use std::u32;
use std::ops::Range;
use std::cmp;
use std::fmt;
use std::rc::Rc;
use std::cell::RefCell;
use susy_wasm::elements::ResizableLimits;
use Error;
use memory_units::{RoundUpTo, Pages, Bytes};
pub const LINEAR_MEMORY_PAGE_SIZE: Bytes = Bytes(65536);
const LINEAR_MEMORY_MAX_PAGES: Pages = Pages(65536);
#[derive(Clone, Debug)]
pub struct MemoryRef(Rc<MemoryInstance>);
impl ::std::ops::Deref for MemoryRef {
type Target = MemoryInstance;
fn deref(&self) -> &MemoryInstance {
&self.0
}
}
pub struct MemoryInstance {
limits: ResizableLimits,
buffer: RefCell<Vec<u8>>,
initial: Pages,
maximum: Option<Pages>,
}
impl fmt::Debug for MemoryInstance {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("MemoryInstance")
.field("limits", &self.limits)
.field("buffer.len", &self.buffer.borrow().len())
.field("maximum", &self.maximum)
.field("initial", &self.initial)
.finish()
}
}
struct CheckedRegion<'a, B: 'a> where B: ::std::ops::Deref<Target=Vec<u8>> {
buffer: &'a B,
offset: usize,
size: usize,
}
impl<'a, B: 'a> CheckedRegion<'a, B> where B: ::std::ops::Deref<Target=Vec<u8>> {
fn range(&self) -> Range<usize> {
self.offset..self.offset+self.size
}
fn slice(&self) -> &[u8] {
&self.buffer[self.range()]
}
fn intersects(&self, other: &Self) -> bool {
let low = cmp::max(self.offset, other.offset);
let high = cmp::min(self.offset + self.size, other.offset + other.size);
low < high
}
}
impl MemoryInstance {
pub fn alloc(initial: Pages, maximum: Option<Pages>) -> Result<MemoryRef, Error> {
validate_memory(initial, maximum).map_err(Error::Memory)?;
let memory = MemoryInstance::new(initial, maximum);
Ok(MemoryRef(Rc::new(memory)))
}
fn new(initial: Pages, maximum: Option<Pages>) -> Self {
let limits = ResizableLimits::new(initial.0 as u32, maximum.map(|p| p.0 as u32));
let initial_size: Bytes = initial.into();
MemoryInstance {
limits: limits,
buffer: RefCell::new(vec![0; initial_size.0]),
initial: initial,
maximum: maximum,
}
}
pub(crate) fn limits(&self) -> &ResizableLimits {
&self.limits
}
pub fn initial(&self) -> Pages {
self.initial
}
pub fn maximum(&self) -> Option<Pages> {
self.maximum
}
pub fn current_size(&self) -> Pages {
Bytes(self.buffer.borrow().len()).round_up_to()
}
pub fn get(&self, offset: u32, size: usize) -> Result<Vec<u8>, Error> {
let buffer = self.buffer.borrow();
let region = self.checked_region(&buffer, offset as usize, size)?;
Ok(region.slice().to_vec())
}
pub fn get_into(&self, offset: u32, target: &mut [u8]) -> Result<(), Error> {
let buffer = self.buffer.borrow();
let region = self.checked_region(&buffer, offset as usize, target.len())?;
target.copy_from_slice(region.slice());
Ok(())
}
pub fn set(&self, offset: u32, value: &[u8]) -> Result<(), Error> {
let mut buffer = self.buffer.borrow_mut();
let range = self.checked_region(&buffer, offset as usize, value.len())?.range();
buffer[range].copy_from_slice(value);
Ok(())
}
pub fn grow(&self, additional: Pages) -> Result<Pages, Error> {
let size_before_grow: Pages = self.current_size();
if additional == Pages(0) {
return Ok(size_before_grow);
}
if additional > Pages(65536) {
return Err(Error::Memory(format!(
"Trying to grow memory by more than 65536 pages"
)));
}
let new_size: Pages = size_before_grow + additional;
let maximum = self.maximum.unwrap_or(LINEAR_MEMORY_MAX_PAGES);
if new_size > maximum {
return Err(Error::Memory(format!(
"Trying to grow memory by {} pages when already have {}",
