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
use std::cmp;
use std::fmt::{self, Debug, Formatter};
use std::io::{self, BufRead, ErrorKind, Read, Seek, SeekFrom};
use std::rc::Rc;
pub struct RcU8Reader<T: AsRef<[u8]> + ?Sized> {
data: Rc<T>,
pos: usize,
}
impl<T: AsRef<[u8]> + ?Sized> Debug for RcU8Reader<T> {
#[inline]
fn fmt(&self, f: &mut Formatter) -> Result<(), fmt::Error> {
debug_helper::impl_debug_for_struct!(RcU8Reader, f, self, let .data = self.data.as_ref().as_ref(), .pos);
}
}
impl<T: AsRef<[u8]> + ?Sized> RcU8Reader<T> {
#[inline]
pub fn new(data: Rc<T>) -> RcU8Reader<T> {
RcU8Reader {
data,
pos: 0,
}
}
}
impl<T: AsRef<[u8]> + ?Sized> BufRead for RcU8Reader<T> {
#[inline]
fn fill_buf(&mut self) -> Result<&[u8], io::Error> {
let data = (*self.data).as_ref();
let amt = cmp::min(self.pos, data.len());
Ok(&data[amt..])
}
#[inline]
fn consume(&mut self, amt: usize) {
self.pos += amt;
}
}
impl<T: AsRef<[u8]> + ?Sized> Read for RcU8Reader<T> {
#[inline]
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
let n = Read::read(&mut self.fill_buf()?, buf)?;
self.pos += n;
Ok(n)
}
#[inline]
fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
let n = buf.len();
Read::read_exact(&mut self.fill_buf()?, buf)?;
self.pos += n;
Ok(())
}
}
impl<T: AsRef<[u8]> + ?Sized> Seek for RcU8Reader<T> {
fn seek(&mut self, style: SeekFrom) -> Result<u64, io::Error> {
let (base_pos, offset) = match style {
SeekFrom::Start(n) => {
let n = if n > usize::max_value() as u64 {
usize::max_value()
} else {
n as usize
};
self.pos = n;
return Ok(n as u64);
}
SeekFrom::End(n) => ((*self.data).as_ref().len(), n),
SeekFrom::Current(n) => (self.pos, n),
};
let offset = if offset > isize::max_value() as i64 {
isize::max_value()
} else if offset < isize::min_value() as i64 {
isize::min_value()
} else {
offset as isize
};
let new_pos = if offset >= 0 {
base_pos.checked_add(offset as usize)
} else {
base_pos.checked_sub((offset.wrapping_neg()) as usize)
};
match new_pos {
Some(n) => {
self.pos = n;
Ok(self.pos as u64)
}
None => {
Err(io::Error::new(
ErrorKind::InvalidInput,
"invalid seek to a negative or overflowing position",
))
}
}
}
}