inspect_format/container/
fuchsia.rs

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1// Copyright 2023 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use crate::{BlockContainer, CopyBytes, ReadBytes, WriteBytes};
6
7#[derive(Debug)]
8pub struct Container {
9    buffer_addr: usize,
10    vmo_size: usize,
11}
12
13impl Container {
14    pub fn read_and_write(size: usize) -> Result<(Self, zx::Vmo), zx::Status> {
15        let vmo = zx::Vmo::create(size as u64)?;
16        let flags = zx::VmarFlags::PERM_READ
17            | zx::VmarFlags::MAP_RANGE
18            | zx::VmarFlags::REQUIRE_NON_RESIZABLE
19            | zx::VmarFlags::PERM_WRITE;
20        let buffer_addr = Self::map_vmo(&vmo, size, flags)?;
21        Ok((Self { buffer_addr, vmo_size: size }, vmo))
22    }
23
24    pub fn read_only(vmo: &zx::Vmo) -> Result<Self, zx::Status> {
25        let vmo_size = vmo.get_size()? as usize;
26        let flags = zx::VmarFlags::PERM_READ | zx::VmarFlags::REQUIRE_NON_RESIZABLE;
27        let buffer_addr = Self::map_vmo(vmo, vmo_size, flags)?;
28        Ok(Self { buffer_addr, vmo_size })
29    }
30
31    fn map_vmo(vmo: &zx::Vmo, vmo_size: usize, flags: zx::VmarFlags) -> Result<usize, zx::Status> {
32        let buffer_addr = fuchsia_runtime::vmar_root_self().map(0, vmo, 0, vmo_size, flags)?;
33        Ok(buffer_addr)
34    }
35}
36
37impl Drop for Container {
38    fn drop(&mut self) {
39        // SAFETY: The memory behind this `Container` is only accessible via references which
40        // at this point must have been invalidated and it is safe to unmap the memory.
41        unsafe {
42            fuchsia_runtime::vmar_root_self()
43                .unmap(self.buffer_addr, self.vmo_size)
44                .expect("failed to unmap Container");
45        }
46    }
47}
48
49impl BlockContainer for Container {
50    type Data = zx::Vmo;
51    type ShareableData = zx::Vmo;
52
53    #[inline]
54    fn len(&self) -> usize {
55        self.vmo_size
56    }
57}
58
59impl ReadBytes for Container {
60    /// Returns a slice of the given size at the given offset if one exists of the exact size.
61    /// The offset is inclusive.
62    #[inline]
63    fn get_slice_at(&self, offset: usize, size: usize) -> Option<&[u8]> {
64        if offset >= self.len() {
65            return None;
66        }
67        let upper_bound = offset.checked_add(size)?;
68        if upper_bound > self.len() {
69            return None;
70        }
71        let ptr = (self.buffer_addr + offset) as *const u8;
72        // SAFETY: the checks above guarantee we have a slice of bytes with `size` elements. Since
73        // we have a shared reference to this container, we can get a shared reference to the
74        // underlying mapped memory, which lifetime is tied to our Container.
75        unsafe { Some(std::slice::from_raw_parts(ptr, size)) }
76    }
77}
78
79impl CopyBytes for Container {
80    #[inline]
81    fn copy_bytes_at(&self, offset: usize, dst: &mut [u8]) {
82        if let Some(slice) = self.get_slice_at(offset, dst.len()) {
83            dst.copy_from_slice(slice);
84        }
85    }
86}
87
88impl WriteBytes for Container {
89    /// Returns a slice of the given size at the given offset if one exists of the exact size.
90    /// The offset is inclusive.
91    #[inline]
92    fn get_slice_mut_at(&mut self, offset: usize, size: usize) -> Option<&mut [u8]> {
93        if offset >= self.len() {
94            return None;
95        }
96        let upper_bound = offset.checked_add(size)?;
97        if upper_bound > self.len() {
98            return None;
99        }
100        let ptr = (self.buffer_addr + offset) as *mut u8;
101        // SAFETY: the checks above guarantee we have a slice of bytes with `size` elements. Since
102        // we have a exclusive reference to this container, we can get a exclusive reference to the
103        // underlying mapped memory, which lifetime is tied to our Container.
104        unsafe { Some(std::slice::from_raw_parts_mut(ptr, size)) }
105    }
106}
107
108impl BlockContainer for zx::Vmo {
109    type Data = Self;
110    type ShareableData = Self;
111
112    #[inline]
113    fn len(&self) -> usize {
114        self.get_size().ok().unwrap() as usize
115    }
116}
117
118impl CopyBytes for zx::Vmo {
119    #[inline]
120    fn copy_bytes_at(&self, offset: usize, dst: &mut [u8]) {
121        self.read(dst, offset as u64).ok();
122    }
123}
inspect_format/container/fuchsia.rs

inspect_format/container/
fuchsia.rs
