mirror of
https://github.com/storytold/effectcraft.git
synced 2026-10-24 18:18:17 -06:00
678 lines
23 KiB
Rust
678 lines
23 KiB
Rust
//! Local object model, content-stream lexer and stream filters. Document objects are read
|
|
//! through the shared parser in `read`; the local lexer remains for content operators and
|
|
//! PostScript-related data.
|
|
|
|
use std::collections::HashMap;
|
|
|
|
#[derive(Clone, Debug, PartialEq)]
|
|
pub enum Obj {
|
|
Null,
|
|
Bool(bool),
|
|
Num(f64),
|
|
Name(String),
|
|
Str(Vec<u8>),
|
|
Array(Vec<Obj>),
|
|
Dict(Dict),
|
|
Ref(u32, u16),
|
|
/// A stream: its dictionary and raw (still encoded) data.
|
|
Stream(Dict, Vec<u8>),
|
|
/// A content-stream operator (or any bare keyword).
|
|
Op(String),
|
|
}
|
|
|
|
pub type Dict = HashMap<String, Obj>;
|
|
|
|
impl Obj {
|
|
pub fn num(&self) -> Option<f64> {
|
|
match self {
|
|
Obj::Num(n) => Some(*n),
|
|
_ => None,
|
|
}
|
|
}
|
|
pub fn name(&self) -> Option<&str> {
|
|
match self {
|
|
Obj::Name(n) => Some(n),
|
|
_ => None,
|
|
}
|
|
}
|
|
pub fn array(&self) -> Option<&[Obj]> {
|
|
match self {
|
|
Obj::Array(a) => Some(a),
|
|
_ => None,
|
|
}
|
|
}
|
|
pub fn dict(&self) -> Option<&Dict> {
|
|
match self {
|
|
Obj::Dict(d) | Obj::Stream(d, _) => Some(d),
|
|
_ => None,
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn is_white(c: u8) -> bool {
|
|
matches!(c, 0 | 9 | 10 | 12 | 13 | 32)
|
|
}
|
|
pub fn is_delim(c: u8) -> bool {
|
|
matches!(c, b'(' | b')' | b'<' | b'>' | b'[' | b']' | b'{' | b'}' | b'/' | b'%')
|
|
}
|
|
|
|
/// A byte lexer producing PDF objects (arrays and dictionaries nested).
|
|
pub struct Lexer<'a> {
|
|
pub data: &'a [u8],
|
|
pub pos: usize,
|
|
}
|
|
|
|
impl<'a> Lexer<'a> {
|
|
pub fn new(data: &'a [u8], pos: usize) -> Self {
|
|
Lexer { data, pos }
|
|
}
|
|
|
|
pub fn skip_ws(&mut self) {
|
|
while self.pos < self.data.len() {
|
|
let c = self.data[self.pos];
|
|
if is_white(c) {
|
|
self.pos += 1;
|
|
} else if c == b'%' {
|
|
while self.pos < self.data.len() && !matches!(self.data[self.pos], b'\n' | b'\r') {
|
|
self.pos += 1;
|
|
}
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
fn word(&mut self) -> &'a [u8] {
|
|
let s = self.pos;
|
|
while self.pos < self.data.len() && !is_white(self.data[self.pos]) && !is_delim(self.data[self.pos]) {
|
|
self.pos += 1;
|
|
}
|
|
&self.data[s..self.pos]
|
|
}
|
|
|
|
/// The next object, `None` at the end. `]` and `>>` come back as `Op`s.
