From 7de0b3f3c083990842523112959f8e27a0d2e5a0 Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Tue, 9 Jan 2024 20:28:28 -0500
Subject: JSONHandler: add fallback handler support

---
 libqpdf/JSONHandler.cc      | 13 ++++++++++++-
 libqpdf/qpdf/JSONHandler.hh |  3 +++
 2 files changed, 15 insertions(+), 1 deletion(-)

(limited to 'libqpdf')

diff --git a/libqpdf/JSONHandler.cc b/libqpdf/JSONHandler.cc
index 4a69fd60..a8116cb0 100644
--- a/libqpdf/JSONHandler.cc
+++ b/libqpdf/JSONHandler.cc
@@ -17,10 +17,10 @@ struct Handlers
     JSONHandler::void_handler_t dict_end_handler{nullptr};
     JSONHandler::json_handler_t array_start_handler{nullptr};
     JSONHandler::void_handler_t array_end_handler{nullptr};
-    JSONHandler::void_handler_t final_handler{nullptr};
     std::map<std::string, std::shared_ptr<JSONHandler>> dict_handlers;
     std::shared_ptr<JSONHandler> fallback_dict_handler;
     std::shared_ptr<JSONHandler> array_item_handler;
+    std::shared_ptr<JSONHandler> fallback_handler;
 };
 
 class JSONHandler::Members
@@ -110,6 +110,12 @@ JSONHandler::addArrayHandlers(
     m->h.array_item_handler = ah;
 }
 
+void
+JSONHandler::addFallbackHandler(std::shared_ptr<JSONHandler> h)
+{
+    m->h.fallback_handler = std::move(h);
+}
+
 void
 JSONHandler::handle(std::string const& path, JSON j)
 {
@@ -169,6 +175,11 @@ JSONHandler::handle(std::string const& path, JSON j)
         return;
     }
 
+    if (m->h.fallback_handler) {
+        m->h.fallback_handler->handle(path, j);
+        return;
+    }
+
     // It would be nice to include information about what type the object was and what types were
     // allowed, but we're relying on schema validation to make sure input is properly structured
     // before calling the handlers. It would be different if this code were trying to be part of a
diff --git a/libqpdf/qpdf/JSONHandler.hh b/libqpdf/qpdf/JSONHandler.hh
index 9b2a0b33..1c53e32d 100644
--- a/libqpdf/qpdf/JSONHandler.hh
+++ b/libqpdf/qpdf/JSONHandler.hh
@@ -45,6 +45,9 @@ class JSONHandler
     void addArrayHandlers(
         json_handler_t start_fn, void_handler_t end_fn, std::shared_ptr<JSONHandler> item_handlers);
 
+    // If no handlers is called, the fallback handler will be used to try to handle the item.
+    void addFallbackHandler(std::shared_ptr<JSONHandler>);
+
     // Apply handlers recursively to a JSON object.
     void handle(std::string const& path, JSON j);
 
-- 
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