_flag() and only apply it when the
   compiler is Clang, so older Clang or a GCC build on macOS still works.
 - Wire up empty RT/SOCKET libraries and test libraries for Darwin.
 - Use the macOS pthread_setname_np signature (current thread only) and
   skip pthread_condattr_setclock(CLOCK_MONOTONIC), which is unavailable.
   On macOS pthread_cond_timedwait() always uses CLOCK_REALTIME, so the
   deadline timespec is built from CLOCK_REALTIME there as well to avoid
   premature timeouts or excessively long waits.
 - In dlt-daemon.c, scope the Linux-only fifo_size local behind
   __linux__ to silence an unused-variable warning on Darwin, and
   replace the broken "#elif __QNX__" with "#elif defined(__QNX__)"
   so the branch is selected by macro presence rather than its value.

Signed-off-by: Felipe Kellermann <felipek@me.com>

Author: felipek

CMakeLists.txt

@@ -261,9 +261,34 @@ add_compile_options(
     -Wcast-qual
     -Wno-system-headers
     -Wno-unused-function
-    -Wno-stringop-truncation
+    $<$<C_COMPILER_ID:GNU>:-Wno-stringop-truncation>
 )
 
+if(APPLE AND CMAKE_C_COMPILER_ID MATCHES "Clang")
+    # Clang on macOS is stricter than GCC on some warnings that are promoted to
+    # errors by -Werror above.  Suppress the ones triggered by current code until
+    # the upstream sources are fixed.  Probe each flag so older Clang versions
+    # (or a non-Clang compiler explicitly selected on macOS) don't fail the
+    # build with "unknown warning option" turned into an error.
+    include(CheckCCompilerFlag)
+    foreach(_dlt_clang_flag
+            -Wno-sign-conversion
+            -Wno-implicit-int-conversion
+            -Wno-shorten-64-to-32
+            -Wno-strict-prototypes
+            -Wno-static-in-inline
+            -Wno-gnu-folding-constant
+            -Wno-gnu-zero-variadic-macro-arguments
+            -Wno-variadic-macro-arguments-omitted
+            -Wno-deprecated-declarations)
+        string(MAKE_C_IDENTIFIER "HAVE_CFLAG_${_dlt_clang_flag}" _dlt_have_var)
+        check_c_compiler_flag("${_dlt_clang_flag}" ${_dlt_have_var})
+        if(${_dlt_have_var})
+            add_compile_options(${_dlt_clang_flag})
+        endif()
+    endforeach()
+endif()
+
 if(WITH_DOC STREQUAL "OFF")
     set(PACKAGE_DOC "#")
 else()

src/daemon/CMakeLists.txt

@@ -50,6 +50,9 @@ endif()
 if("${CMAKE_SYSTEM_NAME}" MATCHES "Linux|CYGWIN|MSYS")
     set(RT_LIBRARY rt)
     set(SOCKET_LIBRARY "")
+elseif("${CMAKE_SYSTEM_NAME}" MATCHES "Darwin")
+    set(RT_LIBRARY "")
+    set(SOCKET_LIBRARY "")
 else()
     set(RT_LIBRARY "")
     set(SOCKET_LIBRARY socket)

src/daemon/dlt-daemon.c

@@ -1958,7 +1958,9 @@ static int dlt_daemon_init_fifo(DltDaemonLocal *daemon_local)
 {
     int ret;
     int fd = -1;
+#ifdef __linux__
     int fifo_size;
+#endif
 
     /* open named pipe(FIFO) to receive DLT messages from users */
     umask(0);
@@ -5703,7 +5705,7 @@ int create_timer_fd(DltDaemonLocal *daemon_local,
                      timer_name, strerror(errno));
             local_fd = DLT_FD_INIT;
         }
-#elif __QNX__
+#elif defined(__QNX__)
         /*
          * Since timerfd is not valid in QNX, new threads are introduced
          * to manage timers and communicate with main thread when timer expires.

