ic_sqlite_vfs/stable/
raw_memory.rs

1//! Stable-memory backend used by the local MemoryManager fork.
2//!
3//! This module keeps only the byte-addressed memory trait and the native/IC
4//! implementations required by SQLite's virtual-memory adapter.
5
6use crate::config::STABLE_PAGE_SIZE;
7use std::cell::RefCell;
8use std::ops::Deref;
9use std::rc::Rc;
10
11pub trait Memory {
12    fn size(&self) -> u64;
13    fn grow(&self, pages: u64) -> i64;
14    fn read(&self, offset: u64, dst: &mut [u8]);
15    fn write(&self, offset: u64, src: &[u8]);
16
17    unsafe fn read_unsafe(&self, offset: u64, dst: *mut u8, count: usize) {
18        std::ptr::write_bytes(dst, 0, count);
19        let slice = std::slice::from_raw_parts_mut(dst, count);
20        self.read(offset, slice);
21    }
22}
23
24#[cfg(target_arch = "wasm32")]
25pub type DefaultMemoryImpl = Ic0StableMemory;
26
27#[cfg(not(target_arch = "wasm32"))]
28pub type DefaultMemoryImpl = VectorMemory;
29
30#[cfg(target_arch = "wasm32")]
31#[derive(Clone, Copy, Default)]
32pub struct Ic0StableMemory;
33
34#[cfg(target_arch = "wasm32")]
35#[link(wasm_import_module = "ic0")]
36extern "C" {
37    fn stable64_size() -> u64;
38    fn stable64_grow(additional_pages: u64) -> i64;
39    fn stable64_read(dst: u64, offset: u64, size: u64);
40    fn stable64_write(offset: u64, src: u64, size: u64);
41}
42
43#[cfg(target_arch = "wasm32")]
44impl Memory for Ic0StableMemory {
45    fn size(&self) -> u64 {
46        unsafe { stable64_size() }
47    }
48
49    fn grow(&self, pages: u64) -> i64 {
50        unsafe { stable64_grow(pages) }
51    }
52
53    fn read(&self, offset: u64, dst: &mut [u8]) {
54        unsafe { stable64_read(dst.as_mut_ptr() as u64, offset, dst.len() as u64) }
55    }
56
57    unsafe fn read_unsafe(&self, offset: u64, dst: *mut u8, count: usize) {
58        stable64_read(dst as u64, offset, count as u64);
59    }
60
61    fn write(&self, offset: u64, src: &[u8]) {
62        unsafe { stable64_write(offset, src.as_ptr() as u64, src.len() as u64) }
63    }
64}
65
66pub type VectorMemory = Rc<RefCell<Vec<u8>>>;
67
68impl Memory for RefCell<Vec<u8>> {
69    fn size(&self) -> u64 {
70        self.borrow().len() as u64 / STABLE_PAGE_SIZE
71    }
72
73    fn grow(&self, pages: u64) -> i64 {
74        let size = self.size();
75        let Some(next_size) = size.checked_add(pages) else {
76            return -1;
77        };
78        let Some(next_bytes) = next_size.checked_mul(STABLE_PAGE_SIZE) else {
79            return -1;
80        };
81        if next_bytes > usize::MAX as u64 {
82            return -1;
83        }
84        self.borrow_mut().resize(next_bytes as usize, 0);
85        size as i64
86    }
87
88    fn read(&self, offset: u64, dst: &mut [u8]) {
89        let end = checked_end(offset, dst.len(), "read");
90        dst.copy_from_slice(&self.borrow()[offset as usize..end as usize]);
91    }
92
93    unsafe fn read_unsafe(&self, offset: u64, dst: *mut u8, count: usize) {
94        let end = checked_end(offset, count, "read");
95        assert!(end as usize <= self.borrow().len(), "read: out of bounds");
96        std::ptr::copy(self.borrow().as_ptr().add(offset as usize), dst, count);
97    }
98
99    fn write(&self, offset: u64, src: &[u8]) {
100        let end = checked_end(offset, src.len(), "write");
101        self.borrow_mut()[offset as usize..end as usize].copy_from_slice(src);
102    }
103}
104
105impl<M: Memory> Memory for Rc<M> {
106    fn size(&self) -> u64 {
107        self.deref().size()
108    }
109
110    fn grow(&self, pages: u64) -> i64 {
111        self.deref().grow(pages)
112    }
113
114    fn read(&self, offset: u64, dst: &mut [u8]) {
115        self.deref().read(offset, dst);
116    }
117
118    unsafe fn read_unsafe(&self, offset: u64, dst: *mut u8, count: usize) {
119        self.deref().read_unsafe(offset, dst, count);
120    }
121
122    fn write(&self, offset: u64, src: &[u8]) {
123        self.deref().write(offset, src);
124    }
125}
126
127fn checked_end(offset: u64, len: usize, operation: &str) -> u64 {
128    let end = offset
129        .checked_add(len as u64)
130        .unwrap_or_else(|| panic!("{operation}: out of bounds"));
131    assert!(end <= usize::MAX as u64, "{operation}: out of bounds");
132    end
133}
ic_sqlite_vfs/stable/raw_memory.rs

ic_sqlite_vfs/stable/
raw_memory.rs
