MDL-71240 filter_tex: Support paranoid mode for openin_any in latex

filter/tex/texdebug.php

@@ -238,12 +238,15 @@
         $output .= "<p>base filename for expression is '$md5'</p>\n";
 
         // temporary paths
-        $tex = "$latex->temp_dir/$md5.tex";
+        $tex = "$md5.tex"; // Absolute paths won't work with openin_any = p setting.
         $dvi = "$latex->temp_dir/$md5.dvi";
         $ps = "$latex->temp_dir/$md5.ps";
         $convertformat = get_config('filter_tex', 'convertformat');
         $img = "$latex->temp_dir/$md5.{$convertformat}";
 
+        // Change directory to temp dir so that we can work with relative paths.
+        chdir($latex->temp_dir);
+
         // put the expression as a file into the temp area
         $expression = html_entity_decode($expression);
         $output .= "<p>Processing TeX expression:</p><pre>$expression</pre>\n";
@@ -252,9 +255,6 @@
         fputs($fh, $doc);
         fclose($fh);
 
-        // cd to temp dir
-        chdir($latex->temp_dir);
-
         // step 1: latex command
         $pathlatex = escapeshellarg($pathlatex);
         $cmd = "$pathlatex --interaction=nonstopmode --halt-on-error $tex";