additional.0, size_before_grow.0,
)));
}
let new_buffer_length: Bytes = new_size.into();
{
let mut buffer = self.buffer.borrow_mut();
debug_assert!(new_buffer_length.0 > buffer.len());
buffer.resize(new_buffer_length.0, 0);
}
Ok(size_before_grow)
}
fn checked_region<'a, B>(&self, buffer: &'a B, offset: usize, size: usize) -> Result<CheckedRegion<'a, B>, Error>
where B: ::std::ops::Deref<Target=Vec<u8>>
{
let end = offset.checked_add(size)
.ok_or_else(|| Error::Memory(format!("trying to access memory block of size {} from offset {}", size, offset)))?;
if end > buffer.len() {
return Err(Error::Memory(format!("trying to access region [{}..{}] in memory [0..{}]", offset, end, buffer.len())));
}
Ok(CheckedRegion {
buffer: buffer,
offset: offset,
size: size,
})
}
pub fn copy(&self, src_offset: usize, dst_offset: usize, len: usize) -> Result<(), Error> {
let buffer = self.buffer.borrow_mut();
let read_region = self.checked_region(&buffer, src_offset, len)?;
let write_region = self.checked_region(&buffer, dst_offset, len)?;
unsafe { ::std::ptr::copy(
buffer[read_region.range()].as_ptr(),
buffer[write_region.range()].as_ptr() as *mut _,
len,
)}
Ok(())
}
pub fn copy_nonoverlapping(&self, src_offset: usize, dst_offset: usize, len: usize) -> Result<(), Error> {
let buffer = self.buffer.borrow_mut();
let read_region = self.checked_region(&buffer, src_offset, len)?;
let write_region = self.checked_region(&buffer, dst_offset, len)?;
if read_region.intersects(&write_region) {
return Err(Error::Memory(format!("non-overlapping copy is used for overlapping regions")))
}
unsafe { ::std::ptr::copy_nonoverlapping(
buffer[read_region.range()].as_ptr(),
buffer[write_region.range()].as_ptr() as *mut _,
len,
)}
Ok(())
}
pub fn clear(&self, offset: usize, new_val: u8, len: usize) -> Result<(), Error> {
let mut buffer = self.buffer.borrow_mut();
let range = self.checked_region(&buffer, offset, len)?.range();
for val in &mut buffer[range] { *val = new_val }
Ok(())
}
pub fn zero(&self, offset: usize, len: usize) -> Result<(), Error> {
self.clear(offset, 0, len)
}
pub fn with_direct_access<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
let buf = self.buffer.borrow();
f(&*buf)
}
pub fn with_direct_access_mut<R, F: FnOnce(&mut [u8]) -> R>(&self, f: F) -> R {
let mut buf = self.buffer.borrow_mut();
f(&mut *buf)
}
}
pub fn validate_memory(initial: Pages, maximum: Option<Pages>) -> Result<(), String> {
if initial > LINEAR_MEMORY_MAX_PAGES {
return Err(format!("initial memory size must be at most {} pages", LINEAR_MEMORY_MAX_PAGES.0));
}
if let Some(maximum) = maximum {
if initial > maximum {
return Err(format!(
"maximum limit {} is less than minimum {}",
maximum.0,
initial.0,
));
}
if maximum > LINEAR_MEMORY_MAX_PAGES {
return Err(format!("maximum memory size must be at most {} pages", LINEAR_MEMORY_MAX_PAGES.0));
}
}
Ok(())
}
#[cfg(test)]
mod tests {
use super::{MemoryInstance, LINEAR_MEMORY_PAGE_SIZE};
use Error;
use memory_units::Pages;
#[test]
fn alloc() {
#[cfg(target_pointer_width = "64")]
let fixtures = &[
(0, None, true),
(0, Some(0), true),
(1, None, true),
(1, Some(1), true),
(0, Some(1), true),
(1, Some(0), false),
(0, Some(65536), true),
(65536, Some(65536), true),
(65536, Some(0), false),
(65536, None, true),
];
#[cfg(target_pointer_width = "32")]
let fixtures = &[
(0, None, true),
(0, Some(0), true),
(1, None, true),
