MacOSX legacy (#1138)

* Branched v4.2
Added workaround for Mac OS X < 10.12.0
(Only tested on 10.11.6, lower versions may need more workaround)

* Added *.dSYM to .gitignore

* Added comments for the macosx detection in Makefile

* Fixed indentation, formatting and missing newline at eof

* Moved includes inside include guard

Co-authored-by: elder-n00b <elder-n00b@yandex.com>

.gitignore

@@ -1,2 +1,3 @@
 *.o
+*.dSYM
 nnn

Makefile

@@ -153,11 +153,26 @@ LOGO64X64 = misc/logo/logo-64x64.png
 GITSTATUS = patches/gitstatus
 NAMEFIRST = patches/namefirst
 
+# test if we are on Mac OS X and get X.Y.Z OS version with system binary /usr/bin/sw_vers
+MACOS_VERSION := $(strip $(shell command -v sw_vers >/dev/null && [ "`sw_vers -productName`" = "Mac OS X" ] && sw_vers -productVersion))
+# if Mac OS X detected, test if its version is below 10.12.0 relying on "sort -c" returning "disorder" message if the input is not sorted
+ifneq ($(MACOS_VERSION),)
+	MACOS_BELOW_1012 := $(if $(strip $(shell printf '10.12.0\n%s' "$(MACOS_VERSION)" | sort -ct. -k1,1n -k2,2n -k3,3n 2>&1)),1)
+endif
+# if Mac OS X version is below 10.12.0, compile in the replacement clock_gettime and define MACOS_BELOW_1012 so that it's included in nnn.c
+ifneq ($(MACOS_BELOW_1012),)
+	GETTIME_C = misc/macos-legacy/mach_gettime.c
+	GETTIME_H = misc/macos-legacy/mach_gettime.h
+	SRC += $(GETTIME_C)
+	HEADERS += $(GETTIME_H)
+	CPPFLAGS += -DMACOS_BELOW_1012
+endif
+
 all: $(BIN)
 
 $(BIN): $(SRC) $(HEADERS)
 	@$(MAKE) --silent prepatch
-	$(CC) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) -o $@ $< $(LDLIBS)
+	$(CC) $(CPPFLAGS) $(CFLAGS) $(LDFLAGS) -o $@ $(GETTIME_C) $< $(LDLIBS)
 	@$(MAKE) --silent postpatch
 
 # targets for backwards compatibility

misc/macos-legacy/mach_gettime.c

@@ -0,0 +1,42 @@
+#include "mach_gettime.h"
+#include <mach/mach_time.h>
+
+#define MT_NANO (+1.0E-9)
+#define MT_GIGA UINT64_C(1000000000)
+
+// TODO create a list of timers,
+static double mt_timebase = 0.0;
+static uint64_t mt_timestart = 0;
+
+int clock_gettime(clockid_t clk_id, struct timespec *tp)
+{
+	kern_return_t retval = KERN_SUCCESS;
+
+	if (clk_id == TIMER_ABSTIME) {
+		if (!mt_timestart) { // only one timer, initialized on the first call to the TIMER
+			mach_timebase_info_data_t tb;
+			mach_timebase_info(&tb);
+			mt_timebase = tb.numer;
+			mt_timebase /= tb.denom;
+			mt_timestart = mach_absolute_time();
+		}
+
+		double diff = (mach_absolute_time() - mt_timestart) * mt_timebase;
+		tp->tv_sec = diff * MT_NANO;
+		tp->tv_nsec = diff - (tp->tv_sec * MT_GIGA);
+	} else { // other clk_ids are mapped to the coresponding mach clock_service
+		clock_serv_t cclock;
+		mach_timespec_t mts;
+
+		host_get_clock_service(mach_host_self(), clk_id, &cclock);
+		retval = clock_get_time(cclock, &mts);
+		mach_port_deallocate(mach_task_self(), cclock);
+
+		tp->tv_sec = mts.tv_sec;
+		tp->tv_nsec = mts.tv_nsec;
+	}
+
+	return retval;
+}
+
+/*  Copyright (c) 2015-2018 Alf Watt - Open Source - https://opensource.org/licenses/MIT */

misc/macos-legacy/mach_gettime.h

@@ -0,0 +1,28 @@
+#ifndef mach_time_h
+#define mach_time_h
+
+#include <sys/types.h>
+#include <sys/_types/_timespec.h>
+#include <mach/mach.h>
+#include <mach/clock.h>
+
+/* The opengroup spec isn't clear on the mapping from REALTIME to CALENDAR
+ being appropriate or not.
+ http://pubs.opengroup.org/onlinepubs/009695299/basedefs/time.h.html */
+
+// XXX only supports a single timer
+#define TIMER_ABSTIME -1
+#define CLOCK_REALTIME CALENDAR_CLOCK
+#define CLOCK_MONOTONIC SYSTEM_CLOCK
+
+typedef int clockid_t;
+
+/* the mach kernel uses struct mach_timespec, so struct timespec
+	is loaded from <sys/_types/_timespec.h> for compatability */
+// struct timespec { time_t tv_sec; long tv_nsec; };
+
+int clock_gettime(clockid_t clk_id, struct timespec *tp);
+
+#endif
+
+/*  Copyright (c) 2015-2018 Alf Watt - Open Source - https://opensource.org/licenses/MIT */

src/nnn.c

@@ -108,6 +108,10 @@
 #include <pwd.h>
 #include <grp.h>
 
+#ifdef MACOS_BELOW_1012
+#include "../misc/macos-legacy/mach_gettime.h"
+#endif
+
 #if !defined(alloca) && defined(__GNUC__)
 /*
  * GCC doesn't expand alloca() to __builtin_alloca() in standards mode