Initial vendor packages

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

1 files changed, 685 insertions, 0 deletions

diff --git a/vendor/jpeg-decoder/src/parser.rs b/vendor/jpeg-decoder/src/parser.rs
new file mode 100644
index 0000000..72ba00d
--- /dev/null
+++ b/vendor/jpeg-decoder/src/parser.rs
@@ -0,0 +1,685 @@
+use alloc::borrow::ToOwned;
+use alloc::{format, vec};
+use alloc::vec::Vec;
+use core::ops::{self, Range};
+use std::io::{self, Read};
+use crate::{read_u16_from_be, read_u8};
+use crate::error::{Error, Result, UnsupportedFeature};
+use crate::huffman::{HuffmanTable, HuffmanTableClass};
+use crate::marker::Marker;
+use crate::marker::Marker::*;
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Dimensions {
+    pub width: u16,
+    pub height: u16,
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum EntropyCoding {
+    Huffman,
+    Arithmetic,
+}
+
+/// Represents the coding process of an image.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum CodingProcess {
+    /// Sequential Discrete Cosine Transform
+    DctSequential,
+    /// Progressive Discrete Cosine Transform
+    DctProgressive,
+    /// Lossless
+    Lossless,
+}
+
+// Table H.1
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum Predictor {
+    NoPrediction,
+    Ra,
+    Rb,
+    Rc,
+    RaRbRc1, // Ra + Rb - Rc
+    RaRbRc2, // Ra + ((Rb - Rc) >> 1)
+    RaRbRc3, // Rb + ((Ra - Rb) >> 1)
+    RaRb,    // (Ra + Rb)/2
+}
+
+
+#[derive(Clone)]
+pub struct FrameInfo {
+    pub is_baseline: bool,
+    pub is_differential: bool,
+    pub coding_process: CodingProcess,
+    pub entropy_coding: EntropyCoding,
+    pub precision: u8,
+
+    pub image_size: Dimensions,
+    pub output_size: Dimensions,
+    pub mcu_size: Dimensions,
+    pub components: Vec<Component>,
+}
+
+#[derive(Debug)]
+pub struct ScanInfo {
+    pub component_indices: Vec<usize>,
+    pub dc_table_indices: Vec<usize>,
+    pub ac_table_indices: Vec<usize>,
+
+    pub spectral_selection: Range<u8>,
+    pub predictor_selection: Predictor, // for lossless
+    pub successive_approximation_high: u8,
+    pub successive_approximation_low: u8,
+    pub point_transform: u8, // for lossless
+}
+
+#[derive(Clone, Debug)]
+pub struct Component {
+    pub identifier: u8,
+
+    pub horizontal_sampling_factor: u8,
+    pub vertical_sampling_factor: u8,
+
+    pub quantization_table_index: usize,
+
+    pub dct_scale: usize,
+
+    pub size: Dimensions,
+    pub block_size: Dimensions,
+}
+
+#[derive(Debug)]
+pub enum AppData {
+    Adobe(AdobeColorTransform),
+    Jfif,
+    Avi1,
+    Icc(IccChunk),
+    Exif(Vec<u8>),
+}
+
+// http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#Adobe
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum AdobeColorTransform {
+    // RGB or CMYK
+    Unknown,
+    YCbCr,
+    // YCbCrK
+    YCCK,
+}
+#[derive(Debug)]
+pub struct IccChunk {
+    pub num_markers: u8,
+    pub seq_no: u8,
+    pub data: Vec<u8>,
+}
+
+impl FrameInfo {
+    pub(crate) fn update_idct_size(&mut self, idct_size: usize) -> Result<()> {
+        for component in &mut self.components {
+            component.dct_scale = idct_size;
+        }
+
+        update_component_sizes(self.image_size, &mut self.components)?;
+
+        self.output_size = Dimensions {
+            width: (self.image_size.width as f32 * idct_size as f32 / 8.0).ceil() as u16,
+            height: (self.image_size.height as f32 * idct_size as f32 / 8.0).ceil() as u16
+        };
+
+        Ok(())
+    }
+}
+
+fn read_length<R: Read>(reader: &mut R, marker: Marker) -> Result<usize> {
+    assert!(marker.has_length());
+
+    // length is including itself.
