Refactor stream filter handling for improved validation.

Simplify and reorganize parsing logic to replace explicit filter name collection with direct filter creation. Added validation for unsupported filters, ensuring filters are cleared and errors returned when necessary. This improves code clarity and robustness.

Refactor stream filter handling for improved validation.
Simplify and reorganize parsing logic to replace explicit filter name collection with direct filter creation. Added validation for unsupported filters, ensuring filters are cleared and errors returned when necessary. This improves code clarity and robustness.
m-holger
1 parent 772cd8d5
Showing 1 changed file with 12 additions and 13 deletions
libqpdf/QPDF_Stream.cc
@@ -352,15 +352,17 @@ Stream::filterable(
  
     auto filter_obj = s->stream_dict.getKey("/Filter");
  
-    std::vector<std::string> filter_names;
-
     if (filter_obj.isNull()) {
         // No filters
         return true;
     }
     if (filter_obj.isName()) {
         // One filter
-        filter_names.emplace_back(filter_obj.getName());
+        auto ff = s->filter_factory(filter_obj.getName());
+        if (!ff) {
+            return false;
+        }
+        filters.emplace_back(ff());
     } else if (filter_obj.isArray()) {
         // Potentially multiple filters
         int n = filter_obj.getArrayNItems();
@@ -370,21 +372,18 @@ Stream::filterable(
                 warn("stream filter type is not name or array");
                 return false;
             }
-            filter_names.emplace_back(item.getName());
+            auto ff = s->filter_factory(item.getName());
+            if (!ff) {
+                filters.clear();
+                return false;
+            }
+            filters.emplace_back(ff());
         }
     } else {
         warn("stream filter type is not name or array");
         return false;
     }
  
-    for (auto& filter_name: filter_names) {
-        if (auto ff = s->filter_factory(filter_name)) {
-            filters.emplace_back(ff());
-            continue;
-        }
-        return false;
-    }
-
     bool filterable = true;
  
     // filters now contains a list of filters to be applied in order. See which ones we can support.
@@ -401,7 +400,7 @@ Stream::filterable(
             decode_parms.push_back(decode_obj.getArrayItem(i));
         }
     } else {
-        for (unsigned int i = 0; i < filter_names.size(); ++i) {
+        for (unsigned int i = 0; i < filters.size(); ++i) {
             decode_parms.push_back(decode_obj);
         }
     }