Source Code

   1  <?php
   2  /**
   3   * functions.php
   4   * -----------------------------------------------------------------------------
   5   * Shared helper library for "What Can I Learn About You?"
   6   *
   7   * Pure PHP, no dependencies. Everything here is safe to call on plain shared
   8   * hosting. Functions are guarded with function_exists() so double-includes are
   9   * harmless.
  10   *
  11   * Contents:
  12   *   - Output helpers ......... e() , eattr()
  13   *   - Time helpers ........... server_time(), utc_time(), http_date()
  14   *   - Visitor counter ........ get_visit_count(), bump_visit_count()
  15   *   - HTTP header tools ...... collect_request_headers(), client_ip(),
  16   *                              http_protocol(), is_https()
  17   *   - ASCII / retro art ...... ascii_logo(), pixel_gif(), spacer_gif(),
  18   *                              button_88x31(), section_icon()
  19   *   - Guestbook helpers ...... read_guestbook(), append_guestbook()
  20   *   - Misc ................... rand_seeded(), human_bytes()
  21   * -----------------------------------------------------------------------------
  22   */
  23  
  24  require_once __DIR__ . '/config.php';
  25  
  26  // =============================================================================
  27  // OUTPUT HELPERS
  28  // =============================================================================
  29  
  30  /**
  31   * Escape text for safe HTML output (element content).
  32   */
  33  if (!function_exists('e')) {
  34      function e($value): string
  35      {
  36          return htmlspecialchars((string)$value, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
  37      }
  38  }
  39  
  40  /**
  41   * Escape text for safe use inside a double-quoted HTML attribute.
  42   * (Same routine as e() but named for intent/readability at call sites.)
  43   */
  44  if (!function_exists('eattr')) {
  45      function eattr($value): string
  46      {
  47          return htmlspecialchars((string)$value, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
  48      }
  49  }
  50  
  51  // =============================================================================
  52  // TIME HELPERS
  53  // =============================================================================
  54  
  55  /**
  56   * Current server local time, formatted BBS-style.
  57   */
  58  if (!function_exists('server_time')) {
  59      function server_time(): string
  60      {
  61          return date('Y-m-d H:i:s T');
  62      }
  63  }
  64  
  65  /**
  66   * Current UTC time, formatted BBS-style.
  67   */
  68  if (!function_exists('utc_time')) {
  69      function utc_time(): string
  70      {
  71          return gmdate('Y-m-d H:i:s') . ' UTC';
  72      }
  73  }
  74  
  75  /**
  76   * RFC-822 style date, used by the RSS feed.
  77   */
  78  if (!function_exists('http_date')) {
  79      function http_date($timestamp = null): string
  80      {
  81          $timestamp = $timestamp === null ? time() : (int)$timestamp;
  82          return gmdate('D, d M Y H:i:s', $timestamp) . ' +0000';
  83      }
  84  }
  85  
  86  // =============================================================================
  87  // VISITOR COUNTER  (flat file; degrades gracefully if not writable)
  88  // =============================================================================
  89  
  90  /**
  91   * Read the current visitor count without incrementing.
  92   * Returns COUNTER_SEED if the file cannot be read.
  93   */
  94  if (!function_exists('get_visit_count')) {
  95      function get_visit_count(): int
  96      {
  97          if (is_readable(COUNTER_FILE)) {
  98              $raw = @file_get_contents(COUNTER_FILE);
  99              if ($raw !== false && $raw !== '') {
 100                  $n = (int)trim($raw);
 101                  if ($n > 0) {
 102                      return $n;
 103                  }
 104              }
 105          }
 106          return COUNTER_SEED;
 107      }
 108  }
 109  
 110  /**
 111   * Increment and persist the visitor count, returning the new value.
 112   * Uses an exclusive lock so concurrent hits do not corrupt the file. If the
 113   * data directory is not writable, we simply return the read-only count so the
 114   * page never breaks.
