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Lazy parse sBIT #556

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Lazy parse sBIT #556

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f50121b
Smaller FormatError
kornelski Dec 22, 2024
5241116
Cloneable FormatErrorInner
kornelski Dec 22, 2024
198a935
Lazy parse sBIT
kornelski Dec 22, 2024
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43 changes: 41 additions & 2 deletions src/common.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
//! Common types shared between the encoder and decoder
use crate::decoder::stream::{FormatError, FormatErrorInner};
use crate::text_metadata::{ITXtChunk, TEXtChunk, ZTXtChunk};
use crate::{chunk, encoder};
use crate::{chunk, encoder, DecodingError};
use io::Write;
use std::{borrow::Cow, convert::TryFrom, fmt, io};

Expand Down Expand Up @@ -580,7 +581,7 @@ pub struct Info<'a> {
pub color_type: ColorType,
pub interlaced: bool,
/// The image's `sBIT` chunk, if present; contains significant bits of the sample.
pub sbit: Option<Cow<'a, [u8]>>,
pub(crate) sbit: Option<Result<[u8; 4], FormatErrorInner>>,
/// The image's `tRNS` chunk, if present; contains the alpha channel of the image's palette, 1 byte per entry.
pub trns: Option<Cow<'a, [u8]>>,
pub pixel_dims: Option<PixelDimensions>,
Expand Down Expand Up @@ -759,6 +760,44 @@ impl Info<'_> {
self.srgb = Some(rendering_intent);
self.icc_profile = None;
}

/// Number of significant bits per channel, according to sBIT chunk
pub fn sbit(&self) -> Result<Option<&[u8]>, DecodingError> {
let sbit = match self.sbit.as_ref() {
None => return Ok(None),
Some(Ok(sbit)) => sbit,
Some(Err(e)) => return Err(FormatError::from(e.clone()).into()),
};

let len = match self.color_type {
ColorType::Grayscale => 1,
ColorType::Rgb | ColorType::Indexed => 3,
ColorType::GrayscaleAlpha => 2,
ColorType::Rgba => 4,
};

let sbit = &sbit[..len];

// The sample depth for color type 3 is fixed at eight bits.
let sample_depth = if self.color_type == ColorType::Indexed {
BitDepth::Eight
} else {
self.bit_depth
};

for &depth in sbit {
if depth < 1 || depth > sample_depth as u8 {
return Err(DecodingError::Format(
FormatErrorInner::InvalidSbit {
sample_depth,
sbit: depth,
}
.into(),
));
}
}
Ok(Some(sbit))
}
}

impl BytesPerPixel {
Expand Down
161 changes: 86 additions & 75 deletions src/decoder/stream.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -153,7 +153,7 @@ pub struct FormatError {
inner: FormatErrorInner,
}

#[derive(Debug)]
#[derive(Debug, Clone)]
pub(crate) enum FormatErrorInner {
/// Bad framing.
CrcMismatch {
Expand Down Expand Up @@ -205,14 +205,14 @@ pub(crate) enum FormatErrorInner {
// Errors specific to particular chunk data to be validated.
/// The palette did not even contain a single pixel data.
ShortPalette {
expected: usize,
len: usize,
expected: u32,
len: u32,
},
/// sBIT chunk size based on color type.
InvalidSbitChunkSize {
color_type: ColorType,
expected: usize,
len: usize,
expected: u32,
len: u32,
},
InvalidSbit {
sample_depth: BitDepth,
Expand Down Expand Up @@ -244,7 +244,7 @@ pub(crate) enum FormatErrorInner {
// Errors specific to the IDAT/fdAT chunks.
/// The compression of the data stream was faulty.
CorruptFlateStream {
err: fdeflate::DecompressionError,
err: CloneDecompressionError,
},
/// The image data chunk was too short for the expected pixel count.
NoMoreImageData,
Expand All @@ -269,6 +269,42 @@ pub(crate) enum FormatErrorInner {
},
}

impl From<fdeflate::DecompressionError> for FormatErrorInner {
fn from(err: fdeflate::DecompressionError) -> Self {
Self::CorruptFlateStream {
err: CloneDecompressionError(err),
}
}
}

