use memory polling (--disable-malloc-replacement) on Mac OS X

* I could not get malloc replacement via dlmalloc to work.
  This does not work like on Linux by overwriting weak malloc() functions.
  It should theoretically be possible to overwrite the default malloc zone
  but I could not properly debug this since I can only build for Mac OS
  via CI.
* memory polling seems to work though - test suite runs through
  and it includes memory limiting test cases.

3 files changed, 21 insertions, 16 deletions

diff --git a/README b/README
index 03f6902..53f4bd5 100644
--- a/README
+++ b/README
@@ -28,10 +28,11 @@ Others might work as well.
 
 Linux, FreeBSD, Windows (MinGW 32/64) ~~and
 [Haiku](https://www.haiku-os.org/) (gcc4)~~ are tested and supported.
+Mac OS X is built during Continuous Integration but is otherwise untested
+and packages also cannot be provided.
+(I am looking for a Mac OS X maintainer!)
 SciTECO compiles with both GCC and Clang.
-SciTECO should compile just fine on other UNIX-compatible platforms,
-like Mac OS X - however I cannot test it regularily and there is currently no
-Mac OS X maintainer.
+SciTECO should compile just fine on other UNIX-compatible platforms.
 However UNIX-compatibility is not strictly required:
 Since SciTECO primarily depends on [glib](https://developer.gnome.org/glib/) and
 some implementation of Curses, it should be easy to port to even more exotic platforms.
diff --git a/configure.ac b/configure.ac
index cca1cd3..2d272c0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -79,17 +79,14 @@ AC_CHECK_TOOL(AR, ar)
 # Whether $CC is Clang
 AM_CONDITIONAL(CLANG, [$CC --version | $GREP -i clang >/dev/null])
 
-# Check for Windows resource compiler and define
-# WIN32 conditional
+# Platform-specific tools and conditionals
 case $host in
 *-mingw*)
 	LT_LANG([Windows Resource])
-	AM_CONDITIONAL(WIN32, [true])
-	;;
-*)
-	AM_CONDITIONAL(WIN32, [false])
+	HOST_WIN32=yes
 	;;
 esac
+AM_CONDITIONAL(WIN32, [test x$HOST_WIN32 = xyes])
 
 # Changing the EXEEXT on emscripten ensures that we don't
 # need a special Makefile rule to generate Javascript files.
@@ -314,7 +311,6 @@ gtk)
 esac
 
 AM_CONDITIONAL(INTERFACE_GTK, [test x$INTERFACE = xgtk])
-AM_CONDITIONAL(GTK_FLOW_BOX_FALLBACK, [test x$GTK_FLOW_BOX_FALLBACK = xtrue])
 
 AC_ARG_WITH(teco-integer,
 	AS_HELP_STRING([--with-teco-integer=SIZE],
@@ -345,10 +341,10 @@ AC_ARG_ENABLE(malloc-replacement,
 	               [Replace the libc malloc() [default=check]]),
 	[malloc_replacement=$enableval], [malloc_replacement=check])
 if [[ $malloc_replacement = check ]]; then
-	# We currently do not support dlmalloc on Windows.
+	# We currently do not support dlmalloc on Windows and Mac OS.
 	case $host in
-	*-mingw*) malloc_replacement=no;;
-	*)        malloc_replacement=yes;;
+	*-*-darwin* | *-mingw*) malloc_replacement=no;;
+	*) malloc_replacement=yes;;
 	esac
 fi
 AM_CONDITIONAL(REPLACE_MALLOC, [test $malloc_replacement = yes])
diff --git a/src/memory.c b/src/memory.c
index 302939b..9846753 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -273,7 +273,7 @@
  * malloc_trim().
  * Malloc overriding can be disabled at compile time to aid in memory
  * debugging.
- * On Windows, we never even try to link in dlmalloc.
+ * On Windows and Mac OS, we never even try to link in dlmalloc.
  * If disabled, we try to directly measure memory consumption using
  * OS APIs.
  * Polling of the RSS takes place in a dedicated thread that is started
@@ -434,7 +434,15 @@ teco_memory_get_usage(void)
  *
  * FIXME: Benchmark whether polling in a thread really
  * improves performances as much as on Linux.
- * Is this even critical or can we link in dlmalloc?
+ * FIXME: There is no malloc_trim() natively on Mac OS - can
+ * we recover from OOMs?
+ * FIXME: We cannot simply overwrite weak malloc() functions
+ * like on Linux since this does not affect shared libraries
+ * unless $DYLD_FORCE_FLAT_NAMESPACE is set.
+ * It should be possible to change the default malloc zone, though.
+ * First experiments have been unsuccessful.
+ * But see https://github.com/gperftools/gperftools/blob/master/src/libc_override_osx.h
+ * https://chromium.googlesource.com/chromium/src/base/+/refs/heads/main/allocator/allocator_interception_mac.mm
  */
 static gsize
 teco_memory_get_usage(void)
@@ -444,7 +452,7 @@ teco_memory_get_usage(void)
 
 	if (G_UNLIKELY(task_info(mach_task_self(), MACH_TASK_BASIC_INFO,
 	                         (task_info_t)&info, &info_count) != KERN_SUCCESS))
-		return 0; // FIXME
+		return 0;
 
 	return info.resident_size;
 }