+    let length = usize::from(read_u16_from_be(reader)?);
+
+    if length < 2 {
+        return Err(Error::Format(format!("encountered {:?} with invalid length {}", marker, length)));
+    }
+
+    Ok(length - 2)
+}
+
+fn skip_bytes<R: Read>(reader: &mut R, length: usize) -> Result<()> {
+    let length = length as u64;
+    let to_skip = &mut reader.by_ref().take(length);
+    let copied = io::copy(to_skip, &mut io::sink())?;
+    if copied < length {
+        Err(Error::Io(io::ErrorKind::UnexpectedEof.into()))
+    } else {
+        Ok(())
+    }
+}
+
+// Section B.2.2
+pub fn parse_sof<R: Read>(reader: &mut R, marker: Marker) -> Result<FrameInfo> {
+    let length = read_length(reader, marker)?;
+
+    if length <= 6 {
+        return Err(Error::Format("invalid length in SOF".to_owned()));
+    }
+
+    let is_baseline = marker == SOF(0);
+    let is_differential = match marker {
+        SOF(0 ..= 3) | SOF(9 ..= 11)  => false,
+        SOF(5 ..= 7) | SOF(13 ..= 15) => true,
+        _ => panic!(),
+    };
+    let coding_process = match marker {
+        SOF(0) | SOF(1) | SOF(5) | SOF(9) | SOF(13) => CodingProcess::DctSequential,
+        SOF(2) | SOF(6) | SOF(10) | SOF(14)         => CodingProcess::DctProgressive,
+        SOF(3) | SOF(7) | SOF(11) | SOF(15)         => CodingProcess::Lossless,
+        _ => panic!(),
+    };
+    let entropy_coding = match marker {
+        SOF(0 ..= 3) | SOF(5 ..= 7)     => EntropyCoding::Huffman,
+        SOF(9 ..= 11) | SOF(13 ..= 15)  => EntropyCoding::Arithmetic,
+        _ => panic!(),
+    };
+
+    let precision = read_u8(reader)?;
+
+    match precision {
+        8 => {},
+        12 => {
+            if is_baseline {
+                return Err(Error::Format("12 bit sample precision is not allowed in baseline".to_owned()));
+            }
+        },
+        _ => {
+            if coding_process != CodingProcess::Lossless || precision > 16 {
+                return Err(Error::Format(format!("invalid precision {} in frame header", precision)))
+            }
+        },
+    }
+
+    let height = read_u16_from_be(reader)?;
+    let width = read_u16_from_be(reader)?;
+
+    // height:
+    // "Value 0 indicates that the number of lines shall be defined by the DNL marker and
+    //     parameters at the end of the first scan (see B.2.5)."
+    if height == 0 {
+        return Err(Error::Unsupported(UnsupportedFeature::DNL));
+    }
+
+    if width == 0 {
+        return Err(Error::Format("zero width in frame header".to_owned()));
+    }
+
+    let component_count = read_u8(reader)?;
+
+    if component_count == 0 {
+        return Err(Error::Format("zero component count in frame header".to_owned()));
+    }
+    if coding_process == CodingProcess::DctProgressive && component_count > 4 {
+        return Err(Error::Format("progressive frame with more than 4 components".to_owned()));
+    }
+
+    if length != 6 + 3 * component_count as usize {
+        return Err(Error::Format("invalid length in SOF".to_owned()));
+    }
+
+    let mut components: Vec<Component> = Vec::with_capacity(component_count as usize);
+
+    for _ in 0 .. component_count {
+        let identifier = read_u8(reader)?;
+
+        // Each component's identifier must be unique.
