M11: Optimizer Clean Up removes invalid links and bookmark destinations and unreferenced named destinations

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/automation/src/lib.rs

@@ -545,6 +545,8 @@ impl Automation {
             ("discard_tags", &mut settings.discard_tags),
             ("discard_print_settings", &mut settings.discard_print_settings),
             ("flate_unencoded", &mut settings.flate_unencoded),
+            ("remove_invalid_links", &mut settings.remove_invalid_links),
+            ("remove_unreferenced_dests", &mut settings.remove_unreferenced_dests),
         ] {
             if let Some(b) = a.opt_bool(key)? {
                 *flag = b;
@@ -579,6 +581,9 @@ impl Automation {
             "alternate_images": o.alternate_images,
             "tags_removed": o.tags_removed,
             "streams_compressed": o.streams_compressed,
+            "invalid_links": o.invalid_links,
+            "invalid_bookmarks": o.invalid_bookmarks,
+            "unreferenced_dests": o.unreferenced_dests,
             "merged_objects": r.merged,
             "discarded": r.discarded.iter().map(|(h, n)| json!({ "category": h.id(), "count": n })).collect::<Vec<_>>(),
         }))

crates/automation/src/tools.rs

@@ -812,7 +812,7 @@ pub fn tools() -> Vec<ToolDef> {
             .with(schema(json!({ "doc": doc() }), &["doc"])),
         t("doc_open_revision", "Open a revision", "Open saved revision `revision` (1 = the oldest) of a document as a new, unsaved document, to see the file as it was then.")
             .with(schema(json!({ "doc": doc(), "revision": { "type": "integer", "minimum": 1 } }), &["doc", "revision"])),
-        t("doc_optimize", "Optimize PDF", "Write an optimized copy to `path` (Acrobat's PDF Optimizer). color / gray: { downsample, ppi, above_ppi, compression: jpeg|zip|retain, quality 1–100 } (defaults: downsample to 150 ppi above 225, JPEG 60). Images are measured where pages draw them and replaced only when smaller. discard_*: thumbnails (default true), alternate_images (true), tags, print_settings; flate_unencoded (true). discard: Remove Hidden Information categories (metadata, attachments, comments, form-fields, hidden-text, hidden-layers, bookmarks, links-actions-scripts, private-data). Signed documents are refused. The open document is unchanged.")
+        t("doc_optimize", "Optimize PDF", "Write an optimized copy to `path` (Acrobat's PDF Optimizer). color / gray: { downsample, ppi, above_ppi, compression: jpeg|zip|retain, quality 1–100 } (defaults: downsample to 150 ppi above 225, JPEG 60). Images are measured where pages draw them and replaced only when smaller. discard_*: thumbnails (default true), alternate_images (true), tags, print_settings; flate_unencoded (true); remove_invalid_links and remove_unreferenced_dests (true). discard: Remove Hidden Information categories (metadata, attachments, comments, form-fields, hidden-text, hidden-layers, bookmarks, links-actions-scripts, private-data). Signed documents are refused. The open document is unchanged.")
             .cmd("optimize.advanced")
             .with(schema(
                 json!({
@@ -825,6 +825,8 @@ pub fn tools() -> Vec<ToolDef> {
                     "discard_tags": { "type": "boolean" },
                     "discard_print_settings": { "type": "boolean" },
                     "flate_unencoded": { "type": "boolean" },
+                    "remove_invalid_links": { "type": "boolean" },
+                    "remove_unreferenced_dests": { "type": "boolean" },
                     "discard": { "type": "array", "items": { "type": "string" } },
                 }),
                 &["doc", "path"],

crates/optimize/src/lib.rs

@@ -17,6 +17,7 @@
 
 mod audit;
 mod images;
+mod links;
 
 pub use audit::{SpaceCategory, SpaceUse, audit_space};
 
