xdpsock 0.1.0

Rust bindings for Linux AF_XDP sockets
Documentation 
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

use libc::{MAP_ANONYMOUS, MAP_FAILED, MAP_HUGETLB, MAP_PRIVATE, PROT_READ, PROT_WRITE};
use std::{convert::TryInto, io, ptr, slice};

#[derive(Debug, PartialEq)]
pub struct MmapArea {
    len: usize,
    mem_ptr: *mut libc::c_void,
}

unsafe impl Send for MmapArea {}
unsafe impl Sync for MmapArea {}

impl MmapArea {
    pub fn new(len: usize, use_huge_pages: bool) -> io::Result<Self> {
        let addr = ptr::null_mut();
        let prot = PROT_READ | PROT_WRITE;
        let file = -1;
        let offset = 0;

        let mut flags = MAP_ANONYMOUS | MAP_PRIVATE;

        if use_huge_pages {
            flags |= MAP_HUGETLB;
        }

        let mem_ptr = unsafe { libc::mmap(addr, len, prot, flags, file, offset as libc::off_t) };

        if mem_ptr == MAP_FAILED {
            Err(io::Error::last_os_error())
        } else {
            Ok(MmapArea { len, mem_ptr })
        }
    }

    pub(in crate::umem) fn as_mut_ptr(&mut self) -> *mut libc::c_void {
        self.mem_ptr
    }

    /// Return a reference to memory at `offset` of length `len`. Does
    /// not perform a bounds check.
    ///
    /// Marked `unsafe` as there is no guarantee that the kernel isn't
    /// currently writing to or reading from the region (since it's
    /// backing the UMEM).
    #[inline]
    pub unsafe fn mem_range(&self, offset: usize, len: usize) -> &[u8] {
        let ptr = self.mem_ptr.offset(offset.try_into().unwrap());

        slice::from_raw_parts(ptr as *const u8, len)
    }

    /// Return a mutable reference to memory at `offset` of length
    /// `len`. Does not perform a bounds check.
    ///
    /// Marked `unsafe` as there is no guarantee that the kernel isn't
    /// currently writing to or reading from the region (since it's
    /// backing the UMEM).
    #[inline]
    pub unsafe fn mem_range_mut(&self, offset: &usize, len: &usize) -> &mut [u8] {
        let ptr = self.mem_ptr.offset((*offset).try_into().unwrap());

        slice::from_raw_parts_mut(ptr as *mut u8, *len)
    }

    pub unsafe fn owned_mem_range(&mut self, offset: &usize, len: &usize) -> Vec<u8> {
        let ptr = self.mem_ptr.offset((*offset).try_into().unwrap());

        Vec::from_raw_parts(ptr as *mut u8, *len, *len)
    }

    #[inline]
    pub fn len(&self) -> usize {
        self.len
    }

    fn mmap_from_raw_parts(ptr: *mut libc::c_void, len: usize) -> Self {
        Self {
            len: len,
            mem_ptr: ptr,
        }
    }

    pub(in crate::umem) fn split(self, offset: usize) -> (Self, Self) {
        if offset > self.len() {
            panic!("split mmap, offset > self.len()");
        }

        let len1 = self.len;
        let len2 = self.len;

        let ptr1 = self.mem_ptr;
        let ptr2 = self.mem_ptr;

        let mmap1 = Self::mmap_from_raw_parts(ptr1, len1);
        let mmap2 = Self::mmap_from_raw_parts(ptr2, len2);

        std::mem::forget(self);
        (mmap1, mmap2)
    }
}

impl Drop for MmapArea {
    fn drop(&mut self) {
        /*
        eprintln!("dropping mmap");
        let err = unsafe { libc::munmap(self.mem_ptr, self.len) };

        if err != 0 {
            error!("munmap() failed: {}", err);
        }
        */
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn confirm_pointer_offset_is_a_single_byte() {
        assert_eq!(std::mem::size_of::<libc::c_void>(), 1);
    }
}