#[repr(transparent)]
#[derive(Debug)]
pub(crate) struct CloneDecompressionError(pub fdeflate::DecompressionError);

impl Clone for CloneDecompressionError {
fn clone(&self) -> Self {
use fdeflate::DecompressionError::*;
Self(match self.0 {
BadZlibHeader => BadZlibHeader,
InsufficientInput => InsufficientInput,
InvalidBlockType => InvalidBlockType,
InvalidUncompressedBlockLength => InvalidUncompressedBlockLength,
InvalidHlit => InvalidHlit,
InvalidHdist => InvalidHdist,
InvalidCodeLengthRepeat => InvalidCodeLengthRepeat,
BadCodeLengthHuffmanTree => BadCodeLengthHuffmanTree,
BadLiteralLengthHuffmanTree => BadLiteralLengthHuffmanTree,
BadDistanceHuffmanTree => BadDistanceHuffmanTree,
InvalidLiteralLengthCode => InvalidLiteralLengthCode,
InvalidDistanceCode => InvalidDistanceCode,
InputStartsWithRun => InputStartsWithRun,
DistanceTooFarBack => DistanceTooFarBack,
WrongChecksum => WrongChecksum,
ExtraInput => ExtraInput,
})
}
}

impl error::Error for DecodingError {
fn cause(&self) -> Option<&(dyn error::Error + 'static)> {
match self {
Expand Down Expand Up @@ -976,7 +1012,10 @@ impl StreamingDecoder {
self.state = Some(State::new_u32(U32ValueKind::Crc(type_str)));
let parse_result = match type_str {
IHDR => self.parse_ihdr(),
chunk::sBIT => self.parse_sbit(),
chunk::sBIT => {
self.parse_sbit();
Ok(Decoded::Nothing)
}
chunk::PLTE => self.parse_plte(),
chunk::tRNS => self.parse_trns(),
chunk::pHYs => self.parse_phys(),
Expand Down Expand Up @@ -1110,76 +1149,49 @@ impl StreamingDecoder {
}
}

fn parse_sbit(&mut self) -> Result<Decoded, DecodingError> {
let mut parse = || {
let info = self.info.as_mut().unwrap();
fn parse_sbit(&mut self) {
let info = self.info.as_mut().unwrap();
let raw_bytes = &self.current_chunk.raw_bytes[..];
let have_idat = self.have_idat;
let parse = || {
if info.palette.is_some() {
return Err(DecodingError::Format(
FormatErrorInner::AfterPlte { kind: chunk::sBIT }.into(),
));
return Err(FormatErrorInner::AfterPlte { kind: chunk::sBIT }.into());
}

if self.have_idat {
return Err(DecodingError::Format(
FormatErrorInner::AfterIdat { kind: chunk::sBIT }.into(),
));
if have_idat {
return Err(FormatErrorInner::AfterIdat { kind: chunk::sBIT }.into());
}

if info.sbit.is_some() {
return Err(DecodingError::Format(
FormatErrorInner::DuplicateChunk { kind: chunk::sBIT }.into(),
));
return Err(FormatErrorInner::DuplicateChunk { kind: chunk::sBIT }.into());
}

let (color_type, bit_depth) = { (info.color_type, info.bit_depth) };
// The sample depth for color type 3 is fixed at eight bits.
let sample_depth = if color_type == ColorType::Indexed {
BitDepth::Eight
} else {
bit_depth
};
self.limits
.reserve_bytes(self.current_chunk.raw_bytes.len())?;
let vec = self.current_chunk.raw_bytes.clone();
let len = vec.len();
let len = raw_bytes.len();

// expected lenth of the chunk
let expected = match color_type {
let expected = match info.color_type {
ColorType::Grayscale => 1,
ColorType::Rgb | ColorType::Indexed => 3,
ColorType::GrayscaleAlpha => 2,
ColorType::Rgba => 4,
};

// Check if the sbit chunk size is valid.
if expected != len {
return Err(DecodingError::Format(
FormatErrorInner::InvalidSbitChunkSize {
color_type,
expected,
len,
}
.into(),
));
}

for sbit in &vec {
if *sbit < 1 || *sbit > sample_depth as u8 {
return Err(DecodingError::Format(
FormatErrorInner::InvalidSbit {
sample_depth,
sbit: *sbit,
}
.into(),
));
if expected as usize != len {
return Err(FormatErrorInner::InvalidSbitChunkSize {
color_type: info.color_type,
expected,
len: len as _,
}
.into());
}
info.sbit = Some(Cow::Owned(vec));
Ok(Decoded::Nothing)

let mut sbit = [0; 4];
sbit[..len].copy_from_slice(&raw_bytes[..len]);
Ok(sbit)
};