@@ -70,6 +71,10 @@ pub struct Settings {
     pub discard_print_settings: bool,
     /// Flate-compress streams stored without a filter.
     pub flate_unencoded: bool,
+    /// Clean Up: remove links (and bookmark destinations) that point nowhere.
+    pub remove_invalid_links: bool,
+    /// Clean Up: remove named destinations nothing refers to.
+    pub remove_unreferenced_dests: bool,
 }
 
 impl Default for Settings {
@@ -83,6 +88,8 @@ impl Default for Settings {
             discard_tags: false,
             discard_print_settings: false,
             flate_unencoded: true,
+            remove_invalid_links: true,
+            remove_unreferenced_dests: true,
         }
     }
 }
@@ -101,6 +108,10 @@ pub struct Report {
     pub tags_removed: bool,
     pub print_settings: usize,
     pub streams_compressed: usize,
+    /// Links removed and bookmarks whose destination was cleared (Clean Up).
+    pub invalid_links: usize,
+    pub invalid_bookmarks: usize,
+    pub unreferenced_dests: usize,
 }
 
 /// Optimize `doc` in place.
@@ -174,6 +185,14 @@ pub fn optimize(doc: &mut Document, settings: &Settings) -> Result<Report, Optim
             _ => {}
         }
     }
+    if settings.remove_invalid_links {
+        let (l, b) = links::remove_invalid(doc, &pages)?;
+        report.invalid_links = l;
+        report.invalid_bookmarks = b;
+    }
+    if settings.remove_unreferenced_dests {
+        report.unreferenced_dests = links::remove_unreferenced_dests(doc)?;
+    }
     if settings.flate_unencoded {
         for num in doc.object_numbers() {
             let r = ObjRef { num, generation: doc.generation(num) };