|
|
pub fn next(&mut self) -> Option<Obj> {
|
|
self.next_depth(0)
|
|
}
|
|
|
|
fn next_depth(&mut self, depth: usize) -> Option<Obj> {
|
|
self.skip_ws();
|
|
let c = *self.data.get(self.pos)?;
|
|
match c {
|
|
b'/' => {
|
|
self.pos += 1;
|
|
let w = self.word();
|
|
Some(Obj::Name(decode_name(w)))
|
|
}
|
|
b'(' => Some(Obj::Str(self.literal_string())),
|
|
b'<' if self.data.get(self.pos + 1) == Some(&b'<') => {
|
|
self.pos += 2;
|
|
let mut d = Dict::new();
|
|
loop {
|
|
if depth > 64 {
|
|
return Some(Obj::Null);
|
|
}
|
|
let k = self.next_depth(depth + 1);
|
|
match k {
|
|
None => break,
|
|
Some(Obj::Op(o)) if o == ">>" => break,
|
|
Some(Obj::Name(k)) => {
|
|
let v = self.next_depth(depth + 1).unwrap_or(Obj::Null);
|
|
let v = self.maybe_ref(v);
|
|
d.insert(k, v);
|
|
}
|
|
Some(_) => {}
|
|
}
|
|
}
|
|
Some(Obj::Dict(d))
|
|
}
|
|
b'<' => {
|
|
self.pos += 1;
|
|
let mut hex = vec![];
|
|
while self.pos < self.data.len() && self.data[self.pos] != b'>' {
|
|
let h = self.data[self.pos];
|
|
if h.is_ascii_hexdigit() {
|
|
hex.push(h);
|
|
}
|
|
self.pos += 1;
|
|
}
|
|
self.pos += 1;
|
|
if hex.len() % 2 == 1 {
|
|
hex.push(b'0');
|
|
}
|
|
Some(Obj::Str(hex.chunks(2).map(|p| (hexv(p[0]) << 4) | hexv(p[1])).collect()))
|
|
}
|
|
b'>' if self.data.get(self.pos + 1) == Some(&b'>') => {
|
|
self.pos += 2;
|
|
Some(Obj::Op(">>".into()))
|
|
}
|
|
b'[' => {
|
|
self.pos += 1;
|
|
let mut a = vec![];
|
|
loop {
|
|
if depth > 64 {
|
|
return Some(Obj::Null);
|
|
}
|
|
match self.next_depth(depth + 1) {
|
|
None => break,
|
|
Some(Obj::Op(o)) if o == "]" => break,
|
|
Some(v) => {
|
|
let v = self.maybe_ref(v);
|
|
a.push(v);
|
|
}
|
|
}
|
|
}
|
|
Some(Obj::Array(a))
|
|
}
|
|
b']' | b'{' | b'}' | b')' | b'>' => {
|
|
self.pos += 1;
|
|
Some(Obj::Op((c as char).to_string()))
|
|
}
|
|
_ => {
|
|
let w = self.word();
|
|
if w.is_empty() {
|
|
self.pos += 1;
|
|
return Some(Obj::Op(String::new()));
|
|
}
|
|
Some(match w {
|
|
b"true" => Obj::Bool(true),
|
|
b"false" => Obj::Bool(false),
|
|
b"null" => Obj::Null,
|
|
_ => match parse_num(w) {
|
|
Some(n) => Obj::Num(n),
|
|
None => Obj::Op(String::from_utf8_lossy(w).into_owned()),
|
|
},
|
|
})
|
|
}
|
|
}
|
|
}
|
|
|
|
/// `n g R` after a number inside arrays and dictionaries.
|
|
pub(super) fn maybe_ref(&mut self, v: Obj) -> Obj {
|
|
let Obj::Num(n) = v else { return v };
|
|
if n.fract() != 0.0 || n < 0.0 {
|
|
return v;
|
|
}
|
|
let save = self.pos;
|
|
self.skip_ws();
|
|
let gp = self.pos;
|
|
let g = self.word();
|
|
if let Some(gn) = parse_num(g).filter(|g| g.fract() == 0.0 && *g >= 0.0) {
|
|
self.skip_ws();
|
|
if self.data.get(self.pos) == Some(&b'R') && self.data.get(self.pos + 1).is_none_or(|c| is_white(*c) || is_delim(*c)) {
|
|
self.pos += 1;
|
|
return Obj::Ref(n as u32, gn as u16);
|
|
}
|
|
}
|
|
let _ = gp;
|
|
self.pos = save;
|
|
v
|
|
}
|
|
|
|
fn literal_string(&mut self) -> Vec<u8> {
|
|
self.pos += 1;
|
|
let mut out = vec![];
|
|
let mut depth = 1;
