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
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
use {
super::*,
memmap::Mmap,
std::{
convert::TryInto,
fmt,
io,
path::{Path},
},
};
#[derive(Clone)]
pub struct Needle {
bytes: Box<[u8]>,
}
impl fmt::Debug for Needle {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("Needle")
.field("bytes", &self.bytes)
.finish()
}
}
impl Needle {
pub fn new(pat: &str) -> Self {
let bytes = pat.as_bytes().to_vec().into_boxed_slice();
Self { bytes }
}
pub fn is_empty(&self) -> bool {
self.bytes.is_empty()
}
pub fn as_str(&self) -> &str {
unsafe { std::str::from_utf8_unchecked(&self.bytes) }
}
fn find_naive_1(&self, hay: &Mmap) -> Option<usize> {
let n = self.bytes[0];
hay.iter().position(|&b| b == n)
}
fn find_naive_2(&self, mut pos: usize, hay: &Mmap) -> Option<usize> {
let max_pos = hay.len() - 2;
let b0 = self.bytes[0];
let b1 = self.bytes[1];
unsafe {
while pos <= max_pos {
if *hay.get_unchecked(pos) == b0 && *hay.get_unchecked(pos + 1) == b1 {
return Some(pos);
}
pos += 1;
}
}
None
}
fn find_naive_3(&self, mut pos: usize, hay: &Mmap) -> Option<usize> {
let max_pos = hay.len() - 3;
let b0 = self.bytes[0];
let b1 = self.bytes[1];
let b2 = self.bytes[2];
unsafe {
while pos <= max_pos {
if *hay.get_unchecked(pos) == b0
&& *hay.get_unchecked(pos + 1) == b1
&& *hay.get_unchecked(pos + 2) == b2
{
return Some(pos);
}
pos += 1;
}
}
None
}
fn find_naive_4(&self, mut pos: usize, hay: &Mmap) -> Option<usize> {
use std::mem::transmute;
let max_pos = hay.len() - 4;
unsafe {
let needle: u32 = transmute::<[u8; 4], u32>((&*self.bytes).try_into().unwrap());
while pos <= max_pos {
if transmute::<[u8; 4], u32>((&hay[pos..pos + 4]).try_into().unwrap()) == needle {
return Some(pos);
}
pos += 1;
}
}
None
}
fn find_naive_6(&self, mut pos: usize, hay: &Mmap) -> Option<usize> {
let max_pos = hay.len() - 6;
let b0 = self.bytes[0];
let b1 = self.bytes[1];
let b2 = self.bytes[2];
let b3 = self.bytes[3];
let b4 = self.bytes[4];
let b5 = self.bytes[5];
unsafe {
while pos <= max_pos {
if *hay.get_unchecked(pos) == b0
&& *hay.get_unchecked(pos + 1) == b1
&& *hay.get_unchecked(pos + 2) == b2
&& *hay.get_unchecked(pos + 3) == b3
&& *hay.get_unchecked(pos + 4) == b4
&& *hay.get_unchecked(pos + 5) == b5
{
return Some(pos);
}
pos += 1;
}
}
None
}
fn is_at_pos(&self, hay_stack: &Mmap, pos: usize) -> bool {
unsafe {
for (i, b) in self.bytes.iter().enumerate() {
if hay_stack.get_unchecked(i + pos) != b {
return false;
}
}
}
true
}
fn find_naive(&self, mut pos: usize, hay: &Mmap) -> Option<usize> {
let max_pos = hay.len() - self.bytes.len();
while pos <= max_pos {
if self.is_at_pos(&hay, pos) {
return Some(pos);
}
pos += 1;
}
None
}
fn search_mmap(&self, hay: &Mmap) -> ContentSearchResult {
if hay.len() < self.bytes.len() {
return ContentSearchResult::NotFound;
}
#[cfg(not(any(target_family = "windows", target_os = "android")))]
unsafe {
libc::posix_madvise(
hay.as_ptr() as *mut std::ffi::c_void,
hay.len(),
libc::POSIX_MADV_SEQUENTIAL,
);
}
let pos = match self.bytes.len() {
1 => self.find_naive_1(&hay),
2 => self.find_naive_2(0, &hay),
3 => self.find_naive_3(0, &hay),
4 => self.find_naive_4(0, &hay),
6 => self.find_naive_6(0, &hay),
_ => self.find_naive(0, &hay),
};
pos.map_or(
ContentSearchResult::NotFound,
|pos| ContentSearchResult::Found { pos },
)
}
pub fn search<P: AsRef<Path>>(&self, hay_path: P) -> io::Result<ContentSearchResult> {
super::get_mmap_if_not_binary(hay_path)
.map(|om| om.map_or(
ContentSearchResult::NotSuitable,
|hay| self.search_mmap(&hay),
))
}
pub fn get_match<P: AsRef<Path>>(
&self,
hay_path: P,
desired_len: usize,
) -> Option<ContentMatch> {
let hay = match get_mmap(hay_path) {
Ok(hay) => hay,
_ => { return None; }
};
match self.search_mmap(&hay) {
ContentSearchResult::Found { pos } => {
Some(ContentMatch::build(&hay, pos, self.as_str(), desired_len))
}
_ => None,
}
}
}
#[cfg(test)]
mod content_search_tests {
use super::*;
#[test]
fn test_found() -> Result<(), io::Error> {
let needle = Needle::new("inception");
let res = needle.search("src/content_search/needle.rs")?;
assert!(res.is_found());
Ok(())
}
}