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Merge pull request #312 from CryZe/remove-encoding-dependencies
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Remove unnecessary `encoding*` dependencies
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@HeroicKatora
HeroicKatora authored Oct 23, 2021
2 parents 4e15653 + 6bc281d commit c24fc93
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Showing 3 changed files with 81 additions and 66 deletions.
1 change: 0 additions & 1 deletion Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,6 @@ include = [
bitflags = "1.0"
crc32fast = "1.2.0"
deflate = "0.9"
encoding = "0.2"
[dependencies.miniz_oxide]
version = "0.4.1"
features = ["no_extern_crate_alloc"]
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12 changes: 6 additions & 6 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -60,7 +60,7 @@
//! ```
//!

#![forbid(unsafe_code)]
#![deny(unsafe_code)]

#[macro_use]
extern crate bitflags;
Expand All @@ -75,9 +75,9 @@ pub mod text_metadata;
mod traits;
mod utils;

pub use crate::common::*;
pub use crate::decoder::{
Decoded, Decoder, DecodingError, Limits, OutputInfo, Reader, StreamingDecoder,
pub use crate::{
common::*,
decoder::{Decoded, Decoder, DecodingError, Limits, OutputInfo, Reader, StreamingDecoder},
encoder::{Encoder, EncodingError, StreamWriter, Writer},
filter::{AdaptiveFilterType, FilterType},
};
pub use crate::encoder::{Encoder, EncodingError, StreamWriter, Writer};
pub use crate::filter::{AdaptiveFilterType, FilterType};
134 changes: 75 additions & 59 deletions src/text_metadata.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,12 +3,18 @@
//! The [PNG spec](https://www.w3.org/TR/2003/REC-PNG-20031110/#11textinfo) optionally allows for
//! embedded text chunks in the file. They may appear either before or after the image data
//! chunks. There are three kinds of text chunks.
//! - `tEXt`: This has a `keyword` and `text` field, and is ISO-8859-1 encoded.
//! - `tEXt`: This has a `keyword` and `text` field, and is ISO 8859-1 encoded.
//! - `zTXt`: This is semantically the same as `tEXt`, i.e. it has the same fields and
//! encoding, but the `text` field is compressed before being written into the PNG file.
//! - `iTXt`: This chunk allows for its `text` field to be any valid UTF-8, and supports
//! compression of the text field as well.
//!
//! The `ISO 8859-1` encoding technically doesn't allow any control characters
//! to be used, but in practice these values are encountered anyway. This can
//! either be the extended `ISO-8859-1` encoding with control characters or the
//! `Windows-1252` encoding. This crate assumes the `ISO-8859-1` encoding is
//! used.
//!
//! ## Reading text chunks
//!
//! As a PNG is decoded, any text chunk encountered is appended the
Expand All @@ -18,9 +24,18 @@
//!
//! ```
//! use std::fs::File;
//! use std::iter::FromIterator;
//! use std::path::PathBuf;
//!
//! // Opening a png file that has a zTXt chunk
//! let decoder = png::Decoder::new(File::open("tests/text_chunk_examples/ztxt_example.png").unwrap());
//! let decoder = png::Decoder::new(
//! File::open(PathBuf::from_iter([
//! "tests",
//! "text_chunk_examples",
//! "ztxt_example.png",
//! ]))
//! .unwrap(),
//! );
//! let mut reader = decoder.read_info().unwrap();
//! // If the text chunk is before the image data frames, `reader.info()` already contains the text.
//! for text_chunk in &reader.info().compressed_latin1_text {
Expand All @@ -37,12 +52,13 @@
//! To add a text chunk at any point in the stream, use the `write_text_chunk` method.
//!
//! ```
//! # use png;
//! # use png::text_metadata::{ITXtChunk, ZTXtChunk};
//! # use std::env;
//! # use std::fs::File;
//! # use std::io::BufWriter;
//! # let file = File::create("/tmp/test.png").unwrap();
//! # use std::iter::FromIterator;
//! # use std::path::PathBuf;
//! # let file = File::create(PathBuf::from_iter(["target", "text_chunk.png"])).unwrap();
//! # let ref mut w = BufWriter::new(file);
//! let mut encoder = png::Encoder::new(w, 2, 1); // Width is 2 pixels and height is 1.
//! encoder.set_color(png::ColorType::Rgba);
Expand Down Expand Up @@ -87,12 +103,9 @@
#![warn(missing_docs)]

use crate::{chunk, encoder, DecodingError, EncodingError};
use deflate::write::ZlibEncoder;
use deflate::Compression;
use encoding::all::{ASCII, ISO_8859_1};
use encoding::{DecoderTrap, EncoderTrap, Encoding};
use deflate::{write::ZlibEncoder, Compression};
use miniz_oxide::inflate::{decompress_to_vec_zlib, decompress_to_vec_zlib_with_limit};
use std::io::Write;
use std::{convert::TryFrom, io::Write};