|
|
while self.pos < self.data.len() {
|
|
let c = self.data[self.pos];
|
|
self.pos += 1;
|
|
match c {
|
|
b'\\' => {
|
|
let Some(&e) = self.data.get(self.pos) else { break };
|
|
self.pos += 1;
|
|
match e {
|
|
b'n' => out.push(b'\n'),
|
|
b'r' => out.push(b'\r'),
|
|
b't' => out.push(b'\t'),
|
|
b'b' => out.push(8),
|
|
b'f' => out.push(12),
|
|
b'\r' => {
|
|
if self.data.get(self.pos) == Some(&b'\n') {
|
|
self.pos += 1;
|
|
}
|
|
}
|
|
b'\n' => {}
|
|
b'0'..=b'7' => {
|
|
let mut v = (e - b'0') as u32;
|
|
for _ in 0..2 {
|
|
match self.data.get(self.pos) {
|
|
Some(d @ b'0'..=b'7') => {
|
|
v = v * 8 + (d - b'0') as u32;
|
|
self.pos += 1;
|
|
}
|
|
_ => break,
|
|
}
|
|
}
|
|
out.push(v as u8);
|
|
}
|
|
other => out.push(other),
|
|
}
|
|
}
|
|
b'(' => {
|
|
depth += 1;
|
|
out.push(c);
|
|
}
|
|
b')' => {
|
|
depth -= 1;
|
|
if depth == 0 {
|
|
break;
|
|
}
|
|
out.push(c);
|
|
}
|
|
_ => out.push(c),
|
|
}
|
|
}
|
|
out
|
|
}
|
|
}
|
|
|
|
fn hexv(c: u8) -> u8 {
|
|
match c {
|
|
b'0'..=b'9' => c - b'0',
|
|
b'a'..=b'f' => c - b'a' + 10,
|
|
b'A'..=b'F' => c - b'A' + 10,
|
|
_ => 0,
|
|
}
|
|
}
|
|
|
|
fn decode_name(w: &[u8]) -> String {
|
|
let mut out = vec![];
|
|
let mut i = 0;
|
|
while i < w.len() {
|
|
if w[i] == b'#' && w.get(i + 1).is_some_and(u8::is_ascii_hexdigit) && w.get(i + 2).is_some_and(u8::is_ascii_hexdigit) {
|
|
out.push((hexv(w[i + 1]) << 4) | hexv(w[i + 2]));
|
|
i += 3;
|
|
} else {
|
|
out.push(w[i]);
|
|
i += 1;
|
|
}
|
|
}
|
|
String::from_utf8_lossy(&out).into_owned()
|
|
}
|
|
|
|
pub fn parse_num(w: &[u8]) -> Option<f64> {
|
|
if w.is_empty() || !w.iter().all(|c| c.is_ascii_digit() || matches!(c, b'+' | b'-' | b'.')) || !w.iter().any(u8::is_ascii_digit) {
|
|
return None;
|
|
}
|
|
let s = std::str::from_utf8(w).ok()?;
|
|
// "--5" and similar malformed numbers: take what parses.
|
|
s.parse::<f64>().ok().or_else(|| s.trim_start_matches(['+', '-']).parse::<f64>().ok().map(|v| if s.starts_with('-') { -v } else { v }))
|
|
}
|
|
|
|
// ------------------------------------------------------------------ filters
|
|
|
|
/// The most bytes one stream filter may decode to. Deflate expands up to about 1000:1, so
|
|
/// unbounded, a few MB of PDF ask for gigabytes and a failed allocation aborts the process. The
|
|
/// largest image `image::decode` accepts (64 Mi pixels) of four 16-bit components is 512 MiB;
|
|
/// 1 GiB leaves room for more components and is PdfCraft's ceiling for one stream. 32-bit
|
|
/// targets (the web build) get a quarter: their whole address space is 4 GiB, and the inflater's
|
|
/// growing buffer can reserve about twice the limit.
|
|
const MAX_INFLATED: usize = if cfg!(target_pointer_width = "32") { 256 << 20 } else { 1 << 30 };
|
|
|
|
/// The bound for ordinary object/xref streams and malformed object-stream recovery.
|
|
/// The shared parser receives this immutable limit when the document is opened;
|
|
/// 32-bit targets retain the app's quarter-sized limit.
