fix(3354345): check if the SRCSET attr is available and adding logic to handle it correctly.

Closes #3354345

pathologic.module

@@ -118,6 +118,36 @@ function _pathologic_filter($text, $settings, $hash) {
  * Process and replace paths. preg_replace_callback() callback.
  */
 function _pathologic_replace($matches) {
+  $pattern_split = '/\s\d+w/';
+  $pattern_match = '/\s(\d+w)/';
+
+  if (
+    $matches[1] === 'srcset' &&
+    preg_match($pattern_split, $matches[2])
+  ) {
+    $output = '';
+    $multiple_parts = preg_split($pattern_split, $matches[2]);
+    preg_match_all($pattern_match, $matches[2], $multiple_matches);
+
+    foreach ($multiple_matches[1] as $index => $key) {
+      $fixed_path = _pathologic_replace_individual(['', '', trim(str_replace(', ', '', $multiple_parts[$index]))]);
+      $fixed_path = trim(str_replace('="', '', $fixed_path));
+      $output .= $fixed_path . ' ' . $key . ', ';
+    }
+
+    $output = $matches[1] . '="' . substr($output, 0, -2) . '"';
+
+    return $output;
+  }
+  else {
+    return _pathologic_replace_individual($matches);
+  }
+}
+
+/**
+ * This function returns replaced pathologic for individual URLs.
+ */
+function _pathologic_replace_individual($matches) {
   // Get the base path.
   global $base_path;