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
|
// Copyright 2017 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//! Helper for creating valid kernel command line strings.
use std::fmt::{self, Display};
use std::result;
/// The error type for command line building operations.
#[derive(PartialEq, Debug)]
pub enum Error {
/// Operation would have resulted in a non-printable ASCII character.
InvalidAscii,
/// Key/Value Operation would have had a space in it.
HasSpace,
/// Key/Value Operation would have had an equals sign in it.
HasEquals,
/// Operation would have made the command line too large.
TooLarge,
}
impl Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::Error::*;
let description = match self {
InvalidAscii => "string contains non-printable ASCII character",
HasSpace => "string contains a space",
HasEquals => "string contains an equals sign",
TooLarge => "inserting string would make command line too long",
};
write!(f, "{}", description)
}
}
/// Specialized Result type for command line operations.
pub type Result<T> = result::Result<T, Error>;
fn valid_char(c: char) -> bool {
matches!(c, ' '..='~')
}
fn valid_str(s: &str) -> Result<()> {
if s.chars().all(valid_char) {
Ok(())
} else {
Err(Error::InvalidAscii)
}
}
fn valid_element(s: &str) -> Result<()> {
if !s.chars().all(valid_char) {
Err(Error::InvalidAscii)
} else if s.contains(' ') {
Err(Error::HasSpace)
} else if s.contains('=') {
Err(Error::HasEquals)
} else {
Ok(())
}
}
/// A builder for a kernel command line string that validates the string as its being built. A
/// `CString` can be constructed from this directly using `CString::new`.
pub struct Cmdline {
line: String,
capacity: usize,
}
impl Cmdline {
/// Constructs an empty Cmdline with the given capacity, which includes the nul terminator.
/// Capacity must be greater than 0.
pub fn new(capacity: usize) -> Cmdline {
assert_ne!(capacity, 0);
Cmdline {
line: String::new(),
capacity,
}
}
fn has_capacity(&self, more: usize) -> Result<()> {
let needs_space = if self.line.is_empty() { 0 } else { 1 };
if self.line.len() + more + needs_space < self.capacity {
Ok(())
} else {
Err(Error::TooLarge)
}
}
fn start_push(&mut self) {
if !self.line.is_empty() {
self.line.push(' ');
}
}
fn end_push(&mut self) {
// This assert is always true because of the `has_capacity` check that each insert method
// uses.
assert!(self.line.len() < self.capacity);
}
/// Validates and inserts a key value pair into this command line
pub fn insert<T: AsRef<str>>(&mut self, key: T, val: T) -> Result<()> {
let k = key.as_ref();
let v = val.as_ref();
valid_element(k)?;
valid_element(v)?;
self.has_capacity(k.len() + v.len() + 1)?;
self.start_push();
self.line.push_str(k);
self.line.push('=');
self.line.push_str(v);
self.end_push();
Ok(())
}
/// Validates and inserts a string to the end of the current command line
pub fn insert_str<T: AsRef<str>>(&mut self, slug: T) -> Result<()> {
let s = slug.as_ref();
valid_str(s)?;
self.has_capacity(s.len())?;
self.start_push();
self.line.push_str(s);
self.end_push();
Ok(())
}
/// Returns the cmdline in progress without nul termination
pub fn as_str(&self) -> &str {
self.line.as_str()
}
}
impl Into<Vec<u8>> for Cmdline {
fn into(self) -> Vec<u8> {
self.line.into_bytes()
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::ffi::CString;
#[test]
fn insert_hello_world() {
let mut cl = Cmdline::new(100);
assert_eq!(cl.as_str(), "");
assert!(cl.insert("hello", "world").is_ok());
assert_eq!(cl.as_str(), "hello=world");
let s = CString::new(cl).expect("failed to create CString from Cmdline");
assert_eq!(s, CString::new("hello=world").unwrap());
}
#[test]
fn insert_multi() {
let mut cl = Cmdline::new(100);
assert!(cl.insert("hello", "world").is_ok());
assert!(cl.insert("foo", "bar").is_ok());
assert_eq!(cl.as_str(), "hello=world foo=bar");
}
#[test]
fn insert_space() {
let mut cl = Cmdline::new(100);
assert_eq!(cl.insert("a ", "b"), Err(Error::HasSpace));
assert_eq!(cl.insert("a", "b "), Err(Error::HasSpace));
assert_eq!(cl.insert("a ", "b "), Err(Error::HasSpace));
assert_eq!(cl.insert(" a", "b"), Err(Error::HasSpace));
assert_eq!(cl.as_str(), "");
}
#[test]
fn insert_equals() {
let mut cl = Cmdline::new(100);
assert_eq!(cl.insert("a=", "b"), Err(Error::HasEquals));
assert_eq!(cl.insert("a", "b="), Err(Error::HasEquals));
assert_eq!(cl.insert("a=", "b "), Err(Error::HasEquals));
assert_eq!(cl.insert("=a", "b"), Err(Error::HasEquals));
assert_eq!(cl.insert("a", "=b"), Err(Error::HasEquals));
assert_eq!(cl.as_str(), "");
}
#[test]
fn insert_emoji() {
let mut cl = Cmdline::new(100);
assert_eq!(cl.insert("heart", "💖"), Err(Error::InvalidAscii));
assert_eq!(cl.insert("💖", "love"), Err(Error::InvalidAscii));
assert_eq!(cl.as_str(), "");
}
#[test]
fn insert_string() {
let mut cl = Cmdline::new(13);
assert_eq!(cl.as_str(), "");
assert!(cl.insert_str("noapic").is_ok());
assert_eq!(cl.as_str(), "noapic");
assert!(cl.insert_str("nopci").is_ok());
assert_eq!(cl.as_str(), "noapic nopci");
}
#[test]
fn insert_too_large() {
let mut cl = Cmdline::new(4);
assert_eq!(cl.insert("hello", "world"), Err(Error::TooLarge));
assert_eq!(cl.insert("a", "world"), Err(Error::TooLarge));
assert_eq!(cl.insert("hello", "b"), Err(Error::TooLarge));
assert!(cl.insert("a", "b").is_ok());
assert_eq!(cl.insert("a", "b"), Err(Error::TooLarge));
assert_eq!(cl.insert_str("a"), Err(Error::TooLarge));
assert_eq!(cl.as_str(), "a=b");
let mut cl = Cmdline::new(10);
assert!(cl.insert("ab", "ba").is_ok()); // adds 5 length
assert_eq!(cl.insert("c", "da"), Err(Error::TooLarge)); // adds 5 (including space) length
assert!(cl.insert("c", "d").is_ok()); // adds 4 (including space) length
}
}
|