Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 1576 insertions, 0 deletions

diff --git a/vendor/png/src/decoder/stream.rs b/vendor/png/src/decoder/stream.rs
new file mode 100644
index 0000000..f5df6e9
--- /dev/null
+++ b/vendor/png/src/decoder/stream.rs
@@ -0,0 +1,1576 @@
+extern crate crc32fast;
+
+use std::convert::From;
+use std::default::Default;
+use std::error;
+use std::fmt;
+use std::io;
+use std::{borrow::Cow, cmp::min};
+
+use crc32fast::Hasher as Crc32;
+
+use super::zlib::ZlibStream;
+use crate::chunk::{self, ChunkType, IDAT, IEND, IHDR};
+use crate::common::{
+    AnimationControl, BitDepth, BlendOp, ColorType, DisposeOp, FrameControl, Info, ParameterError,
+    PixelDimensions, ScaledFloat, SourceChromaticities, Unit,
+};
+use crate::text_metadata::{ITXtChunk, TEXtChunk, TextDecodingError, ZTXtChunk};
+use crate::traits::ReadBytesExt;
+
+/// TODO check if these size are reasonable
+pub const CHUNCK_BUFFER_SIZE: usize = 32 * 1024;
+
+/// Determines if checksum checks should be disabled globally.
+///
+/// This is used only in fuzzing. `afl` automatically adds `--cfg fuzzing` to RUSTFLAGS which can
+/// be used to detect that build.
+const CHECKSUM_DISABLED: bool = cfg!(fuzzing);
+
+#[derive(Debug)]
+enum U32Value {
+    // CHUNKS
+    Length,
+    Type(u32),
+    Crc(ChunkType),
+}
+
+#[derive(Debug)]
+enum State {
+    Signature(u8, [u8; 7]),
+    U32Byte3(U32Value, u32),
+    U32Byte2(U32Value, u32),
+    U32Byte1(U32Value, u32),
+    U32(U32Value),
+    ReadChunk(ChunkType),
+    PartialChunk(ChunkType),
+    DecodeData(ChunkType, usize),
+}
+
+#[derive(Debug)]
+/// Result of the decoding process
+pub enum Decoded {
+    /// Nothing decoded yet
+    Nothing,
+    Header(u32, u32, BitDepth, ColorType, bool),
+    ChunkBegin(u32, ChunkType),
+    ChunkComplete(u32, ChunkType),
+    PixelDimensions(PixelDimensions),
+    AnimationControl(AnimationControl),
+    FrameControl(FrameControl),
+    /// Decoded raw image data.
+    ImageData,
+    /// The last of a consecutive chunk of IDAT was done.
+    /// This is distinct from ChunkComplete which only marks that some IDAT chunk was completed but
+    /// not that no additional IDAT chunk follows.
+    ImageDataFlushed,
+    PartialChunk(ChunkType),
+    ImageEnd,
+}
+
+/// Any kind of error during PNG decoding.
+///
+/// This enumeration provides a very rough analysis on the origin of the failure. That is, each
+/// variant corresponds to one kind of actor causing the error. It should not be understood as a
+/// direct blame but can inform the search for a root cause or if such a search is required.
+#[derive(Debug)]
+pub enum DecodingError {
+    /// An error in IO of the underlying reader.
+    IoError(io::Error),
+    /// The input image was not a valid PNG.
+    ///
+    /// There isn't a lot that can be done here, except if the program itself was responsible for
+    /// creating this image then investigate the generator. This is internally implemented with a
+    /// large Enum. If You are interested in accessing some of the more exact information on the
+    /// variant then we can discuss in an issue.
+    Format(FormatError),
+    /// An interface was used incorrectly.
+    ///
+    /// This is used in cases where it's expected that the programmer might trip up and stability
+    /// could be affected. For example when:
+    ///
+    /// * The decoder is polled for more animation frames despite being done (or not being animated
+    ///   in the first place).
+    /// * The output buffer does not have the required size.
+    ///
+    /// As a rough guideline for introducing new variants parts of the requirements are dynamically
+    /// derived from the (untrusted) input data while the other half is from the caller. In the
+    /// above cases the number of frames respectively the size is determined by the file while the
+    /// number of calls
+    ///
+    /// If you're an application you might want to signal that a bug report is appreciated.
+    Parameter(ParameterError),
+    /// The image would have required exceeding the limits configured with the decoder.
+    ///
+    /// Note that Your allocations, e.g. when reading into a pre-allocated buffer, is __NOT__
+    /// considered part of the limits. Nevertheless, required intermediate buffers such as for
+    /// singular lines is checked against the limit.
+    ///
+    /// Note that this is a best-effort basis.
+    LimitsExceeded,
+}
+
+#[derive(Debug)]
+pub struct FormatError {
+    inner: FormatErrorInner,
+}
+
+#[derive(Debug)]
+pub(crate) enum FormatErrorInner {
+    /// Bad framing.
+    CrcMismatch {
+        /// Stored CRC32 value
+        crc_val: u32,
+        /// Calculated CRC32 sum
+        crc_sum: u32,
+        /// The chunk type that has the CRC mismatch.
+        chunk: ChunkType,
+    },
+    /// Not a PNG, the magic signature is missing.
+    InvalidSignature,
+    /// End of file, within a chunk event.
+    UnexpectedEof,
+    /// End of file, while expecting more image data.
+    UnexpectedEndOfChunk,
+    // Errors of chunk level ordering, missing etc.
+    /// Ihdr must occur.
+    MissingIhdr,
+    /// Fctl must occur if an animated chunk occurs.
+    MissingFctl,
+    /// Image data that was indicated in IHDR or acTL is missing.
+    MissingImageData,
+    /// 4.3., Must be first.
+    ChunkBeforeIhdr {
+        kind: ChunkType,
+    },
+    /// 4.3., some chunks must be before IDAT.
+    AfterIdat {
+        kind: ChunkType,
+    },
+    /// 4.3., some chunks must be before PLTE.
+    AfterPlte {
+        kind: ChunkType,
+    },
+    /// 4.3., some chunks must be between PLTE and IDAT.
+    OutsidePlteIdat {
+        kind: ChunkType,
+    },
+    /// 4.3., some chunks must be unique.
+    DuplicateChunk {
+        kind: ChunkType,
+    },
+    /// Specifically for fdat there is an embedded sequence number for chunks.
+    ApngOrder {
+        /// The sequence number in the chunk.
+        present: u32,
+        /// The one that should have been present.
+        expected: u32,
+    },
+    // Errors specific to particular chunk data to be validated.
+    /// The palette did not even contain a single pixel data.
+    ShortPalette {
+        expected: usize,
+        len: usize,
+    },
+    /// A palletized image did not have a palette.
+    PaletteRequired,
+    /// The color-depth combination is not valid according to Table 11.1.
+    InvalidColorBitDepth {
+        color_type: ColorType,
+        bit_depth: BitDepth,
+    },
+    ColorWithBadTrns(ColorType),
+    InvalidBitDepth(u8),
+    InvalidColorType(u8),
+    InvalidDisposeOp(u8),
+    InvalidBlendOp(u8),
+    InvalidUnit(u8),
+    /// The rendering intent of the sRGB chunk is invalid.
+    InvalidSrgbRenderingIntent(u8),
+    UnknownCompressionMethod(u8),
+    UnknownFilterMethod(u8),
+    UnknownInterlaceMethod(u8),
+    /// The subframe is not in bounds of the image.
+    /// TODO: fields with relevant data.
+    BadSubFrameBounds {},
+    // Errors specific to the IDAT/fDAT chunks.
+    /// The compression of the data stream was faulty.
+    CorruptFlateStream {
+        err: fdeflate::DecompressionError,
+    },
+    /// The image data chunk was too short for the expected pixel count.
