/* Download progress.

   Copyright (C) 2001-2011, 2015, 2018-2024 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.  */

#include "wget.h"

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <assert.h>

#include <unistd.h>

#include <signal.h>

#include <wchar.h>

#include <mbiter.h>

#include "progress.h"

#include "utils.h"

#include "retr.h"

#include "c-strcase.h"

struct progress_implementation {

  const char *name;

  bool interactive;

  void *(*create) (const char *, wgint, wgint);

  void (*update) (void *, wgint, double);

  void (*draw) (void *);

  void (*finish) (void *, double);

  void (*set_params) (const char *);

};

/* Necessary forward declarations. */

static void *dot_create (const char *, wgint, wgint);

static void dot_update (void *, wgint, double);

static void dot_finish (void *, double);

static void dot_draw (void *);

static void dot_set_params (const char *);

static void *bar_create (const char *, wgint, wgint);

static void bar_update (void *, wgint, double);

static void bar_draw (void *);

static void bar_finish (void *, double);

static void bar_set_params (const char *);

static struct progress_implementation implementations[] = {

  { "dot", 0, dot_create, dot_update, dot_draw, dot_finish, dot_set_params },

  { "bar", 1, bar_create, bar_update, bar_draw, bar_finish, bar_set_params }

};

static struct progress_implementation *current_impl;

static int current_impl_locked;

/* Progress implementation used by default.  Can be overridden in

   wgetrc or by the fallback one.  */

#define DEFAULT_PROGRESS_IMPLEMENTATION "bar"

/* Fallback progress implementation should be something that works

   under all display types.  If you put something other than "dot"

   here, remember that bar_set_params tries to switch to this if we're

   not running on a TTY.  So changing this to "bar" could cause

   infloop.  */

#define FALLBACK_PROGRESS_IMPLEMENTATION "dot"

/* Return true if NAME names a valid progress bar implementation.  The

   characters after the first : will be ignored.  */

bool

valid_progress_implementation_p (const char *name)

{

  size_t i;

  struct progress_implementation *pi = implementations;

  char *colon = strchr (name, ':');

  size_t namelen = colon ? (size_t) (colon - name) : strlen (name);

  for (i = 0; i < countof (implementations); i++, pi++)

    if (!strncmp (pi->name, name, namelen))

      return true;

  return false;

}

/* Set the progress implementation to NAME.  */

void

set_progress_implementation (const char *name)

{

  size_t i, namelen;

  struct progress_implementation *pi = implementations;

  const char *colon;

  if (!name)

    name = DEFAULT_PROGRESS_IMPLEMENTATION;

  colon = strchr (name, ':');

  namelen = colon ? (size_t) (colon - name) : strlen (name);

  for (i = 0; i < countof (implementations); i++, pi++)

    if (!strncmp (pi->name, name, namelen))

      {

        current_impl = pi;

        current_impl_locked = 0;

        if (colon)

          /* We call pi->set_params even if colon is NULL because we

             want to give the implementation a chance to set up some

             things it needs to run.  */

          ++colon;

        if (pi->set_params)

          pi->set_params (colon);

        return;

      }

  abort ();

}

static int output_redirected;

void

progress_schedule_redirect (void)

{

  output_redirected = 1;

}

/* Create a progress gauge.  INITIAL is the number of bytes the

   download starts from (zero if the download starts from scratch).

   TOTAL is the expected total number of bytes in this download.  If

   TOTAL is zero, it means that the download size is not known in

   advance.  */

void *

progress_create (const char *f_download, wgint initial, wgint total)

{

  /* Check if the log status has changed under our feet. */

  if (output_redirected)

    {

      if (!current_impl_locked)

        set_progress_implementation (FALLBACK_PROGRESS_IMPLEMENTATION);

      output_redirected = 0;

    }

  return current_impl->create (f_download, initial, total);

}

/* Return true if the progress gauge is "interactive", i.e. if it can

   profit from being called regularly even in absence of data.  The

   progress bar is interactive because it regularly updates the ETA

   and current update.  */

bool

progress_interactive_p (void *progress _GL_UNUSED)

{

  return current_impl->interactive;