(1, Some(1), true),
(0, Some(1), true),
(1, Some(0), false),
];
for (index, &(initial, maybe_max, expected_ok)) in fixtures.iter().enumerate() {
let initial: Pages = Pages(initial);
let maximum: Option<Pages> = maybe_max.map(|m| Pages(m));
let result = MemoryInstance::alloc(initial, maximum);
if result.is_ok() != expected_ok {
panic!(
"unexpected error at {}, initial={:?}, max={:?}, expected={}, result={:?}",
index,
initial,
maybe_max,
expected_ok,
result,
);
}
}
}
#[test]
fn ensure_page_size() {
use memory_units::ByteSize;
assert_eq!(LINEAR_MEMORY_PAGE_SIZE, Pages::byte_size());
}
fn create_memory(initial_content: &[u8]) -> MemoryInstance {
let mem = MemoryInstance::new(Pages(1), Some(Pages(1)));
mem.set(0, initial_content).expect("Successful initialize the memory");
mem
}
#[test]
fn copy_overlaps_1() {
let mem = create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
mem.copy(0, 4, 6).expect("Successfully copy the elements");
let result = mem.get(0, 10).expect("Successfully retrieve the result");
assert_eq!(result, &[0, 1, 2, 3, 0, 1, 2, 3, 4, 5]);
}
#[test]
fn copy_overlaps_2() {
let mem = create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
mem.copy(4, 0, 6).expect("Successfully copy the elements");
let result = mem.get(0, 10).expect("Successfully retrieve the result");
assert_eq!(result, &[4, 5, 6, 7, 8, 9, 6, 7, 8, 9]);
}
#[test]
fn copy_nonoverlapping() {
let mem = create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
mem.copy_nonoverlapping(0, 10, 10).expect("Successfully copy the elements");
let result = mem.get(10, 10).expect("Successfully retrieve the result");
assert_eq!(result, &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
}
#[test]
fn copy_nonoverlapping_overlaps_1() {
let mem = create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
let result = mem.copy_nonoverlapping(0, 4, 6);
match result {
Err(Error::Memory(_)) => {},
_ => panic!("Expected Error::Memory(_) result, but got {:?}", result),
}
}
#[test]
fn copy_nonoverlapping_overlaps_2() {
let mem = create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
let result = mem.copy_nonoverlapping(4, 0, 6);
match result {
Err(Error::Memory(_)) => {},
_ => panic!("Expected Error::Memory(_), but got {:?}", result),
}
}
#[test]
fn clear() {
let mem = create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
mem.clear(0, 0x4A, 10).expect("To successfully clear the memory");
let result = mem.get(0, 10).expect("To successfully retrieve the result");
assert_eq!(result, &[0x4A; 10]);
}
#[test]
fn get_into() {
let mem = MemoryInstance::new(Pages(1), None);
mem.set(6, &[13, 17, 129]).expect("memory set should not fail");
let mut data = [0u8; 2];
mem.get_into(7, &mut data[..]).expect("get_into should not fail");
assert_eq!(data, [17, 129]);
}
#[test]
fn zero_copy() {
let mem = MemoryInstance::alloc(Pages(1), None).unwrap();
mem.with_direct_access_mut(|buf| {
assert_eq!(buf.len(), 65536);
buf[..10].copy_from_slice(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
});
mem.with_direct_access(|buf| {
assert_eq!(buf.len(), 65536);
assert_eq!(&buf[..10], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
});
}
#[should_panic]
#[test]
fn zero_copy_panics_on_nested_access() {
let mem = MemoryInstance::alloc(Pages(1), None).unwrap();
let mem_inner = mem.clone();
mem.with_direct_access(move |_| {
let _ = mem_inner.set(0, &[11, 12, 13]);
});
}
}