+    NoMoreImageData,
+    /// Bad text encoding
+    BadTextEncoding(TextDecodingError),
+}
+
+impl error::Error for DecodingError {
+    fn cause(&self) -> Option<&(dyn error::Error + 'static)> {
+        match self {
+            DecodingError::IoError(err) => Some(err),
+            _ => None,
+        }
+    }
+}
+
+impl fmt::Display for DecodingError {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        use self::DecodingError::*;
+        match self {
+            IoError(err) => write!(fmt, "{}", err),
+            Parameter(desc) => write!(fmt, "{}", &desc),
+            Format(desc) => write!(fmt, "{}", desc),
+            LimitsExceeded => write!(fmt, "limits are exceeded"),
+        }
+    }
+}
+
+impl fmt::Display for FormatError {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        use FormatErrorInner::*;
+        match &self.inner {
+            CrcMismatch {
+                crc_val,
+                crc_sum,
+                chunk,
+                ..
+            } => write!(
+                fmt,
+                "CRC error: expected 0x{:x} have 0x{:x} while decoding {:?} chunk.",
+                crc_val, crc_sum, chunk
+            ),
+            MissingIhdr => write!(fmt, "IHDR chunk missing"),
+            MissingFctl => write!(fmt, "fcTL chunk missing before fdAT chunk."),
+            MissingImageData => write!(fmt, "IDAT or fDAT chunk is missing."),
+            ChunkBeforeIhdr { kind } => write!(fmt, "{:?} chunk appeared before IHDR chunk", kind),
+            AfterIdat { kind } => write!(fmt, "Chunk {:?} is invalid after IDAT chunk.", kind),
+            AfterPlte { kind } => write!(fmt, "Chunk {:?} is invalid after PLTE chunk.", kind),
+            OutsidePlteIdat { kind } => write!(
+                fmt,
+                "Chunk {:?} must appear between PLTE and IDAT chunks.",
+                kind
+            ),
+            DuplicateChunk { kind } => write!(fmt, "Chunk {:?} must appear at most once.", kind),
+            ApngOrder { present, expected } => write!(
+                fmt,
+                "Sequence is not in order, expected #{} got #{}.",
+                expected, present,
+            ),
+            ShortPalette { expected, len } => write!(
+                fmt,
+                "Not enough palette entries, expect {} got {}.",
+                expected, len
+            ),
+            PaletteRequired => write!(fmt, "Missing palette of indexed image."),
+            InvalidColorBitDepth {
+                color_type,
+                bit_depth,
+            } => write!(
+                fmt,
+                "Invalid color/depth combination in header: {:?}/{:?}",
+                color_type, bit_depth,
+            ),
+            ColorWithBadTrns(color_type) => write!(
+                fmt,
+                "Transparency chunk found for color type {:?}.",
+                color_type
+            ),
+            InvalidBitDepth(nr) => write!(fmt, "Invalid dispose operation {}.", nr),
+            InvalidColorType(nr) => write!(fmt, "Invalid color type {}.", nr),
+            InvalidDisposeOp(nr) => write!(fmt, "Invalid dispose op {}.", nr),
+            InvalidBlendOp(nr) => write!(fmt, "Invalid blend op {}.", nr),
+            InvalidUnit(nr) => write!(fmt, "Invalid physical pixel size unit {}.", nr),
+            InvalidSrgbRenderingIntent(nr) => write!(fmt, "Invalid sRGB rendering intent {}.", nr),
+            UnknownCompressionMethod(nr) => write!(fmt, "Unknown compression method {}.", nr),
+            UnknownFilterMethod(nr) => write!(fmt, "Unknown filter method {}.", nr),
+            UnknownInterlaceMethod(nr) => write!(fmt, "Unknown interlace method {}.", nr),
+            BadSubFrameBounds {} => write!(fmt, "Sub frame is out-of-bounds."),
+            InvalidSignature => write!(fmt, "Invalid PNG signature."),
+            UnexpectedEof => write!(fmt, "Unexpected end of data before image end."),
+            UnexpectedEndOfChunk => write!(fmt, "Unexpected end of data within a chunk."),
+            NoMoreImageData => write!(fmt, "IDAT or fDAT chunk is has not enough data for image."),
+            CorruptFlateStream { err } => {
+                write!(fmt, "Corrupt deflate stream. ")?;
+                write!(fmt, "{:?}", err)
+            }
+            // TODO: Wrap more info in the enum variant
+            BadTextEncoding(tde) => {
+                match tde {
+                    TextDecodingError::Unrepresentable => {
+                        write!(fmt, "Unrepresentable data in tEXt chunk.")
+                    }
+                    TextDecodingError::InvalidKeywordSize => {
+                        write!(fmt, "Keyword empty or longer than 79 bytes.")
+                    }
+                    TextDecodingError::MissingNullSeparator => {
+                        write!(fmt, "No null separator in tEXt chunk.")
+                    }
+                    TextDecodingError::InflationError => {
+                        write!(fmt, "Invalid compressed text data.")
+                    }
+                    TextDecodingError::OutOfDecompressionSpace => {
+                        write!(fmt, "Out of decompression space. Try with a larger limit.")
+                    }
+                    TextDecodingError::InvalidCompressionMethod => {
+                        write!(fmt, "Using an unrecognized byte as compression method.")
+                    }
+                    TextDecodingError::InvalidCompressionFlag => {
+                        write!(fmt, "Using a flag that is not 0 or 255 as a compression flag for iTXt chunk.")
+                    }
+                    TextDecodingError::MissingCompressionFlag => {
+                        write!(fmt, "No compression flag in the iTXt chunk.")
+                    }
+                }
+            }
+        }
+    }
+}
+
+impl From<io::Error> for DecodingError {
+    fn from(err: io::Error) -> DecodingError {
+        DecodingError::IoError(err)
+    }
+}
+
+impl From<FormatError> for DecodingError {
+    fn from(err: FormatError) -> DecodingError {
+        DecodingError::Format(err)
+    }
+}
+
+impl From<FormatErrorInner> for FormatError {
+    fn from(inner: FormatErrorInner) -> Self {
+        FormatError { inner }
+    }
+}
+
+impl From<DecodingError> for io::Error {
+    fn from(err: DecodingError) -> io::Error {
+        match err {
+            DecodingError::IoError(err) => err,
+            err => io::Error::new(io::ErrorKind::Other, err.to_string()),
+        }
+    }
+}
+
+impl From<TextDecodingError> for DecodingError {
+    fn from(tbe: TextDecodingError) -> Self {
+        DecodingError::Format(FormatError {
+            inner: FormatErrorInner::BadTextEncoding(tbe),
+        })
+    }
+}
+
+/// Decoder configuration options
+#[derive(Clone)]
+pub struct DecodeOptions {
+    ignore_adler32: bool,
+    ignore_crc: bool,
+    ignore_text_chunk: bool,
+}
+
+impl Default for DecodeOptions {
+    fn default() -> Self {
+        Self {
+            ignore_adler32: true,
+            ignore_crc: false,
+            ignore_text_chunk: false,
+        }
+    }
+}
+
+impl DecodeOptions {
+    /// When set, the decoder will not compute and verify the Adler-32 checksum.
+    ///
+    /// Defaults to `true`.
+    pub fn set_ignore_adler32(&mut self, ignore_adler32: bool) {
+        self.ignore_adler32 = ignore_adler32;
+    }
+
+    /// When set, the decoder will not compute and verify the CRC code.
+    ///
+    /// Defaults to `false`.
+    pub fn set_ignore_crc(&mut self, ignore_crc: bool) {
+        self.ignore_crc = ignore_crc;
+    }
+
+    /// Flag to ignore computing and verifying the Adler-32 checksum and CRC
+    /// code.
+    pub fn set_ignore_checksums(&mut self, ignore_checksums: bool) {
+        self.ignore_adler32 = ignore_checksums;
+        self.ignore_crc = ignore_checksums;
+    }
+
+    /// Ignore text chunks while decoding.
+    ///
+    /// Defaults to `false`.
+    pub fn set_ignore_text_chunk(&mut self, ignore_text_chunk: bool) {
+        self.ignore_text_chunk = ignore_text_chunk;
+    }
+}
+
+/// PNG StreamingDecoder (low-level interface)
+///
+/// By default, the decoder does not verify Adler-32 checksum computation. To
+/// enable checksum verification, set it with [`StreamingDecoder::set_ignore_adler32`]
+/// before starting decompression.