|
|
pub(crate) const MAX_OBJECT_STREAM: usize = if cfg!(target_pointer_width = "32") { 64 << 20 } else { 256 << 20 };
|
|
|
|
/// Decode a stream's data through its `/Filter` chain. Unknown filters (images: DCT, JPX, CCITT,
|
|
/// JBIG2) give `None`.
|
|
pub fn decode_stream(file: &File, d: &Dict, raw: &[u8]) -> Option<Vec<u8>> {
|
|
decode_stream_within(file, d, raw, MAX_INFLATED)
|
|
}
|
|
|
|
/// [`decode_stream`] with every filter's output bounded by `max` bytes. Exceeding the
|
|
/// bound gives `None`, never a truncated prefix; predictors share the same bound.
|
|
pub fn decode_stream_within(file: &File, d: &Dict, raw: &[u8], max: usize) -> Option<Vec<u8>> {
|
|
let filters: Vec<String> = match d.get("Filter").map(|f| file.resolve(f)) {
|
|
None => vec![],
|
|
Some(Obj::Name(n)) => vec![n.clone()],
|
|
Some(Obj::Array(a)) => a.iter().filter_map(|f| file.resolve(f).name().map(str::to_string)).collect(),
|
|
_ => vec![],
|
|
};
|
|
let parms: Vec<Option<Dict>> = match d.get("DecodeParms").or_else(|| d.get("DP")).map(|p| file.resolve(p)) {
|
|
Some(Obj::Dict(p)) => vec![Some(p.clone())],
|
|
Some(Obj::Array(a)) => a.iter().map(|p| file.resolve(p).dict().cloned()).collect(),
|
|
_ => vec![],
|
|
};
|
|
let mut data = raw.to_vec();
|
|
for (i, f) in filters.iter().enumerate() {
|
|
data = match f.as_str() {
|
|
"FlateDecode" | "Fl" => inflate(&data, max)?,
|
|
"ASCIIHexDecode" | "AHx" => ascii_hex(&data, max)?,
|
|
"ASCII85Decode" | "A85" => ascii85_within(&data, max)?,
|
|
"LZWDecode" | "LZW" => {
|
|
lzw(&data, parms.get(i).and_then(|p| p.as_ref()).and_then(|p| p.get("EarlyChange")).and_then(Obj::num).unwrap_or(1.0) != 0.0, max)?
|
|
}
|
|
"RunLengthDecode" | "RL" => run_length(&data, max)?,
|
|
"CCITTFaxDecode" | "CCF" => crate::ccitt::decode(&data, &ccitt_params(file, parms.get(i).and_then(|p| p.as_ref())), max)?,
|
|
_ => return None,
|
|
};
|
|
if data.len() > max {
|
|
return None;
|
|
}
|
|
if let Some(Some(p)) = parms.get(i)
|
|
&& matches!(f.as_str(), "FlateDecode" | "Fl" | "LZWDecode" | "LZW")
|
|
{
|
|
data = predict(&data, p, max)?;
|
|
}
|
|
}
|
|
Some(data)
|
|
}
|
|
|
|
/// `/DecodeParms` of a `CCITTFaxDecode` filter.
|
|
fn ccitt_params(file: &File, d: Option<&Dict>) -> crate::ccitt::Params {
|
|
let mut p = crate::ccitt::Params::default();
|
|
let Some(d) = d else { return p };
|
|
let flag = |k: &str, default: bool| match file.get(d, k) {
|
|
Some(Obj::Bool(b)) => *b,
|
|
_ => default,
|
|
};
|
|
p.k = file.get_num(d, "K").unwrap_or(0.0) as i64;
|
|
p.columns = file.get_num(d, "Columns").map(|c| c.max(1.0) as usize).unwrap_or(1728);
|
|
p.rows = file.get_num(d, "Rows").map(|r| r.max(0.0) as usize).unwrap_or(0);
|
|
p.end_of_line = flag("EndOfLine", false);
|
|
p.byte_align = flag("EncodedByteAlign", false);
|
|
p.end_of_block = flag("EndOfBlock", true);
|
|
p.black_is_1 = flag("BlackIs1", false);
|
|
p
|
|
}
|
|
|
|
/// Inflate zlib data (or raw deflate) to at most `max` bytes. A stream that inflates to more is
|
|
/// undecodable (`None`), not salvaged as a truncated one.
