M11: PDF/A verify reads a Named action's name through a reference (6.5.1)

A Named action whose /N refers to /NextPage (or another page move) is
allowed and survives Save as PDF/A; the test checks that conversion
keeps such an action.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pq7HyDBXygTf7jcqdsjcfn

crates/preflight/src/lib.rs

@@ -770,7 +770,7 @@ fn walk_chain(doc: &Document, a: &Dict, read: &mut usize, seen: &mut std::collec
         if *read > MAX_ACTION_CHAIN {
             return Some("too deeply chained".into());
         }
-        if let Some(s) = action_forbidden(d) {
+        if let Some(s) = action_forbidden(doc, d) {
             return Some(s);
         }
         match d.get(b"Next") {
@@ -789,13 +789,15 @@ fn walk_chain(doc: &Document, a: &Dict, read: &mut usize, seen: &mut std::collec
 }
 
 /// The forbidden kind of the action `d` itself, if it is one: a forbidden type, or a Named
-/// action for anything but the four of [`NAMED_ACTIONS`].
-fn action_forbidden(d: &Dict) -> Option<String> {
+/// action for anything but the four of [`NAMED_ACTIONS`], its name given directly or by
+/// reference.
+fn action_forbidden(doc: &Document, d: &Dict) -> Option<String> {
     let s = d.name(b"S")?;
     if FORBIDDEN_ACTIONS.contains(&s) {
         return Some(String::from_utf8_lossy(s).into_owned());
     }
-    match d.name(b"N") {
+    let n = d.get(b"N").map(|n| doc.resolve(n));
+    match n.as_deref().and_then(Object::as_name) {
         _ if s != b"Named" => None,
         Some(n) if NAMED_ACTIONS.contains(&n) => None,
         Some(n) => Some(format!("Named {}", String::from_utf8_lossy(n))),

crates/preflight/src/tests.rs

@@ -501,6 +501,7 @@ fn set_state_no_op_and_named_actions_are_checked() {
                 "<< /Type /Pages /Kids [] /Count 0 >>",
                 &outline,
                 "<< /Type /Outlines /First 3 0 R /Last 3 0 R /Count 1 >>",
+                "/NextPage",
             ],
             "",
         )
@@ -517,10 +518,26 @@ fn set_state_no_op_and_named_actions_are_checked() {
     for allowed in ["NextPage", "PrevPage", "FirstPage", "LastPage"] {
         assert!(actions(&format!("<< /S /Named /N /{allowed} >>")).is_empty(), "{allowed}");
     }
+    // The name given by reference (object 5 is /NextPage).
+    assert!(actions("<< /S /Named /N 5 0 R >>").is_empty());
     // Save as PDF/A removes them.
     for action in ["<< /S /SetState /T [] >>", "<< /S /NOP >>", "<< /S /Named /N /Print >>"] {
         let mut doc = doc_with(action);
         convert(&mut doc, Level::A2b).unwrap();
         assert!(verify(&doc, Level::A2b).iter().all(|i| i.clause != "6.5.1"), "{action}");
     }
+    // A permitted Named action survives it, also one naming its page move by reference.
+    for action in ["<< /S /Named /N /NextPage >>", "<< /S /Named /N 5 0 R >>"] {
+        let mut doc = doc_with(action);
+        convert(&mut doc, Level::A2b).unwrap();
+        let outline = doc.get(ObjRef { num: 3, generation: 0 });
+        let kept = outline
+            .as_dict()
+            .and_then(|d| d.get(b"A"))
+            .and_then(Object::as_dict)
+            .map(|a| (a.name(b"S").map(<[u8]>::to_vec), a.get(b"N").map(|n| doc.resolve(n))));
+        let (s, n) = kept.unwrap_or_else(|| panic!("{action}: the action is gone"));
+        assert_eq!(s.as_deref(), Some(&b"Named"[..]), "{action}");
+        assert_eq!(n.as_deref().and_then(Object::as_name), Some(&b"NextPage"[..]), "{action}");
+    }
 }