crates/optimize/src/links.rs

@@ -0,0 +1,228 @@
+//! Clean Up: links and bookmarks whose destination doesn't exist, and named destinations nothing
+//! refers to.
+
+use std::collections::{HashSet, VecDeque};
+
+use printcraft_cos::{Dict, Document, ObjRef, Object, PdfString};
+
+/// Named destinations: the `/Names /Dests` tree (entries) and the old `/Dests` dictionary.
+fn named_dests(doc: &Document) -> HashSet<Vec<u8>> {
+    let mut out = HashSet::new();
+    let Some(cat) = doc.root().and_then(|r| doc.get(r).as_dict().cloned()) else { return out };
+    if let Some(d) = cat.get(b"Dests").map(|d| doc.resolve(d)).and_then(|d| d.as_dict().cloned()) {
+        out.extend(d.iter().map(|(k, _)| k.clone()));
+    }
+    if let Some(tree) = names_tree(doc, &cat) {
+        for (k, _) in tree_entries(doc, &tree) {
+            out.insert(k);
+        }
+    }
+    out
+}
+
+fn names_tree(doc: &Document, cat: &Dict) -> Option<Object> {
+    let names = cat.get(b"Names").map(|n| doc.resolve(n)).and_then(|n| n.as_dict().cloned())?;
+    names.get(b"Dests").cloned()
+}
+
+/// A name tree's entries (key bytes, value), flattened.
+fn tree_entries(doc: &Document, node: &Object) -> Vec<(Vec<u8>, Object)> {
+    let mut out = Vec::new();
+    let mut queue = VecDeque::from([(node.clone(), 0usize)]);
+    let mut seen = HashSet::new();
+    while let Some((n, depth)) = queue.pop_front() {
+        if depth > 64 {
+            continue;
+        }
+        if let Object::Ref(r) = n
+            && !seen.insert(r)
+        {
+            continue;
+        }
+        let Some(d) = doc.resolve(&n).as_dict().cloned() else { continue };
+        if let Some(a) = d.get(b"Names").map(|x| doc.resolve(x)).and_then(|x| x.as_array().cloned()) {
+            for pair in a.chunks(2) {
+                if let [k, v] = pair
+                    && let Some(s) = doc.resolve(k).as_string()
+                {
+                    out.push((s.bytes.clone(), v.clone()));
+                }
+            }
+        }
+        if let Some(kids) = d.get(b"Kids").map(|x| doc.resolve(x)).and_then(|x| x.as_array().cloned()) {
+            queue.extend(kids.into_iter().map(|k| (k, depth + 1)));
+        }
+    }
+    out
+}
+
+/// The destination of a link, bookmark or action dictionary: `/Dest`, or a GoTo's `/D`.
+fn destination(doc: &Document, d: &Dict) -> Option<Object> {
+    if let Some(dest) = d.get(b"Dest") {
+        return Some(doc.resolve(dest).as_ref().clone());
+    }
+    let a = d.get(b"A").map(|a| doc.resolve(a)).and_then(|a| a.as_dict().cloned())?;
+    (a.name(b"S") == Some(b"GoTo")).then(|| a.get(b"D").map(|x| doc.resolve(x).as_ref().clone())).flatten()
+}
+
+/// The name a destination refers to, if it is a named one.
+fn dest_name(o: &Object) -> Option<Vec<u8>> {
+    match o {
+        Object::String(s) => Some(s.bytes.clone()),
+        Object::Name(n) => Some(n.to_vec()),
+        _ => None,
+    }
+}
+
+fn valid(o: &Object, pages: &HashSet<ObjRef>, count: usize, names: &HashSet<Vec<u8>>) -> bool {
+    match o {
+        Object::Array(a) => match a.first() {
+            Some(Object::Ref(r)) => pages.contains(r),
+            Some(Object::Int(i)) => *i >= 0 && (*i as usize) < count,
+            _ => false,
+        },
+        other => dest_name(other).is_some_and(|n| names.contains(&n)),
+    }
+}
+
+/// Remove links whose destination is missing, and clear the destination of such bookmarks
+/// (they stay, so their children do too). Returns (links, bookmarks).
+pub(crate) fn remove_invalid(doc: &mut Document, pages: &[ObjRef]) -> Result<(usize, usize), printcraft_cos::CosError> {
+    let set: HashSet<ObjRef> = pages.iter().copied().collect();
+    let names = named_dests(doc);
+    let mut links = 0;
+    for p in pages {
+        let Some(pd) = doc.get(*p).as_dict().cloned() else { continue };
+        let Some(annots) = pd.get(b"Annots").map(|a| doc.resolve(a)).and_then(|a| a.as_array().cloned()) else { continue };
+        let keep: Vec<Object> = annots
+            .iter()
+            .filter(|x| {
+                let d = doc.resolve(x).as_dict().cloned().unwrap_or_default();
+                if d.name(b"Subtype") != Some(b"Link") {
+                    return true;
+                }
+                destination(doc, &d).is_none_or(|dest| valid(&dest, &set, pages.len(), &names))
+            })
+            .cloned()
+            .collect();
+        if keep.len() != annots.len() {
+            links += annots.len() - keep.len();
+            doc.update_dict(*p, |d| d.set(b"Annots".to_vec(), Object::Array(keep)))?;