+        if components.iter().any(|c| c.identifier == identifier) {
+            return Err(Error::Format(format!("duplicate frame component identifier {}", identifier)));
+        }
+
+        let byte = read_u8(reader)?;
+        let horizontal_sampling_factor = byte >> 4;
+        let vertical_sampling_factor = byte & 0x0f;
+
+        if horizontal_sampling_factor == 0 || horizontal_sampling_factor > 4 {
+            return Err(Error::Format(format!("invalid horizontal sampling factor {}", horizontal_sampling_factor)));
+        }
+        if vertical_sampling_factor == 0 || vertical_sampling_factor > 4 {
+            return Err(Error::Format(format!("invalid vertical sampling factor {}", vertical_sampling_factor)));
+        }
+
+        let quantization_table_index = read_u8(reader)?;
+
+        if quantization_table_index > 3 || (coding_process == CodingProcess::Lossless && quantization_table_index != 0) {
+            return Err(Error::Format(format!("invalid quantization table index {}", quantization_table_index)));
+        }
+
+        components.push(Component {
+            identifier,
+            horizontal_sampling_factor,
+            vertical_sampling_factor,
+            quantization_table_index: quantization_table_index as usize,
+            dct_scale: 8,
+            size: Dimensions {width: 0, height: 0},
+            block_size: Dimensions {width: 0, height: 0},
+        });
+    }
+
+    let mcu_size = update_component_sizes(Dimensions { width, height }, &mut components)?;
+
+    Ok(FrameInfo {
+        is_baseline,
+        is_differential,
+        coding_process,
+        entropy_coding,
+        precision,
+        image_size: Dimensions { width, height },
+        output_size: Dimensions { width, height },
+        mcu_size,
+        components,
+    })
+}
+
+/// Returns ceil(x/y), requires x>0
+fn ceil_div(x: u32, y: u32) -> Result<u16> {
+    if x == 0 || y == 0 {
+        // TODO Determine how this error is reached. Can we validate input
+        // earlier and error out then?
+        return Err(Error::Format("invalid dimensions".to_owned()));
+    }
+    Ok((1 + ((x - 1) / y)) as u16)
+}
+
+fn update_component_sizes(size: Dimensions, components: &mut [Component]) -> Result<Dimensions> {
+    let h_max = components.iter().map(|c| c.horizontal_sampling_factor).max().unwrap() as u32;
+    let v_max = components.iter().map(|c| c.vertical_sampling_factor).max().unwrap() as u32;
+
+    let mcu_size = Dimensions {
+        width: ceil_div(size.width as u32, h_max * 8)?,
+        height: ceil_div(size.height as u32, v_max * 8)?,
+    };
+
+    for component in components {
+        component.size.width = ceil_div(size.width as u32 * component.horizontal_sampling_factor as u32 * component.dct_scale as u32, h_max * 8)?;
+        component.size.height = ceil_div(size.height as u32 * component.vertical_sampling_factor as u32 * component.dct_scale as u32, v_max * 8)?;
+
+        component.block_size.width = mcu_size.width * component.horizontal_sampling_factor as u16;
+        component.block_size.height = mcu_size.height * component.vertical_sampling_factor as u16;
+    }
+
+    Ok(mcu_size)
+}
+
+#[test]
+fn test_update_component_sizes() {
+    let mut components = [Component {
+        identifier: 1,
+        horizontal_sampling_factor: 2,
+        vertical_sampling_factor: 2,
+        quantization_table_index: 0,
+        dct_scale: 8,
+        size: Dimensions { width: 0, height: 0 },
+        block_size: Dimensions { width: 0, height: 0 },
+    }];
+    let mcu = update_component_sizes(
+        Dimensions { width: 800, height: 280 },
+        &mut components).unwrap();
+    assert_eq!(mcu, Dimensions { width: 50, height: 18 });
+    assert_eq!(components[0].block_size, Dimensions { width: 100, height: 36 });
+    assert_eq!(components[0].size, Dimensions { width: 800, height: 280 });
+}
+
+// Section B.2.3
+pub fn parse_sos<R: Read>(reader: &mut R, frame: &FrameInfo) -> Result<ScanInfo> {
+    let length = read_length(reader, SOS)?;
+    if 0 == length {
+        return Err(Error::Format("zero length in SOS".to_owned()));
+    }
+
+    let component_count = read_u8(reader)?;
+
+    if component_count == 0 || component_count > 4 {
+        return Err(Error::Format(format!("invalid component count {} in scan header", component_count)));
+    }
+
+    if length != 4 + 2 * component_count as usize {
+        return Err(Error::Format("invalid length in SOS".to_owned()));
+    }
+
+    let mut component_indices = Vec::with_capacity(component_count as usize);
+    let mut dc_table_indices = Vec::with_capacity(component_count as usize);
+    let mut ac_table_indices = Vec::with_capacity(component_count as usize);
+
+    for _ in 0 .. component_count {
+        let identifier = read_u8(reader)?;
+
+        let component_index = match frame.components.iter().position(|c| c.identifier == identifier) {
+            Some(value) => value,
+            None => return Err(Error::Format(format!("scan component identifier {} does not match any of the component identifiers defined in the frame", identifier))),
+        };
+
+        // Each of the scan's components must be unique.
