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diff --git a/src/ptimer.c b/src/ptimer.c
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+/* Portable timers.
+   Copyright (C) 2005-2011, 2015, 2018-2022 Free Software Foundation,
+   Inc.
+
+This file is part of GNU Wget.
+
+GNU Wget is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3 of the License, or
+(at your option) any later version.
+
+GNU Wget 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 Wget.  If not, see <http://www.gnu.org/licenses/>.
+
+Additional permission under GNU GPL version 3 section 7
+
+If you modify this program, or any covered work, by linking or
+combining it with the OpenSSL project's OpenSSL library (or a
+modified version of that library), containing parts covered by the
+terms of the OpenSSL or SSLeay licenses, the Free Software Foundation
+grants you additional permission to convey the resulting work.
+Corresponding Source for a non-source form of such a combination
+shall include the source code for the parts of OpenSSL used as well
+as that of the covered work.  */
+
+/* This file implements "portable timers" (ptimers), objects that
+   measure elapsed time using the primitives most appropriate for the
+   underlying operating system.  The entry points are:
+
+     ptimer_new     -- creates a timer.
+     ptimer_reset   -- resets the timer's elapsed time to zero.
+     ptimer_measure -- measure and return the time elapsed since
+                       creation or last reset.
+     ptimer_read    -- reads the last measured elapsed value.
+     ptimer_destroy -- destroy the timer.
+     ptimer_granularity -- returns the approximate granularity of the timers.
+
+   Timers measure time in seconds, returning the timings as floating
+   point numbers, so they can carry as much precision as the
+   underlying system timer supports.  For example, to measure the time
+   it takes to run a loop, you can use something like:
+
+     ptimer *tmr = ptimer_new ();
+     while (...)
+       ... loop ...
+     double secs = ptimer_measure ();
+     printf ("The loop took %.2fs\n", secs);  */
+
+#include "wget.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <time.h>
+#include <sys/time.h>
+
+/* Cygwin currently (as of 2005-04-08, Cygwin 1.5.14) lacks clock_getres,
+   but still defines _POSIX_TIMERS!  Because of that we simply use the
+   Windows timers under Cygwin.  */
+#ifdef __CYGWIN__
+# include <windows.h>
+#endif
+
+#include "utils.h"
+#include "ptimer.h"
+
+/* Depending on the OS, one and only one of PTIMER_POSIX,
+   PTIMER_GETTIMEOFDAY, or PTIMER_WINDOWS will be defined.  */
+
+#undef PTIMER_POSIX
+#undef PTIMER_GETTIMEOFDAY
+#undef PTIMER_WINDOWS
+
+#if defined(WINDOWS) || defined(__CYGWIN__)
+# define PTIMER_WINDOWS         /* use Windows timers */
+#elif _POSIX_TIMERS - 0 > 0
+# define PTIMER_POSIX           /* use POSIX timers (clock_gettime) */
+#else
+# define PTIMER_GETTIMEOFDAY    /* use gettimeofday */
+#endif
+
+#ifdef PTIMER_POSIX
+/* Elapsed time measurement using POSIX timers: system time is held in
+   struct timespec, time is retrieved using clock_gettime, and
+   resolution using clock_getres.
+
+   This method is used on Unix systems that implement POSIX
+   timers.  */
+
+typedef struct timespec ptimer_system_time;
+
+#define IMPL_init posix_init
+#define IMPL_measure posix_measure
+#define IMPL_diff posix_diff
+#define IMPL_resolution posix_resolution
+
+/* clock_id to use for POSIX clocks.  This tries to use
+   CLOCK_MONOTONIC where available, CLOCK_REALTIME otherwise.  */
+static int posix_clock_id;
+
+/* Resolution of the clock, initialized in posix_init. */
+static double posix_clock_resolution;