parse().ok();
Ok(Decoded::Nothing)
info.sbit = Some(parse());
}

fn parse_trns(&mut self) -> Result<Decoded, DecodingError> {
Expand All @@ -1198,7 +1210,11 @@ impl StreamingDecoder {
ColorType::Grayscale => {
if len < 2 {
return Err(DecodingError::Format(
FormatErrorInner::ShortPalette { expected: 2, len }.into(),
FormatErrorInner::ShortPalette {
expected: 2,
len: len as _,
}
.into(),
));
}
if bit_depth < 16 {
Expand All @@ -1211,7 +1227,11 @@ impl StreamingDecoder {
ColorType::Rgb => {
if len < 6 {
return Err(DecodingError::Format(
FormatErrorInner::ShortPalette { expected: 6, len }.into(),
FormatErrorInner::ShortPalette {
expected: 6,
len: len as _,
}
.into(),
));
}
if bit_depth < 16 {
Expand Down Expand Up @@ -1542,9 +1562,7 @@ impl StreamingDecoder {
info.icc_profile = Some(Cow::Owned(profile));
}
Err(fdeflate::BoundedDecompressionError::DecompressionError { inner: err }) => {
return Err(DecodingError::Format(
FormatErrorInner::CorruptFlateStream { err }.into(),
))
return Err(DecodingError::Format(FormatErrorInner::from(err).into()))
}
Err(fdeflate::BoundedDecompressionError::OutputTooLarge { .. }) => {
return Err(DecodingError::LimitsExceeded);
Expand Down Expand Up @@ -1822,7 +1840,6 @@ mod tests {
use crate::{Decoder, DecodingError, Reader};
use approx::assert_relative_eq;
use byteorder::WriteBytesExt;
use std::borrow::Cow;
use std::cell::RefCell;
use std::collections::VecDeque;
use std::fs::File;
Expand Down Expand Up @@ -2059,24 +2076,18 @@ mod tests {

#[test]
fn image_source_sbit() {
fn trial(path: &str, expected: Option<Cow<[u8]>>) {
fn trial(path: &str, expected: Option<&[u8]>) {
let decoder = crate::Decoder::new(File::open(path).unwrap());
let reader = decoder.read_info().unwrap();
let actual: Option<Cow<[u8]>> = reader.info().sbit.clone();
let actual = reader.info().sbit().ok().flatten();
assert!(actual == expected);
}

trial("tests/sbit/g.png", Some(Cow::Owned(vec![5u8])));
trial("tests/sbit/ga.png", Some(Cow::Owned(vec![5u8, 3u8])));
trial(
"tests/sbit/indexed.png",
Some(Cow::Owned(vec![5u8, 6u8, 5u8])),
);
trial("tests/sbit/rgb.png", Some(Cow::Owned(vec![5u8, 6u8, 5u8])));
trial(
"tests/sbit/rgba.png",
Some(Cow::Owned(vec![5u8, 6u8, 5u8, 8u8])),
);
trial("tests/sbit/g.png", Some(&[5u8]));
trial("tests/sbit/ga.png", Some(&[5u8, 3u8]));
trial("tests/sbit/indexed.png", Some(&[5u8, 6u8, 5u8]));
trial("tests/sbit/rgb.png", Some(&[5u8, 6u8, 5u8]));
trial("tests/sbit/rgba.png", Some(&[5u8, 6u8, 5u8, 8u8]));
}

/// Test handling of a PNG file that contains *two* iCCP chunks.
Expand Down
8 changes: 2 additions & 6 deletions src/decoder/zlib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -100,9 +100,7 @@ impl ZlibStream {
let (in_consumed, out_consumed) = self
.state
.read(data, self.out_buffer.as_mut_slice(), self.out_pos, false)
.map_err(|err| {
DecodingError::Format(FormatErrorInner::CorruptFlateStream { err }.into())
})?;
.map_err(|err| DecodingError::Format(FormatErrorInner::from(err).into()))?;

self.started = true;
self.out_pos += out_consumed;
Expand Down Expand Up @@ -130,9 +128,7 @@ impl ZlibStream {
let (_in_consumed, out_consumed) = self
.state
.read(&[], self.out_buffer.as_mut_slice(), self.out_pos, true)
.map_err(|err| {
DecodingError::Format(FormatErrorInner::CorruptFlateStream { err }.into())
})?;
.map_err(|err| DecodingError::Format(FormatErrorInner::from(err).into()))?;

self.out_pos += out_consumed;

Expand Down
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