+        if component_indices.contains(&component_index) {
+            return Err(Error::Format(format!("duplicate scan component identifier {}", identifier)));
+        }
+
+        // "... the ordering in the scan header shall follow the ordering in the frame header."
+        if component_index < *component_indices.iter().max().unwrap_or(&0) {
+            return Err(Error::Format("the scan component order does not follow the order in the frame header".to_owned()));
+        }
+
+        let byte = read_u8(reader)?;
+        let dc_table_index = byte >> 4;
+        let ac_table_index = byte & 0x0f;
+
+        if dc_table_index > 3 || (frame.is_baseline && dc_table_index > 1) {
+            return Err(Error::Format(format!("invalid dc table index {}", dc_table_index)));
+        }
+        if ac_table_index > 3 || (frame.is_baseline && ac_table_index > 1) {
+            return Err(Error::Format(format!("invalid ac table index {}", ac_table_index)));
+        }
+
+        component_indices.push(component_index);
+        dc_table_indices.push(dc_table_index as usize);
+        ac_table_indices.push(ac_table_index as usize);
+    }
+
+    let blocks_per_mcu = component_indices.iter().map(|&i| {
+        frame.components[i].horizontal_sampling_factor as u32 * frame.components[i].vertical_sampling_factor as u32
+    }).fold(0, ops::Add::add);
+
+    if component_count > 1 && blocks_per_mcu > 10 {
+        return Err(Error::Format("scan with more than one component and more than 10 blocks per MCU".to_owned()));
+    }
+
+    // Also utilized as 'Predictor' in lossless coding, as MEAN in JPEG-LS etc.
+    let spectral_selection_start = read_u8(reader)?;
+    // Also utilized as ILV parameter in JPEG-LS.
+    let mut spectral_selection_end = read_u8(reader)?;
+
+    let byte = read_u8(reader)?;
+    let successive_approximation_high = byte >> 4;
+    let successive_approximation_low = byte & 0x0f;
+
+    // The Differential Pulse-Mode prediction used (similar to png). Only utilized in Lossless
+    // coding. Don't confuse with the JPEG-LS parameter coded using the same scan info portion.
+    let predictor_selection;
+    let point_transform = successive_approximation_low;
+
+    if frame.coding_process == CodingProcess::DctProgressive {
+        predictor_selection = Predictor::NoPrediction;
+        if spectral_selection_end > 63 || spectral_selection_start > spectral_selection_end ||
+                (spectral_selection_start == 0 && spectral_selection_end != 0) {
+            return Err(Error::Format(format!("invalid spectral selection parameters: ss={}, se={}", spectral_selection_start, spectral_selection_end)));
+        }
+        if spectral_selection_start != 0 && component_count != 1 {
+            return Err(Error::Format("spectral selection scan with AC coefficients can't have more than one component".to_owned()));
+        }
+
+        if successive_approximation_high > 13 || successive_approximation_low > 13 {
+            return Err(Error::Format(format!("invalid successive approximation parameters: ah={}, al={}", successive_approximation_high, successive_approximation_low)));
+        }
+
+        // Section G.1.1.1.2
+        // "Each scan which follows the first scan for a given band progressively improves
+        //     the precision of the coefficients by one bit, until full precision is reached."
+        if successive_approximation_high != 0 && successive_approximation_high != successive_approximation_low + 1 {
+            return Err(Error::Format("successive approximation scan with more than one bit of improvement".to_owned()));
+        }
+    }
+    else if frame.coding_process == CodingProcess::Lossless {
+        if spectral_selection_end != 0 {
+            return Err(Error::Format("spectral selection end shall be zero in lossless scan".to_owned()));
+        }
+        if successive_approximation_high != 0 {
+            return Err(Error::Format("successive approximation high shall be zero in lossless scan".to_owned()));
+        }
+        predictor_selection = match spectral_selection_start {
+            0 => Predictor::NoPrediction,
+            1 => Predictor::Ra,
+            2 => Predictor::Rb,
+            3 => Predictor::Rc,
+            4 => Predictor::RaRbRc1,
+            5 => Predictor::RaRbRc2,
+            6 => Predictor::RaRbRc3,
+            7 => Predictor::RaRb,
+            _ => {
+                return Err(Error::Format(format!("invalid predictor selection value: {}", spectral_selection_start)));
+            },
+        };
+    }
+    else {
+        predictor_selection = Predictor::NoPrediction;
+        if spectral_selection_end == 0 {
+            spectral_selection_end = 63;
+        }
+        if spectral_selection_start != 0 || spectral_selection_end != 63 {
+            return Err(Error::Format("spectral selection is not allowed in non-progressive scan".to_owned()));
+        }
+        if successive_approximation_high != 0 || successive_approximation_low != 0 {
+            return Err(Error::Format("successive approximation is not allowed in non-progressive scan".to_owned()));
+        }
+    }
+
+    Ok(ScanInfo {
+        component_indices,
+        dc_table_indices,
+        ac_table_indices,
+        spectral_selection: Range {
+            start: spectral_selection_start,
+            end: spectral_selection_end + 1,
+        },
+        predictor_selection,
+        successive_approximation_high,
+        successive_approximation_low,
+        point_transform,
+    })
+}
+
+// Section B.2.4.1
+pub fn parse_dqt<R: Read>(reader: &mut R) -> Result<[Option<[u16; 64]>; 4]> {
+    let mut length = read_length(reader, DQT)?;
+    let mut tables = [None; 4];
+
+    // Each DQT segment may contain multiple quantization tables.