+pub struct StreamingDecoder {
+    state: Option<State>,
+    current_chunk: ChunkState,
+    /// The inflater state handling consecutive `IDAT` and `fdAT` chunks.
+    inflater: ZlibStream,
+    /// The complete image info read from all prior chunks.
+    pub(crate) info: Option<Info<'static>>,
+    /// The animation chunk sequence number.
+    current_seq_no: Option<u32>,
+    /// Stores where in decoding an `fdAT` chunk we are.
+    apng_seq_handled: bool,
+    have_idat: bool,
+    decode_options: DecodeOptions,
+}
+
+struct ChunkState {
+    /// The type of the current chunk.
+    /// Relevant for `IDAT` and `fdAT` which aggregate consecutive chunks of their own type.
+    type_: ChunkType,
+
+    /// Partial crc until now.
+    crc: Crc32,
+
+    /// Remaining bytes to be read.
+    remaining: u32,
+
+    /// Non-decoded bytes in the chunk.
+    raw_bytes: Vec<u8>,
+}
+
+impl StreamingDecoder {
+    /// Creates a new StreamingDecoder
+    ///
+    /// Allocates the internal buffers.
+    pub fn new() -> StreamingDecoder {
+        StreamingDecoder::new_with_options(DecodeOptions::default())
+    }
+
+    pub fn new_with_options(decode_options: DecodeOptions) -> StreamingDecoder {
+        let mut inflater = ZlibStream::new();
+        inflater.set_ignore_adler32(decode_options.ignore_adler32);
+
+        StreamingDecoder {
+            state: Some(State::Signature(0, [0; 7])),
+            current_chunk: ChunkState::default(),
+            inflater,
+            info: None,
+            current_seq_no: None,
+            apng_seq_handled: false,
+            have_idat: false,
+            decode_options,
+        }
+    }
+
+    /// Resets the StreamingDecoder
+    pub fn reset(&mut self) {
+        self.state = Some(State::Signature(0, [0; 7]));
+        self.current_chunk.crc = Crc32::new();
+        self.current_chunk.remaining = 0;
+        self.current_chunk.raw_bytes.clear();
+        self.inflater.reset();
+        self.info = None;
+        self.current_seq_no = None;
+        self.apng_seq_handled = false;
+        self.have_idat = false;
+    }
+
+    /// Provides access to the inner `info` field
+    pub fn info(&self) -> Option<&Info<'static>> {
+        self.info.as_ref()
+    }
+
+    pub fn set_ignore_text_chunk(&mut self, ignore_text_chunk: bool) {
+        self.decode_options.set_ignore_text_chunk(ignore_text_chunk);
+    }
+
+    /// Return whether the decoder is set to ignore the Adler-32 checksum.
+    pub fn ignore_adler32(&self) -> bool {
+        self.inflater.ignore_adler32()
+    }
+
+    /// Set whether to compute and verify the Adler-32 checksum during
+    /// decompression. Return `true` if the flag was successfully set.
+    ///
+    /// The decoder defaults to `true`.
+    ///
+    /// This flag cannot be modified after decompression has started until the
+    /// [`StreamingDecoder`] is reset.
+    pub fn set_ignore_adler32(&mut self, ignore_adler32: bool) -> bool {
+        self.inflater.set_ignore_adler32(ignore_adler32)
+    }
+
+    /// Set whether to compute and verify the Adler-32 checksum during
+    /// decompression.
+    ///
+    /// The decoder defaults to `false`.
+    pub fn set_ignore_crc(&mut self, ignore_crc: bool) {
+        self.decode_options.set_ignore_crc(ignore_crc)
+    }
+
+    /// Low level StreamingDecoder interface.
+    ///
+    /// Allows to stream partial data to the encoder. Returns a tuple containing the bytes that have
+    /// been consumed from the input buffer and the current decoding result. If the decoded chunk
+    /// was an image data chunk, it also appends the read data to `image_data`.
+    pub fn update(
+        &mut self,
+        mut buf: &[u8],
+        image_data: &mut Vec<u8>,
+    ) -> Result<(usize, Decoded), DecodingError> {
+        let len = buf.len();
+        while !buf.is_empty() && self.state.is_some() {
+            match self.next_state(buf, image_data) {
+                Ok((bytes, Decoded::Nothing)) => buf = &buf[bytes..],
+                Ok((bytes, result)) => {
+                    buf = &buf[bytes..];
+                    return Ok((len - buf.len(), result));
+                }
+                Err(err) => return Err(err),
+            }
+        }
+        Ok((len - buf.len(), Decoded::Nothing))
+    }
+
+    fn next_state<'a>(
+        &'a mut self,
+        buf: &[u8],
+        image_data: &mut Vec<u8>,
+    ) -> Result<(usize, Decoded), DecodingError> {
+        use self::State::*;
+
+        let current_byte = buf[0];
+
+        // Driver should ensure that state is never None
+        let state = self.state.take().unwrap();
+
+        match state {
+            Signature(i, mut signature) if i < 7 => {
+                signature[i as usize] = current_byte;
+                self.state = Some(Signature(i + 1, signature));
+                Ok((1, Decoded::Nothing))
+            }
+            Signature(_, signature)
+                if signature == [137, 80, 78, 71, 13, 10, 26] && current_byte == 10 =>
+            {
+                self.state = Some(U32(U32Value::Length));
+                Ok((1, Decoded::Nothing))
+            }
+            Signature(..) => Err(DecodingError::Format(
+                FormatErrorInner::InvalidSignature.into(),
+            )),
+            U32Byte3(type_, mut val) => {
+                use self::U32Value::*;
+                val |= u32::from(current_byte);
+                match type_ {
+                    Length => {
+                        self.state = Some(U32(Type(val)));
+                        Ok((1, Decoded::Nothing))
+                    }
+                    Type(length) => {
+                        let type_str = ChunkType([
+                            (val >> 24) as u8,
+                            (val >> 16) as u8,
+                            (val >> 8) as u8,
+                            val as u8,
+                        ]);
+                        if type_str != self.current_chunk.type_
+                            && (self.current_chunk.type_ == IDAT
+                                || self.current_chunk.type_ == chunk::fdAT)
+                        {
+                            self.current_chunk.type_ = type_str;
+                            self.inflater.finish_compressed_chunks(image_data)?;
+                            self.inflater.reset();
+                            self.state = Some(U32Byte3(Type(length), val & !0xff));
+                            return Ok((0, Decoded::ImageDataFlushed));
+                        }
+                        self.current_chunk.type_ = type_str;
+                        if !self.decode_options.ignore_crc {
+                            self.current_chunk.crc.reset();
+                            self.current_chunk.crc.update(&type_str.0);
+                        }
+                        self.current_chunk.remaining = length;
+                        self.apng_seq_handled = false;
+                        self.current_chunk.raw_bytes.clear();
+                        self.state = Some(ReadChunk(type_str));
+                        Ok((1, Decoded::ChunkBegin(length, type_str)))
+                    }
+                    Crc(type_str) => {
+                        // If ignore_crc is set, do not calculate CRC. We set
+                        // sum=val so that it short-circuits to true in the next
+                        // if-statement block
+                        let sum = if self.decode_options.ignore_crc {
+                            val
+                        } else {
+                            self.current_chunk.crc.clone().finalize()
+                        };
+
+                        if val == sum || CHECKSUM_DISABLED {
+                            self.state = Some(State::U32(U32Value::Length));
+                            if type_str == IEND {
+                                Ok((1, Decoded::ImageEnd))
+                            } else {
+                                Ok((1, Decoded::ChunkComplete(val, type_str)))
+                            }
+                        } else {
+                            Err(DecodingError::Format(
+                                FormatErrorInner::CrcMismatch {
+                                    crc_val: val,
+                                    crc_sum: sum,
+                                    chunk: type_str,
+                                }
+                                .into(),
+                            ))
+                        }
+                    }
+                }
+            }
+            U32Byte2(type_, val) => {
+                self.state = Some(U32Byte3(type_, val | u32::from(current_byte) << 8));
+                Ok((1, Decoded::Nothing))
+            }
+            U32Byte1(type_, val) => {
+                self.state = Some(U32Byte2(type_, val | u32::from(current_byte) << 16));
+                Ok((1, Decoded::Nothing))
+            }
+            U32(type_) => {
+                self.state = Some(U32Byte1(type_, u32::from(current_byte) << 24));
+                Ok((1, Decoded::Nothing))
+            }
+            PartialChunk(type_str) => {
+                match type_str {
+                    IDAT => {
+                        self.have_idat = true;
+                        self.state = Some(DecodeData(type_str, 0));
+                        Ok((0, Decoded::PartialChunk(type_str)))
+                    }
+                    chunk::fdAT => {
+                        let data_start;
+                        if let Some(seq_no) = self.current_seq_no {
+                            if !self.apng_seq_handled {
+                                data_start = 4;
+                                let mut buf = &self.current_chunk.raw_bytes[..];
+                                let next_seq_no = buf.read_be()?;
+                                if next_seq_no != seq_no + 1 {
+                                    return Err(DecodingError::Format(
+                                        FormatErrorInner::ApngOrder {
+                                            present: next_seq_no,
+                                            expected: seq_no + 1,
+                                        }
+                                        .into(),
+                                    ));
+                                }
+                                self.current_seq_no = Some(next_seq_no);
+                                self.apng_seq_handled = true;
+                            } else {
+                                data_start = 0;
+                            }
+                        } else {
+                            return Err(DecodingError::Format(
+                                FormatErrorInner::MissingFctl.into(),
+                            ));
+                        }
+                        self.state = Some(DecodeData(type_str, data_start));
+                        Ok((0, Decoded::PartialChunk(type_str)))
+                    }
+                    // Handle other chunks
+                    _ => {
+                        if self.current_chunk.remaining == 0 {
+                            // complete chunk
+                            Ok((0, self.parse_chunk(type_str)?))
