filter/tex/lib.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * TeX filter library functions.
  19  *
  20  * @package    filter
  21  * @subpackage tex
  22  * @copyright  2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu
  23  *             Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca
  24  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25  */
  26
  27 defined('MOODLE_INTERNAL') || die();
  28
  29 function filter_tex_get_executable($debug=false) {
  30     global $CFG;
  31
  32     if ((PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows")) {
  33         return "$CFG->dirroot/filter/tex/mimetex.exe";
  34     }
  35
  36     if ($pathmimetex = get_config('filter_tex', 'pathmimetex')) {
  37         if (is_executable($pathmimetex)) {
  38             return $pathmimetex;
  39         } else {
  40             print_error('mimetexnotexecutable', 'error');
  41         }
  42     }
  43
  44     $custom_commandpath = "$CFG->dirroot/filter/tex/mimetex";
  45     if (file_exists($custom_commandpath)) {
  46         if (is_executable($custom_commandpath)) {
  47             return $custom_commandpath;
  48         } else {
  49             print_error('mimetexnotexecutable', 'error');
  50         }
  51     }
  52
  53     switch (PHP_OS) {
  54         case "Linux":   return "$CFG->dirroot/filter/tex/mimetex.linux";
  55         case "Darwin":  return "$CFG->dirroot/filter/tex/mimetex.darwin";
  56         case "FreeBSD": return "$CFG->dirroot/filter/tex/mimetex.freebsd";
  57     }
  58
  59     print_error('mimetexisnotexist', 'error');
  60 }
  61
  62 function filter_tex_sanitize_formula($texexp) {
  63     /// Check $texexp against blacklist (whitelisting could be more complete but also harder to maintain)
  64     $tex_blacklist = array(
  65         'include','command','loop','repeat','open','toks','output',
  66         'input','catcode','name','^^',
  67         '\def','\edef','\gdef','\xdef',
  68         '\every','\errhelp','\errorstopmode','\scrollmode','\nonstopmode',
  69         '\batchmode','\read','\write','csname','\newhelp','\uppercase',
  70         '\lowercase','\relax','\aftergroup',
  71         '\afterassignment','\expandafter','\noexpand','\special',
  72         '\let', '\futurelet','\else','\fi','\chardef','\makeatletter','\afterground',
  73         '\noexpand','\line','\mathcode','\item','\section','\mbox','\declarerobustcommand'
  74     );
  75
  76     return  str_ireplace($tex_blacklist, 'forbiddenkeyword', $texexp);
  77 }
  78
  79 function filter_tex_get_cmd($pathname, $texexp) {
  80     $texexp = filter_tex_sanitize_formula($texexp);
  81     $texexp = escapeshellarg($texexp);
  82     $executable = filter_tex_get_executable(false);
  83
  84     if ((PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows")) {
  85         $executable = str_replace(' ', '^ ', $executable);
  86         return "$executable ++ -e  \"$pathname\" -- $texexp";
  87
  88     } else {
  89         return "\"$executable\" -e \"$pathname\" -- $texexp";
  90     }
  91 }
  92
  93 /**
  94  * Purge all caches when settings changed.
  95  */
  96 function filter_tex_updatedcallback($name) {
  97     global $CFG, $DB;
  98     reset_text_filters_cache();
  99
 100     if (file_exists("$CFG->dataroot/filter/tex")) {
 101         remove_dir("$CFG->dataroot/filter/tex");
 102     }
 103     if (file_exists("$CFG->dataroot/filter/algebra")) {
 104         remove_dir("$CFG->dataroot/filter/algebra");
 105     }
 106     if (file_exists("$CFG->tempdir/latex")) {
 107         remove_dir("$CFG->tempdir/latex");
 108     }
 109
 110     $DB->delete_records('cache_filters', array('filter'=>'tex'));
 111     $DB->delete_records('cache_filters', array('filter'=>'algebra'));
 112
 113     $pathlatex = get_config('filter_tex', 'pathlatex');
 114     if ($pathlatex === false) {
 115         // detailed settings not present yet
 116         return;
 117     }
 118
 119     $pathlatex = trim($pathlatex, " '\"");
 120     $pathdvips = trim(get_config('filter_tex', 'pathdvips'), " '\"");
 121     $pathconvert = trim(get_config('filter_tex', 'pathconvert'), " '\"");
 122     $pathdvisvgm = trim(get_config('filter_tex', 'pathdvisvgm'), " '\"");
 123
 124     $supportedformats = array('gif');
 125     if ((is_file($pathlatex) && is_executable($pathlatex)) &&
 126             (is_file($pathdvips) && is_executable($pathdvips))) {
 127         if (is_file($pathconvert) && is_executable($pathconvert)) {
 128              $supportedformats[] = 'png';
 129         }
 130         if (is_file($pathdvisvgm) && is_executable($pathdvisvgm)) {
 131              $supportedformats[] = 'svg';
 132         }
 133     }
 134     if (!in_array(get_config('filter_tex', 'convertformat'), $supportedformats)) {
 135         set_config('convertformat', array_pop($supportedformats), 'filter_tex');
 136     }
 137
 138 }
 139