pdfcraft/crates/cos/tests/writer.rs

//! Full saves with object streams and cross-reference streams (M1.9), read back by our parser
//! and by hayro, and incremental saves stacked on top of them.

use std::sync::Arc;

use pdfcraft_cos::{Dict, Document, ObjRef, Object, SaveOptions, write_full, write_incremental};

/// Four pages, a shared font, document info with a non-ASCII title.
fn fixture() -> Vec<u8> {
    let mut objs: Vec<String> = vec!["<< /Type /Catalog /Pages 2 0 R >>".into()];
    let kids: Vec<String> = (0..4).map(|i| format!("{} 0 R", 4 + 2 * i)).collect();
    objs.push(format!("<< /Type /Pages /Kids [{}] /Count 4 /MediaBox [0 0 200 300] >>", kids.join(" ")));
    objs.push("<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>".into());
    for i in 0..4 {
        objs.push(format!("<< /Type /Page /Parent 2 0 R /Contents {} 0 R /Resources << /Font << /F1 3 0 R >> >> >>", 5 + 2 * i));
        let body = format!("BT /F1 24 Tf 20 150 Td (Page {}) Tj ET", i + 1);
        objs.push(format!("<< /Length {} >>\nstream\n{body}\nendstream", body.len()));
    }
    objs.push("<< /Title (Caf\\351 \\(draft\\)) >>".into());
    let mut out = b"%PDF-1.4\n".to_vec();
    let mut offsets = Vec::new();
    for (i, o) in objs.iter().enumerate() {
        offsets.push(out.len());
        out.extend_from_slice(format!("{} 0 obj\n{o}\nendobj\n", i + 1).as_bytes());
    }
    let xref = out.len();
    out.extend_from_slice(format!("xref\n0 {}\n0000000000 65535 f \n", objs.len() + 1).as_bytes());
    for o in offsets {
        out.extend_from_slice(format!("{o:010} 00000 n \n").as_bytes());
    }
    out.extend_from_slice(
        format!("trailer\n<< /Size {} /Root 1 0 R /Info {} 0 R >>\nstartxref\n{xref}\n%%EOF\n", objs.len() + 1, objs.len()).as_bytes(),
    );
    out
}

fn title(doc: &Document) -> Vec<u8> {
    let info = doc.resolve(doc.trailer().get(b"Info").unwrap());
    info.as_dict().unwrap().get(b"Title").unwrap().as_string().unwrap().bytes.clone()
}

fn hayro_pages(bytes: &[u8]) -> usize {
    hayro_syntax::Pdf::new(Arc::new(bytes.to_vec())).expect("hayro opens").pages().len()
}

#[test]
fn full_save_packs_objects_into_object_streams() {
    let doc = Document::open(Arc::new(fixture())).unwrap();
    let packed = write_full(&doc, &SaveOptions::default()).unwrap();
    let text = String::from_utf8_lossy(&packed);
    assert!(packed.starts_with(b"%PDF-1.5"), "object streams need PDF 1.5");
    assert!(text.contains("/ObjStm") && text.contains("/XRef"));
    assert!(!text.contains("\nxref\n"), "no classic table");
    assert!(!text.contains("/Type /Catalog") && !text.contains("/Type/Catalog"), "the catalog is compressed");

    let back = Document::open(Arc::new(packed.clone())).unwrap();
    assert!(back.repair_log().is_empty(), "{:?}", back.repair_log());
    assert_eq!(title(&back), b"Caf\xe9 (draft)");
    assert_eq!(hayro_pages(&packed), 4);

    let classic = write_full(&doc, &SaveOptions { object_streams: false, ..SaveOptions::default() }).unwrap();
    assert!(classic.starts_with(b"%PDF-1.4"));
    assert!(String::from_utf8_lossy(&classic).contains("\nxref\n"));
    assert_eq!(hayro_pages(&classic), 4);
}

#[test]
fn incremental_saves_stack_on_an_xref_stream_file() {
    let doc = Document::open(Arc::new(fixture())).unwrap();
    let packed = Arc::new(write_full(&doc, &SaveOptions::default()).unwrap());
    let mut doc = Document::open(packed.clone()).unwrap();
    // Edit an object that lives in an object stream.
    let info = doc.trailer().reference(b"Info").unwrap();
    doc.update_dict(info, |d: &mut Dict| d.set(b"Title".to_vec(), Object::String(pdfcraft_cos::PdfString { bytes: b"Second".to_vec(), hex: false })))
        .unwrap();
    let added = doc.add(Object::Int(42));
    let updated = write_incremental(&doc, &SaveOptions::default()).unwrap();
    assert!(updated.starts_with(&packed), "an incremental save only appends");
    let tail = String::from_utf8_lossy(&updated[packed.len()..]);
    assert!(tail.contains("/XRef") && tail.contains("/Prev"), "the update uses an xref stream too");

    let back = Document::open(Arc::new(updated.clone())).unwrap();
    assert!(back.repair_log().is_empty(), "{:?}", back.repair_log());
    assert_eq!(title(&back), b"Second");
    assert_eq!(*back.get(ObjRef::new(added.num, 0)), Object::Int(42));
    assert_eq!(back.revisions().len(), 2);
    assert_eq!(hayro_pages(&updated), 4);
}