 115   *
 116   * NOTE: This is an aggregate tally only. We do NOT record IPs, timestamps,
 117   * user agents, or anything that could identify a visitor. It is a single
 118   * integer in a text file, in keeping with the site's "we store nothing about
 119   * you" promise.
 120   */
 121  if (!function_exists('bump_visit_count')) {
 122      function bump_visit_count(): int
 123      {
 124          // Make sure the data directory exists (first run on a fresh upload).
 125          if (!is_dir(DATA_DIR)) {
 126              @mkdir(DATA_DIR, 0755, true);
 127          }
 128  
 129          // If we cannot write, just report the current number.
 130          if ((file_exists(COUNTER_FILE) && !is_writable(COUNTER_FILE))
 131              || (!file_exists(COUNTER_FILE) && !is_writable(DATA_DIR))) {
 132              return get_visit_count();
 133          }
 134  
 135          $fp = @fopen(COUNTER_FILE, 'c+');
 136          if ($fp === false) {
 137              return get_visit_count();
 138          }
 139  
 140          $count = COUNTER_SEED;
 141          if (@flock($fp, LOCK_EX)) {
 142              $raw = stream_get_contents($fp);
 143              $current = ($raw !== false && trim($raw) !== '') ? (int)trim($raw) : COUNTER_SEED;
 144              if ($current < COUNTER_SEED) {
 145                  $current = COUNTER_SEED;
 146              }
 147              $count = $current + 1;
 148  
 149              rewind($fp);
 150              ftruncate($fp, 0);
 151              fwrite($fp, (string)$count);
 152              fflush($fp);
 153              @flock($fp, LOCK_UN);
 154          }
 155          fclose($fp);
 156  
 157          return $count;
 158      }
 159  }
 160  
 161  /**
 162   * Render a count as a zero-padded "odometer" string, e.g. 000013337.
 163   */
 164  if (!function_exists('odometer')) {
 165      function odometer(int $n, int $width = 9): string
 166      {
 167          return str_pad((string)$n, $width, '0', STR_PAD_LEFT);
 168      }
 169  }
 170  
 171  // =============================================================================
 172  // HTTP HEADER TOOLS
 173  // =============================================================================
 174  
 175  /**
 176   * Best-effort real client IP. We look at a few common proxy headers but always
 177   * fall back to REMOTE_ADDR. This is only used to enrich the on-screen report
 178   * for the visitor themselves -- it is never stored or logged.
 179   */
 180  if (!function_exists('client_ip')) {
 181      function client_ip(): string
 182      {
 183          $candidates = array();
 184  
 185          if (!empty($_SERVER['HTTP_CF_CONNECTING_IP'])) {
 186              $candidates[] = $_SERVER['HTTP_CF_CONNECTING_IP'];
 187          }
 188          if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
 189              // May be a comma-separated list; the left-most is the origin client.
 190              foreach (explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']) as $part) {
 191                  $candidates[] = trim($part);
 192              }
 193          }
 194          if (!empty($_SERVER['HTTP_X_REAL_IP'])) {
 195              $candidates[] = $_SERVER['HTTP_X_REAL_IP'];
 196          }
 197          if (!empty($_SERVER['REMOTE_ADDR'])) {
 198              $candidates[] = $_SERVER['REMOTE_ADDR'];
 199          }
 200  
 201          foreach ($candidates as $ip) {
 202              $ip = trim($ip);
 203              if (filter_var($ip, FILTER_VALIDATE_IP)) {
 204                  return $ip;
 205              }
 206          }
 207  
 208          return isset($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : '0.0.0.0';
 209      }
 210  }
 211  
 212  /**
 213   * True if the request arrived over HTTPS (directly or via a trusted proxy).
