Add load_meta for faster metadata, improve DMI field handling, parsing optimizations (#23)

Author: itsmeow

.gitignore

@@ -1,2 +1,3 @@
 /target
 Cargo.lock
+tests/resources/save_test.dmi

Cargo.toml

@@ -16,4 +16,5 @@ crc32fast = "1"
 deflate = "1"
 image = { version = "0.25", default-features = false, features = ["png"] }
 inflate = "0.4"
+png = "0.17.16"
 thiserror = "2"

src/chunk.rs

@@ -23,7 +23,7 @@ impl RawGenericChunk {
 		let chunk_length = chunk_bytes.len();
 
 		if chunk_length < 12 {
-			return Err(error::DmiError::Generic(format!("Failed to load Chunk. Supplied reader contained size of {} bytes, lower than the required 12.", chunk_length)));
+			return Err(error::DmiError::Generic(format!("Failed to load Chunk. Supplied reader contained size of {chunk_length} bytes, lower than the required 12.")));
 		};
 
 		let data_length = [
@@ -46,8 +46,7 @@ impl RawGenericChunk {
 			.all(|c| (b'A' <= *c && *c <= b'Z') || (b'a' <= *c && *c <= b'z'))
 		{
 			return Err(error::DmiError::Generic(format!(
-				"Failed to load Chunk. Type contained unlawful characters: {:#?}",
-				chunk_type
+				"Failed to load Chunk. Type contained unlawful characters: {chunk_type:#?}",
 			)));
 		};
 
@@ -61,9 +60,10 @@ impl RawGenericChunk {
 		];
 
 		let recalculated_crc = crc::calculate_chunk_data_crc(chunk_type, &data);
-		if u32::from_be_bytes(crc) != recalculated_crc {
+		let crc_le = u32::from_be_bytes(crc);
+		if crc_le != recalculated_crc {
 			let chunk_name = String::from_utf8(chunk_type.to_vec())?;
-			return Err(error::DmiError::Generic(format!("Failed to load Chunk of type {}. Supplied CRC invalid: {:#?}. Its value ({}) does not match the recalculated one ({}).", chunk_name, crc, u32::from_be_bytes(crc), recalculated_crc)));
+			return Err(error::DmiError::Generic(format!("Failed to load Chunk of type {chunk_name}. Supplied CRC invalid: {crc:#?}. Its value ({crc_le}) does not match the recalculated one ({recalculated_crc}).")));
 		}
 
 		Ok(RawGenericChunk {
@@ -74,40 +74,36 @@ impl RawGenericChunk {
 		})
 	}
 
-	pub fn save<W: Write>(&self, writter: &mut W) -> Result<usize, error::DmiError> {
-		let bytes_written = writter.write(&self.data_length)?;
+	pub fn save<W: Write>(&self, writer: &mut W) -> Result<usize, error::DmiError> {
+		let bytes_written = writer.write(&self.data_length)?;
 		let mut total_bytes_written = bytes_written;
 		if bytes_written < self.data_length.len() {
 			return Err(error::DmiError::Generic(format!(
-				"Failed to save Chunk. Buffer unable to hold the data, only {} bytes written.",
-				total_bytes_written
+				"Failed to save Chunk. Buffer unable to hold the data, only {total_bytes_written} bytes written."
 			)));
 		};
 
-		let bytes_written = writter.write(&self.chunk_type)?;
+		let bytes_written = writer.write(&self.chunk_type)?;
 		total_bytes_written += bytes_written;
 		if bytes_written < self.chunk_type.len() {
 			return Err(error::DmiError::Generic(format!(
-				"Failed to save Chunk. Buffer unable to hold the data, only {} bytes written.",
-				total_bytes_written
+				"Failed to save Chunk. Buffer unable to hold the data, only {total_bytes_written} bytes written."
 			)));
 		};
 
-		let bytes_written = writter.write(&self.data)?;
+		let bytes_written = writer.write(&self.data)?;
 		total_bytes_written += bytes_written;
 		if bytes_written < self.data.len() {
 			return Err(error::DmiError::Generic(format!(
-				"Failed to save Chunk. Buffer unable to hold the data, only {} bytes written.",
-				total_bytes_written
+				"Failed to save Chunk. Buffer unable to hold the data, only {total_bytes_written} bytes written."
 			)));
 		};
 
-		let bytes_written = writter.write(&self.crc)?;
+		let bytes_written = writer.write(&self.crc)?;
 		total_bytes_written += bytes_written;
 		if bytes_written < self.crc.len() {
 			return Err(error::DmiError::Generic(format!(
-				"Failed to save Chunk. Buffer unable to hold the data, only {} bytes written.",
-				total_bytes_written
+				"Failed to save Chunk. Buffer unable to hold the data, only {total_bytes_written} bytes written."
 			)));
 		};
 

src/error.rs

@@ -1,10 +1,13 @@
+use png::DecodingError;
 use std::io;
 use thiserror::Error;
 
 #[derive(Error, Debug)]
 pub enum DmiError {
 	#[error("IO error: {0}")]
 	Io(#[from] io::Error),
+	#[error("PNG decoding error: {0}")]
+	PngDecoding(#[from] DecodingError),
 	#[error("Image-processing error: {0}")]
 	Image(#[from] image::error::ImageError),
 	#[error("FromUtf8 error: {0}")]
@@ -19,6 +22,8 @@ pub enum DmiError {
 	CrcMismatch { stated: u32, calculated: u32 },
 	#[error("Dmi error: {0}")]
 	Generic(String),
+	#[error("Dmi block entry error: {0}")]
+	BlockEntry(String),
 	#[error("Dmi IconState error: {0}")]
 	IconState(String),
 	#[error("Encoding error: {0}")]