#[allow(unused_imports)] use alloc::prelude::v1::*; use core::{ cmp, fmt, ops::Range, u32, }; use memory_units::{Bytes, Pages, RoundUpTo}; use parity_wasm::elements::ResizableLimits; use value::LittleEndianConvert; use Error; /// Size of a page of [linear memory][`MemoryInstance`] - 64KiB. /// /// The size of a memory is always a integer multiple of a page size. /// /// [`MemoryInstance`]: struct.MemoryInstance.html pub const LINEAR_MEMORY_PAGE_SIZE: Bytes = Bytes(65536); /// Reference to a memory (See [`MemoryInstance`] for details). /// /// This reference has a reference-counting semantics. /// /// [`MemoryInstance`]: struct.MemoryInstance.html /// #[derive(Clone, Debug)] pub struct MemoryRef(::MyRc); impl ::core::ops::Deref for MemoryRef { type Target = MemoryInstance; fn deref(&self) -> &MemoryInstance { &self.0 } } /// Runtime representation of a linear memory (or `memory` for short). /// /// A memory is a contiguous, mutable array of raw bytes. Wasm code can load and store values /// from/to a linear memory at any byte address. /// A trap occurs if an access is not within the bounds of the current memory size. /// /// A memory is created with an initial size but can be grown dynamically. /// The growth can be limited by specifying maximum size. /// The size of a memory is always a integer multiple of a [page size][`LINEAR_MEMORY_PAGE_SIZE`] - 64KiB. /// /// At the moment, wasm doesn't provide any way to shrink the memory. /// /// [`LINEAR_MEMORY_PAGE_SIZE`]: constant.LINEAR_MEMORY_PAGE_SIZE.html pub struct MemoryInstance { /// Memory limits. limits: ResizableLimits, /// Linear memory buffer with lazy allocation. buffer: ::MyRefCell>, initial: Pages, current_size: ::MyCell, maximum: Option, lowest_used: ::MyCell, } 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 { offset: usize, size: usize, } impl CheckedRegion { fn range(&self) -> Range { self.offset..self.offset + self.size } 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 { /// Allocate a memory instance. /// /// The memory allocated with initial number of pages specified by `initial`. /// Minimal possible value for `initial` is 0 and maximum possible is `65536`. /// (Since maximum addressible memory is 232 = 4GiB = 65536 * [64KiB][`LINEAR_MEMORY_PAGE_SIZE`]). /// /// It is possible to limit maximum number of pages this memory instance can have by specifying /// `maximum`. If not specified, this memory instance would be able to allocate up to 4GiB. /// /// Allocated memory is always zeroed. /// /// # Errors /// /// Returns `Err` if: /// /// - `initial` is greater than `maximum` /// - either `initial` or `maximum` is greater than `65536`. /// /// [`LINEAR_MEMORY_PAGE_SIZE`]: constant.LINEAR_MEMORY_PAGE_SIZE.html pub fn alloc(initial: Pages, maximum: Option) -> Result { { use core::convert::TryInto; let initial_u32: u32 = initial.0.try_into().map_err(|_| { Error::Memory(format!("initial ({}) can't be coerced to u32", initial.0)) })?; let maximum_u32: Option = match maximum { Some(maximum_pages) => Some(maximum_pages.0.try_into().map_err(|_| { Error::Memory(format!( "maximum ({}) can't be coerced to u32", maximum_pages.0 )) })?), None => None, }; validation::validate_memory(initial_u32, maximum_u32).map_err(Error::Memory)?; } let memory = MemoryInstance::new(initial, maximum); Ok(MemoryRef(::MyRc::new(memory))) } /// Create new linear memory instance. fn new(initial: Pages, maximum: Option) -> 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: ::MyRefCell::new(Vec::with_capacity(4096)), initial: initial, current_size: ::MyCell::new(initial_size.0), maximum: maximum, lowest_used: ::MyCell::new(u32::max_value()), } } /// Return linear memory limits. pub(crate) fn limits(&self) -> &ResizableLimits { &self.limits } /// Returns number of pages this `MemoryInstance` was created with. pub fn initial(&self) -> Pages { self.initial } /// Returns maximum amount of pages this `MemoryInstance` can grow to. /// /// Returns `None` if there is no limit set. /// Maximum memory size cannot exceed `65536` pages or 4GiB. pub fn maximum(&self) -> Option { self.maximum } /// Returns lowest offset ever written or `u32::max_value()` if none. pub fn lowest_used(&self) -> u32 { self.lowest_used.get() } /// Resets tracked lowest offset. pub fn reset_lowest_used(&self, addr: u32) { self.lowest_used.set(addr) } /// Returns current linear memory size. /// /// Maximum memory size cannot exceed `65536` pages or 4GiB. /// /// # Example /// /// To convert number of pages to number of bytes you can use the following code: /// /// ```rust /// use wasmi::MemoryInstance; /// use wasmi::memory_units::*; /// /// let memory = MemoryInstance::alloc(Pages(1), None).unwrap(); /// let byte_size: Bytes = memory.current_size().into(); /// assert_eq!( /// byte_size, /// Bytes(65536), /// ); /// ``` pub fn current_size(&self) -> Pages { Bytes(self.current_size.get()).round_up_to() } /// Returns current used memory size in bytes. /// This is one more than the highest memory address that had been written to. pub fn used_size(&self) -> Bytes { Bytes(self.buffer.borrow().len()) } /// Get value from memory at given offset. pub fn get_value(&self, offset: u32) -> Result { let region = self.checked_region(offset as usize, ::core::mem::size_of::())?; let buffer = self.buffer.borrow(); Ok(T::from_little_endian(&buffer[region.range()]).expect("Slice size is checked")) } /// Copy data from memory at given offset. /// /// This will allocate vector for you. /// If you can provide a mutable slice you can use [`get_into`]. /// /// [`get_into`]: #method.get_into pub fn get(&self, offset: u32, size: usize) -> Result, Error> { let region = self.checked_region(offset as usize, size)?; let buffer = self.buffer.borrow(); Ok(buffer[region.range()].to_vec()) } /// Copy data from given offset in the memory into `target` slice. /// /// # Errors /// /// Returns `Err` if the specified region is out of bounds. pub fn get_into(&self, offset: u32, target: &mut [u8]) -> Result<(), Error> { let region = self.checked_region(offset as usize, target.len())?; let buffer = self.buffer.borrow(); target.copy_from_slice(&buffer[region.range()]); Ok(()) } /// Copy data in the memory at given offset. pub fn set(&self, offset: u32, value: &[u8]) -> Result<(), Error> { let range = self .checked_region(offset as usize, value.len())? .range(); if offset < self.lowest_used.get() { self.lowest_used.set(offset); } let mut buffer = self.buffer.borrow_mut(); buffer[range].copy_from_slice(value); Ok(()) } /// Copy value in the memory at given offset. pub fn set_value(&self, offset: u32, value: T) -> Result<(), Error> { let range = self .checked_region(offset as usize, ::core::mem::size_of::())? .range(); if offset < self.lowest_used.get() { self.lowest_used.set(offset); } let mut buffer = self.buffer.borrow_mut(); value.into_little_endian(&mut buffer[range]); Ok(()) } /// Increases the size of the linear memory by given number of pages. /// Returns previous memory size if succeeds. /// /// # Errors /// /// Returns `Err` if attempted to allocate more memory than permited by the limit. pub fn grow(&self, additional: Pages) -> Result { 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(Pages(validation::LINEAR_MEMORY_MAX_PAGES as usize)); 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(); self.current_size.set(new_buffer_length.0); Ok(size_before_grow) } fn checked_region( &self, offset: usize, size: usize, ) -> Result { let mut buffer = self.buffer.borrow_mut(); 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 <= self.current_size.get() && buffer.len() < end { buffer.resize(end, 0); } if end > buffer.len() { return Err(Error::Memory(format!( "trying to access region [{}..