1 files changed, 519 insertions, 0 deletions
diff --git a/sys_macosx.c b/sys_macosx.c
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+++ b/sys_macosx.c
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+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Richard P. Curnow  1997-2001
+ * Copyright (C) J. Hannken-Illjes  2001
+ * Copyright (C) Bryan Christianson  2015, 2017
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Driver file for the macOS operating system.
+
+  */
+
+#include "config.h"
+
+#ifdef MACOSX
+
+#include "sysincl.h"
+
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+#include <pthread.h>
+
+#include "sys_macosx.h"
+#include "conf.h"
+#include "local.h"
+#include "localp.h"
+#include "logging.h"
+#include "sched.h"
+#include "privops.h"
+#include "util.h"
+
+#ifdef HAVE_MACOS_SYS_TIMEX
+#include <dlfcn.h>
+#include "sys_netbsd.h"
+#include "sys_timex.h"
+
+static int have_ntp_adjtime = 0;
+static int have_bad_adjtime = 0;
+#endif
+
+/* ================================================== */
+
+/* This register contains the number of seconds by which the local
+   clock was estimated to be fast of reference time at the epoch when
+   LCL_ReadRawTime() returned T0 */
+
+static double offset_register;
+
+/* This register contains the epoch to which the offset is referenced */
+
+static struct timespec T0;
+
+/* This register contains the current estimate of the system
+   frequency, in absolute (NOT ppm) */
+
+static double current_freq;
+
+/* This register contains the number of seconds of adjustment that
+   were passed to adjtime last time it was called. */
+
+static double adjustment_requested;
+
+/* Interval in seconds between adjustments to cancel systematic drift */
+
+#define DRIFT_REMOVAL_INTERVAL (4.0)
+#define DRIFT_REMOVAL_INTERVAL_MIN (0.5)
+
+/* If current_drift_removal_interval / drift_removal_interval exceeds this
+   ratio, then restart the drift removal timer */
+
+#define DRIFT_REMOVAL_RESTART_RATIO (8.0)
+
+static double drift_removal_interval;
+static double current_drift_removal_interval;
+static struct timespec Tdrift;
+
+/* weighting applied to error in calculating drift_removal_interval */
+#define ERROR_WEIGHT (0.5)
+
+/* minimum resolution of current_frequency */
+#define FREQUENCY_RES (1.0e-9)
+
+#define NANOS_PER_MSEC (1000000ULL)
+
+/* RTC synchronisation - once an hour */
+
+static struct timespec last_rtc_sync;
+#define RTC_SYNC_INTERVAL (60 * 60.0)
+
+/* ================================================== */
+
+static void
+clock_initialise(void)
+{
+  struct timeval newadj, oldadj;
+
+  offset_register = 0.0;
+  adjustment_requested = 0.0;
+  current_freq = 0.0;
+  drift_removal_interval = DRIFT_REMOVAL_INTERVAL;
+  current_drift_removal_interval = DRIFT_REMOVAL_INTERVAL;
+
+  LCL_ReadRawTime(&T0);
+  Tdrift = T0;
+  last_rtc_sync = T0;
+
+  newadj.tv_sec = 0;
+  newadj.tv_usec = 0;
+
+  if (PRV_AdjustTime(&newadj, &oldadj) < 0) {
+    LOG_FATAL("adjtime() failed");
+  }
+}
+
+/* ================================================== */
+
+static void
+clock_finalise(void)
+{
+  /* Nothing to do yet */
+}
+
+/* ================================================== */
+
+static void
+start_adjust(void)
+{
+  struct timeval newadj, oldadj;
+  struct timespec T1;
+  double elapsed, accrued_error, predicted_error, drift_removal_elapsed;
+  double adjust_required;
+  double rounding_error;
+  double old_adjust_remaining;
+
+  /* Determine the amount of error built up since the last adjustment */
+  LCL_ReadRawTime(&T1);
+
+  elapsed = UTI_DiffTimespecsToDouble(&T1, &T0);
+  accrued_error = elapsed * current_freq;
+
+  drift_removal_elapsed = UTI_DiffTimespecsToDouble(&T1, &Tdrift);
+
+  /* To allow for the clock being stepped either forward or backwards, clamp
+     the elapsed time to bounds [ 0.0, current_drift_removal_interval ] */
+  drift_removal_elapsed = MIN(MAX(0.0, drift_removal_elapsed), current_drift_removal_interval);
+
+  predicted_error = (current_drift_removal_interval - drift_removal_elapsed) / 2.0 * current_freq;
+
+  DEBUG_LOG("drift_removal_elapsed: %.3f current_drift_removal_interval: %.3f predicted_error: %.3f",
+            1.0e6 * drift_removal_elapsed, 1.0e6 * current_drift_removal_interval,
+            1.0e6 * predicted_error);
+
+  adjust_required = - (accrued_error + offset_register + predicted_error);
+
+  UTI_DoubleToTimeval(adjust_required, &newadj);
+  adjustment_requested = UTI_TimevalToDouble(&newadj);
+  rounding_error = adjust_required - adjustment_requested;
+
+  if (PRV_AdjustTime(&newadj, &oldadj) < 0) {
+    LOG_FATAL("adjtime() failed");
+  }
+
+  old_adjust_remaining = UTI_TimevalToDouble(&oldadj);
+
+  offset_register = rounding_error - old_adjust_remaining - predicted_error;
+
+  T0 = T1;
+}
+
+/* ================================================== */
+
+static void
+stop_adjust(void)
+{
+  struct timespec T1;
