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https://github.com/storytold/pdfcraft.git
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aiongg
fc1372a64c
hayro-cmap reads CMap streams with hayro-postscript's token scanner, whose object::read skipped each `<<` and `>>` by calling itself again. A CMap holding a long run of `<` or `>` used one stack frame per pair, overflowed the stack and aborted the process. Vendor hayro-postscript 0.1.0 with read() looping over the delimiters instead (from storytold/craft-libs#263), patched in beside hayro-cmap. Four object::tests cover long `<<` and `>>` runs and the skipped delimiters, plain and nested.
91 lines
2.7 KiB
Rust
91 lines
2.7 KiB
Rust
// Keep in sync with `hayro-syntax/src/filter/ascii_85.rs`.
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use crate::reader::{Reader, is_whitespace};
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use alloc::vec::Vec;
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pub(crate) fn decode_into(data: &[u8], out: &mut Vec<u8>) -> Option<()> {
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const POW_85: [u32; 5] = [52200625, 614125, 7225, 85, 1];
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let mut reader = Reader::new(data);
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let mut read_byte = || -> Option<u8> {
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loop {
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let b = reader.read_byte()?;
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// White space characters should be ignored.
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if !is_whitespace(b) {
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return Some(b);
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}
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}
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};
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let flush_group = |group: &mut Vec<u8>, decoded: &mut Vec<u8>| -> Option<()> {
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let (digits, output_len): ([u32; 5], usize) = match group.len() {
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0 => return Some(()),
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1 => return None, // A single character is not valid.
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2 => (
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[group[0], group[1], b'u', b'u', b'u'].map(|b| (b - b'!') as u32),
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1,
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),
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3 => (
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[group[0], group[1], group[2], b'u', b'u'].map(|b| (b - b'!') as u32),
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2,
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),
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4 => (
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[group[0], group[1], group[2], group[3], b'u'].map(|b| (b - b'!') as u32),
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3,
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),
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5 => (
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[group[0], group[1], group[2], group[3], group[4]].map(|b| (b - b'!') as u32),
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4,
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),
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_ => unreachable!(),
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};
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let value = digits[0]
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.checked_mul(POW_85[0])?
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.checked_add(digits[1].checked_mul(POW_85[1])?)?
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.checked_add(digits[2].checked_mul(POW_85[2])?)?
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.checked_add(digits[3].checked_mul(POW_85[3])?)?
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.checked_add(digits[4])?;
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decoded.extend_from_slice(&value.to_be_bytes()[..output_len]);
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group.clear();
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Some(())
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};
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out.reserve(data.len() * 4 / 5);
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let mut group = Vec::with_capacity(5);
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loop {
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let Some(b) = read_byte() else {
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// Be lenient and accept what we have (see PDFBOX-5910).
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flush_group(&mut group, out)?;
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return Some(());
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};
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match b {
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b'!'..=b'u' => {
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group.push(b);
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if group.len() == 5 {
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flush_group(&mut group, out)?;
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}
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}
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b'z' => {
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flush_group(&mut group, out)?;
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out.extend_from_slice(&[0, 0, 0, 0]);
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}
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b'~' => {
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// Technically requires a '>', but there is a PDF where it isn't
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// appended and decodes fine in other viewers.
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flush_group(&mut group, out)?;
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return Some(());
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}
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_ => return None, // Invalid character.
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}
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}
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}
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