|
|
pub fn inflate(data: &[u8], max: usize) -> Option<Vec<u8>> {
|
|
use miniz_oxide::inflate::{TINFLStatus, decompress_to_vec_with_limit, decompress_to_vec_zlib_with_limit};
|
|
for attempt in [decompress_to_vec_zlib_with_limit, decompress_to_vec_with_limit] {
|
|
match attempt(data, max) {
|
|
Ok(v) => return Some(v),
|
|
Err(e) if e.status == TINFLStatus::HasMoreOutput => return None,
|
|
Err(_) => {}
|
|
}
|
|
}
|
|
// Truncated streams: keep what inflates.
|
|
let mut d = miniz_oxide::inflate::stream::InflateState::new_boxed(miniz_oxide::DataFormat::Zlib);
|
|
let mut out = vec![0u8; salvage_len(data.len(), max)];
|
|
let r = miniz_oxide::inflate::stream::inflate(&mut d, data, &mut out, miniz_oxide::MZFlush::Finish);
|
|
(r.bytes_written > 0).then(|| out[..r.bytes_written].to_vec())
|
|
}
|
|
|
|
/// The buffer [`inflate`] salvages a truncated stream of `data_len` bytes into: eight times that
|
|
/// and 1 KiB, at most `max`. The zlib attempt already stopped within `max`, so the bound loses
|
|
/// nothing, while without it a Flate filter after another could ask for eight times `max`.
|
|
pub fn salvage_len(data_len: usize, max: usize) -> usize {
|
|
data_len.saturating_mul(8).saturating_add(1024).min(max)
|
|
}
|
|
|
|
fn ascii_hex(data: &[u8], max: usize) -> Option<Vec<u8>> {
|
|
let mut out = vec![];
|
|
let mut high = None;
|
|
for c in data.iter().copied().take_while(|c| *c != b'>').filter(u8::is_ascii_hexdigit) {
|
|
if let Some(h) = high.take() {
|
|
if out.len() >= max {
|
|
return None;
|
|
}
|
|
out.push((h << 4) | hexv(c));
|
|
} else {
|
|
high = Some(hexv(c));
|
|
}
|
|
}
|
|
if let Some(h) = high {
|
|
if out.len() >= max {
|
|
return None;
|
|
}
|
|
out.push(h << 4);
|
|
}
|
|
Some(out)
|
|
}
|
|
|
|
pub fn ascii85(data: &[u8]) -> Vec<u8> {
|
|
// The PostScript reader uses this unbounded entry point. No Vec can hold more
|
|
// than usize::MAX bytes, so its output cannot exceed this bound.
|
|
ascii85_within(data, usize::MAX).unwrap_or_default()
|
|
}
|
|
|
|
fn ascii85_within(data: &[u8], max: usize) -> Option<Vec<u8>> {
|
|
let mut out = vec![];
|
|
let mut group = [0u32; 5];
|
|
let mut n = 0;
|
|
let mut i = 0;
|
|
if data.starts_with(b"<~") {
|
|
i = 2;
|
|
}
|
|
while i < data.len() {
|
|
let c = data[i];
|
|
i += 1;
|
|
match c {
|
|
b'~' => break,
|
|
b'z' if n == 0 => {
|
|
if out.len().checked_add(4)? > max {
|
|
return None;
|
|
}
|
|
out.extend_from_slice(&[0; 4]);
|
|
}
|
|
b'!'..=b'u' => {
|
|
group[n] = (c - b'!') as u32;
|
|
n += 1;
|
|
if n == 5 {
|
|
if out.len().checked_add(4)? > max {
|
|
return None;
|
|
}
|
|
let v = group.iter().fold(0u32, |a, &d| a.wrapping_mul(85).wrapping_add(d));
|
|
out.extend_from_slice(&v.to_be_bytes());
|
|
n = 0;
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
if n > 1 {
|
|
if out.len().checked_add(n - 1)? > max {
|
|
return None;
|
|
}
|
|