 214   */
 215  if (!function_exists('is_https')) {
 216      function is_https(): bool
 217      {
 218          if (!empty($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) !== 'off') {
 219              return true;
 220          }
 221          if (isset($_SERVER['SERVER_PORT']) && (int)$_SERVER['SERVER_PORT'] === 443) {
 222              return true;
 223          }
 224          if (!empty($_SERVER['HTTP_X_FORWARDED_PROTO'])
 225              && strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']) === 'https') {
 226              return true;
 227          }
 228          if (!empty($_SERVER['HTTP_CF_VISITOR'])
 229              && stripos($_SERVER['HTTP_CF_VISITOR'], 'https') !== false) {
 230              return true;
 231          }
 232          return false;
 233      }
 234  }
 235  
 236  /**
 237   * The HTTP protocol version string, e.g. "HTTP/1.1" or "HTTP/2".
 238   */
 239  if (!function_exists('http_protocol')) {
 240      function http_protocol(): string
 241      {
 242          return isset($_SERVER['SERVER_PROTOCOL']) ? $_SERVER['SERVER_PROTOCOL'] : 'HTTP/1.0';
 243      }
 244  }
 245  
 246  /**
 247   * Reconstruct the raw request headers from the $_SERVER superarray.
 248   * Returns an associative array of Header-Name => value, with keys normalised to
 249   * canonical "Title-Case" form. Uses getallheaders() when available (Apache) and
 250   * falls back to parsing HTTP_* keys everywhere else.
 251   */
 252  if (!function_exists('collect_request_headers')) {
 253      function collect_request_headers(): array
 254      {
 255          $headers = array();
 256  
 257          if (function_exists('getallheaders')) {
 258              $raw = getallheaders();
 259              if (is_array($raw)) {
 260                  foreach ($raw as $name => $value) {
 261                      $headers[normalize_header_name($name)] = $value;
 262                  }
 263              }
 264          }
 265  
 266          // Always merge the $_SERVER view too (covers non-Apache and CLI-ish SAPIs).
 267          foreach ($_SERVER as $key => $value) {
 268              if (strpos($key, 'HTTP_') === 0) {
 269                  $name = normalize_header_name(str_replace('_', '-', substr($key, 5)));
 270                  if (!isset($headers[$name])) {
 271                      $headers[$name] = $value;
 272                  }
 273              }
 274          }
 275  
 276          // A few useful non-HTTP_ entries that are really request metadata.
 277          if (!empty($_SERVER['CONTENT_TYPE'])) {
 278              $headers['Content-Type'] = $_SERVER['CONTENT_TYPE'];
 279          }
 280          if (!empty($_SERVER['CONTENT_LENGTH'])) {
 281              $headers['Content-Length'] = $_SERVER['CONTENT_LENGTH'];
 282          }
 283  
 284          // Sort for stable, readable display.
 285          ksort($headers, SORT_STRING | SORT_FLAG_CASE);
 286  
 287          return $headers;
 288      }
 289  }
 290  
 291  /**
 292   * Normalise a header name to canonical Title-Case-With-Dashes.
 293   */
 294  if (!function_exists('normalize_header_name')) {
 295      function normalize_header_name(string $name): string
 296      {
 297          $name  = strtolower(trim($name));
 298          $parts = explode('-', $name);
 299          foreach ($parts as $i => $p) {
 300              // Keep well-known acronyms upper-cased.
 301              $upper = strtoupper($p);
 302              if (in_array($upper, array('IP', 'DNT', 'TE', 'UA', 'WWW', 'CF', 'ID', 'URL'), true)) {
 303                  $parts[$i] = $upper;
 304              } else {
 305                  $parts[$i] = ucfirst($p);
 306              }
 307          }
 308          return implode('-', $parts);
 309      }
 310  }
 311  
 312  // =============================================================================
 313  // ASCII / RETRO ART
 314  // =============================================================================
 315  
 316  /**
 317   * The big header logo. Kept as a heredoc so the alignment is exact. Rendered
 318   * inside a <pre> by header.php.
