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// SPDX-License-Identifier: MIT
//! Measured byte-string /Names/Dests trees, ISO 32000-1 ยงยง7.9.6, 12.3.2.3.
//! Validate once in lexical order, then resolve outline keys by binary search.
//! No document content or replacement destination is retained or emitted.
use super::*;
use parser::{MAX_SYNTAX_DEPTH, array_values, xyz_destination_page};
pub(super) struct NamedDestination {
pub name: Vec<u8>,
pub page: PdfRef,
}
enum Step {
Visit(PdfRef, u32),
Finish {
owner: PdfRef,
at: u64,
first: usize,
low: Vec<u8>,
high: Vec<u8>,
},
}
/// Decode a PDF byte string, not Unicode text. Capacity is checked before
/// allocation; a decoded string cannot exceed its original lexical length.
pub(super) fn name_bytes(raw: &[u8], cap: u64) -> Result<Option<Vec<u8>>> {
if !valid_text_string(raw) {
return Ok(None);
}
let mut syntax = Syntax::new(raw);
syntax.skip_space();
let start = syntax.pos;
// Validation above established a complete string.
syntax.skip_value(0).expect("validated PDF string");
let raw = &raw[start..syntax.pos];
let attempted = raw.len() as u64;
let refused = Error::limit("PDF destination name bytes", cap, attempted);
if attempted > cap {
return Err(refused);
}
let mut bytes = Vec::new();
reserve_exact(&mut bytes, raw.len(), refused)?;
let mut i = 1;
if raw[0] == b'<' {
let mut high = None;
for &byte in &raw[1..raw.len() - 1] {
let digit = match byte {
b'0'..=b'9' => byte - b'0',
b'a'..=b'f' => byte - b'a' + 10,
b'A'..=b'F' => byte - b'A' + 10,
_ => continue, // Only whitespace remains after validation.
};
if let Some(first) = high.take() {
bytes.push(first * 16 + digit);
} else {
high = Some(digit);
}
}
if let Some(first) = high {
bytes.push(first * 16);
}
} else {
while i < raw.len() - 1 {
let byte = raw[i];
i += 1;
match byte {
b'\\' => {
let escaped = raw[i];
i += 1;
match escaped {
b'n' => bytes.push(b'\n'),
b'r' => bytes.push(b'\r'),
b't' => bytes.push(b'\t'),
b'b' => bytes.push(8),
b'f' => bytes.push(12),
b'\n' => {}
b'\r' => i += usize::from(raw.get(i) == Some(&b'\n')),
b'0'..=b'7' => {
let mut value = escaped - b'0';
for _ in 0..2 {
match raw.get(i) {
Some(next @ b'0'..=b'7') => {
value = value.wrapping_mul(8).wrapping_add(next - b'0');
i += 1;
}
_ => break,
}
}
bytes.push(value);
}
_ => bytes.push(escaped),
}
}
b'\r' => {
bytes.push(b'\n');
i += usize::from(raw.get(i) == Some(&b'\n'));
}
_ => bytes.push(byte),
}
}
}
Ok(Some(bytes))
}
impl<S: RangedSource, C: Cancellation> Reader<'_, S, C> {
fn destination_object(
&mut self,
reference: PdfRef,
slots: &[Option<XrefSlot>],
index: &PdfIndex,
work: &mut u64,
) -> Result<(ObjectHead, u64)> {
let location = index.metadata_location(reference)?;
let (head, _) = self.load_indexed_object(location.offset, reference, slots, index)?;
*work = work.saturating_add(head.bytes.len() as u64);
if *work > self.limits.max_allocation_bytes {
return Err(Error::limit(
"PDF destination metadata work",
self.limits.max_allocation_bytes,
*work,
)
.at(self.absolute(location.offset))
.in_pdf(Some((reference.number, reference.generation))));
}
if !matches!(head.tail, ObjectTail::EndObject { .. }) {
return Err(self.malformed(
location.offset,
Some(reference),
"destination metadata must not be a stream",
));
}
Ok((head, location.offset))
}
pub(super) fn read_named_destinations(
&mut self,
slots: &[Option<XrefSlot>],
index: &PdfIndex,
page_targets: &[Option<u16>],
) -> Result<Vec<NamedDestination>> {
let catalog_at = index.metadata_location(index.catalog)?.offset;
let reference = index
.catalog_dict
.value(b"Names")
.and_then(exact_reference)
.ok_or_else(|| {
self.problem(
catalog_at,
Some(index.catalog),
ErrorKind::UnsupportedFormat,
"named destinations require an indirect Catalog Names dictionary",
)
})?;
let mut work = 0;
let (head, at) = self.destination_object(reference, slots, index, &mut work)?;
let root = head
.dictionary
.as_ref()
.and_then(|d| d.value(b"Dests"))
.and_then(exact_reference)
.ok_or_else(|| {
self.problem(
at,
Some(reference),
ErrorKind::UnsupportedFormat,
"named destinations require an indirect Dests name tree",
)
})?;
drop(head);
// Every slot was already admitted by PdfIndex's larger slot budget.
