Comment on Partially incorrect MIME type detection for files newly uploaded to the cloud

mario@hub.somaton.com ⁨4⁩ ⁨weeks⁩ ago

• abu@hub.alfredbuehler.ch ⁨4⁩ ⁨weeks⁩ ago

  @Mario Vavti Oh, then I'm simply out of luck that my completely valid CSS file didn't meet the expectations of that function.
  :grinning_squinting_face:

  original
• pepecyb@hub.hubzilla.hu@hub.hubzilla.hu ⁨4⁩ ⁨weeks⁩ ago

  Right, I’ve managed to get a bit further into tracking down the bug. It’s definitely because finfo() doesn’t identify CSS files as such (text/css), but always as text/plain. I’ve tested this on my local machine and on both servers:
  
  

  <?php
  
  $datei = 'shtml01.css'; 
  
  
  if (!file_exists($datei)) {
      echo "Fehler: Die Datei '$datei' wurde nicht gefunden.";
      exit;
  }
  
  try {
      $finfo = finfo_open(FILEINFO_MIME_TYPE);
  
      if ($finfo === false) {
          throw new Exception("Konnte finfo nicht initialisieren.");
      }
  
      $mime_type = finfo_file($finfo, $datei);
  
      finfo_close($finfo);
  
      if ($mime_type !== false && $mime_type !== "") {
          echo "Der MIME-Typ von '$datei' ist: " . $mime_type;
      } else {
          echo "Konnte den MIME-Typ für '$datei' nicht bestimmen.";
      }
  
  } catch (Exception $e) {
      echo "Ein Fehler ist aufgetreten: " . $e->getMessage();
  }
  ?>

  In the hex editor, the file starts with ‘68 31 20 7B’, which corresponds exactly to ‘h1 {’. Nevertheless, it is identified as text/plain.
  
  The problem is probably with libmagic, which apparently cannot recognise CSS. BTW: `file --mime-type shtml01.css` also returns `text/plain`. `file` also relies on libmagic.
  
  I then tried to make the file look a bit more “CSS-like” by adding an `@import` statement right at the start. Even with that, the file was not recognised as `text/css`.
  
  JavaScript, on the other hand, is recognised correctly: application/javascript
  
  This is, of course, unsatisfactory and breaks part of the website app’s functionality.
  
  What could be done to ensure that CSS is recognised correctly and entered into the table?

  original

  • abu@hub.alfredbuehler.ch ⁨4⁩ ⁨weeks⁩ ago

    @Der Pepe (Hubzilla) ⁂
    

    JavaScript, on the other hand, is recognised correctly: application/javascript

    
    
    Mine didn't; it was stored as text/plain, making the browser complain.
    
    var e=Object.defineProperty,t=(t,n)=>{let r={};for(var i in t)e(r,i,{get:t[i],enumerable:!0})

    original
  • mario@hub.somaton.com ⁨4⁩ ⁨weeks⁩ ago

    @Der Pepe (Hubzilla) ⁂
    

    What could be done to ensure that CSS is recognised correctly and entered into the table?

    
    Maybe file an issue to libmagic?
    
    I would rather not rely on file endings to determine the file mime type. We could possibly make an excemption for channels that have code right so that in that case if text/plain is returned from finfo() we compare it to the previously provided mimetype and if it is not the same, revert to the provided one. But i actually do not like this hack!

    original

    • abu@hub.alfredbuehler.ch ⁨4⁩ ⁨weeks⁩ ago

      @Mario Vavti
      

      But i actually do not like this hack!

      
      
      I wouldn't like it either. But what are the chances that it will be fixed in libmagic within a reasonable timespan? Forget it; we need a usable workaround for the Hubzilla webpages ASAP.

      original

      • pepecyb@hub.hubzilla.hu@hub.hubzilla.hu ⁨4⁩ ⁨weeks⁩ ago

        I don’t see any chance of a fix for libmagic either. Particularly because the repository isn’t really very accessible.
        My suggestion would be:
        
        

            // Until here we either used the provided mime type or set mimetype by extension.
            // Both variants are inherently unsafe hence try to find and set the real mimetype before storage.
        
            if (class_exists('finfo') && is_file($os_basepath . $os_relpath)) {
                $finfo = new finfo(FILEINFO_MIME_TYPE);
                $mimetype = $finfo->file($os_basepath . $os_relpath);
        
                if ($mimetype === false) {
                    $mimetype = 'application/octet-stream';
                }
        
                // Workaround for libmagic misidentifying CSS files as text/plain
                if ($mimetype === 'text/plain' && preg_match('/\.css$/i', $os_relpath)) {
                    $mimetype = 'text/css';
                }
            }

        
        This is harmless, only affects CSS and should sort out the problem.

        original

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