#[test]
fn qpdf_accepts_object_stream_output() {
    let Ok(out) = std::process::Command::new("qpdf").arg("--version").output() else {
        eprintln!("qpdf not installed: skipped");
        return;
    };
    assert!(out.status.success());
    let doc = Document::open(Arc::new(fixture())).unwrap();
    let packed = write_full(&doc, &SaveOptions::default()).unwrap();
    let path = std::env::temp_dir().join(format!("pdfcraft-objstm-{}.pdf", std::process::id()));
    std::fs::write(&path, &packed).unwrap();
    let check = std::process::Command::new("qpdf").arg("--check").arg(&path).output().unwrap();
    let _ = std::fs::remove_file(&path);
    let report = String::from_utf8_lossy(&check.stdout);
    assert!(check.status.success() && report.contains("No syntax or stream encoding errors"), "{report}");
}

#[test]
fn objects_referenced_by_the_encrypt_dictionary_stay_outside_object_streams() {
    // Encrypt a document, then move its crypt filters into indirect objects, as some producers
    // do (pdf.js issue7665). A full save must keep them readable before decryption.
    let doc = Document::open(Arc::new(fixture())).unwrap();
    let mut enc = doc.clone();
    enc.set_encryption(&pdfcraft_cos::NewEncryption {
        algorithm: pdfcraft_cos::Algorithm::Aes256,
        user_password: "",
        owner_password: "owner",
        permissions: -4,
        encrypt_metadata: true,
        seed: [7; 32],
    })
    .unwrap();
    let bytes = Arc::new(write_full(&enc, &SaveOptions { object_streams: false, ..SaveOptions::default() }).unwrap());
    let mut doc = Document::open(bytes).unwrap();
    let enc_ref = doc.trailer().reference(b"Encrypt").expect("indirect /Encrypt");
    let cf = doc.get(enc_ref).as_dict().unwrap().get(b"CF").cloned().unwrap();
    let cf_ref = doc.add(cf);
    doc.update_dict(enc_ref, |d| d.set(b"CF".to_vec(), Object::Ref(cf_ref))).unwrap();
    let packed = write_full(&doc, &SaveOptions::default()).unwrap();
    let back = Document::open(Arc::new(packed.clone())).expect("reopens");
    assert!(back.repair_log().is_empty(), "{:?}", back.repair_log());
    assert_eq!(title(&back), b"Caf\xe9 (draft)");
    assert_eq!(hayro_pages(&packed), 4);
}

#[test]
fn page_tree_loops_in_object_streams_do_not_crash_readers() {
    // pdf.js Pages-tree-refs.pdf: /Kids 3 → 4 → 5 → 3. Written faithfully into object streams,
    // it used to overflow hayro-syntax's stack (vendored patch: cycle guard in `resolve_pages`).
    let objs = [
        "<< /Type /Catalog /Pages 2 0 R >>",
        "<< /Type /Pages /Kids [6 0 R 3 0 R] /Count 2 /MediaBox [0 0 595 842] >>",
        "<< /Type /Pages /Kids [4 0 R] /Count 1 >>",
        "<< /Type /Pages /Kids [5 0 R] /Count 1 >>",
        "<< /Type /Pages /Kids [3 0 R] /Count 1 >>",
        "<< /Type /Page /Parent 2 0 R >>",
    ];
    let mut out = b"%PDF-1.7\n".to_vec();
    let mut offsets = Vec::new();
    for (i, o) in objs.iter().enumerate() {
        offsets.push(out.len());
        out.extend_from_slice(format!("{} 0 obj\n{o}\nendobj\n", i + 1).as_bytes());
    }
    let xref = out.len();
    out.extend_from_slice(format!("xref\n0 {}\n0000000000 65535 f \n", objs.len() + 1).as_bytes());
    for o in offsets {
        out.extend_from_slice(format!("{o:010} 00000 n \n").as_bytes());
    }
    out.extend_from_slice(format!("trailer\n<< /Size {} /Root 1 0 R >>\nstartxref\n{xref}\n%%EOF\n", objs.len() + 1).as_bytes());
    let doc = Document::open(Arc::new(out)).unwrap();
    let packed = write_full(&doc, &SaveOptions::default()).unwrap();
    assert!(String::from_utf8_lossy(&packed).contains("/ObjStm"));
    assert_eq!(hayro_pages(&packed), 1);
}