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#[cfg(feature = "read")]
use alloc::borrow::Cow;
use core::convert::TryInto;
use core::fmt::Debug;
use core::hash::Hash;
use core::ops::{Add, AddAssign, Sub};
use crate::common::Format;
use crate::endianity::Endianity;
use crate::leb128;
use crate::read::{Error, Result};
/// An identifier for an offset within a section reader.
///
/// This is used for error reporting. The meaning of this value is specific to
/// each reader implementation. The values should be chosen to be unique amongst
/// all readers. If values are not unique then errors may point to the wrong reader.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct ReaderOffsetId(pub u64);
/// A trait for offsets with a DWARF section.
///
/// This allows consumers to choose a size that is appropriate for their address space.
pub trait ReaderOffset:
Debug + Copy + Eq + Ord + Hash + Add<Output = Self> + AddAssign + Sub<Output = Self>
{
/// Convert a u8 to an offset.
fn from_u8(offset: u8) -> Self;
/// Convert a u16 to an offset.
fn from_u16(offset: u16) -> Self;
/// Convert an i16 to an offset.
fn from_i16(offset: i16) -> Self;
/// Convert a u32 to an offset.
fn from_u32(offset: u32) -> Self;
/// Convert a u64 to an offset.
///
/// Returns `Error::UnsupportedOffset` if the value is too large.
fn from_u64(offset: u64) -> Result<Self>;
/// Convert an offset to a u64.
fn into_u64(self) -> u64;
/// Wrapping (modular) addition. Computes `self + other`.
fn wrapping_add(self, other: Self) -> Self;
/// Checked subtraction. Computes `self - other`.
fn checked_sub(self, other: Self) -> Option<Self>;
}
impl ReaderOffset for u64 {
#[inline]
fn from_u8(offset: u8) -> Self {
u64::from(offset)
}
#[inline]
fn from_u16(offset: u16) -> Self {
u64::from(offset)
}
#[inline]
fn from_i16(offset: i16) -> Self {
offset as u64
}
#[inline]
fn from_u32(offset: u32) -> Self {
u64::from(offset)
}
#[inline]
fn from_u64(offset: u64) -> Result<Self> {
Ok(offset)
}
#[inline]
fn into_u64(self) -> u64 {
self
}
#[inline]
fn wrapping_add(self, other: Self) -> Self {
self.wrapping_add(other)
}
#[inline]
fn checked_sub(self, other: Self) -> Option<Self> {
self.checked_sub(other)
}
}
impl ReaderOffset for u32 {
#[inline]
fn from_u8(offset: u8) -> Self {
u32::from(offset)
}
#[inline]
fn from_u16(offset: u16) -> Self {
u32::from(offset)
}
#[inline]
fn from_i16(offset: i16) -> Self {
offset as u32
}
#[inline]
fn from_u32(offset: u32) -> Self {
offset
}
#[inline]
fn from_u64(offset64: u64) -> Result<Self> {
let offset = offset64 as u32;
if u64::from(offset) == offset64 {
Ok(offset)
} else {
Err(Error::UnsupportedOffset)
}
}
#[inline]
fn into_u64(self) -> u64 {
u64::from(self)
}
#[inline]
fn wrapping_add(self, other: Self) -> Self {
self.wrapping_add(other)
}
#[inline]
fn checked_sub(self, other: Self) -> Option<Self> {
self.checked_sub(other)
}
}
impl ReaderOffset for usize {
#[inline]
fn from_u8(offset: u8) -> Self {
offset as usize
}
#[inline]
fn from_u16(offset: u16) -> Self {
offset as usize
}
#[inline]
fn from_i16(offset: i16) -> Self {
offset as usize
}
#[inline]
fn from_u32(offset: u32) -> Self {
offset as usize
}
#[inline]
fn from_u64(offset64: u64) -> Result<Self> {
let offset = offset64 as usize;
if offset as u64 == offset64 {
Ok(offset)
} else {
Err(Error::UnsupportedOffset)
}
}
#[inline]
fn into_u64(self) -> u64 {
self as u64
}
#[inline]
fn wrapping_add(self, other: Self) -> Self {
self.wrapping_add(other)
}
#[inline]
fn checked_sub(self, other: Self) -> Option<Self> {
self.checked_sub(other)
}
}
#[cfg(not(feature = "read"))]
pub(crate) mod seal_if_no_alloc {
#[derive(Debug)]
pub struct Sealed;
}
/// A trait for reading the data from a DWARF section.
///
/// All read operations advance the section offset of the reader
/// unless specified otherwise.
///
/// ## Choosing a `Reader` Implementation
///
/// `gimli` comes with a few different `Reader` implementations and lets you
/// choose the one that is right for your use case. A `Reader` is essentially a
/// view into the raw bytes that make up some DWARF, but this view might borrow
/// the underlying data or use reference counting ownership, and it might be
/// thread safe or not.