+                        } else {
+                            // Make sure we have room to read more of the chunk.
+                            // We need it fully before parsing.
+                            self.reserve_current_chunk()?;
+
+                            self.state = Some(ReadChunk(type_str));
+                            Ok((0, Decoded::PartialChunk(type_str)))
+                        }
+                    }
+                }
+            }
+            ReadChunk(type_str) => {
+                // The _previous_ event wanted to return the contents of raw_bytes, and let the
+                // caller consume it,
+                if self.current_chunk.remaining == 0 {
+                    self.state = Some(U32(U32Value::Crc(type_str)));
+                    Ok((0, Decoded::Nothing))
+                } else {
+                    let ChunkState {
+                        crc,
+                        remaining,
+                        raw_bytes,
+                        type_: _,
+                    } = &mut self.current_chunk;
+
+                    let buf_avail = raw_bytes.capacity() - raw_bytes.len();
+                    let bytes_avail = min(buf.len(), buf_avail);
+                    let n = min(*remaining, bytes_avail as u32);
+                    if buf_avail == 0 {
+                        self.state = Some(PartialChunk(type_str));
+                        Ok((0, Decoded::Nothing))
+                    } else {
+                        let buf = &buf[..n as usize];
+                        if !self.decode_options.ignore_crc {
+                            crc.update(buf);
+                        }
+                        raw_bytes.extend_from_slice(buf);
+
+                        *remaining -= n;
+                        if *remaining == 0 {
+                            self.state = Some(PartialChunk(type_str));
+                        } else {
+                            self.state = Some(ReadChunk(type_str));
+                        }
+                        Ok((n as usize, Decoded::Nothing))
+                    }
+                }
+            }
+            DecodeData(type_str, mut n) => {
+                let chunk_len = self.current_chunk.raw_bytes.len();
+                let chunk_data = &self.current_chunk.raw_bytes[n..];
+                let c = self.inflater.decompress(chunk_data, image_data)?;
+                n += c;
+                if n == chunk_len && c == 0 {
+                    self.current_chunk.raw_bytes.clear();
+                    self.state = Some(ReadChunk(type_str));
+                    Ok((0, Decoded::ImageData))
+                } else {
+                    self.state = Some(DecodeData(type_str, n));
+                    Ok((0, Decoded::ImageData))
+                }
+            }
+        }
+    }
+
+    fn reserve_current_chunk(&mut self) -> Result<(), DecodingError> {
+        // FIXME: use limits, also do so in iccp/zlib decompression.
+        const MAX: usize = 0x10_0000;
+        let buffer = &mut self.current_chunk.raw_bytes;
+
+        // Double if necessary, but no more than until the limit is reached.
+        let reserve_size = MAX.saturating_sub(buffer.capacity()).min(buffer.len());
+        buffer.reserve_exact(reserve_size);
+
+        if buffer.capacity() == buffer.len() {
+            Err(DecodingError::LimitsExceeded)
+        } else {
+            Ok(())
+        }
+    }
+
+    fn parse_chunk(&mut self, type_str: ChunkType) -> Result<Decoded, DecodingError> {
+        self.state = Some(State::U32(U32Value::Crc(type_str)));
+        if self.info.is_none() && type_str != IHDR {
+            return Err(DecodingError::Format(
+                FormatErrorInner::ChunkBeforeIhdr { kind: type_str }.into(),
+            ));
+        }
+        match match type_str {
+            IHDR => self.parse_ihdr(),
+            chunk::PLTE => self.parse_plte(),
+            chunk::tRNS => self.parse_trns(),
+            chunk::pHYs => self.parse_phys(),
+            chunk::gAMA => self.parse_gama(),
+            chunk::acTL => self.parse_actl(),
+            chunk::fcTL => self.parse_fctl(),
+            chunk::cHRM => self.parse_chrm(),
+            chunk::sRGB => self.parse_srgb(),
+            chunk::iCCP => self.parse_iccp(),
+            chunk::tEXt if !self.decode_options.ignore_text_chunk => self.parse_text(),
+            chunk::zTXt if !self.decode_options.ignore_text_chunk => self.parse_ztxt(),
+            chunk::iTXt if !self.decode_options.ignore_text_chunk => self.parse_itxt(),
+            _ => Ok(Decoded::PartialChunk(type_str)),
+        } {
+            Err(err) => {
+                // Borrow of self ends here, because Decoding error does not borrow self.
