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
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
|
#[repr(packed)]
#[derive(Debug, Clone, Copy)]
struct Header {
secs: u32,
micros: u32,
len: u32,
}
impl Header {
fn time(&self) -> std::time::Duration {
std::time::Duration::from_micros(
u64::from(self.secs) * 1_000_000 + u64::from(self.micros),
)
}
fn len(&self) -> usize {
usize::try_from(self.len).unwrap_or_else(|_| {
panic!("this library requires sizeof(usize) to be at least 4")
})
}
}
/// Parses ttyrec streams.
///
/// Designed to be able to be used in a streaming/asynchronous fashion. As you
/// read bytes from the ttyrec stream (whether from a file or whatever else),
/// call the [`add_bytes`](Parser::add_bytes) method to add them to the
/// internal buffer. At any point, you can call
/// [`next_frame`](Parser::next_frame) to then return the next complete frame
/// if one has been read.
#[derive(Debug, Default, Clone)]
pub struct Parser {
reading: std::collections::VecDeque<u8>,
read_state: Option<Header>,
offset: Option<std::time::Duration>,
}
impl Parser {
/// Create a new [`Parser`](Self).
#[must_use]
pub fn new() -> Self {
Self::default()
}
/// Add more bytes to the internal buffer.
pub fn add_bytes(&mut self, bytes: &[u8]) {
self.reading.extend(bytes.iter());
}
/// Try to read a frame from the internal buffer.
///
/// If a complete frame is found, the bytes for that frame will be removed
/// from the internal buffer and the frame object will be returned. If a
/// complete frame is not found, this method will return [`None`].
pub fn next_frame(&mut self) -> Option<crate::frame::Frame> {
let header = if let Some(header) = &self.read_state {
header
} else {
if self.reading.len() < std::mem::size_of::<Header>() {
return None;
}
// these unwraps are guaranteed safe by the length check above
let secs1 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let secs2 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let secs3 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let secs4 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let secs = u32::from_le_bytes([secs1, secs2, secs3, secs4]);
let micros1 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let micros2 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let micros3 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let micros4 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let micros =
u32::from_le_bytes([micros1, micros2, micros3, micros4]);
let len1 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let len2 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let len3 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let len4 =
self.reading.pop_front().unwrap_or_else(|| unreachable!());
let len = u32::from_le_bytes([len1, len2, len3, len4]);
let header = Header { secs, micros, len };
self.read_state = Some(header);
// unwrap is safe because we just set self.read_state to Some
self.read_state.as_ref().unwrap_or_else(|| unreachable!())
};
if self.reading.len() < header.len() {
return None;
}
let mut data = vec![];
for _ in 0..header.len() {
data.push(
// unwrap is safe because we just checked that there are
// sufficient bytes in self.reading
self.reading.pop_front().unwrap_or_else(|| unreachable!()),
);
}
let time = header.time();
self.read_state = None;
if self.offset.is_none() {
self.offset = Some(time);
}
Some(crate::frame::Frame { time, data })
}
/// How much the timestamps in this file should be offset by.
///
/// Ttyrec files are allowed to be generated by just inserting the current
/// absolute timestamp as the header. This means that during playback, we
/// need to take the timestamp of the first frame as the start time, and
/// each frame timestamp after that should be offset by that same amount.
///
/// Returns [`None`] if no frames have been read yet.
#[must_use]
pub fn offset(&self) -> Option<std::time::Duration> {
self.offset
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_basic() {
let bytes = vec![
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 38, 0, 0, 0, 64, 226, 1, 0,
10, 0, 0, 0, 27, 91, 50, 74, 102, 111, 111, 98, 97, 114,
];
let mut parser = Parser::new();
for (i, c) in bytes.into_iter().enumerate() {
parser.add_bytes(&[c]);
let expected = match i {
11 => {
let time = std::time::Duration::new(0, 0);
let data = b"".to_vec();
Some(crate::frame::Frame { time, data })
}
33 => {
let time = std::time::Duration::new(38, 123_456_000);
let data = b"\x1b[2Jfoobar".to_vec();
Some(crate::frame::Frame { time, data })
}
_ => None,
};
let got = parser.next_frame();
assert_eq!(got, expected);
}
}
}
|