/// Default decompression limit for compressed text chunks.
pub const DECOMPRESSION_LIMIT: usize = 2097152; // 2 MiB
Expand Down Expand Up @@ -144,6 +157,36 @@ pub struct TEXtChunk {
pub text: String,
}

fn decode_iso_8859_1(text: &[u8]) -> String {
text.iter().map(|&b| b as char).collect()
}

fn encode_iso_8859_1(text: &str) -> Result<Vec<u8>, TextEncodingError> {
encode_iso_8859_1_iter(text).collect()
}

fn encode_iso_8859_1_into(buf: &mut Vec<u8>, text: &str) -> Result<(), TextEncodingError> {
for b in encode_iso_8859_1_iter(text) {
buf.push(b?);
}
Ok(())
}

fn encode_iso_8859_1_iter(text: &str) -> impl Iterator<Item = Result<u8, TextEncodingError>> + '_ {
text.chars()
.map(|c| u8::try_from(c as u32).map_err(|_| TextEncodingError::Unrepresentable))
}

#[allow(unsafe_code)]
fn decode_ascii(text: &[u8]) -> Result<&str, TextDecodingError> {
if text.is_ascii() {
// SAFETY: ASCII is a subset of UTF-8.
unsafe { Ok(std::str::from_utf8_unchecked(text)) }
} else {
Err(TextDecodingError::Unrepresentable)
}
}

impl TEXtChunk {
/// Constructs a new TEXtChunk.
/// Not sure whether it should take &str or String.
Expand All @@ -165,32 +208,24 @@ impl TEXtChunk {
}

Ok(Self {
keyword: ISO_8859_1
.decode(keyword_slice, DecoderTrap::Strict)
.map_err(|_| TextDecodingError::Unrepresentable)?,
text: ISO_8859_1
.decode(text_slice, DecoderTrap::Strict)
.map_err(|_| TextDecodingError::Unrepresentable)?,
keyword: decode_iso_8859_1(keyword_slice),
text: decode_iso_8859_1(text_slice),
})
}
}

impl EncodableTextChunk for TEXtChunk {
/// Encodes TEXtChunk to a Writer. The keyword and text are separated by a byte of zeroes.
fn encode<W: Write>(&self, w: &mut W) -> Result<(), EncodingError> {
let mut data = ISO_8859_1
.encode(&self.keyword, EncoderTrap::Strict)
.map_err(|_| EncodingError::from(TextEncodingError::Unrepresentable))?;
let mut data = encode_iso_8859_1(&self.keyword)?;

if data.is_empty() || data.len() > 79 {
return Err(TextEncodingError::InvalidKeywordSize.into());
}

data.push(0);

ISO_8859_1
.encode_to(&self.text, EncoderTrap::Strict, &mut data)
.map_err(|_| EncodingError::from(TextEncodingError::Unrepresentable))?;
encode_iso_8859_1_into(&mut data, &self.text)?;

encoder::write_chunk(w, chunk::tEXt, &data)
}
Expand Down Expand Up @@ -237,10 +272,8 @@ impl ZTXtChunk {
}

Ok(Self {
keyword: ISO_8859_1
.decode(keyword_slice, DecoderTrap::Strict)
.map_err(|_| TextDecodingError::Unrepresentable)?,
text: OptCompressed::Compressed(text_slice.iter().cloned().collect()),
keyword: decode_iso_8859_1(keyword_slice),
text: OptCompressed::Compressed(text_slice.to_vec()),
})
}

Expand All @@ -264,11 +297,7 @@ impl ZTXtChunk {
return Err(DecodingError::from(TextDecodingError::InflationError));
}
};
self.text = OptCompressed::Uncompressed(
ISO_8859_1
.decode(&uncompressed_raw, DecoderTrap::Strict)
.map_err(|_| DecodingError::from(TextDecodingError::Unrepresentable))?,
);
self.text = OptCompressed::Uncompressed(decode_iso_8859_1(&uncompressed_raw));
}
OptCompressed::Uncompressed(_) => {}
};
Expand All @@ -282,9 +311,7 @@ impl ZTXtChunk {
OptCompressed::Compressed(v) => {
let uncompressed_raw = decompress_to_vec_zlib(&v[..])
.map_err(|_| DecodingError::from(TextDecodingError::InflationError))?;
ISO_8859_1
.decode(&uncompressed_raw, DecoderTrap::Strict)
.map_err(|_| DecodingError::from(TextDecodingError::Unrepresentable))
Ok(decode_iso_8859_1(&uncompressed_raw))
}
OptCompressed::Uncompressed(s) => Ok(s.clone()),
}
Expand All @@ -294,9 +321,7 @@ impl ZTXtChunk {
pub fn compress_text(&mut self) -> Result<(), EncodingError> {
match &self.text {
OptCompressed::Uncompressed(s) => {
let uncompressed_raw = ISO_8859_1
.encode(s, EncoderTrap::Strict)
.map_err(|_| EncodingError::from(TextEncodingError::Unrepresentable))?;
let uncompressed_raw = encode_iso_8859_1(s)?;
let mut encoder = ZlibEncoder::new(Vec::new(), Compression::Fast);
encoder
.write_all(&uncompressed_raw)
Expand All @@ -316,9 +341,7 @@ impl ZTXtChunk {