{}] in memory [0..{}]", offset, end, buffer.len() ))); } Ok(CheckedRegion { offset: offset, size: size, }) } fn checked_region_pair( &self, offset1: usize, size1: usize, offset2: usize, size2: usize, ) -> Result<(CheckedRegion, CheckedRegion), Error> { let end1 = offset1.checked_add(size1).ok_or_else(|| { Error::Memory(format!( "trying to access memory block of size {} from offset {}", size1, offset1 )) })?; let end2 = offset2.checked_add(size2).ok_or_else(|| { Error::Memory(format!( "trying to access memory block of size {} from offset {}", size2, offset2 )) })?; let mut buffer = self.buffer.borrow_mut(); let max = cmp::max(end1, end2); if max <= self.current_size.get() && buffer.len() < max { buffer.resize(max, 0); } if end1 > buffer.len() { return Err(Error::Memory(format!( "trying to access region [{}..{}] in memory [0..{}]", offset1, end1, buffer.len() ))); } if end2 > buffer.len() { return Err(Error::Memory(format!( "trying to access region [{}..{}] in memory [0..{}]", offset2, end2, buffer.len() ))); } Ok(( CheckedRegion { offset: offset1, size: size1, }, CheckedRegion { offset: offset2, size: size2, }, )) } /// Copy contents of one memory region to another. /// /// Semantically equivalent to `memmove`. /// /// # Errors /// /// Returns `Err` if either of specified regions is out of bounds. pub fn copy(&self, src_offset: usize, dst_offset: usize, len: usize) -> Result<(), Error> { let (read_region, write_region) = self.checked_region_pair(src_offset, len, dst_offset, len)?; if dst_offset < self.lowest_used.get() as usize { self.lowest_used.set(dst_offset as u32); } let mut buffer = self.buffer.borrow_mut(); unsafe { ::core::ptr::copy( buffer[read_region.range()].as_ptr(), buffer[write_region.range()].as_mut_ptr(), len, ) } Ok(()) } /// Copy contents of one memory region to another (non-overlapping version). /// /// Semantically equivalent to `memcpy`. /// but returns Error if source overlaping with destination. /// /// # Errors /// /// Returns `Err` if: /// /// - either of specified regions is out of bounds, /// - these regions overlaps. pub fn copy_nonoverlapping( &self, src_offset: usize, dst_offset: usize, len: usize, ) -> Result<(), Error> { let (read_region, write_region) = self.checked_region_pair(src_offset, len, dst_offset, len)?; if read_region.intersects(&write_region) { return Err(Error::Memory(format!( "non-overlapping copy is used for overlapping regions" ))); } if dst_offset < self.lowest_used.get() as usize { self.lowest_used.set(dst_offset as u32); } let mut buffer = self.buffer.borrow_mut(); unsafe { ::core::ptr::copy_nonoverlapping( buffer[read_region.range()].as_ptr(), buffer[write_region.range()].as_mut_ptr(), len, ) } Ok(()) } /// Copy memory between two (possibly distinct) memory instances. /// /// If the same memory instance passed as `src` and `dst` then usual `copy` will be used. pub fn transfer( src: &MemoryRef, src_offset: usize, dst: &MemoryRef, dst_offset: usize, len: usize, ) -> Result<(), Error> { if ::MyRc::ptr_eq(&src.0, &dst.0) { // `transfer` is invoked with with same source and destination. Let's assume that regions may // overlap and use `copy`. return src.copy(src_offset, dst_offset, len); } let src_range = src .checked_region(src_offset, len)? .range(); let dst_range = dst .checked_region(dst_offset, len)? .range(); if dst_offset < dst.lowest_used.get() as usize { dst.lowest_used.set(dst_offset as u32); } let mut dst_buffer = dst.buffer.borrow_mut(); let src_buffer = src.buffer.borrow(); dst_buffer[dst_range].copy_from_slice(&src_buffer[src_range]); Ok(()) } /// Fill the memory region with the specified value. /// /// Semantically equivalent to `memset`. /// /// # Errors /// /// Returns `Err` if the specified region is out of bounds. pub fn clear(&self, offset: usize, new_val: u8, len: usize) -> Result<(), Error> { let range = self.checked_region(offset, len)?.range(); if offset < self.lowest_used.get() as usize { self.lowest_used.set(offset as u32); } let mut buffer = self.buffer.borrow_mut(); for val in &mut buffer[range] { *val = new_val } Ok(()) } /// Fill the specified memory region with zeroes. /// /// # Errors /// /// Returns `Err` if the specified region is out of bounds. pub fn zero(&self, offset: usize, len: usize) -> Result<(), Error> { self.clear(offset, 0, len) } /// Provides direct access to the underlying memory buffer. /// /// # Panics /// /// Any call that requires write access to memory (such as [`set`], [`clear`], etc) made within /// the closure will panic. Note that the buffer size may be arbitraty. Proceed with caution. /// /// [`set`]: #method.get /// [`clear`]: #method.set pub fn with_direct_access R>(&self, f: F) -> R { let buf = self.buffer.borrow(); f(&*buf) } /// Provides direct mutable access to the underlying memory buffer. /// /// # Panics /// /// Any calls that requires either read or write access to memory (such as [`get`], [`set`], [`copy`], etc) made /// within the closure will panic. Note that the buffer size may be arbitraty. /// The closure may however resize it. Proceed with caution. /// /// [`get`]: #method.get /// [`set`]: #method.set /// [`copy`]: #method.copy pub fn with_direct_access_mut) -> R>(&self, f: F) -> R { let mut buf = self.buffer.borrow_mut(); f(&mut buf) } } #[cfg(test)] mod tests { use super::{MemoryInstance, MemoryRef, LINEAR_MEMORY_PAGE_SIZE}; use memory_units::Pages; use Error; #[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 = 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 transfer_works() { let src = MemoryRef(::MyRc::new(create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]))); let dst = MemoryRef(::MyRc::new(create_memory(&[ 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, ]))); MemoryInstance::transfer(&src, 4, &dst, 0, 3).unwrap(); assert_eq!(src.get(0, 10).unwrap(), &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]); assert_eq!( dst.get(0, 10).unwrap(), &[4, 5, 6, 13, 14, 15, 16, 17, 18, 19] ); } #[test] fn transfer_still_works_with_same_memory() { let src = MemoryRef(::MyRc::new(create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]))); MemoryInstance::transfer(&src, 4, &src, 0, 3).unwrap(); assert_eq!(src.get(0, 10).unwrap(), &[4, 5, 6, 3, 4, 5, 6, 7, 8, 9]); } #[test] fn transfer_oob_with_same_memory_errors() { let src = MemoryRef(::MyRc::new(create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]))); assert!(MemoryInstance::transfer(&src, 65535, &src, 0, 3).is_err()); // Check that memories content left untouched assert_eq!(src.get(0, 10).unwrap(), &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]); } #[test] fn transfer_oob_errors() { let src = MemoryRef(::MyRc::new(create_memory(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]))); let dst = MemoryRef(::MyRc::new(create_memory(&[ 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, ]))); assert!(MemoryInstance::transfer(&src, 65535, &dst, 0, 3).is_err()); // Check that memories content left untouched assert_eq!(src.get(0, 10).unwrap(), &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]); assert_eq!( dst.get(0, 10).unwrap(), &[10, 11, 12, 13, 14, 15, 16, 17, 18, 19] ); } #[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.set(100, &[0]).expect("memory set should not fail"); mem.with_direct_access_mut(|buf| { assert_eq!(buf.len(), 101); buf[..10].copy_from_slice(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]); }); mem.with_direct_access(|buf| { assert_eq!(buf.len(), 101); assert_eq!(&buf[..10], &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]); }); } // this test works only in the non-thread-safe variant, it deadlocks otherwise. #[cfg(not(feature = "threadsafe"))] #[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]); }); } }