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-rw-r--r--vendor/jpeg-decoder/src/parser.rs685
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diff --git a/vendor/jpeg-decoder/src/parser.rs b/vendor/jpeg-decoder/src/parser.rs
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+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)
+}
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