+  struct timeval zeroadj, remadj;
+  double adjustment_remaining, adjustment_achieved;
+  double elapsed, elapsed_plus_adjust;
+
+  zeroadj.tv_sec = 0;
+  zeroadj.tv_usec = 0;
+
+  if (PRV_AdjustTime(&zeroadj, &remadj) < 0) {
+    LOG_FATAL("adjtime() failed");
+  }
+
+  LCL_ReadRawTime(&T1);
+
+  elapsed = UTI_DiffTimespecsToDouble(&T1, &T0);
+  adjustment_remaining = UTI_TimevalToDouble(&remadj);
+
+  adjustment_achieved = adjustment_requested - adjustment_remaining;
+  elapsed_plus_adjust = elapsed - adjustment_achieved;
+
+  offset_register += current_freq * elapsed_plus_adjust - adjustment_remaining;
+
+  adjustment_requested = 0.0;
+  T0 = T1;
+}
+
+/* ================================================== */
+
+/* Positive offset means system clock is fast of true time, therefore
+   slew backwards */
+
+static void
+accrue_offset(double offset, double corr_rate)
+{
+  stop_adjust();
+  offset_register += offset;
+  start_adjust();
+}
+
+/* ================================================== */
+
+/* Positive offset means system clock is fast of true time, therefore
+   step backwards */
+
+static int
+apply_step_offset(double offset)
+{
+  struct timespec old_time, new_time, T1;
+  struct timeval new_time_tv;
+
+  stop_adjust();
+
+  LCL_ReadRawTime(&old_time);
+
+  UTI_AddDoubleToTimespec(&old_time, -offset, &new_time);
+  UTI_TimespecToTimeval(&new_time, &new_time_tv);
+
+  if (PRV_SetTime(&new_time_tv, NULL) < 0) {
+    DEBUG_LOG("settimeofday() failed");
+    return 0;
+  }
+
+  UTI_AddDoubleToTimespec(&T0, -offset, &T1);
+  T0 = T1;
+
+  start_adjust();
+
+  return 1;
+}
+
+/* ================================================== */
+
+static double
+set_frequency(double new_freq_ppm)
+{
+  stop_adjust();
+  current_freq = new_freq_ppm * 1.0e-6;
+  start_adjust();
+
+  return current_freq * 1.0e6;
+}
+
+/* ================================================== */
+
+static double
+read_frequency(void)
+{
+  return current_freq * 1.0e6;
+}
+
+/* ================================================== */
+
+static void
+get_offset_correction(struct timespec *raw,
+                      double *corr, double *err)
+{
+  stop_adjust();
+  *corr = -offset_register;
+  start_adjust();
+  if (err)
+    *err = 0.0;
+}
+
+/* ================================================== */
+
+/* Cancel systematic drift */
+
+static SCH_TimeoutID drift_removal_id;
+
+/* ================================================== */
+/* This is the timer callback routine which is called periodically to
+ invoke a time adjustment to take out the machine's drift.
+ Otherwise, times reported through this software (e.g. by running
+ ntpdate from another machine) show the machine being correct (since
+ they correct for drift build-up), but any program on this machine
+ that reads the system time will be given an erroneous value, the
+ degree of error depending on how long it is since
+ get_offset_correction was last called. */
+
+static void
+drift_removal_timeout(SCH_ArbitraryArgument not_used)
+{
+
+  stop_adjust();
+
+  LCL_ReadRawTime(&Tdrift);
+
+  current_drift_removal_interval = drift_removal_interval;
+
+  start_adjust();
+
+  drift_removal_id = SCH_AddTimeoutByDelay(drift_removal_interval, drift_removal_timeout, NULL);
+}
+
+/* ================================================== */
+
+/* use est_error to calculate the drift_removal_interval and
+   update the RTC */
+
+static void
+set_sync_status(int synchronised, double est_error, double max_error)
+{
+  double interval;
+
+  if (!synchronised) {
+    drift_removal_interval = MAX(drift_removal_interval, DRIFT_REMOVAL_INTERVAL);
+  } else {
+    if (CNF_GetRtcSync()) {
+      struct timespec now;
+      double rtc_sync_elapsed;
+
+      SCH_GetLastEventTime(NULL, NULL, &now);
+      rtc_sync_elapsed = UTI_DiffTimespecsToDouble(&now, &last_rtc_sync);
+      if (fabs(rtc_sync_elapsed) >= RTC_SYNC_INTERVAL) {
+        /* update the RTC by applying a step of 0.0 secs */
+        apply_step_offset(0.0);
+        last_rtc_sync = now;
+        DEBUG_LOG("rtc synchronised");
+      }
+    }
+
+    interval = ERROR_WEIGHT * est_error / (fabs(current_freq) + FREQUENCY_RES);
+    drift_removal_interval = MAX(interval, DRIFT_REMOVAL_INTERVAL_MIN);
+
+    DEBUG_LOG("est_error: %.3f current_freq: %.3f est drift_removal_interval: %.3f act drift_removal_interval: %.3f",
+                est_error * 1.0e6, current_freq * 1.0e6, interval, drift_removal_interval);
+  }
+
+  if (current_drift_removal_interval / drift_removal_interval > DRIFT_REMOVAL_RESTART_RATIO) {
+    /* recover from a large est_error by resetting the timer */
+    SCH_ArbitraryArgument unused;
+    SCH_RemoveTimeout(drift_removal_id);
+    unused = NULL;
+    drift_removal_timeout(unused);
+  }
+}
+
+/* ================================================== */
+/*
+  Give chronyd real time priority so that time critical calculations
+  are not pre-empted by the kernel.