+                self.state = None;
+                Err(err)
+            }
+            ok => ok,
+        }
+    }
+
+    fn parse_fctl(&mut self) -> Result<Decoded, DecodingError> {
+        let mut buf = &self.current_chunk.raw_bytes[..];
+        let next_seq_no = buf.read_be()?;
+
+        // Assuming that fcTL is required before *every* fdAT-sequence
+        self.current_seq_no = Some(if let Some(seq_no) = self.current_seq_no {
+            if next_seq_no != seq_no + 1 {
+                return Err(DecodingError::Format(
+                    FormatErrorInner::ApngOrder {
+                        expected: seq_no + 1,
+                        present: next_seq_no,
+                    }
+                    .into(),
+                ));
+            }
+            next_seq_no
+        } else {
+            if next_seq_no != 0 {
+                return Err(DecodingError::Format(
+                    FormatErrorInner::ApngOrder {
+                        expected: 0,
+                        present: next_seq_no,
+                    }
+                    .into(),
+                ));
+            }
+            0
+        });
+        self.inflater.reset();
+        let fc = FrameControl {
+            sequence_number: next_seq_no,
+            width: buf.read_be()?,
+            height: buf.read_be()?,
+            x_offset: buf.read_be()?,
+            y_offset: buf.read_be()?,
+            delay_num: buf.read_be()?,
+            delay_den: buf.read_be()?,
+            dispose_op: {
+                let dispose_op = buf.read_be()?;
+                match DisposeOp::from_u8(dispose_op) {
+                    Some(dispose_op) => dispose_op,
+                    None => {
+                        return Err(DecodingError::Format(
+                            FormatErrorInner::InvalidDisposeOp(dispose_op).into(),
+                        ))
+                    }
+                }
+            },
+            blend_op: {
+                let blend_op = buf.read_be()?;
+                match BlendOp::from_u8(blend_op) {
+                    Some(blend_op) => blend_op,
+                    None => {
+                        return Err(DecodingError::Format(
+                            FormatErrorInner::InvalidBlendOp(blend_op).into(),
+                        ))
+                    }
+                }
+            },
+        };
+        self.info.as_ref().unwrap().validate(&fc)?;
+        self.info.as_mut().unwrap().frame_control = Some(fc);
+        Ok(Decoded::FrameControl(fc))
+    }
+
+    fn parse_actl(&mut self) -> Result<Decoded, DecodingError> {
+        if self.have_idat {
+            Err(DecodingError::Format(
+                FormatErrorInner::AfterIdat { kind: chunk::acTL }.into(),
+            ))
+        } else {
+            let mut buf = &self.current_chunk.raw_bytes[..];
+            let actl = AnimationControl {
+                num_frames: buf.read_be()?,
+                num_plays: buf.read_be()?,
+            };
+            self.info.as_mut().unwrap().animation_control = Some(actl);
+            Ok(Decoded::AnimationControl(actl))
+        }
+    }
+
+    fn parse_plte(&mut self) -> Result<Decoded, DecodingError> {
+        let info = self.info.as_mut().unwrap();
+        if info.palette.is_some() {
+            // Only one palette is allowed
+            Err(DecodingError::Format(
+                FormatErrorInner::DuplicateChunk { kind: chunk::PLTE }.into(),
+            ))
+        } else {
+            info.palette = Some(Cow::Owned(self.current_chunk.raw_bytes.clone()));
+            Ok(Decoded::Nothing)
+        }
+    }
+
+    fn parse_trns(&mut self) -> Result<Decoded, DecodingError> {
+        let info = self.info.as_mut().unwrap();
+        if info.trns.is_some() {
+            return Err(DecodingError::Format(
+                FormatErrorInner::DuplicateChunk { kind: chunk::PLTE }.into(),
+            ));
+        }
+        let (color_type, bit_depth) = { (info.color_type, info.bit_depth as u8) };
+        let mut vec = self.current_chunk.raw_bytes.clone();
+        let len = vec.len();
+        match color_type {
+            ColorType::Grayscale => {
+                if len < 2 {
+                    return Err(DecodingError::Format(
+                        FormatErrorInner::ShortPalette { expected: 2, len }.into(),
+                    ));
+                }
+                if bit_depth < 16 {
+                    vec[0] = vec[1];
+                    vec.truncate(1);
+                }
+                info.trns = Some(Cow::Owned(vec));
+                Ok(Decoded::Nothing)
+            }
+            ColorType::Rgb => {
+                if len < 6 {
+                    return Err(DecodingError::Format(
+                        FormatErrorInner::ShortPalette { expected: 6, len }.into(),
+                    ));
+                }
+                if bit_depth < 16 {
+                    vec[0] = vec[1];
+                    vec[1] = vec[3];
+                    vec[2] = vec[5];
+                    vec.truncate(3);
+                }
+                info.trns = Some(Cow::Owned(vec));
+                Ok(Decoded::Nothing)
+            }
+            ColorType::Indexed => {
+                // The transparency chunk must be after the palette chunk and
+                // before the data chunk.
+                if info.palette.is_none() {
+                    return Err(DecodingError::Format(
+                        FormatErrorInner::AfterPlte { kind: chunk::tRNS }.into(),
+                    ));
+                } else if self.have_idat {
+                    return Err(DecodingError::Format(
+                        FormatErrorInner::OutsidePlteIdat { kind: chunk::tRNS }.into(),
+                    ));
+                }
+
+                info.trns = Some(Cow::Owned(vec));
+                Ok(Decoded::Nothing)
+            }
+            c => Err(DecodingError::Format(
+                FormatErrorInner::ColorWithBadTrns(c).into(),
+            )),
+        }
+    }
+
+    fn parse_phys(&mut self) -> Result<Decoded, DecodingError> {
+        let info = self.info.as_mut().unwrap();
+        if self.have_idat {
+            Err(DecodingError::Format(
+                FormatErrorInner::AfterIdat { kind: chunk::pHYs }.into(),
+            ))
+        } else if info.pixel_dims.is_some() {
+            Err(DecodingError::Format(
+                FormatErrorInner::DuplicateChunk { kind: chunk::pHYs }.into(),
+            ))
+        } else {
+            let mut buf = &self.current_chunk.raw_bytes[..];
+            let xppu = buf.read_be()?;
+            let yppu = buf.read_be()?;
+            let unit = buf.read_be()?;
+            let unit = match Unit::from_u8(unit) {
+                Some(unit) => unit,
+                None => {
+                    return Err(DecodingError::Format(
+                        FormatErrorInner::InvalidUnit(unit).into(),
+                    ))
+                }
+            };
+            let pixel_dims = PixelDimensions { xppu, yppu, unit };
+            info.pixel_dims = Some(pixel_dims);
+            Ok(Decoded::PixelDimensions(pixel_dims))
+        }
+    }
+
+    fn parse_chrm(&mut self) -> Result<Decoded, DecodingError> {
+        let info = self.info.as_mut().unwrap();
+        if self.have_idat {
+            Err(DecodingError::Format(
+                FormatErrorInner::AfterIdat { kind: chunk::cHRM }.into(),
+            ))
+        } else if info.chrm_chunk.is_some() {
+            Err(DecodingError::Format(
+                FormatErrorInner::DuplicateChunk { kind: chunk::cHRM }.into(),
+            ))
+        } else {
+            let mut buf = &self.current_chunk.raw_bytes[..];
+            let white_x: u32 = buf.read_be()?;
+            let white_y: u32 = buf.read_be()?;
+            let red_x: u32 = buf.read_be()?;
+            let red_y: u32 = buf.read_be()?;
+            let green_x: u32 = buf.read_be()?;
+            let green_y: u32 = buf.read_be()?;
+            let blue_x: u32 = buf.read_be()?;
+            let blue_y: u32 = buf.read_be()?;
+
+            let source_chromaticities = SourceChromaticities {
+                white: (
+                    ScaledFloat::from_scaled(white_x),
+                    ScaledFloat::from_scaled(white_y),
+                ),
+                red: (
+                    ScaledFloat::from_scaled(red_x),
+                    ScaledFloat::from_scaled(red_y),
+                ),
+                green: (
+                    ScaledFloat::from_scaled(green_x),
+                    ScaledFloat::from_scaled(green_y),
+                ),
+                blue: (
+                    ScaledFloat::from_scaled(blue_x),
+                    ScaledFloat::from_scaled(blue_y),
+                ),
+            };
+
+            info.chrm_chunk = Some(source_chromaticities);
+            // Ignore chromaticities if sRGB profile is used.
+            if info.srgb.is_none() {
+                info.source_chromaticities = Some(source_chromaticities);
+            }
+
+            Ok(Decoded::Nothing)
+        }
+    }
+
+    fn parse_gama(&mut self) -> Result<Decoded, DecodingError> {
+        let info = self.info.as_mut().unwrap();
+        if self.have_idat {
+            Err(DecodingError::Format(
+                FormatErrorInner::AfterIdat { kind: chunk::gAMA }.into(),
+            ))
+        } else if info.gama_chunk.is_some() {
+            Err(DecodingError::Format(
+                FormatErrorInner::DuplicateChunk { kind: chunk::gAMA }.into(),
+            ))
+        } else {
+            let mut buf = &self.current_chunk.raw_bytes[..];
+            let source_gamma: u32 = buf.read_be()?;
+            let source_gamma = ScaledFloat::from_scaled(source_gamma);
+
+            info.gama_chunk = Some(source_gamma);
+            // Ignore chromaticities if sRGB profile is used.