///
/// | Implementation | Ownership | Thread Safe | Notes |
/// |:------------------|:------------------|:------------|:------|
/// | [`EndianSlice`](./struct.EndianSlice.html) | Borrowed | Yes | Fastest, but requires that all of your code work with borrows. |
/// | [`EndianRcSlice`](./struct.EndianRcSlice.html) | Reference counted | No | Shared ownership via reference counting, which alleviates the borrow restrictions of `EndianSlice` but imposes reference counting increments and decrements. Cannot be sent across threads, because the reference count is not atomic. |
/// | [`EndianArcSlice`](./struct.EndianArcSlice.html) | Reference counted | Yes | The same as `EndianRcSlice`, but uses atomic reference counting, and therefore reference counting operations are slower but `EndianArcSlice`s may be sent across threads. |
/// | [`EndianReader<T>`](./struct.EndianReader.html) | Same as `T` | Same as `T` | Escape hatch for easily defining your own type of `Reader`. |
pub trait Reader: Debug + Clone {
/// The endianity of bytes that are read.
type Endian: Endianity;
/// The type used for offsets and lengths.
type Offset: ReaderOffset;
/// Return the endianity of bytes that are read.
fn endian(&self) -> Self::Endian;
/// Return the number of bytes remaining.
fn len(&self) -> Self::Offset;
/// Set the number of bytes remaining to zero.
fn empty(&mut self);
/// Set the number of bytes remaining to the specified length.
fn truncate(&mut self, len: Self::Offset) -> Result<()>;
/// Return the offset of this reader's data relative to the start of
/// the given base reader's data.
///
/// May panic if this reader's data is not contained within the given
/// base reader's data.
fn offset_from(&self, base: &Self) -> Self::Offset;
/// Return an identifier for the current reader offset.
fn offset_id(&self) -> ReaderOffsetId;
/// Return the offset corresponding to the given `id` if
/// it is associated with this reader.
fn lookup_offset_id(&self, id: ReaderOffsetId) -> Option<Self::Offset>;
/// Find the index of the first occurrence of the given byte.
/// The offset of the reader is not changed.
fn find(&self, byte: u8) -> Result<Self::Offset>;
/// Discard the specified number of bytes.
fn skip(&mut self, len: Self::Offset) -> Result<()>;
/// Split a reader in two.
///
/// A new reader is returned that can be used to read the next
/// `len` bytes, and `self` is advanced so that it reads the remainder.
fn split(&mut self, len: Self::Offset) -> Result<Self>;
/// This trait cannot be implemented if "read" feature is not enabled.
///
/// `Reader` trait has a few methods that depend on `alloc` crate.
/// Disallowing `Reader` trait implementation prevents a crate that only depends on
/// "read-core" from being broken if another crate depending on `gimli` enables
/// "read" feature.
#[cfg(not(feature = "read"))]
fn cannot_implement() -> seal_if_no_alloc::Sealed;
/// Return all remaining data as a clone-on-write slice.
///
/// The slice will be borrowed where possible, but some readers may
/// always return an owned vector.
///
/// Does not advance the reader.
#[cfg(feature = "read")]
fn to_slice(&self) -> Result<Cow<'_, [u8]>>;
/// Convert all remaining data to a clone-on-write string.
///
/// The string will be borrowed where possible, but some readers may
/// always return an owned string.
///
/// Does not advance the reader.
///
/// Returns an error if the data contains invalid characters.
#[cfg(feature = "read")]
fn to_string(&self) -> Result<Cow<'_, str>>;
/// Convert all remaining data to a clone-on-write string, including invalid characters.
///
/// The string will be borrowed where possible, but some readers may
/// always return an owned string.
///
/// Does not advance the reader.
#[cfg(feature = "read")]
fn to_string_lossy(&self) -> Result<Cow<'_, str>>;
/// Read exactly `buf.len()` bytes into `buf`.
fn read_slice(&mut self, buf: &mut [u8]) -> Result<()>;
/// Read a u8 array.
#[inline]
fn read_u8_array<A>(&mut self) -> Result<A>
where
A: Sized + Default + AsMut<[u8]>,
{
let mut val = Default::default();
self.read_slice(<A as AsMut<[u8]>>::as_mut(&mut val))?;
Ok(val)
}
/// Return true if the number of bytes remaining is zero.
#[inline]
fn is_empty(&self) -> bool {
self.len() == Self::Offset::from_u8(0)
}
/// Read a u8.
#[inline]
fn read_u8(&mut self) -> Result<u8> {
let a: [u8; 1] = self.read_u8_array()?;
Ok(a[0])
}
/// Read an i8.
#[inline]
fn read_i8(&mut self) -> Result<i8> {
let a: [u8; 1] = self.read_u8_array()?;
Ok(a[0] as i8)
}
/// Read a u16.
#[inline]
fn read_u16(&mut self) -> Result<u16> {
let a: [u8; 2] = self.read_u8_array()?;
Ok(self.endian().read_u16(&a))
}
/// Read an i16.
#[inline]
fn read_i16(&mut self) -> Result<i16> {
let a: [u8; 2] = self.read_u8_array()?;
Ok(self.endian().read_i16(&a))
}
/// Read a u32.