}

/* Inform the progress gauge of newly received bytes.  DLTIME is the

   time since the beginning of the download.  */

void

progress_update (void *progress, wgint howmuch, double dltime)

{

  // sanitize input

  if (dltime >= INT_MAX)

    dltime = INT_MAX - 1;

  else if (dltime < 0)

    dltime = 0;

  if (howmuch < 0)

    howmuch = 0;

  current_impl->update (progress, howmuch, dltime);

  current_impl->draw (progress);

}

/* Tell the progress gauge to clean up.  Calling this will free the

   PROGRESS object, the further use of which is not allowed.  */

void

progress_finish (void *progress, double dltime)

{

  // sanitize input

  if (dltime >= INT_MAX)

    dltime = INT_MAX - 1;

  else if (dltime < 0)

    dltime = 0;

  current_impl->finish (progress, dltime);

}

/* Dot-printing. */

struct dot_progress {

  wgint initial_length;         /* how many bytes have been downloaded

                                   previously. */

  wgint total_length;           /* expected total byte count when the

                                   download finishes */

  wgint accumulated;            /* number of bytes accumulated after

                                   the last printed dot */

  double dltime;                /* download time so far */

  wgint rows;                   /* number of rows printed so far */

  int dots;                     /* number of dots printed in this row */

  double last_timer_value;

};

/* Dot-progress backend for progress_create. */

static void *

dot_create (const char *f_download _GL_UNUSED, wgint initial, wgint total)

{

  struct dot_progress *dp = xnew0 (struct dot_progress);

  dp->initial_length = initial;

  dp->total_length   = total;

  if (dp->initial_length)

    {

      int dot_bytes = opt.dot_bytes;

      const wgint ROW_BYTES = opt.dot_bytes * opt.dots_in_line;

      int remainder = dp->initial_length % ROW_BYTES;

      wgint skipped = dp->initial_length - remainder;

      if (skipped)

        {

          wgint skipped_k = skipped / 1024; /* skipped amount in K */

          int skipped_k_len = numdigit (skipped_k);

          if (skipped_k_len < 6)

            skipped_k_len = 6;

          /* Align the [ skipping ... ] line with the dots.  To do

             that, insert the number of spaces equal to the number of

             digits in the skipped amount in K.  */

          logprintf (LOG_PROGRESS, _("\n%*s[ skipping %sK ]"),

                     2 + skipped_k_len, "",

                     number_to_static_string (skipped_k));

        }

      logprintf (LOG_PROGRESS, "\n%6sK",

                 number_to_static_string (skipped / 1024));

      for (; remainder >= dot_bytes; remainder -= dot_bytes)

        {

          if (dp->dots % opt.dot_spacing == 0)

            logputs (LOG_PROGRESS, " ");

          logputs (LOG_PROGRESS, ",");

          ++dp->dots;

        }

      assert (dp->dots < opt.dots_in_line);

      dp->accumulated = remainder;

      dp->rows = skipped / ROW_BYTES;

    }

  return dp;

}

static const char *eta_to_human_short (int, bool);

/* ADD_DOT_ROWS_THRS - minimal (1 << ADD_DOT_ROWS_THRS) ROWS to be added

   to the current row if dp->accumulated too much.

   Allows to reduce dot_draw io, times.

   According to the way progress_update is currently has being called, this

   should happens only when fuzzing, or (paranoia) if somehow buffer will

   be too large.

   Can be disabled by default if this is not fuzzing build. */

#ifndef ADD_DOT_ROWS_THRS

#if FUZZING

#define ADD_DOT_ROWS_THRS 2

#else

#define ADD_DOT_ROWS_THRS 2

#endif

#endif /* ADD_DOT_ROWS_THRS */

/* Prints the stats (percentage of completion, speed, ETA) for current

   row.  DLTIME is the time spent downloading the data in current

   row.