 319   */
 320  if (!function_exists('ascii_logo')) {
 321      function ascii_logo(): string
 322      {
 323          return <<<'ART'
 324   __        __         _     ____                  _
 325   \ \      / /_ _  ___| |_  / ___|__ _ _ __     _ | |
 326    \ \ /\ / / _` |/ __| __| \___ / _` | '_ \  _| || |
 327     \ V  V / (_| | (__| |_   ___) | (_| | | | ||_   _|
 328      \_/\_/ \__,_|\___|\__| |____/ \__,_|_| |_|  |_|
 329  
 330    _                          _    _                 _
 331   | |    ___  __ _ _ __ _ __ | |  / \   _ __  ___  _| |_
 332   | |   / _ \/ _` | '__| '_ \| | / _ \ | '_ \/ _ \|_   _|
 333   | |__|  __/ (_| | |  | | | |_|/ ___ \| |_) | (_) | |_|
 334   |_____\___|\__,_|_|  |_| |_(_)_/   \_\ .__/ \___/  (_)
 335                                        |_|
 336               W H A T   C A N   I   L E A R N   ?
 337  ART;
 338      }
 339  }
 340  
 341  /**
 342   * Return a 1x1 transparent GIF as a data URI. Used for classic spacer.gif
 343   * layout tricks and as a base for coloured pixel blocks.
 344   */
 345  if (!function_exists('spacer_gif')) {
 346      function spacer_gif(): string
 347      {
 348          // Standard 1x1 transparent GIF89a.
 349          return 'data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7';
 350      }
 351  }
 352  
 353  /**
 354   * Emit a <img> tag for the transparent spacer at a given size. The web-1.0 way
 355   * to do layout and padding.
 356   */
 357  if (!function_exists('spacer')) {
 358      function spacer(int $w = 1, int $h = 1): string
 359      {
 360          return '<img src="' . spacer_gif() . '" width="' . $w . '" height="' . $h
 361               . '" alt="" border="0">';
 362      }
 363  }
 364  
 365  /**
 366   * A solid coloured "pixel GIF" block, produced with CSS on top of the spacer so
 367   * we never have to upload any binaries. Handy for status LEDs and bar charts.
 368   */
 369  if (!function_exists('pixel_gif')) {
 370      function pixel_gif(string $color, int $w = 10, int $h = 10, string $title = ''): string
 371      {
 372          $t = $title !== '' ? ' title="' . eattr($title) . '"' : '';
 373          return '<img src="' . spacer_gif() . '" width="' . $w . '" height="' . $h
 374               . '" alt=""' . $t . ' style="background:' . eattr($color)
 375               . ';line-height:0;font-size:0;border:0;vertical-align:middle">';
 376      }
 377  }
 378  
 379  /**
 380   * Render one classic 88x31 button as a pure-CSS box (no image upload needed).
 381   * $btn = [top-text, bottom-text, fg-color, bg-color]
 382   */
 383  if (!function_exists('button_88x31')) {
 384      function button_88x31(array $btn): string
 385      {
 386          list($top, $bottom, $fg, $bg) = $btn;
 387          $style = 'display:inline-block;width:88px;height:31px;'
 388                 . 'background:' . eattr($bg) . ';color:' . eattr($fg) . ';'
 389                 . 'border:1px solid #808080;text-align:center;'
 390                 . 'font-family:\'Courier New\',monospace;line-height:1;'
 391                 . 'overflow:hidden;vertical-align:middle;margin:2px;'
 392                 . 'box-sizing:border-box;';
 393          $out  = '<span class="btn88" style="' . $style . '">';
 394          $out .= '<span style="display:block;font-size:9px;padding-top:5px;letter-spacing:1px">'
 395                . e($top) . '</span>';
 396          $out .= '<span style="display:block;font-size:12px;font-weight:bold;letter-spacing:1px">'
 397                . e($bottom) . '</span>';
 398          $out .= '</span>';
 399          return $out;
 400      }
 401  }
 402  
 403  /**
 404   * Tiny monochrome pixel-art icon for a section, drawn as an inline SVG data-URI
 405   * so it stays crisp and needs no binary upload. Supported names:
 406   *   monitor, globe, chip, lock, warning, folder, eye, key, disk, plug
 407   * Falls back to a small square for unknown names.