+
+/* Decide which clock_id to use.  */
+
+static void
+posix_init (void)
+{
+  /* List of clocks we want to support: some systems support monotonic
+     clocks, Solaris has "high resolution" clock (sometimes
+     unavailable except to superuser), and all should support the
+     real-time clock.  */
+#define NO_SYSCONF_CHECK -1
+  static const struct {
+    int id;
+    int sysconf_name;
+  } clocks[] = {
+#if defined(_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK - 0 >= 0
+    { CLOCK_MONOTONIC, _SC_MONOTONIC_CLOCK },
+#endif
+#ifdef CLOCK_HIGHRES
+    { CLOCK_HIGHRES, NO_SYSCONF_CHECK },
+#endif
+    { CLOCK_REALTIME, NO_SYSCONF_CHECK },
+  };
+  size_t i;
+
+  /* Determine the clock we can use.  For a clock to be usable, it
+     must be confirmed with sysconf (where applicable) and with
+     clock_getres.  If no clock is found, CLOCK_REALTIME is used.  */
+
+  for (i = 0; i < countof (clocks); i++)
+    {
+      struct timespec r;
+      if (clocks[i].sysconf_name != NO_SYSCONF_CHECK)
+        if (sysconf (clocks[i].sysconf_name) < 0)
+          continue;             /* sysconf claims this clock is unavailable */
+      if (clock_getres (clocks[i].id, &r) < 0)
+        continue;               /* clock_getres doesn't work for this clock */
+      posix_clock_id = clocks[i].id;
+      posix_clock_resolution = (double) r.tv_sec + r.tv_nsec / 1e9;
+      /* Guard against nonsense returned by a broken clock_getres.  */
+      if (posix_clock_resolution == 0)
+        posix_clock_resolution = 1e-3;
+      break;
+    }
+  if (i == countof (clocks))
+    {
+      /* If no clock was found, it means that clock_getres failed for
+         the realtime clock.  */
+      logprintf (LOG_NOTQUIET, _("Cannot get REALTIME clock frequency: %s\n"),
+                 strerror (errno));
+      /* Use CLOCK_REALTIME, but invent a plausible resolution. */
+      posix_clock_id = CLOCK_REALTIME;
+      posix_clock_resolution = 1e-3;
+    }
+}
+
+static inline void
+posix_measure (ptimer_system_time *pst)
+{
+  clock_gettime (posix_clock_id, pst);
+}
+
+static inline double
+posix_diff (ptimer_system_time *pst1, ptimer_system_time *pst2)
+{
+  return ((pst1->tv_sec - pst2->tv_sec)
+          + (pst1->tv_nsec - pst2->tv_nsec) / 1e9);
+}
+
+static inline double
+posix_resolution (void)
+{
+  return posix_clock_resolution;
+}
+#endif  /* PTIMER_POSIX */
+
+#ifdef PTIMER_GETTIMEOFDAY
+/* Elapsed time measurement using gettimeofday: system time is held in
+   struct timeval, retrieved using gettimeofday, and resolution is
+   unknown.
+
+   This method is used Unix systems without POSIX timers.  */
+
+typedef struct timeval ptimer_system_time;
+
+#define IMPL_measure gettimeofday_measure
+#define IMPL_diff gettimeofday_diff
+#define IMPL_resolution gettimeofday_resolution
+
+static inline void
+gettimeofday_measure (ptimer_system_time *pst)
+{
+  gettimeofday (pst, NULL);
+}
+
+static inline double
+gettimeofday_diff (ptimer_system_time *pst1, ptimer_system_time *pst2)
+{
+  return ((pst1->tv_sec - pst2->tv_sec)
+          + (pst1->tv_usec - pst2->tv_usec) / 1e6);
+}
+
+static inline double
+gettimeofday_resolution (void)
+{
+  /* Granularity of gettimeofday varies wildly between architectures.
+     However, it appears that on modern machines it tends to be better
+     than 1ms.  Assume 100 usecs.  */
+  return 0.1;
+}
+#endif  /* PTIMER_GETTIMEOFDAY */
+
+#ifdef PTIMER_WINDOWS
+/* Elapsed time measurement on Windows: where high-resolution timers
+   are available, time is stored in a LARGE_INTEGER and retrieved
+   using QueryPerformanceCounter.  Otherwise, it is stored in a DWORD
+   and retrieved using GetTickCount.
