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
168
169
170
171
172
173
174
175
176
177
178
179
#![doc(html_logo_url =
"https://raw.githubusercontent.com/RustCrypto/meta/master/logo_small.png")]
#![no_std]
extern crate byteorder;
use byteorder::{LE, ByteOrder};
use core::iter::Iterator;
pub struct BlobIterator<'a> {
data: &'a [u8],
size: IndexSize,
}
impl<'a> BlobIterator<'a> {
pub fn new(data: &'a [u8]) -> Result<Self, &'static str> {
if data.len() < 7 { Err("data is too small")? }
let (header, data) = data.split_at(7);
let size = match header {
b"blobby1" => IndexSize::N8,
b"blobby2" => IndexSize::N16,
b"blobby4" => IndexSize::N32,
b"blobby8" => IndexSize::N64,
_ => Err("invalid data header")?,
};
Ok(BlobIterator { data, size })
}
}
impl<'a> Iterator for BlobIterator<'a> {
type Item = &'a [u8];
fn next(&mut self) -> Option<&'a [u8]> {
if self.data.len() == 0 { return None; }
let (val, leftover) = self.size.read(self.data);
self.data = leftover;
Some(val)
}
}
pub struct Blob2Iterator<'a> {
inner: BlobIterator<'a>,
}
impl<'a> Blob2Iterator<'a> {
pub fn new(data: &'a [u8]) -> Result<Self, &'static str> {
Ok(Self { inner: BlobIterator::new(data)? })
}
}
impl<'a> Iterator for Blob2Iterator<'a> {
type Item = [&'a [u8]; 2];
fn next(&mut self) -> Option<Self::Item> {
let mut res = Self::Item::default();
for (i, v) in res.iter_mut().enumerate() {
*v = match self.inner.next() {
Some(val) => val,
None if i == 0 => return None,
None => panic!("failed to get 2 blobs, not enough elements."),
};
}
Some(res)
}
}
pub struct Blob3Iterator<'a> {
inner: BlobIterator<'a>,
}
impl<'a> Blob3Iterator<'a> {
pub fn new(data: &'a [u8]) -> Result<Self, &'static str> {
Ok(Self { inner: BlobIterator::new(data)? })
}
}
impl<'a> Iterator for Blob3Iterator<'a> {
type Item = [&'a [u8]; 3];
fn next(&mut self) -> Option<Self::Item> {
let mut res = Self::Item::default();
for (i, v) in res.iter_mut().enumerate() {
*v = match self.inner.next() {
Some(val) => val,
None if i == 0 => return None,
None => panic!("failed to get 3 blobs, not enough elements."),
};
}
Some(res)
}
}
pub struct Blob4Iterator<'a> {
inner: BlobIterator<'a>,
}
impl<'a> Blob4Iterator<'a> {
pub fn new(data: &'a [u8]) -> Result<Self, &'static str> {
Ok(Self { inner: BlobIterator::new(data)? })
}
}
impl<'a> Iterator for Blob4Iterator<'a> {
type Item = [&'a [u8]; 4];
fn next(&mut self) -> Option<Self::Item> {
let mut res = Self::Item::default();
for (i, v) in res.iter_mut().enumerate() {
*v = match self.inner.next() {
Some(val) => val,
None if i == 0 => return None,
None => panic!("failed to get 4 blobs, not enough elements."),
};
}
Some(res)
}
}
#[derive(Copy, Clone)]
enum IndexSize {
N8,
N16,
N32,
N64,
}
macro_rules! branch_read {
($data:ident, $n:expr, $method:ident) => {{
let (size, data) = $data.split_at($n);
let n = LE::$method(size) as usize;
data.split_at(n)
}}
}
impl IndexSize {
fn read<'a>(self, data: &'a [u8]) -> (&'a [u8], &'a [u8]) {
match self {
IndexSize::N8 => {
let n = data[0] as usize;
data[1..].split_at(n)
},
IndexSize::N16 => branch_read!(data, 2, read_u16),
IndexSize::N32 => branch_read!(data, 4, read_u32),
IndexSize::N64 => branch_read!(data, 8, read_u64),
}
}
}