+            if info.srgb.is_none() {
+                info.source_gamma = Some(source_gamma);
+            }
+
+            Ok(Decoded::Nothing)
+        }
+    }
+
+    fn parse_srgb(&mut self) -> Result<Decoded, DecodingError> {
+        let info = self.info.as_mut().unwrap();
+        if self.have_idat {
+            Err(DecodingError::Format(
+                FormatErrorInner::AfterIdat { kind: chunk::acTL }.into(),
+            ))
+        } else if info.srgb.is_some() {
+            Err(DecodingError::Format(
+                FormatErrorInner::DuplicateChunk { kind: chunk::sRGB }.into(),
+            ))
+        } else {
+            let mut buf = &self.current_chunk.raw_bytes[..];
+            let raw: u8 = buf.read_be()?; // BE is is nonsense for single bytes, but this way the size is checked.
+            let rendering_intent = crate::SrgbRenderingIntent::from_raw(raw).ok_or_else(|| {
+                FormatError::from(FormatErrorInner::InvalidSrgbRenderingIntent(raw))
+            })?;
+
+            // Set srgb and override source gamma and chromaticities.
+            info.srgb = Some(rendering_intent);
+            info.source_gamma = Some(crate::srgb::substitute_gamma());
+            info.source_chromaticities = Some(crate::srgb::substitute_chromaticities());
+            Ok(Decoded::Nothing)
+        }
+    }
+
+    fn parse_iccp(&mut self) -> Result<Decoded, DecodingError> {
+        let info = self.info.as_mut().unwrap();
+        if self.have_idat {
+            Err(DecodingError::Format(
+                FormatErrorInner::AfterIdat { kind: chunk::iCCP }.into(),
+            ))
+        } else if info.icc_profile.is_some() {
+            Err(DecodingError::Format(
+                FormatErrorInner::DuplicateChunk { kind: chunk::iCCP }.into(),
+            ))
+        } else {
+            let mut buf = &self.current_chunk.raw_bytes[..];
+
+            // read profile name
+            let _: u8 = buf.read_be()?;
+            for _ in 1..80 {
+                let raw: u8 = buf.read_be()?;
+                if raw == 0 {
+                    break;
+                }
+            }
+
+            match buf.read_be()? {
+                // compression method
+                0u8 => (),
+                n => {
+                    return Err(DecodingError::Format(
+                        FormatErrorInner::UnknownCompressionMethod(n).into(),
+                    ))
+                }
+            }
+
+            let mut profile = Vec::new();
+            let mut inflater = ZlibStream::new();
+            while !buf.is_empty() {
+                let consumed_bytes = inflater.decompress(buf, &mut profile)?;
+                if profile.len() > 8000000 {
+                    // TODO: this should use Limits.bytes
+                    return Err(DecodingError::LimitsExceeded);
+                }
+                buf = &buf[consumed_bytes..];
+            }
+            inflater.finish_compressed_chunks(&mut profile)?;
+
+            info.icc_profile = Some(Cow::Owned(profile));
+            Ok(Decoded::Nothing)
+        }
+    }
+
+    fn parse_ihdr(&mut self) -> Result<Decoded, DecodingError> {
+        if self.info.is_some() {
+            return Err(DecodingError::Format(
+                FormatErrorInner::DuplicateChunk { kind: IHDR }.into(),
+            ));
+        }
+        let mut buf = &self.current_chunk.raw_bytes[..];
+        let width = buf.read_be()?;
+        let height = buf.read_be()?;
+        let bit_depth = buf.read_be()?;
+        let bit_depth = match BitDepth::from_u8(bit_depth) {
+            Some(bits) => bits,
+            None => {
+                return Err(DecodingError::Format(
+                    FormatErrorInner::InvalidBitDepth(bit_depth).into(),
+                ))
+            }
+        };
+        let color_type = buf.read_be()?;
+        let color_type = match ColorType::from_u8(color_type) {
+            Some(color_type) => {
+                if color_type.is_combination_invalid(bit_depth) {
+                    return Err(DecodingError::Format(
+                        FormatErrorInner::InvalidColorBitDepth {
+                            color_type,
+                            bit_depth,
+                        }
+                        .into(),
+                    ));
+                } else {
+                    color_type
+                }
+            }
+            None => {
+                return Err(DecodingError::Format(
+                    FormatErrorInner::InvalidColorType(color_type).into(),
+                ))
+            }
+        };
+        match buf.read_be()? {
+            // compression method
+            0u8 => (),
+            n => {
+                return Err(DecodingError::Format(
+                    FormatErrorInner::UnknownCompressionMethod(n).into(),
+                ))
+            }
+        }
+        match buf.read_be()? {
+            // filter method
+            0u8 => (),
+            n => {
+                return Err(DecodingError::Format(
+                    FormatErrorInner::UnknownFilterMethod(n).into(),
+                ))
+            }
+        }
+        let interlaced = match buf.read_be()? {
+            0u8 => false,
+            1 => true,
+            n => {
+                return Err(DecodingError::Format(
+                    FormatErrorInner::UnknownInterlaceMethod(n).into(),
+                ))
+            }
+        };
+
+        self.info = Some(Info {
+            width,
+            height,
+            bit_depth,
+            color_type,
+            interlaced,
+            ..Default::default()
+        });
+
+        Ok(Decoded::Header(
+            width, height, bit_depth, color_type, interlaced,
+        ))
+    }
+
+    fn split_keyword(buf: &[u8]) -> Result<(&[u8], &[u8]), DecodingError> {
+        let null_byte_index = buf
+            .iter()
+            .position(|&b| b == 0)
+            .ok_or_else(|| DecodingError::from(TextDecodingError::MissingNullSeparator))?;
+
+        if null_byte_index == 0 || null_byte_index > 79 {
+            return Err(DecodingError::from(TextDecodingError::InvalidKeywordSize));
+        }
+
+        Ok((&buf[..null_byte_index], &buf[null_byte_index + 1..]))
+    }
+
+    fn parse_text(&mut self) -> Result<Decoded, DecodingError> {
+        let buf = &self.current_chunk.raw_bytes[..];
+
+        let (keyword_slice, value_slice) = Self::split_keyword(buf)?;
+
+        self.info
+            .as_mut()
+            .unwrap()
+            .uncompressed_latin1_text
+            .push(TEXtChunk::decode(keyword_slice, value_slice).map_err(DecodingError::from)?);
+
+        Ok(Decoded::Nothing)
+    }
+
+    fn parse_ztxt(&mut self) -> Result<Decoded, DecodingError> {
+        let buf = &self.current_chunk.raw_bytes[..];
+
+        let (keyword_slice, value_slice) = Self::split_keyword(buf)?;
+
+        let compression_method = *value_slice
+            .first()
+            .ok_or_else(|| DecodingError::from(TextDecodingError::InvalidCompressionMethod))?;
+
+        let text_slice = &value_slice[1..];
+
+        self.info.as_mut().unwrap().compressed_latin1_text.push(
+            ZTXtChunk::decode(keyword_slice, compression_method, text_slice)
+                .map_err(DecodingError::from)?,
+        );
+
+        Ok(Decoded::Nothing)
+    }
+
+    fn parse_itxt(&mut self) -> Result<Decoded, DecodingError> {
+        let buf = &self.current_chunk.raw_bytes[..];
+
+        let (keyword_slice, value_slice) = Self::split_keyword(buf)?;
+
+        let compression_flag = *value_slice
+            .first()
+            .ok_or_else(|| DecodingError::from(TextDecodingError::MissingCompressionFlag))?;
+
+        let compression_method = *value_slice
+            .get(1)
+            .ok_or_else(|| DecodingError::from(TextDecodingError::InvalidCompressionMethod))?;
+
+        let second_null_byte_index = value_slice[2..]
+            .iter()
+            .position(|&b| b == 0)
+            .ok_or_else(|| DecodingError::from(TextDecodingError::MissingNullSeparator))?
+            + 2;
+
+        let language_tag_slice = &value_slice[2..second_null_byte_index];
+
+        let third_null_byte_index = value_slice[second_null_byte_index + 1..]
+            .iter()
+            .position(|&b| b == 0)
+            .ok_or_else(|| DecodingError::from(TextDecodingError::MissingNullSeparator))?
