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
#![allow(unused)]
pub mod eh;
use core::mem;
pub struct DwarfReader {
pub ptr: *const u8,
}
#[repr(C,packed)]
struct Unaligned<T>(T);
impl DwarfReader {
pub fn new(ptr: *const u8) -> DwarfReader {
DwarfReader { ptr: ptr }
}
pub unsafe fn read<T: Copy>(&mut self) -> T {
let Unaligned(result) = *(self.ptr as *const Unaligned<T>);
self.ptr = self.ptr.offset(mem::size_of::<T>() as isize);
result
}
pub unsafe fn read_uleb128(&mut self) -> u64 {
let mut shift: usize = 0;
let mut result: u64 = 0;
let mut byte: u8;
loop {
byte = self.read::<u8>();
result |= ((byte & 0x7F) as u64) << shift;
shift += 7;
if byte & 0x80 == 0 {
break;
}
}
result
}
pub unsafe fn read_sleb128(&mut self) -> i64 {
let mut shift: usize = 0;
let mut result: u64 = 0;
let mut byte: u8;
loop {
byte = self.read::<u8>();
result |= ((byte & 0x7F) as u64) << shift;
shift += 7;
if byte & 0x80 == 0 {
break;
}
}
if shift < 8 * mem::size_of::<u64>() && (byte & 0x40) != 0 {
result |= (!0 as u64) << shift;
}
result as i64
}
}
#[test]
fn dwarf_reader() {
let encoded: &[u8] = &[1, 2, 3, 4, 5, 6, 7, 0xE5, 0x8E, 0x26, 0x9B, 0xF1, 0x59, 0xFF, 0xFF];
let mut reader = DwarfReader::new(encoded.as_ptr());
unsafe {
assert!(reader.read::<u8>() == u8::to_be(1u8));
assert!(reader.read::<u16>() == u16::to_be(0x0203));
assert!(reader.read::<u32>() == u32::to_be(0x04050607));
assert!(reader.read_uleb128() == 624485);
assert!(reader.read_sleb128() == -624485);
assert!(reader.read::<i8>() == i8::to_be(-1));
}
}