Add a setting to disable the plugin functionality

The setting is default-enabled, which should allow network activation for all blogs on a multisite instance while letting individual blogs retake control in case of problems.

wp-mat.php

@@ -14,10 +14,20 @@ if (!defined("WP_MAT_ENDPOINT")) {
     define("WP_MAT_ENDPOINT", "http://localhost:7111/api/cleanup");
 }
 
+// This is generally useful for debugging.
+if (!function_exists('wp_handle_upload_error')) {
+    function wp_handle_upload_error(&$file, $message) {
+        error_log("wp_handle_upload_error: ".$message);
+        return array( "error" => $message );
+    }
+}
+
+class WP_Mat {
+
     // Check if the mime type is one of those we want to clean up.
     // Use a blacklist, currently empty. Send everything by default
     // except video.
-function wp_mat_is_supported_mime_type($mimetype) {
+    function is_supported_mime_type($mimetype) {
         if (substr($mimetype, 0, 6) === "video/") {
             return false;
         }
@@ -26,7 +36,7 @@ function wp_mat_is_supported_mime_type($mimetype) {
 
     // Make a POST request to the MAT service with the uploaded file and
     // store the results into '$output_path'.
-function wp_mat_issue_request($path, $mimetype, $output_path) {
+    function issue_cleanup_request($path, $mimetype, $output_path) {
         $upfile = new CURLFile($path, $mimetype, 'input');
     
         $curl = curl_init();
@@ -52,10 +62,14 @@ function wp_mat_issue_request($path, $mimetype, $output_path) {
         return $ret;
     }
 
-function wp_mat_handle_upload_prefilter($file) {
+    // Filter uploaded files before they are processed by Wordpress.
+    function handle_upload_prefilter($file) {
         if (isset($file['error']) && $file['error']) {
             return $file;
         }
+        if (get_option('wpmat_disabled')) {
+            return $file;
+        }
 
         // Autodetect MIME type if not passed by the browser.
         if (!$file['type']) {
@@ -63,7 +77,7 @@ function wp_mat_handle_upload_prefilter($file) {
         }
 
         // Check if it's one of the MIME types we support.
-    if (!wp_mat_is_supported_mime_type($file['type'])) {
+        if (!$this->is_supported_mime_type($file['type'])) {
             error_log("wp-mat: unsupported mime type ".$file['type']);
             return $file;
         }
@@ -71,7 +85,7 @@ function wp_mat_handle_upload_prefilter($file) {
         // Issue a request to the MAT API, and if successful replace the
         // file with the sanitized one.
         $new_tmp_file = tempnam("", "wp_mat_");
-    if (wp_mat_issue_request($file['tmp_name'], $file['type'], $new_tmp_file)) {
+        if ($this->issue_cleanup_request($file['tmp_name'], $file['type'], $new_tmp_file)) {
             // Rename the cleaned up file to the original file, or WP
             // will not pass the is_uploaded_file() check in wp_handle_upload().
             unlink($file['tmp_name']);
@@ -94,12 +108,45 @@ function wp_mat_handle_upload_prefilter($file) {
         return $file;
     }
 
-add_filter('wp_handle_upload_prefilter', 'wp_mat_handle_upload_prefilter');
+    function settings_api_init() {
+        // Add the section to reading settings so we can add our
+        // fields to it.
+        add_settings_section(
+            'wpmat_settings_section',
+            'Metadata anonymization for uploads',
+            array($this, 'settings_section_callback'),
+            'writing'
+        );
 
-// This is generally useful for debugging.
-if (!function_exists('wp_handle_upload_error')) {
-    function wp_handle_upload_error(&$file, $message) {
-        error_log("wp_handle_upload_error: ".$message);
-        return array( "error" => $message );
+        // Add the field with the names and function to use for our new
+        // settings, put it in our new section.
+        add_settings_field(
+            'wpmat_disabled',
+            'Disable metadata anonymization',
+            array($this, 'settings_field_callback'),
+            'writing',
+            'wpmat_settings_section'
+        );
+
+        // Register our setting so that $_POST handling is done for us and
+        // our callback function just has to echo the <input>.
+        register_setting('writing', 'wpmat_disabled');
+    }
+
+    function settings_section_callback() {
+        echo('<p>Control whether uploaded files are run through metadata anonymization (using MAT2).</p>');
     }
+
+    function settings_field_callback() {
+        echo('<input name="wpmat_disabled" id="wpmat_disabled" type="checkbox" value="1" class="code" ' . checked(1, get_option('wpmat_disabled'), false) . ' /> <label for="wpmat_disabled">Disable metadata anonymization</label>');
+    }
+
+    function __construct() {
+        add_filter('wp_handle_upload_prefilter', array($this, 'handle_upload_prefilter'));
+        add_action('admin_init', array($this, 'settings_api_init'));
     }
+
+}
+
+new WP_Mat();
+