+    while length > 0 {
+        let byte = read_u8(reader)?;
+        let precision = (byte >> 4) as usize;
+        let index = (byte & 0x0f) as usize;
+
+        // The combination of 8-bit sample precision and 16-bit quantization tables is explicitly
+        // disallowed by the JPEG spec:
+        //     "An 8-bit DCT-based process shall not use a 16-bit precision quantization table."
+        //     "Pq: Quantization table element precision – Specifies the precision of the Qk
+        //      values. Value 0 indicates 8-bit Qk values; value 1 indicates 16-bit Qk values. Pq
+        //      shall be zero for 8 bit sample precision P (see B.2.2)."
+        // libjpeg allows this behavior though, and there are images in the wild using it. So to
+        // match libjpeg's behavior we are deviating from the JPEG spec here.
+        if precision > 1 {
+            return Err(Error::Format(format!("invalid precision {} in DQT", precision)));
+        }
+        if index > 3 {
+            return Err(Error::Format(format!("invalid destination identifier {} in DQT", index)));
+        }
+        if length < 65 + 64 * precision {
+            return Err(Error::Format("invalid length in DQT".to_owned()));
+        }
+
+        let mut table = [0u16; 64];
+
+        for item in table.iter_mut() {
+            *item = match precision {
+                0 => u16::from(read_u8(reader)?),
+                1 => read_u16_from_be(reader)?,
+                _ => unreachable!(),
+            };
+        }
+
+        if table.iter().any(|&val| val == 0) {
+            return Err(Error::Format("quantization table contains element with a zero value".to_owned()));
+        }
+
+        tables[index] = Some(table);
+        length -= 65 + 64 * precision;
+    }
+
+    Ok(tables)
+}
+
+// Section B.2.4.2
+pub fn parse_dht<R: Read>(reader: &mut R, is_baseline: Option<bool>) -> Result<(Vec<Option<HuffmanTable>>, Vec<Option<HuffmanTable>>)> {
+    let mut length = read_length(reader, DHT)?;
+    let mut dc_tables = vec![None, None, None, None];
+    let mut ac_tables = vec![None, None, None, None];
+
+    // Each DHT segment may contain multiple huffman tables.
+    while length > 17 {
+        let byte = read_u8(reader)?;
+        let class = byte >> 4;
+        let index = (byte & 0x0f) as usize;
+
+        if class != 0 && class != 1 {
+            return Err(Error::Format(format!("invalid class {} in DHT", class)));
+        }
+        if is_baseline == Some(true) && index > 1 {
+            return Err(Error::Format("a maximum of two huffman tables per class are allowed in baseline".to_owned()));
+        }
+        if index > 3 {
+            return Err(Error::Format(format!("invalid destination identifier {} in DHT", index)));
+        }
+
+        let mut counts = [0u8; 16];
+        reader.read_exact(&mut counts)?;
+
+        let size = counts.iter().map(|&val| val as usize).fold(0, ops::Add::add);
+
+        if size == 0 {
+            return Err(Error::Format("encountered table with zero length in DHT".to_owned()));
+        }
+        else if size > 256 {
+            return Err(Error::Format("encountered table with excessive length in DHT".to_owned()));
+        }
+        else if size > length - 17 {
+            return Err(Error::Format("invalid length in DHT".to_owned()));
+        }
+
+        let mut values = vec![0u8; size];
+        reader.read_exact(&mut values)?;
+
+        match class {
+            0 => dc_tables[index] = Some(HuffmanTable::new(&counts, &values, HuffmanTableClass::DC)?),
+            1 => ac_tables[index] = Some(HuffmanTable::new(&counts, &values, HuffmanTableClass::AC)?),
+            _ => unreachable!(),
+        }
+
+        length -= 17 + size;
+    }
+
+    if length != 0 {
+        return Err(Error::Format("invalid length in DHT".to_owned()));
+    }
+
+    Ok((dc_tables, ac_tables))
+}
+
+// Section B.2.4.4
+pub fn parse_dri<R: Read>(reader: &mut R) -> Result<u16> {
+    let length = read_length(reader, DRI)?;
+
+    if length != 2 {
+        return Err(Error::Format("DRI with invalid length".to_owned()));
+    }
+
+    Ok(read_u16_from_be(reader)?)