   #### This function is somewhat uglified by the fact that current

   row and last row have somewhat different stats requirements.  It

   might be worthwhile to split it to two different functions.  */

static void

#if ADD_DOT_ROWS_THRS

print_row_stats (struct dot_progress *dp, double dltime, bool last, wgint added_rows)

#else

print_row_stats (struct dot_progress *dp, double dltime, bool last)

#endif

{

  const wgint ROW_BYTES = opt.dot_bytes * opt.dots_in_line;

  /* bytes_displayed is the number of bytes indicated to the user by

     dots printed so far, includes the initially "skipped" amount */

  wgint bytes_displayed = dp->rows * ROW_BYTES + dp->dots * opt.dot_bytes;

  if (last)

    /* For last row also count bytes accumulated after last dot */

    bytes_displayed += dp->accumulated;

  if (bytes_displayed < 0)

    bytes_displayed = 0;

  if (dp->total_length)

    {

      /* Round to floor value to provide gauge how much data *has*

         been retrieved.  12.8% will round to 12% because the 13% mark

         has not yet been reached.  100% is only shown when done.  */

      int percentage = 100.0 * bytes_displayed / dp->total_length;

      logprintf (LOG_PROGRESS, "%3d%%", percentage);

    }

  {

    static char names[] = {' ', 'K', 'M', 'G', 'T'};

    int units;

    double rate;

    wgint bytes_this_row;

    if (!last)

#if ADD_DOT_ROWS_THRS

      bytes_this_row = ROW_BYTES * added_rows;

#else

      bytes_this_row = ROW_BYTES;

#endif

    else

      /* For last row also include bytes accumulated after last dot.  */

      bytes_this_row = dp->dots * opt.dot_bytes + dp->accumulated;

    /* Don't count the portion of the row belonging to initial_length */

    if (dp->rows == dp->initial_length / ROW_BYTES)

      bytes_this_row -= dp->initial_length % ROW_BYTES;

    rate = calc_rate (bytes_this_row, dltime - dp->last_timer_value, &units);

    logprintf (LOG_PROGRESS, " %4.*f%c",

               rate >= 99.95 ? 0 : rate >= 9.995 ? 1 : 2,

               rate, names[units]);

    dp->last_timer_value = dltime;

  }

  if (!last)

    {

      /* Display ETA based on average speed.  Inspired by Vladi

         Belperchinov-Shabanski's "wget-new-percentage" patch.  */

      if (dp->total_length)

        {

          wgint bytes_remaining = dp->total_length > bytes_displayed ? dp->total_length - bytes_displayed : 0;

          /* The quantity downloaded in this download run. */

          wgint bytes_sofar = bytes_displayed > dp->initial_length ? bytes_displayed - dp->initial_length : 1;

          double eta = dltime * bytes_remaining / bytes_sofar;

          if (eta < 0)

            eta = 0;

          if (eta < INT_MAX - 1)

            logprintf (LOG_PROGRESS, " %s",

                       eta_to_human_short ((int) (eta + 0.5), true));

        }

    }

  else

    {

      /* When done, print the total download time */

      if (dltime >= 10)

        logprintf (LOG_PROGRESS, "=%s",

                   eta_to_human_short ((int) (dltime + 0.5), true));

      else

        logprintf (LOG_PROGRESS, "=%ss", print_decimal (dltime));

    }

}

/* Dot-progress backend for progress_update. */

static void

dot_update (void *progress, wgint howmuch, double dltime)

{

  // sanitize input

  if (dltime >= INT_MAX)

    dltime = INT_MAX - 1;

  else if (dltime < 0)

    dltime = 0;

  if (howmuch < 0)

    howmuch = 0;

  struct dot_progress *dp = progress;

  dp->accumulated += howmuch;

  dp->dltime = dltime;

}

static void

dot_draw (void *progress)

{

  struct dot_progress *dp = progress;

  int dot_bytes = opt.dot_bytes;

  wgint ROW_BYTES = opt.dot_bytes * opt.dots_in_line;

  log_set_flush (false);

  while (dp->accumulated >= dot_bytes)

    {

      dp->accumulated -= dot_bytes;

      if (dp->dots == 0)

        logprintf (LOG_PROGRESS, "\n%6sK",

                   number_to_static_string (dp->rows * ROW_BYTES / 1024));

      if (dp->dots % opt.dot_spacing == 0)

        logputs (LOG_PROGRESS, " ");

      logputs (LOG_PROGRESS, ".");

      ++dp->dots;

      if (dp->dots >= opt.dots_in_line)

        {

          dp->dots = 0;