+*/
+
+static int
+set_realtime(void)
+{
+  /* https://developer.apple.com/library/ios/technotes/tn2169/_index.html */
+
+  mach_timebase_info_data_t timebase_info;
+  double clock2abs;
+  thread_time_constraint_policy_data_t policy;
+  int kr;
+
+  mach_timebase_info(&timebase_info);
+  clock2abs = ((double)timebase_info.denom / (double)timebase_info.numer) * NANOS_PER_MSEC;
+
+  policy.period = 0;
+  policy.computation = (uint32_t)(5 * clock2abs); /* 5 ms of work */
+  policy.constraint = (uint32_t)(10 * clock2abs);
+  policy.preemptible = 0;
+
+  kr = thread_policy_set(
+          pthread_mach_thread_np(pthread_self()),
+          THREAD_TIME_CONSTRAINT_POLICY,
+          (thread_policy_t)&policy,
+          THREAD_TIME_CONSTRAINT_POLICY_COUNT);
+
+  if (kr != KERN_SUCCESS) {
+    LOG(LOGS_WARN, "Cannot set real-time priority: %d", kr);
+    return -1;
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+void
+SYS_MacOSX_SetScheduler(int SchedPriority)
+{
+  if (SchedPriority) {
+    set_realtime();
+  }
+}
+
+/* ================================================== */
+
+#ifdef FEAT_PRIVDROP
+void SYS_MacOSX_DropRoot(uid_t uid, gid_t gid)
+{
+  PRV_StartHelper();
+
+  UTI_DropRoot(uid, gid);
+}
+#endif
+
+/* ================================================== */
+
+static void
+legacy_MacOSX_Initialise(void)
+{
+  clock_initialise();
+
+  lcl_RegisterSystemDrivers(read_frequency, set_frequency,
+                            accrue_offset, apply_step_offset,
+                            get_offset_correction,
+                            NULL /* set_leap */,
+                            set_sync_status);
+
+
+  drift_removal_id = SCH_AddTimeoutByDelay(drift_removal_interval, drift_removal_timeout, NULL);
+}
+
+/* ================================================== */
+
+static void
+legacy_MacOSX_Finalise(void)
+{
+  SCH_RemoveTimeout(drift_removal_id);
+
+  clock_finalise();
+}
+
+/* ================================================== */
+
+#ifdef HAVE_MACOS_SYS_TIMEX
+/*
+    Test adjtime() to see if Apple have fixed the signed/unsigned bug
+*/
+static int
+test_adjtime()
+{
+  struct timeval tv1 = {-1, 0};
+  struct timeval tv2 = {0, 0};
+  struct timeval tv;
+
+  if (PRV_AdjustTime(&tv1, &tv) != 0) {
+    return 0;
+  }
+  if (PRV_AdjustTime(&tv2, &tv) != 0) {
+    return 0;
+  }
+  if (tv.tv_sec < -1 || tv.tv_sec > 1) {
+    return 0;
+  }
+  return 1;
+}
+#endif
+
+/* ================================================== */
+
+void
+SYS_MacOSX_Initialise(void)
+{
+#ifdef HAVE_MACOS_SYS_TIMEX
+  have_ntp_adjtime = (dlsym(RTLD_NEXT, "ntp_adjtime") != NULL);
+  if (have_ntp_adjtime) {
+    have_bad_adjtime = !test_adjtime();
+    if (have_bad_adjtime) {
+      LOG(LOGS_WARN, "adjtime() is buggy - using timex driver");
+      SYS_Timex_Initialise();
+    } else {
+      SYS_NetBSD_Initialise();
+    }
+    return;
+  }
+#endif
+  legacy_MacOSX_Initialise();
+}
+
+/* ================================================== */
+
+void
+SYS_MacOSX_Finalise(void)
+{
+#ifdef HAVE_MACOS_SYS_TIMEX
+  if (have_ntp_adjtime) {
+    if (have_bad_adjtime) {
+      SYS_Timex_Finalise();
+    } else {
+      SYS_NetBSD_Finalise();
+    }
+    return;
+  }
+#endif
+  legacy_MacOSX_Finalise();
+}
+
+#endif