From 0a0eb92a71f2a6f396651a30a98b4c6a042b3847 Mon Sep 17 00:00:00 2001
From: m-holger <m.holger@qpdf.org>
Date: Tue, 4 Nov 2025 14:45:36 +0000
Subject: [PATCH] Refactor `QPDF::getRoot`: improve error handling for invalid trailer `/Root` and simplify logic. Update related test outputs and release notes.

---
 libqpdf/QPDF.cc                 | 16 ++++++++--------
 manual/release-notes.rst        |  4 ++++
 qpdf/qtest/qpdf/c-oh-errors.out |  8 ++++----
 qpdf/qtest/qpdf/test73.out      |  2 +-
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index 9e444ce..890a6d2 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -651,17 +651,17 @@ QPDF::getTrailer()
 QPDFObjectHandle
 QPDF::getRoot()
 {
-    QPDFObjectHandle root = m->trailer.getKey("/Root");
-    if (!root.isDictionary()) {
+    Dictionary Root = m->trailer["/Root"];
+    if (!Root) {
         throw m->c.damagedPDF("", -1, "unable to find /Root dictionary");
-    } else if (
-        // Check_mode is an interim solution to request #810 pending a more comprehensive review of
-        // the approach to more extensive checks and warning levels.
-        m->cf.check_mode() && !root.getKey("/Type").isNameAndEquals("/Catalog")) {
+    }
+    // Check_mode is an interim solution to request #810 pending a more comprehensive review of the
+    // approach to more extensive checks and warning levels.
+    if (m->cf.check_mode() && Name(Root["/Type"]) != "/Catalog") {
         warn(m->c.damagedPDF("", -1, "catalog /Type entry missing or invalid"));
-        root.replaceKey("/Type", "/Catalog"_qpdf);
+        Root.replaceKey("/Type", Name("/Catalog"));
     }
-    return root;
+    return Root.oh();
 }
 
 std::map<QPDFObjGen, QPDFXRefEntry>
diff --git a/manual/release-notes.rst b/manual/release-notes.rst
index 72c8e93..db330b8 100644
--- a/manual/release-notes.rst
+++ b/manual/release-notes.rst
@@ -65,6 +65,10 @@ more detail.
 
   - Other changes
 
+    - Calling ``QPDF::getRoot`` on a file with invalid trailer now throws a
+      ``damaged_pdf`` error with message "unable to find /Root dictionary"
+      rather than an internal error.
+
 .. _r12-3-0-deprecate:
 
     - The following are believed to be not in use and have been deprecated.
diff --git a/qpdf/qtest/qpdf/c-oh-errors.out b/qpdf/qtest/qpdf/c-oh-errors.out
index aaeedef..c79544e 100644
--- a/qpdf/qtest/qpdf/c-oh-errors.out
+++ b/qpdf/qtest/qpdf/c-oh-errors.out
@@ -1,8 +1,8 @@
-get root: attempted to dereference an uninitialized QPDFObjectHandle
-  code: 1
-  file: 
+get root: closed input source: unable to find /Root dictionary
+  code: 5
+  file: closed input source
   pos: 0
-  text: attempted to dereference an uninitialized QPDFObjectHandle
+  text: unable to find /Root dictionary
 bad parse: parsed object (offset 1): unknown token while reading object; treating as string
   code: 5
   file: parsed object
diff --git a/qpdf/qtest/qpdf/test73.out b/qpdf/qtest/qpdf/test73.out
index ad6fb78..54e241a 100644
--- a/qpdf/qtest/qpdf/test73.out
+++ b/qpdf/qtest/qpdf/test73.out
@@ -1,3 +1,3 @@
-getRoot: attempted to dereference an uninitialized QPDFObjectHandle
+getRoot: closed input source: unable to find /Root dictionary
 WARNING: closed input source: object 4/0: error reading object: QPDF operation attempted on a QPDF object with no input source. QPDF operations are invalid before processFile (or another process method) or after closeInputSource
 test 73 done
--
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