#[inline]
fn read_u32(&mut self) -> Result<u32> {
let a: [u8; 4] = self.read_u8_array()?;
Ok(self.endian().read_u32(&a))
}
/// Read an i32.
#[inline]
fn read_i32(&mut self) -> Result<i32> {
let a: [u8; 4] = self.read_u8_array()?;
Ok(self.endian().read_i32(&a))
}
/// Read a u64.
#[inline]
fn read_u64(&mut self) -> Result<u64> {
let a: [u8; 8] = self.read_u8_array()?;
Ok(self.endian().read_u64(&a))
}
/// Read an i64.
#[inline]
fn read_i64(&mut self) -> Result<i64> {
let a: [u8; 8] = self.read_u8_array()?;
Ok(self.endian().read_i64(&a))
}
/// Read a f32.
#[inline]
fn read_f32(&mut self) -> Result<f32> {
let a: [u8; 4] = self.read_u8_array()?;
Ok(self.endian().read_f32(&a))
}
/// Read a f64.
#[inline]
fn read_f64(&mut self) -> Result<f64> {
let a: [u8; 8] = self.read_u8_array()?;
Ok(self.endian().read_f64(&a))
}
/// Read an unsigned n-bytes integer u64.
///
/// # Panics
///
/// Panics when nbytes < 1 or nbytes > 8
#[inline]
fn read_uint(&mut self, n: usize) -> Result<u64> {
let mut buf = [0; 8];
self.read_slice(&mut buf[..n])?;
Ok(self.endian().read_uint(&buf[..n]))
}
/// Read a null-terminated slice, and return it (excluding the null).
fn read_null_terminated_slice(&mut self) -> Result<Self> {
let idx = self.find(0)?;
let val = self.split(idx)?;
self.skip(Self::Offset::from_u8(1))?;
Ok(val)
}
/// Skip a LEB128 encoded integer.
fn skip_leb128(&mut self) -> Result<()> {
leb128::read::skip(self)
}
/// Read an unsigned LEB128 encoded integer.
fn read_uleb128(&mut self) -> Result<u64> {
leb128::read::unsigned(self)
}
/// Read an unsigned LEB128 encoded u32.
fn read_uleb128_u32(&mut self) -> Result<u32> {
leb128::read::unsigned(self)?
.try_into()
.map_err(|_| Error::BadUnsignedLeb128)
}
/// Read an unsigned LEB128 encoded u16.
fn read_uleb128_u16(&mut self) -> Result<u16> {
leb128::read::u16(self)
}
/// Read a signed LEB128 encoded integer.
fn read_sleb128(&mut self) -> Result<i64> {
leb128::read::signed(self)
}
/// Read an initial length field.
///
/// This field is encoded as either a 32-bit length or
/// a 64-bit length, and the returned `Format` indicates which.
fn read_initial_length(&mut self) -> Result<(Self::Offset, Format)> {
const MAX_DWARF_32_UNIT_LENGTH: u32 = 0xffff_fff0;
const DWARF_64_INITIAL_UNIT_LENGTH: u32 = 0xffff_ffff;
let val = self.read_u32()?;
if val < MAX_DWARF_32_UNIT_LENGTH {
Ok((Self::Offset::from_u32(val), Format::Dwarf32))
} else if val == DWARF_64_INITIAL_UNIT_LENGTH {
let val = self.read_u64().and_then(Self::Offset::from_u64)?;
Ok((val, Format::Dwarf64))
} else {
Err(Error::UnknownReservedLength)
}
}
/// Read an address-sized integer, and return it as a `u64`.
fn read_address(&mut self, address_size: u8) -> Result<u64> {
match address_size {
1 => self.read_u8().map(u64::from),
2 => self.read_u16().map(u64::from),
4 => self.read_u32().map(u64::from),
8 => self.read_u64(),
otherwise => Err(Error::UnsupportedAddressSize(otherwise)),
}
}
/// Parse a word-sized integer according to the DWARF format.
///
/// These are always used to encode section offsets or lengths,
/// and so have a type of `Self::Offset`.
fn read_word(&mut self, format: Format) -> Result<Self::Offset> {
match format {
Format::Dwarf32 => self.read_u32().map(Self::Offset::from_u32),
Format::Dwarf64 => self.read_u64().and_then(Self::Offset::from_u64),
}
}
/// Parse a word-sized section length according to the DWARF format.
#[inline]
fn read_length(&mut self, format: Format) -> Result<Self::Offset> {
self.read_word(format)
}
/// Parse a word-sized section offset according to the DWARF format.
#[inline]
fn read_offset(&mut self, format: Format) -> Result<Self::Offset> {
self.read_word(format)
}
/// Parse a section offset of the given size.
///
/// This is used for `DW_FORM_ref_addr` values in DWARF version 2.
fn read_sized_offset(&mut self, size: u8) -> Result<Self::Offset> {
match size {
1 => self.read_u8().map(u64::from),
2 => self.read_u16().map(u64::from),
4 => self.read_u32().map(u64::from),
8 => self.read_u64(),
otherwise => Err(Error::UnsupportedOffsetSize(otherwise)),
}
.and_then(Self::Offset::from_u64)
}
}