src/lib/CMakeLists.txt

@@ -34,6 +34,9 @@ add_library(dlt ${dlt_LIB_SRCS})
 if("${CMAKE_SYSTEM_NAME}" MATCHES "Linux|CYGWIN|MSYS")
     set(RT_LIBRARY rt)
     set(SOCKET_LIBRARY "")
+elseif("${CMAKE_SYSTEM_NAME}" MATCHES "Darwin")
+    set(RT_LIBRARY "")
+    set(SOCKET_LIBRARY "")
 else()
     set(RT_LIBRARY "")
     set(SOCKET_LIBRARY socket)

src/lib/dlt_user.c

@@ -3949,7 +3949,11 @@ void *dlt_user_trace_network_segmented_thread(void *unused)
     /* Unused on purpose. */
     (void)unused;
 #ifdef DLT_USE_PTHREAD_SETNAME_NP
+#ifdef __APPLE__
+    if (pthread_setname_np("dlt_segmented"))
+#else
     if (pthread_setname_np(dlt_user.dlt_segmented_nwt_handle, "dlt_segmented"))
+#endif
         dlt_log(LOG_WARNING, "Failed to rename segmented thread!\n");
 #elif linux
     if (prctl(PR_SET_NAME, "dlt_segmented", 0, 0, 0) < 0)
@@ -4835,7 +4839,11 @@ void *dlt_user_housekeeperthread_function(void *ptr)
 #endif
 
 #ifdef DLT_USE_PTHREAD_SETNAME_NP
+#ifdef __APPLE__
+    if (pthread_setname_np("dlt_housekeeper"))
+#else
     if (pthread_setname_np(dlt_housekeeperthread_handle, "dlt_housekeeper"))
+#endif
         dlt_log(LOG_WARNING, "Failed to rename housekeeper thread!\n");
 #elif linux
     if (prctl(PR_SET_NAME, "dlt_housekeeper", 0, 0, 0) < 0)
@@ -7349,6 +7357,18 @@ void dlt_user_test_corrupt_message_size(int enable, int16_t size)
 #endif
 
 
+/*
+ * Clock used to derive deadlines for pthread_cond_timedwait().  On macOS that
+ * function always uses CLOCK_REALTIME (pthread_condattr_setclock() is not
+ * available), so the deadline has to be built from CLOCK_REALTIME or the
+ * timed wait can return immediately or block far longer than intended.
+ */
+#ifdef __APPLE__
+#  define DLT_COND_TIMEDWAIT_CLOCK CLOCK_REALTIME
+#else
+#  define DLT_COND_TIMEDWAIT_CLOCK CLOCK_MONOTONIC
+#endif
+
 int dlt_start_threads()
 {
     struct timespec time_to_wait, single_wait;
@@ -7357,12 +7377,17 @@ int dlt_start_threads()
     atomic_bool dlt_housekeeper_running = false;
 
     /*
-    * Configure the condition varibale to use CLOCK_MONOTONIC.
-    * This makes sure we're protected against changes in the system clock
+    * Configure the condition variable to use CLOCK_MONOTONIC.
+    * This makes sure we're protected against changes in the system clock.
+    * On macOS, pthread_condattr_setclock() is unavailable and
+    * pthread_cond_timedwait() always uses CLOCK_REALTIME, so the deadline
+    * has to be computed from CLOCK_REALTIME there (see DLT_TIMER_CLOCK).
      */
     pthread_condattr_t attr;
     pthread_condattr_init(&attr);
+#ifndef __APPLE__
     pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
+#endif
     pthread_cond_init(&dlt_housekeeper_running_cond, &attr);
 
     if (pthread_create(&(dlt_housekeeperthread_handle),
@@ -7373,7 +7398,7 @@ int dlt_start_threads()
         return -1;
     }
 
-    clock_gettime(CLOCK_MONOTONIC, &now);
+    clock_gettime(DLT_COND_TIMEDWAIT_CLOCK, &now);
     /* wait at most 10s */
     time_to_wait.tv_sec = now.tv_sec + 10;
     time_to_wait.tv_nsec = now.tv_nsec;
@@ -7399,7 +7424,7 @@ int dlt_start_threads()
         * this makes sure we don't block too long
         * even if we missed the signal
          */
-        clock_gettime(CLOCK_MONOTONIC, &now);
+        clock_gettime(DLT_COND_TIMEDWAIT_CLOCK, &now);
         if (now.tv_nsec >= 500000000) {
             single_wait.tv_sec = now.tv_sec + 1;
             single_wait.tv_nsec = now.tv_nsec - 500000000;

tests/CMakeLists.txt

@@ -27,6 +27,8 @@ if("${CMAKE_SYSTEM_NAME}" MATCHES "Linux|CYGWIN")
     set(LIBRARIES "")
 elseif("${CMAKE_SYSTEM_NAME}" MATCHES "QNX")
     set(LIBRARIES regex)
+elseif("${CMAKE_SYSTEM_NAME}" MATCHES "Darwin")
+    set(LIBRARIES "")
 else()
     set(LIBRARIES socket)
 endif()