+            + (second_null_byte_index + 1);
+
+        let translated_keyword_slice =
+            &value_slice[second_null_byte_index + 1..third_null_byte_index];
+
+        let text_slice = &value_slice[third_null_byte_index + 1..];
+
+        self.info.as_mut().unwrap().utf8_text.push(
+            ITXtChunk::decode(
+                keyword_slice,
+                compression_flag,
+                compression_method,
+                language_tag_slice,
+                translated_keyword_slice,
+                text_slice,
+            )
+            .map_err(DecodingError::from)?,
+        );
+
+        Ok(Decoded::Nothing)
+    }
+}
+
+impl Info<'_> {
+    fn validate(&self, fc: &FrameControl) -> Result<(), DecodingError> {
+        // Validate mathematically: fc.width + fc.x_offset <= self.width
+        let in_x_bounds = Some(fc.width) <= self.width.checked_sub(fc.x_offset);
+        // Validate mathematically: fc.height + fc.y_offset <= self.height
+        let in_y_bounds = Some(fc.height) <= self.height.checked_sub(fc.y_offset);
+
+        if !in_x_bounds || !in_y_bounds {
+            return Err(DecodingError::Format(
+                // TODO: do we want to display the bad bounds?
+                FormatErrorInner::BadSubFrameBounds {}.into(),
+            ));
+        }
+
+        Ok(())
+    }
+}
+
+impl Default for StreamingDecoder {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Default for ChunkState {
+    fn default() -> Self {
+        ChunkState {
+            type_: ChunkType([0; 4]),
+            crc: Crc32::new(),
+            remaining: 0,
+            raw_bytes: Vec::with_capacity(CHUNCK_BUFFER_SIZE),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::ScaledFloat;
+    use super::SourceChromaticities;
+    use std::fs::File;
+
+    #[test]
+    fn image_gamma() -> Result<(), ()> {
+        fn trial(path: &str, expected: Option<ScaledFloat>) {
+            let decoder = crate::Decoder::new(File::open(path).unwrap());
+            let reader = decoder.read_info().unwrap();
+            let actual: Option<ScaledFloat> = reader.info().source_gamma;
+            assert!(actual == expected);
+        }
+        trial("tests/pngsuite/f00n0g08.png", None);
+        trial("tests/pngsuite/f00n2c08.png", None);
+        trial("tests/pngsuite/f01n0g08.png", None);
+        trial("tests/pngsuite/f01n2c08.png", None);
+        trial("tests/pngsuite/f02n0g08.png", None);
+        trial("tests/pngsuite/f02n2c08.png", None);
+        trial("tests/pngsuite/f03n0g08.png", None);
+        trial("tests/pngsuite/f03n2c08.png", None);
+        trial("tests/pngsuite/f04n0g08.png", None);
+        trial("tests/pngsuite/f04n2c08.png", None);
+        trial("tests/pngsuite/f99n0g04.png", None);
+        trial("tests/pngsuite/tm3n3p02.png", None);
+        trial("tests/pngsuite/g03n0g16.png", Some(ScaledFloat::new(0.35)));
+        trial("tests/pngsuite/g03n2c08.png", Some(ScaledFloat::new(0.35)));
+        trial("tests/pngsuite/g03n3p04.png", Some(ScaledFloat::new(0.35)));
+        trial("tests/pngsuite/g04n0g16.png", Some(ScaledFloat::new(0.45)));
+        trial("tests/pngsuite/g04n2c08.png", Some(ScaledFloat::new(0.45)));
+        trial("tests/pngsuite/g04n3p04.png", Some(ScaledFloat::new(0.45)));
+        trial("tests/pngsuite/g05n0g16.png", Some(ScaledFloat::new(0.55)));
+        trial("tests/pngsuite/g05n2c08.png", Some(ScaledFloat::new(0.55)));
+        trial("tests/pngsuite/g05n3p04.png", Some(ScaledFloat::new(0.55)));
+        trial("tests/pngsuite/g07n0g16.png", Some(ScaledFloat::new(0.7)));
+        trial("tests/pngsuite/g07n2c08.png", Some(ScaledFloat::new(0.7)));
+        trial("tests/pngsuite/g07n3p04.png", Some(ScaledFloat::new(0.7)));
+        trial("tests/pngsuite/g10n0g16.png", Some(ScaledFloat::new(1.0)));
+        trial("tests/pngsuite/g10n2c08.png", Some(ScaledFloat::new(1.0)));
+        trial("tests/pngsuite/g10n3p04.png", Some(ScaledFloat::new(1.0)));
+        trial("tests/pngsuite/g25n0g16.png", Some(ScaledFloat::new(2.5)));
+        trial("tests/pngsuite/g25n2c08.png", Some(ScaledFloat::new(2.5)));
+        trial("tests/pngsuite/g25n3p04.png", Some(ScaledFloat::new(2.5)));
+        Ok(())
+    }
+
+    #[test]
+    fn image_source_chromaticities() -> Result<(), ()> {
+        fn trial(path: &str, expected: Option<SourceChromaticities>) {
+            let decoder = crate::Decoder::new(File::open(path).unwrap());
+            let reader = decoder.read_info().unwrap();
+            let actual: Option<SourceChromaticities> = reader.info().source_chromaticities;
+            assert!(actual == expected);
+        }
+        trial(
+            "tests/pngsuite/ccwn2c08.png",
+            Some(SourceChromaticities::new(
+                (0.3127, 0.3290),
+                (0.64, 0.33),
+                (0.30, 0.60),
+                (0.15, 0.06),
+            )),
+        );
+        trial(
+            "tests/pngsuite/ccwn3p08.png",
+            Some(SourceChromaticities::new(
+                (0.3127, 0.3290),
+                (0.64, 0.33),
+                (0.30, 0.60),
+                (0.15, 0.06),
+            )),
+        );
+        trial("tests/pngsuite/basi0g01.png", None);
+        trial("tests/pngsuite/basi0g02.png", None);
+        trial("tests/pngsuite/basi0g04.png", None);
+        trial("tests/pngsuite/basi0g08.png", None);
+        trial("tests/pngsuite/basi0g16.png", None);
+        trial("tests/pngsuite/basi2c08.png", None);
+        trial("tests/pngsuite/basi2c16.png", None);
+        trial("tests/pngsuite/basi3p01.png", None);
+        trial("tests/pngsuite/basi3p02.png", None);
+        trial("tests/pngsuite/basi3p04.png", None);
+        trial("tests/pngsuite/basi3p08.png", None);
+        trial("tests/pngsuite/basi4a08.png", None);
+        trial("tests/pngsuite/basi4a16.png", None);
+        trial("tests/pngsuite/basi6a08.png", None);
+        trial("tests/pngsuite/basi6a16.png", None);
+        trial("tests/pngsuite/basn0g01.png", None);
+        trial("tests/pngsuite/basn0g02.png", None);
+        trial("tests/pngsuite/basn0g04.png", None);
+        trial("tests/pngsuite/basn0g08.png", None);
+        trial("tests/pngsuite/basn0g16.png", None);
+        trial("tests/pngsuite/basn2c08.png", None);
+        trial("tests/pngsuite/basn2c16.png", None);
+        trial("tests/pngsuite/basn3p01.png", None);
+        trial("tests/pngsuite/basn3p02.png", None);
+        trial("tests/pngsuite/basn3p04.png", None);
+        trial("tests/pngsuite/basn3p08.png", None);
+        trial("tests/pngsuite/basn4a08.png", None);
+        trial("tests/pngsuite/basn4a16.png", None);
+        trial("tests/pngsuite/basn6a08.png", None);
+        trial("tests/pngsuite/basn6a16.png", None);
+        trial("tests/pngsuite/bgai4a08.png", None);
