1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145

use crate::error::Result;
use crate::id3::v2::tag::Id3v2Tag;
use crate::macros::{err, try_vec};
use crate::probe::ParsingMode;

use std::io::{Read, Seek, SeekFrom};
use std::marker::PhantomData;

use byteorder::{ByteOrder, ReadBytesExt};

pub(crate) struct Chunks<B>
where
	B: ByteOrder,
{
	pub fourcc: [u8; 4],
	pub size: u32,
	remaining_size: u64,
	_phantom: PhantomData<B>,
}

impl<B: ByteOrder> Chunks<B> {
	#[must_use]
	pub const fn new(file_size: u64) -> Self {
		Self {
			fourcc: [0; 4],
			size: 0,
			remaining_size: file_size,
			_phantom: PhantomData,
		}
	}

	pub fn next<R>(&mut self, data: &mut R) -> Result<()>
	where
		R: Read,
	{
		data.read_exact(&mut self.fourcc)?;
		self.size = data.read_u32::<B>()?;

		self.remaining_size = self.remaining_size.saturating_sub(8);

		Ok(())
	}

	pub fn read_cstring<R>(&mut self, data: &mut R) -> Result<String>
	where
		R: Read + Seek,
	{
		let cont = self.content(data)?;
		self.correct_position(data)?;

		let value_str = std::str::from_utf8(&cont)?;

		Ok(value_str.trim_end_matches('\0').to_string())
	}

	pub fn read_pstring<R>(&mut self, data: &mut R, size: Option<u32>) -> Result<String>
	where
		R: Read + Seek,
	{
		let cont = if let Some(size) = size {
			self.read(data, u64::from(size))?
		} else {
			self.content(data)?
		};

		if cont.len() % 2 != 0 {
			data.seek(SeekFrom::Current(1))?;
		}

		Ok(String::from_utf8(cont)?)
	}

	pub fn content<R>(&mut self, data: &mut R) -> Result<Vec<u8>>
	where
		R: Read,
	{
		self.read(data, u64::from(self.size))
	}

	fn read<R>(&mut self, data: &mut R, size: u64) -> Result<Vec<u8>>
	where
		R: Read,
	{
		if size > self.remaining_size {
			err!(SizeMismatch);
		}

		let mut content = try_vec![0; size as usize];
		data.read_exact(&mut content)?;

		self.remaining_size = self.remaining_size.saturating_sub(size);
		Ok(content)
	}

	pub fn id3_chunk<R>(&mut self, data: &mut R, parse_mode: ParsingMode) -> Result<Id3v2Tag>
	where
		R: Read + Seek,
	{
		use crate::id3::v2::read::parse_id3v2;
		use crate::id3::v2::read_id3v2_header;

		let content = self.content(data)?;

		let reader = &mut &*content;

		let header = read_id3v2_header(reader)?;
		let id3v2 = parse_id3v2(reader, header, parse_mode)?;

		// Skip over the footer
		if id3v2.flags().footer {
			data.seek(SeekFrom::Current(10))?;
		}

		self.correct_position(data)?;

		Ok(id3v2)
	}

	pub fn skip<R>(&mut self, data: &mut R) -> Result<()>
	where
		R: Read + Seek,
	{
		data.seek(SeekFrom::Current(i64::from(self.size)))?;
		self.correct_position(data)?;

		self.remaining_size = self.remaining_size.saturating_sub(u64::from(self.size));

		Ok(())
	}

	pub fn correct_position<R>(&mut self, data: &mut R) -> Result<()>
	where
		R: Read + Seek,
	{
		// Chunks are expected to start on even boundaries, and are padded
		// with a 0 if necessary. This is NOT the null terminator of the value,
		// and it is NOT included in the chunk's size
		if self.size % 2 != 0 {
			data.seek(SeekFrom::Current(1))?;
			self.remaining_size = self.remaining_size.saturating_sub(1);
		}

		Ok(())
	}
}