for g in group.iter_mut().skip(n) {
|
|
*g = 84;
|
|
}
|
|
let v = group.iter().fold(0u32, |a, &d| a.wrapping_mul(85).wrapping_add(d));
|
|
out.extend_from_slice(&v.to_be_bytes()[..n - 1]);
|
|
}
|
|
Some(out)
|
|
}
|
|
|
|
fn lzw(data: &[u8], early: bool, max: usize) -> Option<Vec<u8>> {
|
|
let mut out = vec![];
|
|
let mut table: Vec<Vec<u8>> = (0..=255u16).map(|b| vec![b as u8]).collect();
|
|
table.push(vec![]);
|
|
table.push(vec![]);
|
|
let (mut bits, mut acc, mut nbits) = (9u32, 0u32, 0u32);
|
|
let mut prev: Option<Vec<u8>> = None;
|
|
for &b in data {
|
|
acc = (acc << 8) | b as u32;
|
|
nbits += 8;
|
|
while nbits >= bits {
|
|
let code = ((acc >> (nbits - bits)) & ((1 << bits) - 1)) as usize;
|
|
nbits -= bits;
|
|
match code {
|
|
256 => {
|
|
table.truncate(258);
|
|
bits = 9;
|
|
prev = None;
|
|
continue;
|
|
}
|
|
257 => return Some(out),
|
|
_ => {}
|
|
}
|
|
let entry = if code < table.len() {
|
|
table[code].clone()
|
|
} else if let Some(p) = &prev {
|
|
let mut e = p.clone();
|
|
e.push(p[0]);
|
|
e
|
|
} else {
|
|
return Some(out);
|
|
};
|
|
if out.len().checked_add(entry.len())? > max {
|
|
return None;
|
|
}
|
|
out.extend_from_slice(&entry);
|
|
// PDF codes have at most 12 bits. Freeze a full table until a clear code.
|
|
if let Some(p) = prev
|
|
&& table.len() < 4096
|
|
{
|
|
let mut e = p;
|
|
e.push(entry[0]);
|
|
table.push(e);
|
|
}
|
|
prev = Some(entry);
|
|
let limit = table.len() + usize::from(early);
|
|
if limit >= (1 << bits) && bits < 12 {
|
|
bits += 1;
|
|
}
|
|
}
|
|
}
|
|
Some(out)
|
|
}
|
|
|
|
fn run_length(data: &[u8], max: usize) -> Option<Vec<u8>> {
|
|
let mut out = vec![];
|
|
let mut i = 0;
|
|
while i < data.len() {
|
|
let l = data[i] as usize;
|
|
i += 1;
|
|
if l < 128 {
|
|
let end = i.saturating_add(l + 1).min(data.len());
|
|
let literal = data.get(i..end)?;
|
|
if out.len().checked_add(literal.len())? > max {
|
|
return None;
|
|
}
|
|
out.extend_from_slice(literal);
|
|
i = end;
|
|
} else if l > 128 {
|
|
if let Some(&b) = data.get(i) {
|
|
if out.len().checked_add(257 - l)? > max {
|
|
return None;
|
|
}
|
|
out.extend(std::iter::repeat_n(b, 257 - l));
|
|
}
|
|
i = i.saturating_add(1);
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
Some(out)
|
|
}
|
|
|
|
/// PNG / TIFF predictors (`/Predictor`, `/Colors`, `/BitsPerComponent`, `/Columns`).
|
|
fn predict(data: &[u8], p: &Dict, max: usize) -> Option<Vec<u8>> {
|
|
if data.len() > max {
|
|
return None;
|
|
}
|
|
let g = |k: &str, d: f64| p.get(k).and_then(Obj::num).unwrap_or(d) as usize;
|
|
let pred = g("Predictor", 1.0);
|
|
if pred < 10 {
|
|
return Some(data.to_vec());
|
|
}
|
|
// A row that is zero bytes wide, overflows, or is not shorter than the data leaves no
|
|
// complete row: nothing comes out, as it always did for the first and last, and the row
|
|
// buffer (sized from `/Columns`) is not allocated.