 408   */
 409  if (!function_exists('section_icon')) {
 410      function section_icon(string $name, string $color = '#00FF00', int $size = 16): string
 411      {
 412          // 8x8 pixel grids. '1' = filled pixel. Deliberately chunky/retro.
 413          $grids = array(
 414              'monitor' => array(
 415                  '11111111',
 416                  '10000001',
 417                  '10111101',
 418                  '10100101',
 419                  '10111101',
 420                  '11111111',
 421                  '00111100',
 422                  '01111110',
 423              ),
 424              'globe' => array(
 425                  '00111100',
 426                  '01100110',
 427                  '11011011',
 428                  '10111101',
 429                  '10111101',
 430                  '11011011',
 431                  '01100110',
 432                  '00111100',
 433              ),
 434              'chip' => array(
 435                  '00100100',
 436                  '11111111',
 437                  '10111101',
 438                  '10100101',
 439                  '10100101',
 440                  '10111101',
 441                  '11111111',
 442                  '00100100',
 443              ),
 444              'lock' => array(
 445                  '00111100',
 446                  '01100110',
 447                  '01100110',
 448                  '11111111',
 449                  '11011011',
 450                  '11000011',
 451                  '11011011',
 452                  '11111111',
 453              ),
 454              'warning' => array(
 455                  '00011000',
 456                  '00011000',
 457                  '00111100',
 458                  '00111100',
 459                  '01100110',
 460                  '01111110',
 461                  '11100111',
 462                  '11111111',
 463              ),
 464              'folder' => array(
 465                  '00000000',
 466                  '11100000',
 467                  '11111110',
 468                  '10000010',
 469                  '10000010',
 470                  '10000010',
 471                  '11111110',
 472                  '00000000',
 473              ),
 474              'eye' => array(
 475                  '00000000',
 476                  '00111100',
 477                  '01000010',
 478                  '10011001',
 479                  '10011001',
 480                  '01000010',
 481                  '00111100',
 482                  '00000000',
 483              ),
 484              'key' => array(
 485                  '00111000',
 486                  '01000100',
 487                  '01000100',
 488                  '00111000',
 489                  '00010000',
 490                  '00011000',
 491                  '00010000',
 492                  '00011000',
 493              ),
 494              'disk' => array(
 495                  '11111110',
 496                  '10011010',
 497                  '10011010',
 498                  '11111110',
 499                  '10000010',
 500                  '10111010',
 501                  '10111010',
 502                  '11111110',
 503              ),
 504              'plug' => array(
 505                  '00100100',
 506                  '00100100',
 507                  '01111110',
 508                  '01111110',
 509                  '00111100',
 510                  '00011000',
 511                  '00011000',
 512                  '00111100',
 513              ),
 514          );
 515  
 516          $grid = isset($grids[$name]) ? $grids[$name] : array(
 517              '11111111','10000001','10000001','10000001',
 518              '10000001','10000001','10000001','11111111',
 519          );
 520  
 521          // Build a compact SVG with one <rect> per filled pixel.
