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+//! Working with byte slices that have an associated endianity.
+
+#[cfg(feature = "read")]
+use alloc::borrow::Cow;
+#[cfg(feature = "read")]
+use alloc::string::String;
+use core::fmt;
+use core::ops::{Deref, Range, RangeFrom, RangeTo};
+use core::str;
+
+use crate::endianity::Endianity;
+use crate::read::{Error, Reader, ReaderOffsetId, Result};
+
+/// A `&[u8]` slice with endianity metadata.
+///
+/// This implements the `Reader` trait, which is used for all reading of DWARF sections.
+#[derive(Default, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct EndianSlice<'input, Endian>
+where
+ Endian: Endianity,
+{
+ slice: &'input [u8],
+ endian: Endian,
+}
+
+impl<'input, Endian> EndianSlice<'input, Endian>
+where
+ Endian: Endianity,
+{
+ /// Construct a new `EndianSlice` with the given slice and endianity.
+ #[inline]
+ pub fn new(slice: &'input [u8], endian: Endian) -> EndianSlice<'input, Endian> {
+ EndianSlice { slice, endian }
+ }
+
+ /// Return a reference to the raw slice.
+ #[inline]
+ #[doc(hidden)]
+ #[deprecated(note = "Method renamed to EndianSlice::slice; use that instead.")]
+ pub fn buf(&self) -> &'input [u8] {
+ self.slice
+ }
+
+ /// Return a reference to the raw slice.
+ #[inline]
+ pub fn slice(&self) -> &'input [u8] {
+ self.slice
+ }
+
+ /// Split the slice in two at the given index, resulting in the tuple where
+ /// the first item has range [0, idx), and the second has range [idx,
+ /// len). Panics if the index is out of bounds.
+ #[inline]
+ pub fn split_at(
+ &self,
+ idx: usize,
+ ) -> (EndianSlice<'input, Endian>, EndianSlice<'input, Endian>) {
+ (self.range_to(..idx), self.range_from(idx..))
+ }
+
+ /// Find the first occurrence of a byte in the slice, and return its index.
+ #[inline]
+ pub fn find(&self, byte: u8) -> Option<usize> {
+ self.slice.iter().position(|ch| *ch == byte)
+ }
+
+ /// Return the offset of the start of the slice relative to the start
+ /// of the given slice.
+ #[inline]
+ pub fn offset_from(&self, base: EndianSlice<'input, Endian>) -> usize {
+ let base_ptr = base.slice.as_ptr() as *const u8 as usize;
+ let ptr = self.slice.as_ptr() as *const u8 as usize;
+ debug_assert!(base_ptr <= ptr);
+ debug_assert!(ptr + self.slice.len() <= base_ptr + base.slice.len());
+ ptr - base_ptr
+ }
+
+ /// Converts the slice to a string using `str::from_utf8`.
+ ///
+ /// Returns an error if the slice contains invalid characters.
+ #[inline]
+ pub fn to_string(&self) -> Result<&'input str> {
+ str::from_utf8(self.slice).map_err(|_| Error::BadUtf8)
+ }
+
+ /// Converts the slice to a string, including invalid characters,
+ /// using `String::from_utf8_lossy`.
+ #[cfg(feature = "read")]
+ #[inline]
+ pub fn to_string_lossy(&self) -> Cow<'input, str> {
+ String::from_utf8_lossy(self.slice)
+ }
+
+ #[inline]
+ fn read_slice(&mut self, len: usize) -> Result<&'input [u8]> {
+ if self.slice.len() < len {
+ Err(Error::UnexpectedEof(self.offset_id()))
+ } else {
+ let val = &self.slice[..len];
+ self.slice = &self.slice[len..];
+ Ok(val)
+ }
+ }
+}
+
+/// # Range Methods
+///
+/// Unfortunately, `std::ops::Index` *must* return a reference, so we can't
+/// implement `Index<Range<usize>>` to return a new `EndianSlice` the way we would
+/// like to. Instead, we abandon fancy indexing operators and have these plain
+/// old methods.
