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     $error_message1 = "Your system is not configured to run mimeTeX. You need to download the appropriate<br />"
  33                      ."executable for you ".PHP_OS." platform from <a href=\"http://moodle.org/download/mimetex/\">"
  34                      ."http://moodle.org/download/mimetex/</a>, or obtain the C source<br /> "
  35                      ."from <a href=\"http://www.forkosh.com/mimetex.zip\">"
  36                      ."http://www.forkosh.com/mimetex.zip</a>, compile it and "
  37                      ."put the executable into your<br /> moodle/filter/tex/ directory.";
  38
  39     $error_message2 = "Custom mimetex is not executable!<br /><br />";
  40
  41     if ((PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows")) {
  42         return "$CFG->dirroot/filter/tex/mimetex.exe";
  43     }
  44
  45     if ($pathmimetex = get_config('filter_tex', 'pathmimetex')) {
  46         if (is_executable($pathmimetex)) {
  47             return $pathmimetex;
  48         } else {
  49             print_error('mimetexnotexecutable', 'error');
  50         }
  51     }
  52
  53     $custom_commandpath = "$CFG->dirroot/filter/tex/mimetex";
  54     if (file_exists($custom_commandpath)) {
  55         if (is_executable($custom_commandpath)) {
  56             return $custom_commandpath;
  57         } else {
  58             print_error('mimetexnotexecutable', 'error');
  59         }
  60     }
  61
  62     switch (PHP_OS) {
  63         case "Linux":   return "$CFG->dirroot/filter/tex/mimetex.linux";
  64         case "Darwin":  return "$CFG->dirroot/filter/tex/mimetex.darwin";
  65         case "FreeBSD": return "$CFG->dirroot/filter/tex/mimetex.freebsd";
  66     }
  67
  68     print_error('mimetexisnotexist', 'error');
  69 }
  70
  71 function filter_tex_sanitize_formula($texexp) {
  72     /// Check $texexp against blacklist (whitelisting could be more complete but also harder to maintain)
  73     $tex_blacklist = array(
  74         'include','command','loop','repeat','open','toks','output',
  75         'input','catcode','name','^^',
  76         '\def','\edef','\gdef','\xdef',
  77         '\every','\errhelp','\errorstopmode','\scrollmode','\nonstopmode',
  78         '\batchmode','\read','\write','csname','\newhelp','\uppercase',
  79         '\lowercase','\relax','\aftergroup',
  80         '\afterassignment','\expandafter','\noexpand','\special',
  81         '\let', '\futurelet','\else','\fi','\chardef','\makeatletter','\afterground',
  82         '\noexpand','\line','\mathcode','\item','\section','\mbox','\declarerobustcommand'
  83     );
  84
  85     return  str_ireplace($tex_blacklist, 'forbiddenkeyword', $texexp);
  86 }
  87
  88 function filter_tex_get_cmd($pathname, $texexp) {
  89     $texexp = filter_tex_sanitize_formula($texexp);
  90     $texexp = escapeshellarg($texexp);
  91     $executable = filter_tex_get_executable(false);
  92
  93     if ((PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows")) {
  94         $executable = str_replace(' ', '^ ', $executable);
  95         return "$executable ++ -e  \"$pathname\" -- $texexp";
  96
  97     } else {
  98         return "\"$executable\" -e \"$pathname\" -- $texexp";
  99     }
 100 }
 101
 102 /**
 103  * Purge all caches when settings changed.
 104  */
 105 function filter_tex_updatedcallback($name) {
 106     global $CFG, $DB;
 107     reset_text_filters_cache();
 108
 109     if (file_exists("$CFG->dataroot/filter/tex")) {
 110         remove_dir("$CFG->dataroot/filter/tex");
 111     }
 112     if (file_exists("$CFG->dataroot/filter/algebra")) {
 113         remove_dir("$CFG->dataroot/filter/algebra");
 114     }
 115     if (file_exists("$CFG->tempdir/latex")) {
 116         remove_dir("$CFG->tempdir/latex");
 117     }
 118
 119     $DB->delete_records('cache_filters', array('filter'=>'tex'));
 120     $DB->delete_records('cache_filters', array('filter'=>'algebra'));
 121
 122     $pathlatex = get_config('filter_tex', 'pathlatex');
 123     if ($pathlatex === false) {
 124         // detailed settings not present yet
 125         return;
 126     }
 127
 128     $pathlatex = trim($pathlatex, " '\"");
 129     $pathdvips = trim(get_config('filter_tex', 'pathdvips'), " '\"");
 130     $pathconvert = trim(get_config('filter_tex', 'pathconvert'), " '\"");
 131
 132     if (!(is_file($pathlatex) && is_executable($pathlatex) &&
 133           is_file($pathdvips) && is_executable($pathdvips) &&
 134           is_file($pathconvert) && is_executable($pathconvert))) {
 135         // LaTeX, dvips or convert are not available, and mimetex can only produce GIFs so...
 136         set_config('convertformat', 'gif', 'filter_tex');
 137     }
 138 }
 139
 140