core\io\io_slice/
repr_windows.rs

1use crate::marker::PhantomData;
2use crate::slice;
3
4#[repr(C)]
5#[derive(Clone, Copy)]
6struct WSABUF {
7    len: u32,
8    buf: *mut u8,
9}
10
11#[derive(Copy, Clone)]
12#[repr(transparent)]
13pub(crate) struct IoSlice<'a> {
14    vec: WSABUF,
15    _p: PhantomData<&'a [u8]>,
16}
17
18impl<'a> IoSlice<'a> {
19    #[inline]
20    pub(crate) fn new(buf: &'a [u8]) -> IoSlice<'a> {
21        assert!(buf.len() <= u32::MAX as usize);
22        IoSlice {
23            vec: WSABUF { len: buf.len() as u32, buf: buf.as_ptr() as *mut u8 },
24            _p: PhantomData,
25        }
26    }
27
28    #[inline]
29    pub(crate) fn advance(&mut self, n: usize) {
30        if (self.vec.len as usize) < n {
31            panic!("advancing IoSlice beyond its length");
32        }
33
34        // SAFETY:
35        //  * `n <= len` as asserted above.
36        //  * The allocation pointed to by `buf` is valid up to `buf + len`.
37        unsafe {
38            self.vec.len -= n as u32;
39            self.vec.buf = self.vec.buf.add(n);
40        }
41    }
42
43    #[inline]
44    pub(crate) const fn as_slice(&self) -> &'a [u8] {
45        // SAFETY:
46        //  * `buf` and `len` come from a prior decomposition of a valid slice.
47        unsafe { slice::from_raw_parts(self.vec.buf, self.vec.len as usize) }
48    }
49}
50
51#[repr(transparent)]
52pub(crate) struct IoSliceMut<'a> {
53    vec: WSABUF,
54    _p: PhantomData<&'a mut [u8]>,
55}
56
57impl<'a> IoSliceMut<'a> {
58    #[inline]
59    pub(crate) fn new(buf: &'a mut [u8]) -> IoSliceMut<'a> {
60        assert!(buf.len() <= u32::MAX as usize);
61        IoSliceMut { vec: WSABUF { len: buf.len() as u32, buf: buf.as_mut_ptr() }, _p: PhantomData }
62    }
63
64    #[inline]
65    pub(crate) fn advance(&mut self, n: usize) {
66        if (self.vec.len as usize) < n {
67            panic!("advancing IoSliceMut beyond its length");
68        }
69
70        // SAFETY:
71        //  * `n <= len` as asserted above.
72        //  * The allocation pointed to by `buf` is valid up to `buf + len`.
73        unsafe {
74            self.vec.len -= n as u32;
75            self.vec.buf = self.vec.buf.add(n);
76        }
77    }
78
79    #[inline]
80    pub(crate) fn as_slice(&self) -> &[u8] {
81        // SAFETY:
82        //  * `buf` and `len` come from a prior decomposition of a valid slice.
83        unsafe { slice::from_raw_parts(self.vec.buf, self.vec.len as usize) }
84    }
85
86    #[inline]
87    pub(crate) const fn into_slice(self) -> &'a mut [u8] {
88        // SAFETY:
89        //  * `buf` and `len` come from a prior decomposition of a valid slice.
90        unsafe { slice::from_raw_parts_mut(self.vec.buf, self.vec.len as usize) }
91    }
92
93    #[inline]
94    pub(crate) fn as_mut_slice(&mut self) -> &mut [u8] {
95        // SAFETY:
96        //  * `buf` and `len` come from a prior decomposition of a valid slice.
97        unsafe { slice::from_raw_parts_mut(self.vec.buf, self.vec.len as usize) }
98    }
99}
core\io\io_slice/repr_windows.rs

core\io\io_slice/
repr_windows.rs