+        }
+    }
+    // Bookmarks, depth-first.
+    let mut bookmarks = 0;
+    let first = doc
+        .root()
+        .and_then(|r| doc.get(r).as_dict().cloned())
+        .and_then(|c| c.get(b"Outlines").map(|o| doc.resolve(o)).and_then(|o| o.as_dict().and_then(|d| d.reference(b"First"))));
+    let mut stack: Vec<ObjRef> = first.into_iter().collect();
+    let mut seen = HashSet::new();
+    while let Some(r) = stack.pop() {
+        if !seen.insert(r) || seen.len() > 100_000 {
+            continue;
+        }
+        let Some(d) = doc.get(r).as_dict().cloned() else { continue };
+        if let Some(n) = d.reference(b"Next") {
+            stack.push(n);
+        }
+        if let Some(f) = d.reference(b"First") {
+            stack.push(f);
+        }
+        if let Some(dest) = destination(doc, &d)
+            && !valid(&dest, &set, pages.len(), &names)
+        {
+            doc.update_dict(r, |d| {
+                d.remove(b"Dest");
+                d.remove(b"A");
+            })?;
+            bookmarks += 1;
+        }
+    }
+    Ok((links, bookmarks))
+}
+
+/// Every named destination some object refers to (links, bookmarks, actions, open action).
+fn referenced_names(doc: &Document) -> HashSet<Vec<u8>> {
+    let mut out = HashSet::new();
+    let mut visit = |o: &Object| {
+        let mut stack = vec![o.clone()];
+        while let Some(o) = stack.pop() {
+            match o {
+                Object::Dict(d) => {
+                    if let Some(n) = d.get(b"Dest").and_then(dest_name) {
+                        out.insert(n);
+                    }
+                    if matches!(d.name(b"S"), Some(b"GoTo" | b"GoToR" | b"GoToE"))
+                        && let Some(n) = d.get(b"D").and_then(dest_name)
+                    {
+                        out.insert(n);
+                    }
+                    stack.extend(d.iter().map(|(_, v)| v.clone()));
+                }
+                Object::Array(a) => stack.extend(a),
+                Object::Stream(s) => stack.push(Object::Dict(s.dict.clone())),
+                _ => {}
+            }
+        }
+    };
+    for num in doc.object_numbers() {
+        visit(&doc.get(ObjRef::new(num, doc.generation(num))));
+    }
+    if let Some(r) = doc.root() {
+        visit(&doc.get(r));
+    }
+    out
+}
+
+/// Remove named destinations nothing refers to. Returns how many went.
+pub(crate) fn remove_unreferenced_dests(doc: &mut Document) -> Result<usize, printcraft_cos::CosError> {
+    let Some(root) = doc.root() else { return Ok(0) };
+    let cat = doc.get(root).as_dict().cloned().unwrap_or_default();
+    let used = referenced_names(doc);
+    let mut removed = 0;
+    if let Some(tree) = names_tree(doc, &cat) {
+        let entries = tree_entries(doc, &tree);
+        let keep: Vec<(Vec<u8>, Object)> = entries.iter().filter(|(k, _)| used.contains(k)).cloned().collect();
+        if keep.len() != entries.len() {
+            removed += entries.len() - keep.len();
+            let mut keep = keep;
+            keep.sort_by(|a, b| a.0.cmp(&b.0));
+            let mut arr = Vec::with_capacity(keep.len() * 2);
+            for (k, v) in keep {
+                arr.push(Object::String(PdfString::literal(k)));
+                arr.push(v);
+            }
+            let mut node = Dict::new();
+            node.set(b"Names".to_vec(), Object::Array(arr));
+            let node = doc.add(Object::Dict(node));
+            let names_obj = cat.get(b"Names").cloned();
+            match names_obj {
+                Some(Object::Ref(r)) => doc.update_dict(r, |n| n.set(b"Dests".to_vec(), Object::Ref(node)))?,
+                _ => doc.update_dict(root, |c| {
+                    if let Some(Object::Dict(n)) = c.get_mut(b"Names") {
+                        n.set(b"Dests".to_vec(), Object::Ref(node));
+                    }
+                })?,
+            }
+        }
+    }
+    if let Some(old) = cat.get(b"Dests") {
+        let d = doc.resolve(old).as_dict().cloned().unwrap_or_default();
+        let mut keep = Dict::new();
+        for (k, v) in d.iter() {
+            if used.contains(k) {
+                keep.set(k.clone(), v.clone());
+            } else {
+                removed += 1;
+            }
+        }
+        if keep.len() != d.len() {
+            match old {
+                Object::Ref(r) => doc.set(*r, Object::Dict(keep)),
+                _ => doc.update_dict(root, |c| c.set(b"Dests".to_vec(), Object::Dict(keep)))?,
+            }
+        }
+    }
+    Ok(removed)
+}

