Fix writing to opus

Cargo.toml

@@ -4,7 +4,7 @@ version = "0.1.1"
 authors = ["Serial <69764315+Serial-ATA@users.noreply.github.com>", "Tianyi <ShiTianyi2001@outlook.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
-description = "Fork of https://github.com/TianyiShi2001/audiotags, adding support for more file types and (optionally) duration"
+description = "Unified IO for different types of audio metadata"
 repository = "https://github.com/Serial-ATA/lofty-rs"
 keywords = ["tags", "audio", "metadata"]
 categories = ["accessibility", "multimedia::audio"]

src/components/logic/write.rs

@@ -53,26 +53,61 @@ where
 	Ok(c.into_inner())
 }
 
+struct Page {
+	pub size_idx: usize,
+	pub content: Vec<u8>,
+	pub header_type: u8,
+	pub start: usize,
+	pub end: usize,
+}
+
 pub(crate) fn opus<T>(mut data: T, packet: &[u8]) -> Result<Vec<u8>>
 where
 	T: Read + Seek,
 {
-	let mut beginning_sig = [0; 4];
-	data.read_exact(&mut beginning_sig)?;
+	fn read_page<V>(mut data: V) -> Result<Page>
+	where
+		V: Read + Seek,
+	{
+		let mut sig = [0; 4];
+		data.read_exact(&mut sig)?;
 
-	if &beginning_sig != b"OggS" {
-		return Err(Error::UnknownFormat);
+		if &sig != b"OggS" {
+			return Err(Error::UnknownFormat);
+		}
+
+		let mut info = [0; 2];
+		data.read_exact(&mut info)?;
+
+		let header_type = info[1];
+
+		let mut page = [0; 21];
+		data.read_exact(&mut page)?;
+
+		let size_idx = data.seek(SeekFrom::Current(0))? as usize;
+
+		let mut segment_table = vec![0; page[20] as usize];
+		data.read_exact(&mut segment_table)?;
+
+		let start = data.seek(SeekFrom::Current(0))? as usize;
+
+		let mut content = vec![0; segment_table.iter().map(|&b| b as usize).sum()];
+		data.read_exact(&mut content)?;
+
+		let end = data.seek(SeekFrom::Current(0))? as usize;
+
+		Ok(Page {
+			size_idx,
+			content,
+			header_type,
+			start,
+			end,
+		})
 	}
 
-	let mut first_page = [0; 23];
-	data.read_exact(&mut first_page)?;
-
-	let mut segment_table = vec![0; first_page[22] as usize];
-	data.read_exact(&mut segment_table)?;
-
-	let mut head = vec![0; segment_table.iter().map(|&b| b as usize).sum()];
-	data.read_exact(&mut head)?;
+	let first_page = read_page(&mut data)?;
 
+	let head = first_page.content;
 	let (ident, head) = head.split_at(8);
 
 	if ident != b"OpusHead" {
@@ -87,40 +122,38 @@ where
 		data.read_exact(&mut channel_mapping)?;
 	}
 
-	let mut sig = [0; 4];
-	data.read_exact(&mut sig)?;
-
-	if &sig != b"OggS" {
-		return Err(Error::UnknownFormat);
-	}
-
-	let mut second_page = [0; 23];
-	data.read_exact(&mut second_page)?;
-
-	let size_pos = data.seek(SeekFrom::Current(0))? as usize;
-
-	let mut segment_table = vec![0; second_page[22] as usize];
-	data.read_exact(&mut segment_table)?;
-
-	let start = data.seek(SeekFrom::Current(0))? as usize;
-
-	let mut tags = vec![0; segment_table.iter().map(|&b| b as usize).sum()];
-	data.read_exact(&mut tags)?;
-
-	let end = data.seek(SeekFrom::Current(0))? as usize;
+	let second_page = read_page(&mut data)?;
+	let tags = second_page.content;
+	let size_pos = second_page.size_idx;
+	let start = second_page.start;
+	let end = second_page.end;
 
 	if &tags[0..8] != b"OpusTags" {
 		return Err(Error::UnknownFormat);
 	}
 
+	let last_len = (packet.len() % 255) as u8;
+	let needed = (packet.len() / 255) + 1;
+
+	let mut segments = Vec::with_capacity(needed);
+
+	for i in 0..needed {
+		if i + 1 < needed {
+			segments.push(255)
+		} else {
+			segments.push(last_len)
+		}
+	}
+
 	data.seek(SeekFrom::Start(0))?;
 
 	let mut content = Vec::new();
 	data.read_to_end(&mut content)?;
 
 	content.splice(start..end, packet.to_vec());
-	content.insert(size_pos, (packet.len() % 255) as u8);
-	content.remove(size_pos + 1);
+	content.insert(size_pos - 1, needed as u8);
+	content.remove(size_pos);
+	content.splice(size_pos..start, segments);
 
 	Ok(content)
 }