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use crate::{StandardDecodeError, StandardPartialDecoderError};
impl From<ReadError> for StandardDecodeError {
fn from(_: ReadError) -> StandardDecodeError {
StandardDecodeError::ExhaustedInput
}
}
impl From<ReadError> for StandardPartialDecoderError {
fn from(_: ReadError) -> StandardPartialDecoderError {
StandardPartialDecoderError::ExhaustedInput
}
}
#[derive(Debug, PartialEq, Eq, Copy, Clone)]
pub enum ReadError {
ExhaustedInput,
IOError(&'static str),
}
/// a trait defining how `Item`-sized words are read at `Address`-positioned offsets into some
/// stream of data. for *most* uses, [`crate::U8Reader`] probably is sufficient. when
/// reading from data sources that aren't `&[u8]`, `Address` isn't a multiple of `u8`, or `Item`
/// isn't a multiple of 8 bits, `U8Reader` won't be sufficient.
pub trait Reader<Address, Item> {
fn next(&mut self) -> Result<Item, ReadError>;
/// read `buf`-many items from this reader in bulk. if `Reader` cannot read `buf`-many items,
/// return `ReadError::ExhaustedInput`.
fn next_n(&mut self, buf: &mut [Item]) -> Result<(), ReadError>;
/// mark the current position as where to measure `offset` against.
fn mark(&mut self);
/// the difference, in `Address`, between the current `Reader` position and its last `mark`.
/// when created, a `Reader`'s initial position is `mark`ed, so creating a `Reader` and
/// immediately calling `offset()` must return `Address::zero()`.
fn offset(&mut self) -> Address;
/// the difference, in `Address`, between the current `Reader` position and the initial offset
/// when constructed.
fn total_offset(&mut self) -> Address;
}
/// a trait defining how to build a `Reader<Address, Item>` from some data source (`Self`).
/// definitions of `ReaderBuilder` are provided for `U8Reader` on `Address` and `Word` types that
/// `yaxpeax_arch` provides - external decoder implementations should also provide `ReaderBuilder`
/// impls if they use custom `Reader` types.
pub trait ReaderBuilder<Address: crate::AddressBase, Item> where Self: Sized {
type Result: Reader<Address, Item>;
/// construct a reader from `data` beginning at `addr` from its beginning.
fn read_at(data: Self, addr: Address) -> Self::Result;
/// construct a reader from `data` beginning at the start of `data`.
fn read_from(data: Self) -> Self::Result {
Self::read_at(data, Address::zero())
}
}
/// a struct for `Reader` impls that can operate on units of `u8`.
pub struct U8Reader<'a> {
start: *const u8,
data: *const u8,
end: *const u8,
mark: *const u8,
_lifetime: core::marker::PhantomData<&'a [u8]>,
}
impl<'a> U8Reader<'a> {
pub fn new(data: &'a [u8]) -> U8Reader<'a> {
// WHY: either on <64b systems we panic on `data.len() > isize::MAX`, or we compute end
// without `offset` (which would be UB for such huge slices)
#[cfg(not(target_pointer_width = "64"))]
let end = data.as_ptr().wrapping_add(data.len());
// SAFETY: the slice was valid, so data + data.len() does not overflow. at the moment,
// there aren't 64-bit systems with 63 bits of virtual address space, so it's not possible
// to have a slice length larger than 64-bit isize::MAX.
#[cfg(target_pointer_width = "64")]
let end = unsafe { data.as_ptr().offset(data.len() as isize) };
U8Reader {
start: data.as_ptr(),
data: data.as_ptr(),
end,
mark: data.as_ptr(),
_lifetime: core::marker::PhantomData,
}
}
}
/* a `std::io::Read`-friendly `Reader` would take some thought. this was an old impl, and now would
* require something like
* ```
* pub struct IoReader<'io, T: std::io::Read> {
* io: &io mut T,
* count: u64,
* start: u64,
* }
* ```
*/
/*
#[cfg(feature = "std")]
impl<T: std::io::Read> Reader<u8> for T {
fn next(&mut self) -> Result<u8, ReadError> {
let mut buf = [0u8];
match self.read(&mut buf) {
Ok(0) => { Err(ReadError::ExhaustedInput) }
Ok(1) => { Ok(buf[0]) }
Err(_) => {
Err(ReadError::IOError("error"))
}
}
}
}
*/
macro_rules! word_wrapper {
($name:ident, $underlying:ident) => {
#[derive(Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Copy, Clone)]
pub struct $name(pub $underlying);
impl core::fmt::Display for $name {
fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
write!(f, "{}", self.0)
}
}
}
}
word_wrapper!(U16le, u16);
word_wrapper!(U16be, u16);
word_wrapper!(U32le, u32);
word_wrapper!(U32be, u32);
word_wrapper!(U64le, u64);
word_wrapper!(U64be, u64);
macro_rules! u8reader_reader_impl {
($addr_size:ident, $word:ident, $word_from_slice:expr, $words_from_slice:expr) => {
impl Reader<$addr_size, $word> for U8Reader<'_> {
#[inline]
fn next(&mut self) -> Result<$word, ReadError> {
let data_size = self.end as usize - self.data as usize;
if core::mem::size_of::<$word>() > data_size {
return Err(ReadError::ExhaustedInput);
}
// `word_from_slice` knows that we have bounds-checked that `word`-many bytes are
// available.
let word = $word_from_slice(self.data);
unsafe {
self.data = self.data.offset(core::mem::size_of::<$word>() as isize);
}
Ok(word)
}
#[inline]
fn next_n(&mut self, buf: &mut [$word]) -> Result<(), ReadError> {
let data_size = self.end as usize - self.data as usize;
let words_size_bytes = buf.len() * core::mem::size_of::<$word>();
if words_size_bytes > data_size {
return Err(ReadError::ExhaustedInput);
}
// `word_from_slice` knows that we have bounds-checked that `word`-many bytes are
// available.
