1 files changed, 137 insertions, 0 deletions
diff --git a/vendor/object/src/read/read_ref.rs b/vendor/object/src/read/read_ref.rs
new file mode 100644
index 000000000..2f547a4e2
--- /dev/null
+++ b/vendor/object/src/read/read_ref.rs
@@ -0,0 +1,137 @@
+#![allow(clippy::len_without_is_empty)]
+
+use core::convert::TryInto;
+use core::ops::Range;
+use core::{mem, result};
+
+use crate::pod::{from_bytes, slice_from_bytes, Pod};
+
+type Result<T> = result::Result<T, ()>;
+
+/// A trait for reading references to `Pod` types from a block of data.
+///
+/// This allows parsers to handle both of these cases:
+/// - the block of data exists in memory, and it is desirable
+///   to use references to this block instead of copying it,
+/// - the block of data exists in storage, and it is desirable
+///   to read on demand to minimize I/O and memory usage.
+///
+/// The methods accept `self` by value because `Self` is expected to behave
+/// similar to a reference: it may be a reference with a lifetime of `'a`,
+/// or it may be a wrapper of a reference.
+///
+/// The `Clone` and `Copy` bounds are for convenience, and since `Self` is
+/// expected to be similar to a reference, these are easily satisfied.
+///
+/// Object file parsers typically use offsets to locate the structures
+/// in the block, and will most commonly use the `*_at` methods to
+/// read a structure at a known offset.
+///
+/// Occasionally file parsers will need to treat the block as a stream,
+/// and so convenience methods are provided that update an offset with
+/// the size that was read.
+//
+// An alternative would be for methods to accept `&mut self` and use a
+// `seek` method instead of the `offset` parameters, but this is less
+// convenient for implementers.
+pub trait ReadRef<'a>: Clone + Copy {
+    /// The total size of the block of data.
+    fn len(self) -> Result<u64>;
+
+    /// Get a reference to a `u8` slice at the given offset.
+    ///
+    /// Returns an error if offset or size are out of bounds.
+    fn read_bytes_at(self, offset: u64, size: u64) -> Result<&'a [u8]>;
+
+    /// Get a reference to a delimited `u8` slice which starts at range.start.
+    ///
+    /// Does not include the delimiter.
+    ///
+    /// Returns an error if the range is out of bounds or the delimiter is
+    /// not found in the range.
+    fn read_bytes_at_until(self, range: Range<u64>, delimiter: u8) -> Result<&'a [u8]>;
+
+    /// Get a reference to a `u8` slice at the given offset, and update the offset.
+    ///
+    /// Returns an error if offset or size are out of bounds.
+    fn read_bytes(self, offset: &mut u64, size: u64) -> Result<&'a [u8]> {
+        let bytes = self.read_bytes_at(*offset, size)?;
+        *offset = offset.wrapping_add(size);
+        Ok(bytes)
+    }
+
+    /// Get a reference to a `Pod` type at the given offset, and update the offset.
+    ///
+    /// Returns an error if offset or size are out of bounds.
+    ///
+    /// The default implementation uses `read_bytes`, and returns an error if
+    /// `read_bytes` does not return bytes with the correct alignment for `T`.
+    /// Implementors may want to provide their own implementation that ensures
+    /// the alignment can be satisified. Alternatively, only use this method with
+    /// types that do not need alignment (see the `unaligned` feature of this crate).
+    fn read<T: Pod>(self, offset: &mut u64) -> Result<&'a T> {
+        let size = mem::size_of::<T>().try_into().map_err(|_| ())?;
+        let bytes = self.read_bytes(offset, size)?;
+        let (t, _) = from_bytes(bytes)?;
+        Ok(t)
+    }
+
+    /// Get a reference to a `Pod` type at the given offset.
+    ///
+    /// Returns an error if offset or size are out of bounds.
+    ///
+    /// Also see the `read` method for information regarding alignment of `T`.
+    fn read_at<T: Pod>(self, mut offset: u64) -> Result<&'a T> {
+        self.read(&mut offset)
+    }
+
+    /// Get a reference to a slice of a `Pod` type at the given offset, and update the offset.
+    ///
+    /// Returns an error if offset or size are out of bounds.
+    ///
+    /// Also see the `read` method for information regarding alignment of `T`.
+    fn read_slice<T: Pod>(self, offset: &mut u64, count: usize) -> Result<&'a [T]> {
+        let size = count
+            .checked_mul(mem::size_of::<T>())
+            .ok_or(())?
+            .try_into()
+            .map_err(|_| ())?;
+        let bytes = self.read_bytes(offset, size)?;
+        let (t, _) = slice_from_bytes(bytes, count)?;
+        Ok(t)
+    }
+
+    /// Get a reference to a slice of a `Pod` type at the given offset.
+    ///
+    /// Returns an error if offset or size are out of bounds.
+    ///
+    /// Also see the `read` method for information regarding alignment of `T`.
+    fn read_slice_at<T: Pod>(self, mut offset: u64, count: usize) -> Result<&'a [T]> {
+        self.read_slice(&mut offset, count)
+    }
+}
+
+impl<'a> ReadRef<'a> for &'a [u8] {
+    fn len(self) -> Result<u64> {
+        self.len().try_into().map_err(|_| ())
+    }
+
+    fn read_bytes_at(self, offset: u64, size: u64) -> Result<&'a [u8]> {
+        let offset: usize = offset.try_into().map_err(|_| ())?;
+        let size: usize = size.try_into().map_err(|_| ())?;
+        self.get(offset..).ok_or(())?.get(..size).ok_or(())
+    }
+
+    fn read_bytes_at_until(self, range: Range<u64>, delimiter: u8) -> Result<&'a [u8]> {
+        let start: usize = range.start.try_into().map_err(|_| ())?;
+        let end: usize = range.end.try_into().map_err(|_| ())?;
+        let bytes = self.get(start..end).ok_or(())?;
+        match memchr::memchr(delimiter, bytes) {
+            Some(len) => {
+                // This will never fail.
+                bytes.get(..len).ok_or(())
+            }
+            None => Err(()),
+        }
+    }
+}