impl EncodableTextChunk for ZTXtChunk {
fn encode<W: Write>(&self, w: &mut W) -> Result<(), EncodingError> {
let mut data = ISO_8859_1
.encode(&self.keyword, EncoderTrap::Strict)
.map_err(|_| EncodingError::from(TextEncodingError::Unrepresentable))?;
let mut data = encode_iso_8859_1(&self.keyword)?;

if data.is_empty() || data.len() > 79 {
return Err(TextEncodingError::InvalidKeywordSize.into());
Expand All @@ -336,9 +359,7 @@ impl EncodableTextChunk for ZTXtChunk {
}
OptCompressed::Uncompressed(s) => {
// This code may have a bug. Check for correctness.
let uncompressed_raw = ISO_8859_1
.encode(s, EncoderTrap::Strict)
.map_err(|_| EncodingError::from(TextEncodingError::Unrepresentable))?;
let uncompressed_raw = encode_iso_8859_1(s)?;
let mut encoder = ZlibEncoder::new(data, Compression::Fast);
encoder
.write_all(&uncompressed_raw)
Expand Down Expand Up @@ -391,9 +412,7 @@ impl ITXtChunk {
if keyword_slice.is_empty() || keyword_slice.len() > 79 {
return Err(TextDecodingError::InvalidKeywordSize);
}
let keyword = ISO_8859_1
.decode(keyword_slice, DecoderTrap::Strict)
.map_err(|_| TextDecodingError::Unrepresentable)?;
let keyword = decode_iso_8859_1(keyword_slice);

let compressed = match compression_flag {
0 => false,
Expand All @@ -405,18 +424,16 @@ impl ITXtChunk {
return Err(TextDecodingError::InvalidCompressionMethod);
}

let language_tag = ASCII
.decode(language_tag_slice, DecoderTrap::Strict)
.map_err(|_| TextDecodingError::Unrepresentable)?;
let language_tag = decode_ascii(language_tag_slice)?.to_owned();

let translated_keyword = std::str::from_utf8(translated_keyword_slice)
.map_err(|_| TextDecodingError::Unrepresentable)?
.to_string();
let text = if compressed {
OptCompressed::Compressed(text_slice.iter().cloned().collect())
OptCompressed::Compressed(text_slice.to_vec())
} else {
OptCompressed::Uncompressed(
String::from_utf8(text_slice.iter().cloned().collect())
String::from_utf8(text_slice.to_vec())
.map_err(|_| TextDecodingError::Unrepresentable)?,
)
};
Expand Down Expand Up @@ -481,7 +498,7 @@ impl ITXtChunk {
let uncompressed_raw = s.as_bytes();
let mut encoder = ZlibEncoder::new(Vec::new(), Compression::Fast);
encoder
.write_all(&uncompressed_raw)
.write_all(uncompressed_raw)
.map_err(|_| EncodingError::from(TextEncodingError::CompressionError))?;
self.text = OptCompressed::Compressed(
encoder
Expand All @@ -499,9 +516,7 @@ impl ITXtChunk {
impl EncodableTextChunk for ITXtChunk {
fn encode<W: Write>(&self, w: &mut W) -> Result<(), EncodingError> {
// Keyword
let mut data = ISO_8859_1
.encode(&self.keyword, EncoderTrap::Strict)
.map_err(|_| EncodingError::from(TextEncodingError::Unrepresentable))?;
let mut data = encode_iso_8859_1(&self.keyword)?;

if data.is_empty() || data.len() > 79 {
return Err(TextEncodingError::InvalidKeywordSize.into());
Expand All @@ -521,15 +536,16 @@ impl EncodableTextChunk for ITXtChunk {
data.push(0);

// Language tag
ASCII
.encode_to(&self.language_tag, EncoderTrap::Strict, &mut data)
.map_err(|_| EncodingError::from(TextEncodingError::Unrepresentable))?;
if !self.language_tag.is_ascii() {
return Err(EncodingError::from(TextEncodingError::Unrepresentable));
}
data.extend(self.language_tag.as_bytes());

// Null separator
data.push(0);

// Translated keyword
data.extend_from_slice(&self.translated_keyword.as_bytes());
data.extend_from_slice(self.translated_keyword.as_bytes());

// Null separator
data.push(0);
Expand All @@ -544,7 +560,7 @@ impl EncodableTextChunk for ITXtChunk {
let uncompressed_raw = s.as_bytes();
let mut encoder = ZlibEncoder::new(data, Compression::Fast);
encoder
.write_all(&uncompressed_raw)
.write_all(uncompressed_raw)
.map_err(|_| EncodingError::from(TextEncodingError::CompressionError))?;
data = encoder
.finish()
Expand Down

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