+
+   This method is used on Windows.  */
+
+typedef union {
+  DWORD lores;          /* In case GetTickCount is used */
+  LARGE_INTEGER hires;  /* In case high-resolution timer is used */
+} ptimer_system_time;
+
+#define IMPL_init windows_init
+#define IMPL_measure windows_measure
+#define IMPL_diff windows_diff
+#define IMPL_resolution windows_resolution
+
+/* Whether high-resolution timers are used.  Set by ptimer_initialize_once
+   the first time ptimer_new is called. */
+static bool windows_hires_timers;
+
+/* Frequency of high-resolution timers -- number of updates per
+   second.  Calculated the first time ptimer_new is called provided
+   that high-resolution timers are available. */
+static double windows_hires_freq;
+
+static void
+windows_init (void)
+{
+  LARGE_INTEGER freq;
+  freq.QuadPart = 0;
+  QueryPerformanceFrequency (&freq);
+  if (freq.QuadPart != 0)
+    {
+      windows_hires_timers = true;
+      windows_hires_freq = (double) freq.QuadPart;
+    }
+}
+
+static inline void
+windows_measure (ptimer_system_time *pst)
+{
+  if (windows_hires_timers)
+    QueryPerformanceCounter (&pst->hires);
+  else
+    /* Where hires counters are not available, use GetTickCount rather
+       GetSystemTime, because it is unaffected by clock skew and
+       simpler to use.  Note that overflows don't affect us because we
+       never use absolute values of the ticker, only the
+       differences.  */
+    pst->lores = GetTickCount ();
+}
+
+static inline double
+windows_diff (ptimer_system_time *pst1, ptimer_system_time *pst2)
+{
+  if (windows_hires_timers)
+    return (pst1->hires.QuadPart - pst2->hires.QuadPart) / windows_hires_freq;
+  else
+    return pst1->lores - pst2->lores;
+}
+
+static double
+windows_resolution (void)
+{
+  if (windows_hires_timers)
+    return 1.0 / windows_hires_freq;
+  else
+    return 10;                  /* according to MSDN */
+}
+#endif  /* PTIMER_WINDOWS */
+
+/* The code below this point is independent of timer implementation. */
+
+struct ptimer {
+  /* The starting point in time which, subtracted from the current
+     time, yields elapsed time. */
+  ptimer_system_time start;
+
+  /* The most recent elapsed time, calculated by ptimer_measure().  */
+  double elapsed_last;
+
+  /* Approximately, the time elapsed between the true start of the
+     measurement and the time represented by START.  This is used for
+     adjustment when clock skew is detected.  */
+  double elapsed_pre_start;
+};
+
+/* Allocate a new timer and reset it.  Return the new timer. */
+
+struct ptimer *
+ptimer_new (void)
+{
+  struct ptimer *pt = xnew0 (struct ptimer);
+#ifdef IMPL_init
+  static bool init_done;
+  if (!init_done)
+    {
+      init_done = true;
+      IMPL_init ();
+    }
+#endif
+  ptimer_reset (pt);
+  return pt;
+}
+
+/* Free the resources associated with the timer.  Its further use is
+   prohibited.  */
+
+void
+ptimer_destroy (struct ptimer *pt)
+{
+  xfree (pt);
+}
+
+/* Reset timer PT.  This establishes the starting point from which
+   ptimer_measure() will return the elapsed time in seconds.  It is
+   allowed to reset a previously used timer.  */
+
+void
+ptimer_reset (struct ptimer *pt)
+{
+  /* Set the start time to the current time. */
+  IMPL_measure (&pt->start);
+  pt->elapsed_last = 0;
+  pt->elapsed_pre_start = 0;
+}
+
+/* Measure the elapsed time since timer creation/reset.  This causes
+   the timer to internally call clock_gettime (or gettimeofday, etc.)
+   to update its idea of current time.  The time is returned, but is
+   also stored for later access through ptimer_read().
+
+   This function handles clock skew, i.e. time that moves backwards is
+   ignored.  */
+
+double
+ptimer_measure (struct ptimer *pt)
+{
+  ptimer_system_time now;
+  double elapsed;
+
+  IMPL_measure (&now);
+  elapsed = pt->elapsed_pre_start + IMPL_diff (&now, &pt->start);
+
+  /* Ideally we'd just return the difference between NOW and
+     pt->start.  However, the system timer can be set back, and we
+     could return a value smaller than when we were last called, even
+     a negative value.  Both of these would confuse the callers, which
+     expect us to return monotonically nondecreasing values.
+
+     Therefore: if ELAPSED is smaller than its previous known value,
+     we reset pt->start to the current time and effectively start
+     measuring from this point.  But since we don't want the elapsed
+     value to start from zero, we set elapsed_pre_start to the last
+     elapsed time and increment all future calculations by that
+     amount.
+
+     This cannot happen with Windows and POSIX monotonic/highres
+     timers, but the check is not expensive.  */
+
+  if (elapsed < pt->elapsed_last)
+    {
+      pt->start = now;
+      pt->elapsed_pre_start = pt->elapsed_last;
+      elapsed = pt->elapsed_last;
+    }
+
+  pt->elapsed_last = elapsed;
+  return elapsed;
+}
+
+/* Return the most recent elapsed time measured with ptimer_measure.
+   If ptimer_measure has not yet been called since the timer was
+   created or reset, this returns 0.  */
+
+double
+ptimer_read (const struct ptimer *pt)
+{
+  return pt->elapsed_last;
+}
+
+/* Return the assessed resolution of the timer implementation, in
+   seconds.  This is used by code that tries to substitute a better
+   value for timers that have returned zero.  */
+
+double
+ptimer_resolution (void)
+{
+  return IMPL_resolution ();
+}