crates/optimize/tests/optimize.rs

@@ -192,3 +192,57 @@ fn space_audit_shares_the_file_out_by_kind() {
     assert_eq!(audit.iter().map(|u| u.bytes).sum::<u64>(), bytes.len() as u64);
     assert!((audit.iter().map(|u| u.percent).sum::<f64>() - 100.0).abs() < 1e-6);
 }
+
+#[test]
+fn invalid_links_and_unreferenced_destinations_go() {
+    let mut doc = Document::new_empty();
+    let p = page(&mut doc, &[], "BT ET");
+    let link = |doc: &mut Document, dest: Object| {
+        let mut d = Dict::new();
+        d.set(b"Type".to_vec(), Object::name("Annot"));
+        d.set(b"Subtype".to_vec(), Object::name("Link"));
+        d.set(b"Rect".to_vec(), Object::Array(vec![0.into(), 0.into(), 10.into(), 10.into()]));
+        d.set(b"Dest".to_vec(), dest);
+        Object::Ref(doc.add(Object::Dict(d)))
+    };
+    let s = |t: &str| Object::String(printcraft_cos::PdfString::literal(t.as_bytes().to_vec()));
+    let annots = vec![
+        link(&mut doc, Object::Array(vec![Object::Ref(p), Object::name("Fit")])),
+        link(&mut doc, Object::Array(vec![Object::Ref(ObjRef::new(999, 0)), Object::name("Fit")])),
+        link(&mut doc, s("gone")),
+        link(&mut doc, s("kept")),
+    ];
+    doc.update_dict(p, |d| d.set(b"Annots".to_vec(), Object::Array(annots))).unwrap();
+    // Named destinations "kept" (used) and "unused"; a bookmark to a missing name.
+    let fit = Object::Array(vec![Object::Ref(p), Object::name("Fit")]);
+    let mut tree = Dict::new();
+    tree.set(b"Names".to_vec(), Object::Array(vec![s("kept"), fit.clone(), s("unused"), fit]));
+    let tree = doc.add(Object::Dict(tree));
+    let mut names = Dict::new();
+    names.set(b"Dests".to_vec(), Object::Ref(tree));
+    let outlines = doc.add(Object::Null);
+    let mut item = Dict::new();
+    item.set(b"Title".to_vec(), s("Lost"));
+    item.set(b"Parent".to_vec(), Object::Ref(outlines));
+    item.set(b"Dest".to_vec(), s("nowhere"));
+    let item = doc.add(Object::Dict(item));
+    let mut o = Dict::new();
+    o.set(b"First".to_vec(), Object::Ref(item));
+    o.set(b"Last".to_vec(), Object::Ref(item));
+    doc.set(outlines, Object::Dict(o));
+    let root = doc.root().unwrap();
+    doc.update_dict(root, |c| {
+        c.set(b"Names".to_vec(), Object::Dict(names));
+        c.set(b"Outlines".to_vec(), Object::Ref(outlines));
+    })
+    .unwrap();
+    let report = optimize(&mut doc, &Settings::default()).unwrap();
+    assert_eq!((report.invalid_links, report.invalid_bookmarks, report.unreferenced_dests), (2, 1, 1));
+    let left = doc.get(p).as_dict().unwrap().get(b"Annots").unwrap().as_array().unwrap().len();
+    assert_eq!(left, 2);
+    assert!(doc.get(item).as_dict().unwrap().get(b"Dest").is_none(), "the bookmark stays, without its broken destination");
+    // Off: nothing changes.
+    let mut again = doc.clone();
+    let off = Settings { remove_invalid_links: false, remove_unreferenced_dests: false, ..Settings::default() };
+    assert_eq!(optimize(&mut again, &off).unwrap().invalid_links, 0);
+}

crates/ui-egui/src/optimize_ui.rs

@@ -129,6 +129,8 @@ pub(crate) fn body(ui: &mut egui::Ui, d: &mut OptimizeDraft, t: &Tokens) -> (boo
         }
         OptimizeTab::CleanUp => {
             ui.checkbox(&mut s.flate_unencoded, "Use Flate to encode streams that are not encoded");
+            ui.checkbox(&mut s.remove_invalid_links, "Remove invalid links and bookmarks");
+            ui.checkbox(&mut s.remove_unreferenced_dests, "Remove unreferenced named destinations");
             ui.add_enabled(false, egui::Checkbox::new(&mut true, "Compress document structure (object streams)"));
             ui.add_enabled(false, egui::Checkbox::new(&mut true, "Remove unused objects and merge identical ones"));
         }

parity/acrobat-features.toml

@@ -7403,11 +7403,11 @@ title = "Remove invalid links, bookmarks and unreferenced destinations"
 area = "K"
 tier = "P1"
 milestone = "M11"
-status = "planned"
+status = "shipped"
-commands = []
+commands = ["optimize.advanced"]
-tools = []
+tools = ["doc_optimize"]
-evidence = []
+evidence = ["crates/optimize/tests/optimize.rs::invalid_links_and_unreferenced_destinations_go"]
-notes = ""
+notes = "Clean Up: links to missing pages or names are removed; bookmarks keep their place (and children) but lose a broken destination; named destinations nothing refers to (links, bookmarks, actions anywhere) are removed from the name tree and the old /Dests; counts reported"
 
 [[feature]]
 id = "optimize.optimize-content"