let mut visited = Vec::new();
reserve_exact(
&mut visited,
slots.len(),
self.allocation_limit(
at,
Some(root),
"PDF destination visited index",
slots.len() as u64,
),
)?;
visited.resize(slots.len(), false);
let cap = self.limits.max_allocation_bytes / 8;
let mut names: Vec<NamedDestination> = Vec::new();
let mut name_bytes_used = 0_u64;
let mut stack = Vec::new();
push_bounded(
&mut stack,
Step::Visit(root, 0),
cap,
"PDF destination tree stack",
)
.map_err(self.locator(at, Some(root)))?;
while let Some(step) = stack.pop() {
if self.cancellation.is_cancelled() {
return Err(ErrorKind::Cancelled.into());
}
let (owner, depth) = match step {
Step::Visit(owner, depth) => (owner, depth),
Step::Finish {
owner,
at,
first,
low,
high,
} => {
if names.len() == first
|| names[first].name != low
|| names.last().is_none_or(|entry| entry.name != high)
{
return Err(self.malformed(
at,
Some(owner),
"destination name-tree Limits disagree with descendants",
));
}
continue;
}
};
let at = index.metadata_location(owner)?.offset;
if depth > MAX_SYNTAX_DEPTH {
return Err(Error::limit(
"PDF destination tree depth",
u64::from(MAX_SYNTAX_DEPTH),
u64::from(depth),
)
.at(self.absolute(at))
.in_pdf(Some((owner.number, owner.generation))));
}
if std::mem::replace(&mut visited[owner.number as usize], true) {
return Err(self.malformed(
at,
Some(owner),
"destination name tree contains a cycle or shared node",
));
}
let (head, _) = self.destination_object(owner, slots, index, &mut work)?;
let dictionary = head.dictionary.ok_or_else(|| {
self.malformed(
at,
Some(owner),
"destination name-tree node is not a dictionary",
)
})?;
let range = self.range;
let absolute = self.absolute(at);
let bad = || {
located_problem(
range,
at,
Some(owner),
ErrorKind::Malformed,
"invalid destination name-tree node",
)
};
let (kids, values) = (dictionary.value(b"Kids"), dictionary.value(b"Names"));
if kids.is_some() == values.is_some()
|| dictionary.entries.len() != if depth == 0 { 1 } else { 2 }
{
return Err(bad());
}
let decode = |raw: &[u8], used: &mut u64| -> Result<Vec<u8>> {
let value = name_bytes(raw, cap.saturating_sub(*used))
.map_err(|error| {
error
.at(absolute)
.in_pdf(Some((owner.number, owner.generation)))
})?
.ok_or_else(bad)?;
// Charge reserved lexical capacity, including temporary Limits strings.
*used = used.saturating_add(value.capacity() as u64);
if *used > cap {
return Err(Error::limit("PDF destination name bytes", cap, *used)
.at(absolute)
.in_pdf(Some((owner.number, owner.generation))));
}
Ok(value)
};
if depth != 0 {
let mut bounds = array_values(dictionary.value(b"Limits").ok_or_else(bad)?)
.map_err(|_| bad())?;
let low = decode(
bounds
.next()
.transpose()
.map_err(|_| bad())?
.ok_or_else(bad)?,
&mut name_bytes_used,
)?;
let high = decode(
bounds
.next()
.transpose()
.map_err(|_| bad())?
.ok_or_else(bad)?,
&mut name_bytes_used,
)?;
if low > high || bounds.next().is_some() {
return Err(bad());
}
push_bounded(
&mut stack,
Step::Finish {
owner,
at,
first: names.len(),
low,
high,
},
cap,
"PDF destination tree stack",
)
.map_err(self.locator(at, Some(owner)))?;
}
if let Some(kids) = kids {
let children = reference_array(kids, slots.len())
.filter(|v| !v.is_empty())
.ok_or_else(bad)?;
for child in children.into_iter().rev() {
push_bounded(
&mut stack,
Step::Visit(child, depth + 1),
cap,
"PDF destination tree stack",
)
.map_err(self.locator(at, Some(owner)))?;
}
} else {
let mut entries =
array_values(values.expect("exactly one Names or Kids")).map_err(|_| bad())?;
let first = names.len();
while let Some(raw) = entries.next() {
if self.cancellation.is_cancelled() {
return Err(ErrorKind::Cancelled.into());
}
let name = decode(raw.map_err(|_| bad())?, &mut name_bytes_used)?;
if names.last().is_some_and(|previous| previous.name >= name) {
return Err(self.malformed(
at,
Some(owner),
"destination names are duplicated or out of order",
));
}
let value = entries
.next()
.transpose()
.map_err(|_| bad())?
.ok_or_else(bad)?;
let target = exact_reference(value).ok_or_else(|| {
self.problem(
at,
Some(owner),
ErrorKind::UnsupportedFormat,
"named destination must be an indirect XYZ array",
)
})?;
let (destination, target_at) =
self.destination_object(target, slots, index, &mut work)?;
let page = destination
.scalar
.as_ref()
.and_then(|span| xyz_destination_page(&destination.bytes[span.clone()]))
.ok_or_else(|| {
self.problem(
target_at,
Some(target),
ErrorKind::UnsupportedFormat,
"named destination must be an indirect XYZ array",
)
})?;
if page_targets.get(page.number as usize).copied().flatten()
!= Some(page.generation)
{
return Err(self.malformed(
target_at,
Some(target),
"named destination does not target a page",
));
}
push_bounded(
&mut names,
NamedDestination { name, page },
cap,
"PDF named destination index",
)
.map_err(self.locator(at, Some(owner)))?;
}
if names.len() == first {
return Err(self.malformed(
at,
Some(owner),
"destination name-tree leaf is empty",
));
}
}
}
Ok(names)
}
}