#if ADD_DOT_ROWS_THRS

          {

            wgint added_rows = 1;

            if (dp->accumulated >= (ROW_BYTES << ADD_DOT_ROWS_THRS))

              {

                added_rows += dp->accumulated / ROW_BYTES;

                dp->accumulated %= ROW_BYTES;

              }

            if (WGINT_MAX - dp->rows >= added_rows)

              dp->rows += added_rows;

            else

              dp->rows = WGINT_MAX;

            print_row_stats (dp, dp->dltime, false, added_rows);

          }

#else

          if (dp->rows < WGINT_MAX)

            ++dp->rows;

          print_row_stats (dp, dp->dltime, false);

#endif /* ADD_DOT_ROWS_THRS */

        }

    }

  log_set_flush (true);

}

/* Dot-progress backend for progress_finish. */

static void

dot_finish (void *progress, double dltime)

{

  struct dot_progress *dp = progress;

  wgint ROW_BYTES = opt.dot_bytes * opt.dots_in_line;

  int i;

  log_set_flush (false);

  if (dp->dots == 0)

    logprintf (LOG_PROGRESS, "\n%6sK",

               number_to_static_string (dp->rows * ROW_BYTES / 1024));

  for (i = dp->dots; i < opt.dots_in_line; i++)

    {

      if (i % opt.dot_spacing == 0)

        logputs (LOG_PROGRESS, " ");

      logputs (LOG_PROGRESS, " ");

    }

  // sanitize input

  if (dltime >= INT_MAX)

    dltime = INT_MAX - 1;

  else if (dltime < 0)

    dltime = 0;

#if ADD_DOT_ROWS_THRS

  print_row_stats (dp, dltime, true, 1);

#else

  print_row_stats (dp, dltime, true);

#endif

  logputs (LOG_PROGRESS, "\n\n");

  log_set_flush (false);

  xfree (dp);

}

/* This function interprets the progress "parameters".  For example,

   if Wget is invoked with --progress=dot:mega, it will set the

   "dot-style" to "mega".  Valid styles are default, binary, mega, and

   giga.  */

static void

dot_set_params (const char *params)

{

  current_impl->interactive = false;

  if (!params || !*params)

    params = opt.dot_style;

  if (!params)

    return;

  /* We use this to set the retrieval style.  */

  if (!c_strcasecmp (params, "default"))

    {

      /* Default style: 1K dots, 10 dots in a cluster, 50 dots in a

         line.  */

      opt.dot_bytes = 1024;

      opt.dot_spacing = 10;

      opt.dots_in_line = 50;

    }

  else if (!c_strcasecmp (params, "binary"))

    {

      /* "Binary" retrieval: 8K dots, 16 dots in a cluster, 48 dots

         (384K) in a line.  */

      opt.dot_bytes = 8192;

      opt.dot_spacing = 16;

      opt.dots_in_line = 48;

    }

  else if (!c_strcasecmp (params, "mega"))

    {

      /* "Mega" retrieval, for retrieving very long files; each dot is

         64K, 8 dots in a cluster, 6 clusters (3M) in a line.  */

      opt.dot_bytes = 65536L;

      opt.dot_spacing = 8;

      opt.dots_in_line = 48;

    }

  else if (!c_strcasecmp (params, "giga"))

    {

      /* "Giga" retrieval, for retrieving very very *very* long files;

         each dot is 1M, 8 dots in a cluster, 4 clusters (32M) in a

         line.  */

      opt.dot_bytes = (1L << 20);

      opt.dot_spacing = 8;

      opt.dots_in_line = 32;

    }

  else

    fprintf (stderr,

             _("Invalid dot style specification %s; leaving unchanged.\n"),

             quote (params));

}

/* "Thermometer" (bar) progress. */

/* Assumed screen width if we can't find the real value.  */

#define DEFAULT_SCREEN_WIDTH 80

/* Minimum screen width we'll try to work with.  If this is too small,

   create_image will overflow the buffer.

   width = width/4 + 1 + PROGRESS_PERCENT_LEN + PROGRESS_FILESIZE_LEN

           + PROGRESS_DWNLOAD_RATE + PROGRESS_ETA_LEN => widh = 38*4/3 (+1) */

#define MINIMUM_SCREEN_WIDTH 51

/* The last known screen width.  This can be updated by the code that

   detects that SIGWINCH was received (but it's never updated from the

   signal handler).  */

static int screen_width;