+}
+
+// Section B.2.4.5
+pub fn parse_com<R: Read>(reader: &mut R) -> Result<Vec<u8>> {
+    let length = read_length(reader, COM)?;
+    let mut buffer = vec![0u8; length];
+
+    reader.read_exact(&mut buffer)?;
+
+    Ok(buffer)
+}
+
+// Section B.2.4.6
+pub fn parse_app<R: Read>(reader: &mut R, marker: Marker) -> Result<Option<AppData>> {
+    let length = read_length(reader, marker)?;
+    let mut bytes_read = 0;
+    let mut result = None;
+
+    match marker {
+        APP(0) => {
+            if length >= 5 {
+                let mut buffer = [0u8; 5];
+                reader.read_exact(&mut buffer)?;
+                bytes_read = buffer.len();
+
+                // http://www.w3.org/Graphics/JPEG/jfif3.pdf
+                if buffer[0..5] == *b"JFIF\0" {
+                    result = Some(AppData::Jfif);
+                // https://sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#AVI1
+                } else if buffer[0..5] == *b"AVI1\0" {
+                    result = Some(AppData::Avi1);
+                }
+            }
+        }
+        // Exif Data
+        APP(1) => {
+            if length >= 6 {
+                let mut buffer = [0u8; 6];
+                reader.read_exact(&mut buffer)?;
+                bytes_read = buffer.len();
+
+                // https://web.archive.org/web/20190624045241if_/http://www.cipa.jp:80/std/documents/e/DC-008-Translation-2019-E.pdf
+                // 4.5.4 Basic Structure of JPEG Compressed Data
+                if buffer == *b"Exif\x00\x00" {
+                    let mut data = vec![0; length - bytes_read];
+                    reader.read_exact(&mut data)?;
+                    bytes_read += data.len();
+                    result = Some(AppData::Exif(data));
+                }
+            }
+        }
+        APP(2) => {
+            if length > 14 {
+                let mut buffer = [0u8; 14];
+                reader.read_exact(&mut buffer)?;
+                bytes_read = buffer.len();
+
+                // http://www.color.org/ICC_Minor_Revision_for_Web.pdf
+                // B.4 Embedding ICC profiles in JFIF files
+                if buffer[0..12] == *b"ICC_PROFILE\0" {
+                    let mut data = vec![0; length - bytes_read];
+                    reader.read_exact(&mut data)?;
+                    bytes_read += data.len();
+                    result = Some(AppData::Icc(IccChunk {
+                        seq_no: buffer[12],
+                        num_markers: buffer[13],
+                        data,
+                    }));
+                }
+            }
+        }
+        APP(14) => {
+            if length >= 12 {
+                let mut buffer = [0u8; 12];
+                reader.read_exact(&mut buffer)?;
+                bytes_read = buffer.len();
+
+                // http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#Adobe
+                if buffer[0 .. 6] == *b"Adobe\0" {
+                    let color_transform = match buffer[11] {
+                        0 => AdobeColorTransform::Unknown,
+                        1 => AdobeColorTransform::YCbCr,
+                        2 => AdobeColorTransform::YCCK,
+                        _ => return Err(Error::Format("invalid color transform in adobe app segment".to_owned())),
+                    };
+
+                    result = Some(AppData::Adobe(color_transform));
+                }
+            }
+        },
+        _ => {},
+    }
+
+    skip_bytes(reader, length - bytes_read)?;
+    Ok(result)
+}