+impl<'input, Endian> EndianSlice<'input, Endian>
+where
+ Endian: Endianity,
+{
+ /// Take the given `start..end` range of the underlying slice and return a
+ /// new `EndianSlice`.
+ ///
+ /// ```
+ /// use gimli::{EndianSlice, LittleEndian};
+ ///
+ /// let slice = &[0x01, 0x02, 0x03, 0x04];
+ /// let endian_slice = EndianSlice::new(slice, LittleEndian);
+ /// assert_eq!(endian_slice.range(1..3),
+ /// EndianSlice::new(&slice[1..3], LittleEndian));
+ /// ```
+ pub fn range(&self, idx: Range<usize>) -> EndianSlice<'input, Endian> {
+ EndianSlice {
+ slice: &self.slice[idx],
+ endian: self.endian,
+ }
+ }
+
+ /// Take the given `start..` range of the underlying slice and return a new
+ /// `EndianSlice`.
+ ///
+ /// ```
+ /// use gimli::{EndianSlice, LittleEndian};
+ ///
+ /// let slice = &[0x01, 0x02, 0x03, 0x04];
+ /// let endian_slice = EndianSlice::new(slice, LittleEndian);
+ /// assert_eq!(endian_slice.range_from(2..),
+ /// EndianSlice::new(&slice[2..], LittleEndian));
+ /// ```
+ pub fn range_from(&self, idx: RangeFrom<usize>) -> EndianSlice<'input, Endian> {
+ EndianSlice {
+ slice: &self.slice[idx],
+ endian: self.endian,
+ }
+ }
+
+ /// Take the given `..end` range of the underlying slice and return a new
+ /// `EndianSlice`.
+ ///
+ /// ```
+ /// use gimli::{EndianSlice, LittleEndian};
+ ///
+ /// let slice = &[0x01, 0x02, 0x03, 0x04];
+ /// let endian_slice = EndianSlice::new(slice, LittleEndian);
+ /// assert_eq!(endian_slice.range_to(..3),
+ /// EndianSlice::new(&slice[..3], LittleEndian));
+ /// ```
+ pub fn range_to(&self, idx: RangeTo<usize>) -> EndianSlice<'input, Endian> {
+ EndianSlice {
+ slice: &self.slice[idx],
+ endian: self.endian,
+ }
+ }
+}
+
+impl<'input, Endian> Deref for EndianSlice<'input, Endian>
+where
+ Endian: Endianity,
+{
+ type Target = [u8];
+ fn deref(&self) -> &Self::Target {
+ self.slice
+ }
+}
+
+impl<'input, Endian: Endianity> fmt::Debug for EndianSlice<'input, Endian> {
+ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> core::result::Result<(), fmt::Error> {
+ fmt.debug_tuple("EndianSlice")
+ .field(&self.endian)
+ .field(&DebugBytes(self.slice))
+ .finish()
+ }
+}
+
+struct DebugBytes<'input>(&'input [u8]);
+
+impl<'input> core::fmt::Debug for DebugBytes<'input> {
+ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> core::result::Result<(), fmt::Error> {
+ let mut list = fmt.debug_list();
+ list.entries(self.0.iter().take(8).copied().map(DebugByte));
+ if self.0.len() > 8 {
+ list.entry(&DebugLen(self.0.len()));
+ }
+ list.finish()
+ }
+}
+
+struct DebugByte(u8);
+
+impl fmt::Debug for DebugByte {
+ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(fmt, "0x{:02x}", self.0)
+ }
+}
+
+struct DebugLen(usize);
+
+impl fmt::Debug for DebugLen {
+ fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(fmt, "...; {}", self.0)
+ }
+}
+
+impl<'input, Endian> Reader for EndianSlice<'input, Endian>