/* A flag that, when set, means SIGWINCH was received.  */

static volatile sig_atomic_t received_sigwinch;

/* Size of the download speed history ring. */

#define DLSPEED_HISTORY_SIZE 20

/* The minimum time length of a history sample.  By default, each

   sample is at least 150ms long, which means that, over the course of

   20 samples, "current" download speed spans at least 3s into the

   past.  */

#define DLSPEED_SAMPLE_MIN 0.15

/* The time after which the download starts to be considered

   "stalled", i.e. the current bandwidth is not printed and the recent

   download speeds are scratched.  */

#define STALL_START_TIME 5

/* Time between screen refreshes will not be shorter than this, so

   that Wget doesn't swamp the TTY with output.  */

#define REFRESH_INTERVAL 0.2

/* Don't refresh the ETA too often to avoid jerkiness in predictions.

   This allows ETA to change approximately once per second.  */

#define ETA_REFRESH_INTERVAL 0.99

struct bar_progress {

  char *f_download;             /* Filename of the downloaded file */

  wgint initial_length;         /* how many bytes have been downloaded

                                   previously. */

  wgint total_length;           /* expected total byte count when the

                                   download finishes */

  wgint count;                  /* bytes downloaded so far */

  double last_screen_update;    /* time of the last screen update,

                                   measured since the beginning of

                                   download. */

  double dltime;                /* download time so far */

  int width;                    /* screen width we're using at the

                                   time the progress gauge was

                                   created.  this is different from

                                   the screen_width global variable in

                                   that the latter can be changed by a

                                   signal. */

  char *buffer;                 /* buffer where the bar "image" is

                                   stored. */

  int tick;                     /* counter used for drawing the

                                   progress bar where the total size

                                   is not known. */

  /* The following variables (kept in a struct for namespace reasons)

     keep track of recent download speeds.  See bar_update() for

     details.  */

  struct bar_progress_hist {

    int pos;

    double times[DLSPEED_HISTORY_SIZE];

    wgint bytes[DLSPEED_HISTORY_SIZE];

    /* The sum of times and bytes respectively, maintained for

       efficiency. */

    double total_time;

    wgint total_bytes;

  } hist;

  double recent_start;          /* timestamp of beginning of current

                                   position. */

  wgint recent_bytes;           /* bytes downloaded so far. */

  bool stalled;                 /* set when no data arrives for longer

                                   than STALL_START_TIME, then reset

                                   when new data arrives. */

  /* create_image() uses these to make sure that ETA information

     doesn't flicker. */

  double last_eta_time;         /* time of the last update to download

                                   speed and ETA, measured since the

                                   beginning of download. */

  int last_eta_value;

};

static void create_image (struct bar_progress *, double, bool);

static void display_image (char *);

#if USE_NLS_PROGRESS_BAR

static size_t

prepare_filename (char *dest, const char *src)

{

  size_t ret = 1;

  if (src)

    {

      mbi_iterator_t iter;

      mbchar_t mbc;

      mbi_init (iter, src, strlen (src));

      while (mbi_avail (iter))

        {

          size_t i;

          mbc = mbi_cur(iter);

          /* replace invalid || unprintable || zero-width mbc ws hexdgt code */

          if (!mb_isprint (mbc) || !mb_width (mbc))

            for (i=0; i < mb_len (mbc); i++)

              {

                if (dest)

                  dest += sprintf (dest, "%%%02x", (unsigned char) *(mb_ptr(mbc) + i));

                ret  += 3;

              }

          else

            {

              if (dest)

                for (i=0; i < mb_len (mbc); i++)

                  *dest++ = *(mb_ptr (mbc) + i);

              ret += mb_len (mbc);

            }

          mbi_advance (iter);

        }

    }

  if (dest)

    *dest = 0;

  return ret;

}

#else

#include <ctype.h>

static size_t

prepare_filename (char *dest, const char *src)

{

  size_t ret = 1;

  if (src)

    while (*src)

      {

        /* isprint with some lang return false for some chars */

        if(!iscntrl (*src))