 522          $rects = '';
 523          foreach ($grid as $y => $row) {
 524              $len = strlen($row);
 525              for ($x = 0; $x < $len; $x++) {
 526                  if ($row[$x] === '1') {
 527                      $rects .= '<rect x="' . $x . '" y="' . $y . '" width="1" height="1"/>';
 528                  }
 529              }
 530          }
 531          $svg = '<svg xmlns="http://www.w3.org/2000/svg" width="' . $size . '" height="' . $size
 532               . '" viewBox="0 0 8 8" shape-rendering="crispEdges" fill="' . $color . '">'
 533               . $rects . '</svg>';
 534  
 535          $uri = 'data:image/svg+xml;base64,' . base64_encode($svg);
 536          return '<img src="' . $uri . '" width="' . $size . '" height="' . $size
 537               . '" alt="' . eattr($name) . '" title="' . eattr($name)
 538               . '" border="0" style="vertical-align:middle;image-rendering:pixelated">';
 539      }
 540  }
 541  
 542  // =============================================================================
 543  // GUESTBOOK HELPERS  (flat file; append-only; no database)
 544  // =============================================================================
 545  
 546  /**
 547   * Read guestbook entries, newest first. Each entry is one line stored as
 548   * pipe-separated: epoch|name|message  (name/message are already sanitised on
 549   * write). Returns an array of ['time'=>int,'name'=>string,'message'=>string].
 550   */
 551  if (!function_exists('read_guestbook')) {
 552      function read_guestbook(int $limit = 100): array
 553      {
 554          $entries = array();
 555          if (!is_readable(GUESTBOOK_FILE)) {
 556              return $entries;
 557          }
 558          $lines = @file(GUESTBOOK_FILE, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
 559          if ($lines === false) {
 560              return $entries;
 561          }
 562          foreach ($lines as $line) {
 563              $parts = explode('|', $line, 3);
 564              if (count($parts) === 3) {
 565                  $entries[] = array(
 566                      'time'    => (int)$parts[0],
 567                      'name'    => guestbook_decode($parts[1]),
 568                      'message' => guestbook_decode($parts[2]),
 569                  );
 570              }
 571          }
 572          // Newest first.
 573          $entries = array_reverse($entries);
 574          if ($limit > 0 && count($entries) > $limit) {
 575              $entries = array_slice($entries, 0, $limit);
 576          }
 577          return $entries;
 578      }
 579  }
 580  
 581  /**
 582   * Encode a field for single-line flat-file storage (strip pipes/newlines).
 583   */
 584  if (!function_exists('guestbook_encode')) {
 585      function guestbook_encode(string $s): string
 586      {
 587          // Store as URL-encoded so pipes and newlines can never break the format.
 588          return rawurlencode($s);
 589      }
 590  }
 591  
 592  /**
 593   * Decode a stored guestbook field.
 594   */
 595  if (!function_exists('guestbook_decode')) {
 596      function guestbook_decode(string $s): string
 597      {
 598          return rawurldecode($s);
 599      }
 600  }
 601  
 602  /**
 603   * Append a sanitised entry to the guestbook. Returns [ok(bool), message(str)].
 604   * Enforces length limits, strips control characters, and caps total entries.
 605   * Stores time + name + message only -- never IP, never user agent.
 606   */
 607  if (!function_exists('append_guestbook')) {
 608      function append_guestbook(string $name, string $message): array
 609      {
 610          $name    = trim($name);
 611          $message = trim($message);
 612  
 613          if ($name === '' || $message === '') {
 614              return array(false, 'Both a handle and a message are required.');
 615          }
 616  
 617          // Collapse whitespace / strip control chars.