|
|
let Some(pixel_bits) = g("Colors", 1.0).checked_mul(g("BitsPerComponent", 8.0)) else { return Some(vec![]) };
|
|
let Some(bpp) = pixel_bits.checked_add(7).map(|n| (n / 8).max(1)) else { return Some(vec![]) };
|
|
let Some(row) = g("Columns", 1.0).checked_mul(pixel_bits).and_then(|n| n.checked_add(7)).map(|n| n / 8).filter(|&n| n > 0 && n < data.len()) else {
|
|
return Some(vec![]);
|
|
};
|
|
let stride = row.checked_add(1)?;
|
|
let mut out = Vec::with_capacity(data.len());
|
|
let mut prev = vec![0u8; row];
|
|
for chunk in data.chunks(stride) {
|
|
if chunk.len() < stride {
|
|
break;
|
|
}
|
|
let ft = chunk[0];
|
|
let mut cur = chunk[1..].to_vec();
|
|
for i in 0..row {
|
|
let a = if i >= bpp { cur[i - bpp] as i32 } else { 0 };
|
|
let b = prev[i] as i32;
|
|
let c = if i >= bpp { prev[i - bpp] as i32 } else { 0 };
|
|
let add = match ft {
|
|
1 => a,
|
|
2 => b,
|
|
3 => (a + b) / 2,
|
|
4 => {
|
|
let pp = a + b - c;
|
|
let (pa, pb, pc) = ((pp - a).abs(), (pp - b).abs(), (pp - c).abs());
|
|
if pa <= pb && pa <= pc {
|
|
a
|
|
} else if pb <= pc {
|
|
b
|
|
} else {
|
|
c
|
|
}
|
|
}
|
|
_ => 0,
|
|
};
|
|
cur[i] = (cur[i] as i32 + add) as u8;
|
|
}
|
|
out.extend_from_slice(&cur);
|
|
prev = cur;
|
|
}
|
|
Some(out)
|
|
}
|
|
|
|
// ------------------------------------------------------------------ the file
|
|
|
|
/// Every indirect object of a PDF file, plus the trailer dictionaries found.
|
|
pub struct File {
|
|
pub objects: HashMap<(u32, u16), Obj>,
|
|
pub trailers: Vec<Dict>,
|
|
pub repairs: Vec<String>,
|
|
}
|
|
|
|
impl File {
|
|
pub fn parse(data: &[u8]) -> Result<File, crate::Error> {
|
|
crate::read::open(data)
|
|
}
|
|
|
|
/// Follow references (bounded).
|
|
pub fn resolve<'a>(&'a self, o: &'a Obj) -> &'a Obj {
|
|
let mut o = o;
|
|
for _ in 0..32 {
|
|
match o {
|
|
Obj::Ref(n, g) => match self.objects.get(&(*n, *g)) {
|
|
Some(x) => o = x,
|
|
None => return &Obj::Null,
|
|
},
|
|
_ => return o,
|
|
}
|
|
}
|
|
&Obj::Null
|
|
}
|
|
|
|
pub fn get<'a>(&'a self, d: &'a Dict, key: &str) -> Option<&'a Obj> {
|
|
d.get(key).map(|o| self.resolve(o)).filter(|o| !matches!(o, Obj::Null))
|
|
}
|
|
|
|
pub fn get_dict<'a>(&'a self, d: &'a Dict, key: &str) -> Option<&'a Dict> {
|
|
self.get(d, key)?.dict()
|
|
}
|
|
|
|
pub fn get_num(&self, d: &Dict, key: &str) -> Option<f64> {
|
|
self.get(d, key)?.num()
|
|
}
|
|
|
|
/// Numbers of an array (references resolved).
|
|
pub fn nums(&self, o: &Obj) -> Vec<f64> {
|
|
self.resolve(o).array().map(|a| a.iter().filter_map(|x| self.resolve(x).num()).collect()).unwrap_or_default()
|
|
}
|
|
|
|
/// The document catalog.
|
|
pub fn catalog(&self) -> Option<&Dict> {
|
|
for t in self.trailers.iter().rev() {
|
|
if let Some(Obj::Dict(d)) = t.get("Root").map(|r| self.resolve(r)) {
|
|
return Some(d);
|
|
}
|
|
}
|
|
let mut cats: Vec<(&(u32, u16), &Obj)> =
|
|
self.objects.iter().filter(|(_, o)| matches!(o, Obj::Dict(d) if d.get("Type").and_then(Obj::name) == Some("Catalog"))).collect();
|
|
cats.sort_by_key(|(n, _)| **n);
|
|
cats.last().and_then(|(_, o)| o.dict())
|
|
}
|
|
}
|