          {

            if (dest)

              *dest++ = *src;

            ret++;

          }

        else

          {

            if (dest)

              dest += sprintf (dest, "%%%02x", (unsigned char) *src );

            ret += 3;

          }

        src++;

      }

  if (dest)

    *dest = 0;

  return ret;

}

#endif /* USE_NLS_PROGRESS_BAR */

static void *

bar_create (const char *f_download, wgint initial, wgint total)

{

  struct bar_progress *bp = xnew0 (struct bar_progress);

  /* In theory, our callers should take care of this pathological

     case, but it can sometimes happen. */

  if (initial > total)

    total = initial;

  bp->initial_length = initial;

  bp->total_length   = total;

  /* Zero-width mbc must be replaced to avoid buffer overflow.

     Another way is to allocate a buffer that allows contain

     full f_download, but in this case some escape sequences may break "bar" */

  bp->f_download  = xmalloc (prepare_filename (NULL, f_download));

  prepare_filename (bp->f_download, f_download);

  /* Initialize screen_width if this hasn't been done or if it might

     have changed, as indicated by receiving SIGWINCH.  */

  if (!screen_width || received_sigwinch)

    {

      screen_width = determine_screen_width ();

      if (!screen_width)

        screen_width = DEFAULT_SCREEN_WIDTH;

      else if (screen_width < MINIMUM_SCREEN_WIDTH)

        screen_width = MINIMUM_SCREEN_WIDTH;

      received_sigwinch = 0;

    }

  /* - 1 because we don't want to use the last screen column. */

  bp->width = screen_width - 1;

  /* + enough space for the terminating zero, and hopefully enough room

   * for multibyte characters. */

#define BUF_LEN (bp->width * 2 + 100)

  bp->buffer = xcalloc (BUF_LEN, 1);

  logputs (LOG_VERBOSE, "\n");

  create_image (bp, 0, false);

  display_image (bp->buffer);

  return bp;

}

static void update_speed_ring (struct bar_progress *, wgint, double);

static void

bar_update (void *progress, wgint howmuch, double dltime)

{

  struct bar_progress *bp = progress;

  bp->dltime = dltime;

  if (WGINT_MAX - (bp->count + bp->initial_length) >= howmuch)

    bp->count += howmuch;

  else

    bp->count = WGINT_MAX - bp->initial_length;

  if (bp->total_length > 0

      && bp->count + bp->initial_length > bp->total_length)

    /* We could be downloading more than total_length, e.g. when the

       server sends an incorrect Content-Length header.  In that case,

       adjust bp->total_length to the new reality, so that the code in

       create_image() that depends on total size being smaller or

       equal to the expected size doesn't abort.  */

    bp->total_length = bp->initial_length + bp->count;

  update_speed_ring (bp, howmuch, dltime);

}

static void

bar_draw (void *progress)

{

  bool force_screen_update = false;

  struct bar_progress *bp = progress;

  /* If SIGWINCH (the window size change signal) been received,

     determine the new screen size and update the screen.  */

  if (received_sigwinch)

    {

      int old_width = screen_width;

      screen_width = determine_screen_width ();

      if (!screen_width)

        screen_width = DEFAULT_SCREEN_WIDTH;

      else if (screen_width < MINIMUM_SCREEN_WIDTH)

        screen_width = MINIMUM_SCREEN_WIDTH;

      if (screen_width != old_width)

        {

          bp->width = screen_width - 1;

          bp->buffer = xrealloc (bp->buffer, BUF_LEN);

          force_screen_update = true;

        }

      received_sigwinch = 0;

    }

  if (bp->dltime - bp->last_screen_update < REFRESH_INTERVAL && !force_screen_update)

    /* Don't update more often than five times per second. */

    return;

  create_image (bp, bp->dltime, false);

  display_image (bp->buffer);

  bp->last_screen_update = bp->dltime;

}

static void

bar_finish (void *progress, double dltime)

{

  struct bar_progress *bp = progress;

  if (bp->total_length > 0

      && bp->count + bp->initial_length > bp->total_length)

    /* See bar_update() for explanation. */

    bp->total_length = bp->initial_length + bp->count;

  create_image (bp, dltime, true);

  display_image (bp->buffer);

  logputs (LOG_VERBOSE, "\n");

  logputs (LOG_PROGRESS, "\n");

  xfree (bp->f_download);

  xfree (bp->buffer);

  xfree (bp);

}

/* This code attempts to maintain the notion of a "current" download

   speed, over the course of no less than 3s.  (Shorter intervals

   produce very erratic results.)

