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
|
// SPDX-License-Identifier: GPL-2.0
//! Extensions to [`Vec`] for fallible allocations.
use super::{AllocError, Flags};
use alloc::vec::Vec;
/// Extensions to [`Vec`].
pub trait VecExt<T>: Sized {
/// Creates a new [`Vec`] instance with at least the given capacity.
///
/// # Examples
///
/// ```
/// let v = Vec::<u32>::with_capacity(20, GFP_KERNEL)?;
///
/// assert!(v.capacity() >= 20);
/// # Ok::<(), Error>(())
/// ```
fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError>;
/// Appends an element to the back of the [`Vec`] instance.
///
/// # Examples
///
/// ```
/// let mut v = Vec::new();
/// v.push(1, GFP_KERNEL)?;
/// assert_eq!(&v, &[1]);
///
/// v.push(2, GFP_KERNEL)?;
/// assert_eq!(&v, &[1, 2]);
/// # Ok::<(), Error>(())
/// ```
fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError>;
/// Pushes clones of the elements of slice into the [`Vec`] instance.
///
/// # Examples
///
/// ```
/// let mut v = Vec::new();
/// v.push(1, GFP_KERNEL)?;
///
/// v.extend_from_slice(&[20, 30, 40], GFP_KERNEL)?;
/// assert_eq!(&v, &[1, 20, 30, 40]);
///
/// v.extend_from_slice(&[50, 60], GFP_KERNEL)?;
/// assert_eq!(&v, &[1, 20, 30, 40, 50, 60]);
/// # Ok::<(), Error>(())
/// ```
fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>
where
T: Clone;
/// Ensures that the capacity exceeds the length by at least `additional` elements.
///
/// # Examples
///
/// ```
/// let mut v = Vec::new();
/// v.push(1, GFP_KERNEL)?;
///
/// v.reserve(10, GFP_KERNEL)?;
/// let cap = v.capacity();
/// assert!(cap >= 10);
///
/// v.reserve(10, GFP_KERNEL)?;
/// let new_cap = v.capacity();
/// assert_eq!(new_cap, cap);
///
/// # Ok::<(), Error>(())
/// ```
fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError>;
}
impl<T> VecExt<T> for Vec<T> {
fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError> {
let mut v = Vec::new();
<Self as VecExt<_>>::reserve(&mut v, capacity, flags)?;
Ok(v)
}
fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> {
<Self as VecExt<_>>::reserve(self, 1, flags)?;
let s = self.spare_capacity_mut();
s[0].write(v);
// SAFETY: We just initialised the first spare entry, so it is safe to increase the length
// by 1. We also know that the new length is <= capacity because of the previous call to
// `reserve` above.
unsafe { self.set_len(self.len() + 1) };
Ok(())
}
fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>
where
T: Clone,
{
<Self as VecExt<_>>::reserve(self, other.len(), flags)?;
for (slot, item) in core::iter::zip(self.spare_capacity_mut(), other) {
slot.write(item.clone());
}
// SAFETY: We just initialised the `other.len()` spare entries, so it is safe to increase
// the length by the same amount. We also know that the new length is <= capacity because
// of the previous call to `reserve` above.
unsafe { self.set_len(self.len() + other.len()) };
Ok(())
}
#[cfg(any(test, testlib))]
fn reserve(&mut self, additional: usize, _flags: Flags) -> Result<(), AllocError> {
Vec::reserve(self, additional);
Ok(())
}
#[cfg(not(any(test, testlib)))]
fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError> {
let len = self.len();
let cap = self.capacity();
if cap - len >= additional {
return Ok(());
}
if core::mem::size_of::<T>() == 0 {
// The capacity is already `usize::MAX` for SZTs, we can't go higher.
return Err(AllocError);
}
// We know cap is <= `isize::MAX` because `Layout::array` fails if the resulting byte size
// is greater than `isize::MAX`. So the multiplication by two won't overflow.
let new_cap = core::cmp::max(cap * 2, len.checked_add(additional).ok_or(AllocError)?);
let layout = core::alloc::Layout::array::<T>(new_cap).map_err(|_| AllocError)?;
let (ptr, len, cap) = destructure(self);
// SAFETY: `ptr` is valid because it's either NULL or comes from a previous call to
// `krealloc_aligned`. We also verified that the type is not a ZST.
let new_ptr = unsafe { super::allocator::krealloc_aligned(ptr.cast(), layout, flags) };
if new_ptr.is_null() {
// SAFETY: We are just rebuilding the existing `Vec` with no changes.
unsafe { rebuild(self, ptr, len, cap) };
Err(AllocError)
} else {
// SAFETY: `ptr` has been reallocated with the layout for `new_cap` elements. New cap
// is greater than `cap`, so it continues to be >= `len`.
unsafe { rebuild(self, new_ptr.cast::<T>(), len, new_cap) };
Ok(())
}
}
}
#[cfg(not(any(test, testlib)))]
fn destructure<T>(v: &mut Vec<T>) -> (*mut T, usize, usize) {
let mut tmp = Vec::new();
core::mem::swap(&mut tmp, v);
let mut tmp = core::mem::ManuallyDrop::new(tmp);
let len = tmp.len();
let cap = tmp.capacity();
(tmp.as_mut_ptr(), len, cap)
}
/// Rebuilds a `Vec` from a pointer, length, and capacity.
///
/// # Safety
///
/// The same as [`Vec::from_raw_parts`].
#[cfg(not(any(test, testlib)))]
unsafe fn rebuild<T>(v: &mut Vec<T>, ptr: *mut T, len: usize, cap: usize) {
// SAFETY: The safety requirements from this function satisfy those of `from_raw_parts`.
let mut tmp = unsafe { Vec::from_raw_parts(ptr, len, cap) };
core::mem::swap(&mut tmp, v);
}
|
