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     $custom_commandpath = "$CFG->dirroot/filter/tex/mimetex";
  46     if (file_exists($custom_commandpath)) {
  47         if (is_executable($custom_commandpath)) {
  48             return $custom_commandpath;
  49         } else {
  50             print_error('mimetexnotexecutable', 'error');
  51         }
  52     }
  53
  54     switch (PHP_OS) {
  55         case "Linux":   return "$CFG->dirroot/filter/tex/mimetex.linux";
  56         case "Darwin":  return "$CFG->dirroot/filter/tex/mimetex.darwin";
  57         case "FreeBSD": return "$CFG->dirroot/filter/tex/mimetex.freebsd";
  58     }
  59
  60     print_error('mimetexisnotexist', 'error');
  61 }
  62
  63 function filter_tex_sanitize_formula($texexp) {
  64     /// Check $texexp against blacklist (whitelisting could be more complete but also harder to maintain)
  65     $tex_blacklist = array(
  66         'include','command','loop','repeat','open','toks','output',
  67         'input','catcode','name','^^',
  68         '\def','\edef','\gdef','\xdef',
  69         '\every','\errhelp','\errorstopmode','\scrollmode','\nonstopmode',
  70         '\batchmode','\read','\write','csname','\newhelp','\uppercase',
  71         '\lowercase','\relax','\aftergroup',
  72         '\afterassignment','\expandafter','\noexpand','\special',
  73         '\let', '\futurelet','\else','\fi','\chardef','\makeatletter','\afterground',
  74         '\noexpand','\line','\mathcode','\item','\section','\mbox','\declarerobustcommand'
  75     );
  76
  77     return  str_ireplace($tex_blacklist, 'forbiddenkeyword', $texexp);
  78 }
  79
  80 function filter_tex_get_cmd($pathname, $texexp) {
  81     $texexp = filter_tex_sanitize_formula($texexp);
  82     $texexp = escapeshellarg($texexp);
  83     $executable = filter_tex_get_executable(false);
  84
  85     if ((PHP_OS == "WINNT") || (PHP_OS == "WIN32") || (PHP_OS == "Windows")) {
  86         $executable = str_replace(' ', '^ ', $executable);
  87         return "$executable ++ -e  \"$pathname\" -- $texexp";
  88
  89     } else {
  90         return "\"$executable\" -e \"$pathname\" -- $texexp";
  91     }
  92 }
  93
  94 /**
  95  * Purge all caches when settings changed.
  96  */
  97 function filter_tex_updatedcallback($name) {
  98     global $CFG, $DB;
  99     reset_text_filters_cache();
 100
 101     if (file_exists("$CFG->dataroot/filter/tex")) {
 102         remove_dir("$CFG->dataroot/filter/tex");
 103     }
 104     if (file_exists("$CFG->dataroot/filter/algebra")) {
 105         remove_dir("$CFG->dataroot/filter/algebra");
 106     }
 107     if (file_exists("$CFG->tempdir/latex")) {
 108         remove_dir("$CFG->tempdir/latex");
 109     }
 110
 111     $DB->delete_records('cache_filters', array('filter'=>'tex'));
 112     $DB->delete_records('cache_filters', array('filter'=>'algebra'));
 113
 114     if (!isset($CFG->filter_tex_pathlatex)) {
 115         // detailed settings not present yet
 116         return;
 117     }
 118
 119     if (!(is_file($CFG->filter_tex_pathlatex) && is_executable($CFG->filter_tex_pathlatex) &&
 120           is_file($CFG->filter_tex_pathdvips) && is_executable($CFG->filter_tex_pathdvips) &&
 121           is_file($CFG->filter_tex_pathconvert) && is_executable($CFG->filter_tex_pathconvert))) {
 122         // LaTeX, dvips or convert are not available, and mimetex can only produce GIFs so...
 123         set_config('filter_tex_convertformat', 'gif');
 124     }
 125 }
 126
 127