$words_from_slice(self.data, buf);
unsafe {
self.data = self.data.offset(words_size_bytes as isize);
}
Ok(())
}
#[inline]
fn mark(&mut self) {
self.mark = self.data;
}
#[inline]
fn offset(&mut self) -> $addr_size {
(self.data as usize - self.mark as usize) as $addr_size /
(core::mem::size_of::<$word>() as $addr_size)
}
#[inline]
fn total_offset(&mut self) -> $addr_size {
(self.data as usize - self.start as usize) as $addr_size /
(core::mem::size_of::<$word>() as $addr_size)
}
}
impl<'data> ReaderBuilder<$addr_size, $word> for &'data [u8] {
type Result = U8Reader<'data>;
fn read_at(data: Self, addr: $addr_size) -> Self::Result {
U8Reader::new(&data[(addr as usize)..])
}
}
}
}
macro_rules! u8reader_each_addr_size {
($word:ident, $word_from_slice:expr, $words_from_slice:expr) => {
u8reader_reader_impl!(u64, $word, $word_from_slice, $words_from_slice);
u8reader_reader_impl!(u32, $word, $word_from_slice, $words_from_slice);
u8reader_reader_impl!(u16, $word, $word_from_slice, $words_from_slice);
}
}
u8reader_each_addr_size!(u8,
|ptr: *const u8| { unsafe { core::ptr::read(ptr) } },
|ptr: *const u8, buf: &mut [u8]| {
unsafe {
core::ptr::copy_nonoverlapping(ptr, buf.as_mut_ptr(), buf.len())
}
}
);
u8reader_each_addr_size!(U16le,
|ptr: *const u8| {
let mut word = [0u8; 2];
unsafe {
core::ptr::copy_nonoverlapping(ptr, word.as_mut_ptr(), word.len());
}
U16le(u16::from_le_bytes(word))
},
|ptr: *const u8, buf: &mut [U16le]| {
// `U16le` are layout-identical to u16, so we can just copy into buf
unsafe {
core::ptr::copy_nonoverlapping(ptr, buf.as_mut_ptr() as *mut u8, buf.len() * core::mem::size_of::<U16le>())
}
}
);
u8reader_each_addr_size!(U32le,
|ptr: *const u8| {
let mut word = [0u8; 4];
unsafe {
core::ptr::copy_nonoverlapping(ptr, word.as_mut_ptr(), word.len());
}
U32le(u32::from_le_bytes(word))
},
|ptr: *const u8, buf: &mut [U32le]| {
// `U32le` are layout-identical to u32, so we can just copy into buf
unsafe {
core::ptr::copy_nonoverlapping(ptr, buf.as_mut_ptr() as *mut u8, buf.len() * core::mem::size_of::<U32le>())
}
}
);
u8reader_each_addr_size!(U64le,
|ptr: *const u8| {
let mut word = [0u8; 8];
unsafe {
core::ptr::copy_nonoverlapping(ptr, word.as_mut_ptr(), word.len());
}
U64le(u64::from_le_bytes(word))
},
|ptr: *const u8, buf: &mut [U64le]| {
// `U64le` are layout-identical to u64, so we can just copy into buf
unsafe {
core::ptr::copy_nonoverlapping(ptr, buf.as_mut_ptr() as *mut u8, buf.len() * core::mem::size_of::<U64le>())
}
}
);
u8reader_each_addr_size!(U16be,
|ptr: *const u8| {
let mut word = [0u8; 2];
unsafe {
core::ptr::copy_nonoverlapping(ptr, word.as_mut_ptr(), word.len());
}
U16be(u16::from_be_bytes(word))
},
|ptr: *const u8, buf: &mut [U16be]| {
// `U16be` are layout-identical to u16, so we can just copy into buf
unsafe {
core::ptr::copy_nonoverlapping(ptr, buf.as_mut_ptr() as *mut u8, buf.len() * core::mem::size_of::<U16be>())
}
// but now we have to bswap all the words
for i in 0..buf.len() {
buf[i] = U16be(buf[i].0.swap_bytes());
}
}
);
u8reader_each_addr_size!(U32be,
|ptr: *const u8| {
let mut word = [0u8; 4];
unsafe {
core::ptr::copy_nonoverlapping(ptr, word.as_mut_ptr(), word.len());
}
U32be(u32::from_be_bytes(word))
},
|ptr: *const u8, buf: &mut [U32be]| {
// `U32be` are layout-identical to u32, so we can just copy into buf
unsafe {
core::ptr::copy_nonoverlapping(ptr, buf.as_mut_ptr() as *mut u8, buf.len() * core::mem::size_of::<U32be>())
}
// but now we have to bswap all the words
for i in 0..buf.len() {
buf[i] = U32be(buf[i].0.swap_bytes());
}
}
);
u8reader_each_addr_size!(U64be,
|ptr: *const u8| {
let mut word = [0u8; 8];
unsafe {
core::ptr::copy_nonoverlapping(ptr, word.as_mut_ptr(), word.len());
}
U64be(u64::from_be_bytes(word))
},
|ptr: *const u8, buf: &mut [U64be]| {
// `U64be` are layout-identical to u64, so we can just copy into buf
unsafe {
core::ptr::copy_nonoverlapping(ptr, buf.as_mut_ptr() as *mut u8, buf.len() * core::mem::size_of::<U64be>())
}
// but now we have to bswap all the words
for i in 0..buf.len() {
buf[i] = U64be(buf[i].0.swap_bytes());
}
}
);