 618          $name    = preg_replace('/[\x00-\x1F\x7F]+/u', ' ', $name);
 619          $message = preg_replace('/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/u', ' ', $message);
 620  
 621          if (function_exists('mb_substr')) {
 622              $name    = mb_substr($name, 0, GUESTBOOK_MAX_NAME);
 623              $message = mb_substr($message, 0, GUESTBOOK_MAX_MESSAGE);
 624          } else {
 625              $name    = substr($name, 0, GUESTBOOK_MAX_NAME);
 626              $message = substr($message, 0, GUESTBOOK_MAX_MESSAGE);
 627          }
 628  
 629          if (!is_dir(DATA_DIR)) {
 630              @mkdir(DATA_DIR, 0755, true);
 631          }
 632          if ((file_exists(GUESTBOOK_FILE) && !is_writable(GUESTBOOK_FILE))
 633              || (!file_exists(GUESTBOOK_FILE) && !is_writable(DATA_DIR))) {
 634              return array(false, 'Guestbook is read-only on this server (data/ not writable).');
 635          }
 636  
 637          $line = time() . '|' . guestbook_encode($name) . '|' . guestbook_encode($message) . "\n";
 638  
 639          $ok = @file_put_contents(GUESTBOOK_FILE, $line, FILE_APPEND | LOCK_EX);
 640          if ($ok === false) {
 641              return array(false, 'Could not write to the guestbook.');
 642          }
 643  
 644          // Trim to the last GUESTBOOK_MAX_ENTRIES lines to keep the file bounded.
 645          trim_guestbook();
 646  
 647          return array(true, 'Signed. Thanks for stopping by.');
 648      }
 649  }
 650  
 651  /**
 652   * Keep the guestbook file bounded to GUESTBOOK_MAX_ENTRIES lines.
 653   */
 654  if (!function_exists('trim_guestbook')) {
 655      function trim_guestbook(): void
 656      {
 657          if (!is_readable(GUESTBOOK_FILE) || !is_writable(GUESTBOOK_FILE)) {
 658              return;
 659          }
 660          $lines = @file(GUESTBOOK_FILE, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
 661          if ($lines === false) {
 662              return;
 663          }
 664          if (count($lines) > GUESTBOOK_MAX_ENTRIES) {
 665              $lines = array_slice($lines, -GUESTBOOK_MAX_ENTRIES);
 666              @file_put_contents(GUESTBOOK_FILE, implode("\n", $lines) . "\n", LOCK_EX);
 667          }
 668      }
 669  }
 670  
 671  // =============================================================================
 672  // MISC
 673  // =============================================================================
 674  
 675  /**
 676   * Deterministic pseudo-random int in [min,max] from a string seed. Used for
 677   * flavour text that should stay stable within a request.
 678   */
 679  if (!function_exists('rand_seeded')) {
 680      function rand_seeded(string $seed, int $min, int $max): int
 681      {
 682          if ($max <= $min) {
 683              return $min;
 684          }
 685          $h = crc32($seed);
 686          return $min + ($h % ($max - $min + 1));
 687      }
 688  }
 689  
 690  /**
 691   * Human-readable byte size, e.g. 1536 -> "1.5 KB".
 692   */
 693  if (!function_exists('human_bytes')) {
 694      function human_bytes($bytes): string
 695      {
 696          $bytes = (float)$bytes;
 697          $units = array('B', 'KB', 'MB', 'GB', 'TB');
 698          $i = 0;
 699          while ($bytes >= 1024 && $i < count($units) - 1) {
 700              $bytes /= 1024;
 701              $i++;
 702          }
 703          return ($i === 0 ? (string)(int)$bytes : number_format($bytes, 1)) . ' ' . $units[$i];
 704      }
 705  }
 706  
 707  /**
 708   * Pick the "newest" feature/date from the update log, used by the NEW! easter
 709   * egg and the RSS <lastBuildDate>.
 710   */
 711  if (!function_exists('latest_update_timestamp')) {
 712      function latest_update_timestamp(): int
 713      {
 714          $latest = 0;
 715          if (!empty($GLOBALS['UPDATE_LOG']) && is_array($GLOBALS['UPDATE_LOG'])) {
 716              foreach ($GLOBALS['UPDATE_LOG'] as $row) {
 717                  $ts = strtotime($row[0] . ' 12:00:00 UTC');
 718                  if ($ts && $ts > $latest) {
 719                      $latest = $ts;
 720                  }
 721              }
 722          }
 723          return $latest > 0 ? $latest : time();
 724      }
 725  }
 726