Add basic gltf format checking

Signed-off-by: Justin Georgi <justin.georgi@gmail.com>

includes/GlModelHooks.php

@@ -124,6 +124,41 @@ class GlModelHooks {
         $out->addModules('ext.glmv.upl');
     }
 
+    /**
+     * Perform upload verification, based on both file properties like MIME type
+     * (same as UploadVerifyFile) and the information entered by the user (upload
+     * comment, file page contents etc.).
+     * 
+     * @param UploadBase $upload Instance of UploadBase, with all info about the upload
+     * @param User $user User uploading this file
+     * @param array | null $props File properties, as returned by MWFileProps::getPropsFromPath()
+     * @param string $comment Upload log comment (also used as edit summary)
+     * @param string | false $pageText File description page text (only used for new uploads)
+     * @param array | MessageSpecifier | null &$error Output: If the file upload should be prevented, set this to the reason
+     * @return bool|void True or no return value to continue or false to abort
+     */
+    public static function onUploadVerifyUpload	($upload, $user, ?array	$props, $comment, $pageText, &$error) {
+        if ($props['mime'] != 'model/gltf-binary') {
+            return true;
+        } else {
+            $path = $upload->getTempPath();
+            $gltf = fopen($path, 'r');
+            $glHeader = fread($gltf, 4);
+            fclose($gltf);
+
+            if ($glHeader == 'glTF') {
+                return true;
+            } else {
+                $error = array(
+                    "glmv-load-error-format",
+                    $upload->getTitle()->getRootText()
+                );
+                return false;
+            }
+        }
+    }
+    
+
     /**
      * MWHook: Called just before the upload data, like wpUploadDescription, are processed, so extensions get a chance to manipulate them.
      *