How can I prevent uploading bmp image?

2 comments

1. The magic is in get_allowed_mime_types() which calls the upload_mimes filter. That is filtering a default array consisting of keys as a non-terminated regular expression of file-extensions and the mapped mime-type as values:

   array(
       'jpg|jpeg|jpe' => 'image/jpeg',
       'gif' => 'image/gif',
       'png' => 'image/png',
       'bmp' => 'image/bmp',
       'tif|tiff' => 'image/tiff',
       'ico' => 'image/x-icon',
       ....
   }
   

   so hooking into that filter and removing bmp should do the job for the moment:

   /** prevent uploading of .bmp files. */
   add_filter('upload_mimes', function(array $mimes)
       { 
           unset($mimes['bmp']);
           return $mimes;
       })
       ;
   

   Just copy that over into a file named no-bmp-upload.php and place it into the wp-contentmu-plugins folder.

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2. I have found the solution from here. And its working!

   WordPress has a set of restricted filetypes it will allow you to upload via the media library. Whilst this is a great security feature, there may be times where you’d like to add other files that are restricted by default, or maybe even the opposite where you’d only like to allow a few extensions to be uploaded. Fortunately, WordPress makes this dead easy with a small snippet of PHP code.

   If you’d like to add or remove a specific filetype that can be uploaded to wordpress via the media library, you can insert this PHP code in your theme functions.php file:

   
   function my_myme_types($mime_types){
   //Adjust the $mime_types, which is an associative array
   //where the key is extension and value is mime type.
       return $mime_types;
   }
   add_filter('upload_mimes', 'my_myme_types', 1, 1);
   

   Here is an example of what you can do to add and remove a new filetype (in this example, I’m adding an extension that already exists, but the concept is the same):

   
   function my_myme_types($mime_types){
       $mime_types['avi'] = 'video/avi'; //Adding avi extension
       unset($mime_types['pdf']); //Removing the pdf extension
       return $mime_types;
   }
   add_filter('upload_mimes', 'my_myme_types', 1, 1);
   

   You can also reset the allowed filetypes by creating a new array within the function and returning these values:

   
   function my_myme_types($mime_types){
       //Creating a new array will reset the allowed filetypes
       $mime_types = array(
           'jpg|jpeg|jpe' => 'image/jpeg',
           'gif' => 'image/gif',
           'png' => 'image/png',
           'bmp' => 'image/bmp',
           'tif|tiff' => 'image/tiff'
       );
       return $mime_types;
   }
   add_filter('upload_mimes', 'my_myme_types', 1, 1);
   

   If you’d like to see what filetypes are currently supported by wordpress, check out the function get_allowed_mime_types located in the wp-includes/functions.php file.

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