+where
+ Endian: Endianity,
+{
+ type Endian = Endian;
+ type Offset = usize;
+
+ #[inline]
+ fn endian(&self) -> Endian {
+ self.endian
+ }
+
+ #[inline]
+ fn len(&self) -> usize {
+ self.slice.len()
+ }
+
+ #[inline]
+ fn is_empty(&self) -> bool {
+ self.slice.is_empty()
+ }
+
+ #[inline]
+ fn empty(&mut self) {
+ self.slice = &[];
+ }
+
+ #[inline]
+ fn truncate(&mut self, len: usize) -> Result<()> {
+ if self.slice.len() < len {
+ Err(Error::UnexpectedEof(self.offset_id()))
+ } else {
+ self.slice = &self.slice[..len];
+ Ok(())
+ }
+ }
+
+ #[inline]
+ fn offset_from(&self, base: &Self) -> usize {
+ self.offset_from(*base)
+ }
+
+ #[inline]
+ fn offset_id(&self) -> ReaderOffsetId {
+ ReaderOffsetId(self.slice.as_ptr() as u64)
+ }
+
+ #[inline]
+ fn lookup_offset_id(&self, id: ReaderOffsetId) -> Option<Self::Offset> {
+ let id = id.0;
+ let self_id = self.slice.as_ptr() as u64;
+ let self_len = self.slice.len() as u64;
+ if id >= self_id && id <= self_id + self_len {
+ Some((id - self_id) as usize)
+ } else {
+ None
+ }
+ }
+
+ #[inline]
+ fn find(&self, byte: u8) -> Result<usize> {
+ self.find(byte)
+ .ok_or_else(|| Error::UnexpectedEof(self.offset_id()))
+ }
+
+ #[inline]
+ fn skip(&mut self, len: usize) -> Result<()> {
+ if self.slice.len() < len {
+ Err(Error::UnexpectedEof(self.offset_id()))
+ } else {
+ self.slice = &self.slice[len..];
+ Ok(())
+ }
+ }
+
+ #[inline]
+ fn split(&mut self, len: usize) -> Result<Self> {
+ let slice = self.read_slice(len)?;
+ Ok(EndianSlice::new(slice, self.endian))
+ }
+
+ #[cfg(not(feature = "read"))]
+ fn cannot_implement() -> super::reader::seal_if_no_alloc::Sealed {
+ super::reader::seal_if_no_alloc::Sealed
+ }
+
+ #[cfg(feature = "read")]
+ #[inline]
+ fn to_slice(&self) -> Result<Cow<[u8]>> {
+ Ok(self.slice.into())
+ }
+
+ #[cfg(feature = "read")]
+ #[inline]
+ fn to_string(&self) -> Result<Cow<str>> {
+ match str::from_utf8(self.slice) {
+ Ok(s) => Ok(s.into()),
+ _ => Err(Error::BadUtf8),
+ }
+ }
+
+ #[cfg(feature = "read")]
+ #[inline]
+ fn to_string_lossy(&self) -> Result<Cow<str>> {
+ Ok(String::from_utf8_lossy(self.slice))
+ }
+
+ #[inline]
+ fn read_slice(&mut self, buf: &mut [u8]) -> Result<()> {
+ let slice = self.read_slice(buf.len())?;
+ buf.copy_from_slice(slice);
+ Ok(())
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use crate::endianity::NativeEndian;
+
+ #[test]
+ fn test_endian_slice_split_at() {
+ let endian = NativeEndian;
+ let slice = &[1, 2, 3, 4, 5, 6, 7, 8, 9, 0];
+ let eb = EndianSlice::new(slice, endian);
+ assert_eq!(
+ eb.split_at(3),
+ (
+ EndianSlice::new(&slice[..3], endian),
+ EndianSlice::new(&slice[3..], endian)
+ )
+ );
+ }
+
+ #[test]
+ #[should_panic]
+ fn test_endian_slice_split_at_out_of_bounds() {
+ let slice = &[1, 2, 3, 4, 5, 6, 7, 8, 9, 0];
+ let eb = EndianSlice::new(slice, NativeEndian);
+ eb.split_at(30);
+ }
+}