+        trial("tests/pngsuite/bgai4a16.png", None);
+        trial("tests/pngsuite/bgan6a08.png", None);
+        trial("tests/pngsuite/bgan6a16.png", None);
+        trial("tests/pngsuite/bgbn4a08.png", None);
+        trial("tests/pngsuite/bggn4a16.png", None);
+        trial("tests/pngsuite/bgwn6a08.png", None);
+        trial("tests/pngsuite/bgyn6a16.png", None);
+        trial("tests/pngsuite/cdfn2c08.png", None);
+        trial("tests/pngsuite/cdhn2c08.png", None);
+        trial("tests/pngsuite/cdsn2c08.png", None);
+        trial("tests/pngsuite/cdun2c08.png", None);
+        trial("tests/pngsuite/ch1n3p04.png", None);
+        trial("tests/pngsuite/ch2n3p08.png", None);
+        trial("tests/pngsuite/cm0n0g04.png", None);
+        trial("tests/pngsuite/cm7n0g04.png", None);
+        trial("tests/pngsuite/cm9n0g04.png", None);
+        trial("tests/pngsuite/cs3n2c16.png", None);
+        trial("tests/pngsuite/cs3n3p08.png", None);
+        trial("tests/pngsuite/cs5n2c08.png", None);
+        trial("tests/pngsuite/cs5n3p08.png", None);
+        trial("tests/pngsuite/cs8n2c08.png", None);
+        trial("tests/pngsuite/cs8n3p08.png", None);
+        trial("tests/pngsuite/ct0n0g04.png", None);
+        trial("tests/pngsuite/ct1n0g04.png", None);
+        trial("tests/pngsuite/cten0g04.png", None);
+        trial("tests/pngsuite/ctfn0g04.png", None);
+        trial("tests/pngsuite/ctgn0g04.png", None);
+        trial("tests/pngsuite/cthn0g04.png", None);
+        trial("tests/pngsuite/ctjn0g04.png", None);
+        trial("tests/pngsuite/ctzn0g04.png", None);
+        trial("tests/pngsuite/f00n0g08.png", None);
+        trial("tests/pngsuite/f00n2c08.png", None);
+        trial("tests/pngsuite/f01n0g08.png", None);
+        trial("tests/pngsuite/f01n2c08.png", None);
+        trial("tests/pngsuite/f02n0g08.png", None);
+        trial("tests/pngsuite/f02n2c08.png", None);
+        trial("tests/pngsuite/f03n0g08.png", None);
+        trial("tests/pngsuite/f03n2c08.png", None);
+        trial("tests/pngsuite/f04n0g08.png", None);
+        trial("tests/pngsuite/f04n2c08.png", None);
+        trial("tests/pngsuite/f99n0g04.png", None);
+        trial("tests/pngsuite/g03n0g16.png", None);
+        trial("tests/pngsuite/g03n2c08.png", None);
+        trial("tests/pngsuite/g03n3p04.png", None);
+        trial("tests/pngsuite/g04n0g16.png", None);
+        trial("tests/pngsuite/g04n2c08.png", None);
+        trial("tests/pngsuite/g04n3p04.png", None);
+        trial("tests/pngsuite/g05n0g16.png", None);
+        trial("tests/pngsuite/g05n2c08.png", None);
+        trial("tests/pngsuite/g05n3p04.png", None);
+        trial("tests/pngsuite/g07n0g16.png", None);
+        trial("tests/pngsuite/g07n2c08.png", None);
+        trial("tests/pngsuite/g07n3p04.png", None);
+        trial("tests/pngsuite/g10n0g16.png", None);
+        trial("tests/pngsuite/g10n2c08.png", None);
+        trial("tests/pngsuite/g10n3p04.png", None);
+        trial("tests/pngsuite/g25n0g16.png", None);
+        trial("tests/pngsuite/g25n2c08.png", None);
+        trial("tests/pngsuite/g25n3p04.png", None);
+        trial("tests/pngsuite/oi1n0g16.png", None);
+        trial("tests/pngsuite/oi1n2c16.png", None);
+        trial("tests/pngsuite/oi2n0g16.png", None);
+        trial("tests/pngsuite/oi2n2c16.png", None);
+        trial("tests/pngsuite/oi4n0g16.png", None);
+        trial("tests/pngsuite/oi4n2c16.png", None);
+        trial("tests/pngsuite/oi9n0g16.png", None);
+        trial("tests/pngsuite/oi9n2c16.png", None);
+        trial("tests/pngsuite/PngSuite.png", None);
+        trial("tests/pngsuite/pp0n2c16.png", None);
+        trial("tests/pngsuite/pp0n6a08.png", None);
+        trial("tests/pngsuite/ps1n0g08.png", None);
+        trial("tests/pngsuite/ps1n2c16.png", None);
+        trial("tests/pngsuite/ps2n0g08.png", None);
+        trial("tests/pngsuite/ps2n2c16.png", None);
+        trial("tests/pngsuite/s01i3p01.png", None);
+        trial("tests/pngsuite/s01n3p01.png", None);
+        trial("tests/pngsuite/s02i3p01.png", None);
+        trial("tests/pngsuite/s02n3p01.png", None);
+        trial("tests/pngsuite/s03i3p01.png", None);
+        trial("tests/pngsuite/s03n3p01.png", None);
+        trial("tests/pngsuite/s04i3p01.png", None);
+        trial("tests/pngsuite/s04n3p01.png", None);
+        trial("tests/pngsuite/s05i3p02.png", None);
+        trial("tests/pngsuite/s05n3p02.png", None);
+        trial("tests/pngsuite/s06i3p02.png", None);
+        trial("tests/pngsuite/s06n3p02.png", None);
+        trial("tests/pngsuite/s07i3p02.png", None);
+        trial("tests/pngsuite/s07n3p02.png", None);
+        trial("tests/pngsuite/s08i3p02.png", None);
+        trial("tests/pngsuite/s08n3p02.png", None);
+        trial("tests/pngsuite/s09i3p02.png", None);
+        trial("tests/pngsuite/s09n3p02.png", None);
+        trial("tests/pngsuite/s32i3p04.png", None);
+        trial("tests/pngsuite/s32n3p04.png", None);
+        trial("tests/pngsuite/s33i3p04.png", None);
+        trial("tests/pngsuite/s33n3p04.png", None);
+        trial("tests/pngsuite/s34i3p04.png", None);
+        trial("tests/pngsuite/s34n3p04.png", None);
+        trial("tests/pngsuite/s35i3p04.png", None);
+        trial("tests/pngsuite/s35n3p04.png", None);
+        trial("tests/pngsuite/s36i3p04.png", None);
+        trial("tests/pngsuite/s36n3p04.png", None);
+        trial("tests/pngsuite/s37i3p04.png", None);
+        trial("tests/pngsuite/s37n3p04.png", None);
+        trial("tests/pngsuite/s38i3p04.png", None);
+        trial("tests/pngsuite/s38n3p04.png", None);
+        trial("tests/pngsuite/s39i3p04.png", None);
+        trial("tests/pngsuite/s39n3p04.png", None);
+        trial("tests/pngsuite/s40i3p04.png", None);
+        trial("tests/pngsuite/s40n3p04.png", None);
+        trial("tests/pngsuite/tbbn0g04.png", None);
+        trial("tests/pngsuite/tbbn2c16.png", None);
+        trial("tests/pngsuite/tbbn3p08.png", None);
+        trial("tests/pngsuite/tbgn2c16.png", None);
+        trial("tests/pngsuite/tbgn3p08.png", None);
+        trial("tests/pngsuite/tbrn2c08.png", None);
+        trial("tests/pngsuite/tbwn0g16.png", None);
+        trial("tests/pngsuite/tbwn3p08.png", None);
+        trial("tests/pngsuite/tbyn3p08.png", None);
+        trial("tests/pngsuite/tm3n3p02.png", None);
+        trial("tests/pngsuite/tp0n0g08.png", None);
+        trial("tests/pngsuite/tp0n2c08.png", None);
+        trial("tests/pngsuite/tp0n3p08.png", None);
+        trial("tests/pngsuite/tp1n3p08.png", None);
+        trial("tests/pngsuite/z00n2c08.png", None);
+        trial("tests/pngsuite/z03n2c08.png", None);
+        trial("tests/pngsuite/z06n2c08.png", None);
+        Ok(())
+    }
+}