   To do so, it samples the speed in 150ms intervals and stores the

   recorded samples in a FIFO history ring.  The ring stores no more

   than 20 intervals, hence the history covers the period of at least

   three seconds and at most 20 reads into the past.  This method

   should produce reasonable results for downloads ranging from very

   slow to very fast.

   The idea is that for fast downloads, we get the speed over exactly

   the last three seconds.  For slow downloads (where a network read

   takes more than 150ms to complete), we get the speed over a larger

   time period, as large as it takes to complete twenty reads.  This

   is good because slow downloads tend to fluctuate more and a

   3-second average would be too erratic.  */

static void

update_speed_ring (struct bar_progress *bp, wgint howmuch, double dltime)

{

  struct bar_progress_hist *hist = &bp->hist;

  double recent_age = dltime - bp->recent_start;

  /* Update the download count. */

  bp->recent_bytes += howmuch;

  /* For very small time intervals, we return after having updated the

     "recent" download count.  When its age reaches or exceeds minimum

     sample time, it will be recorded in the history ring.  */

  if (recent_age < DLSPEED_SAMPLE_MIN)

    return;

  if (howmuch == 0)

    {

      /* If we're not downloading anything, we might be stalling,

         i.e. not downloading anything for an extended period of time.

         Since 0-reads do not enter the history ring, recent_age

         effectively measures the time since last read.  */

      if (recent_age >= STALL_START_TIME)

        {

          /* If we're stalling, reset the ring contents because it's

             stale and because it will make bar_update stop printing

             the (bogus) current bandwidth.  */

          bp->stalled = true;

          xzero (*hist);

          bp->recent_bytes = 0;

        }

      return;

    }

  /* We now have a non-zero amount of to store to the speed ring.  */

  /* If the stall status was acquired, reset it. */

  if (bp->stalled)

    {

      bp->stalled = false;

      /* "recent_age" includes the entire stalled period, which

         could be very long.  Don't update the speed ring with that

         value because the current bandwidth would start too small.

         Start with an arbitrary (but more reasonable) time value and

         let it level out.  */

      recent_age = 1;

    }

  /* Store "recent" bytes and download time to history ring at the

     position POS.  */

  /* To correctly maintain the totals, first invalidate existing data

     (least recent in time) at this position. */

  hist->total_time  -= hist->times[hist->pos];

  hist->total_bytes -= hist->bytes[hist->pos];

  /* Now store the new data and update the totals. */

  hist->times[hist->pos] = recent_age;

  hist->bytes[hist->pos] = bp->recent_bytes;

  hist->total_time  += recent_age;

  hist->total_bytes += bp->recent_bytes;

  /* Start a new "recent" period. */

  bp->recent_start = dltime;

  bp->recent_bytes = 0;

  /* Advance the current ring position. */

  if (++hist->pos == DLSPEED_HISTORY_SIZE)

    hist->pos = 0;

#if 0

  /* Sledgehammer check to verify that the totals are accurate. */

  {

    int i;

    double sumt = 0, sumb = 0;

    for (i = 0; i < DLSPEED_HISTORY_SIZE; i++)

      {

        sumt += hist->times[i];

        sumb += hist->bytes[i];

      }

    assert (sumb == hist->total_bytes);

    /* We can't use assert(sumt==hist->total_time) because some

       precision is lost by adding and subtracting floating-point

       numbers.  But during a download this precision should not be

       detectable, i.e. no larger than 1ns.  */

    double diff = sumt - hist->total_time;

    if (diff < 0) diff = -diff;

    assert (diff < 1e-9);

  }

#endif

}

#if USE_NLS_PROGRESS_BAR

static int

count_cols (const char *mbs)

{

  mbchar_t mbc;

  mbi_iterator_t iter;

  int cols = 0;

  mbi_init (iter, mbs, strlen(mbs));