1 files changed, 425 insertions, 0 deletions
diff --git a/vendor/object/src/read/util.rs b/vendor/object/src/read/util.rs
new file mode 100644
index 0000000..7d85b27
--- /dev/null
+++ b/vendor/object/src/read/util.rs
@@ -0,0 +1,425 @@
+use alloc::string::String;
+use core::convert::TryInto;
+use core::fmt;
+use core::marker::PhantomData;
+
+use crate::pod::{from_bytes, slice_from_bytes, Pod};
+use crate::ReadRef;
+
+/// A newtype for byte slices.
+///
+/// It has these important features:
+/// - no methods that can panic, such as `Index`
+/// - convenience methods for `Pod` types
+/// - a useful `Debug` implementation
+#[derive(Default, Clone, Copy, PartialEq, Eq)]
+pub struct Bytes<'data>(pub &'data [u8]);
+
+impl<'data> fmt::Debug for Bytes<'data> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        debug_list_bytes(self.0, fmt)
+    }
+}
+
+impl<'data> Bytes<'data> {
+    /// Return the length of the byte slice.
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    /// Return true if the byte slice is empty.
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+
+    /// Skip over the given number of bytes at the start of the byte slice.
+    ///
+    /// Modifies the byte slice to start after the bytes.
+    ///
+    /// Returns an error if there are too few bytes.
+    #[inline]
+    pub fn skip(&mut self, offset: usize) -> Result<(), ()> {
+        match self.0.get(offset..) {
+            Some(tail) => {
+                self.0 = tail;
+                Ok(())
+            }
+            None => {
+                self.0 = &[];
+                Err(())
+            }
+        }
+    }
+
+    /// Return a reference to the given number of bytes at the start of the byte slice.
+    ///
+    /// Modifies the byte slice to start after the bytes.
+    ///
+    /// Returns an error if there are too few bytes.
+    #[inline]
+    pub fn read_bytes(&mut self, count: usize) -> Result<Bytes<'data>, ()> {
+        match (self.0.get(..count), self.0.get(count..)) {
+            (Some(head), Some(tail)) => {
+                self.0 = tail;
+                Ok(Bytes(head))
+            }
+            _ => {
+                self.0 = &[];
+                Err(())
+            }
+        }
+    }
+
+    /// Return a reference to the given number of bytes at the given offset of the byte slice.
+    ///
+    /// Returns an error if the offset is invalid or there are too few bytes.
+    #[inline]
+    pub fn read_bytes_at(mut self, offset: usize, count: usize) -> Result<Bytes<'data>, ()> {
+        self.skip(offset)?;
+        self.read_bytes(count)
+    }
+
+    /// Return a reference to a `Pod` struct at the start of the byte slice.
+    ///
+    /// Modifies the byte slice to start after the bytes.
+    ///
+    /// Returns an error if there are too few bytes or the slice is incorrectly aligned.
+    #[inline]
+    pub fn read<T: Pod>(&mut self) -> Result<&'data T, ()> {
+        match from_bytes(self.0) {
+            Ok((value, tail)) => {
+                self.0 = tail;
+                Ok(value)
+            }
+            Err(()) => {
+                self.0 = &[];
+                Err(())
+            }
+        }
+    }
+
+    /// Return a reference to a `Pod` struct at the given offset of the byte slice.
+    ///
+    /// Returns an error if there are too few bytes or the offset is incorrectly aligned.
+    #[inline]
+    pub fn read_at<T: Pod>(mut self, offset: usize) -> Result<&'data T, ()> {
+        self.skip(offset)?;
+        self.read()
+    }
+
+    /// Return a reference to a slice of `Pod` structs at the start of the byte slice.
+    ///
+    /// Modifies the byte slice to start after the bytes.
+    ///
+    /// Returns an error if there are too few bytes or the offset is incorrectly aligned.
+    #[inline]
+    pub fn read_slice<T: Pod>(&mut self, count: usize) -> Result<&'data [T], ()> {
+        match slice_from_bytes(self.0, count) {
+            Ok((value, tail)) => {
+                self.0 = tail;
+                Ok(value)
+            }
+            Err(()) => {
+                self.0 = &[];
+                Err(())
+            }
+        }
+    }
+
+    /// Return a reference to a slice of `Pod` structs at the given offset of the byte slice.
+    ///
+    /// Returns an error if there are too few bytes or the offset is incorrectly aligned.
+    #[inline]
+    pub fn read_slice_at<T: Pod>(mut self, offset: usize, count: usize) -> Result<&'data [T], ()> {
+        self.skip(offset)?;
+        self.read_slice(count)
+    }
+
+    /// Read a null terminated string.
+    ///
+    /// Does not assume any encoding.
+    /// Reads past the null byte, but doesn't return it.
+    #[inline]
+    pub fn read_string(&mut self) -> Result<&'data [u8], ()> {
+        match memchr::memchr(b'\0', self.0) {
+            Some(null) => {
+                // These will never fail.
+                let bytes = self.read_bytes(null)?;
+                self.skip(1)?;
+                Ok(bytes.0)
+            }
+            None => {
+                self.0 = &[];
+                Err(())
+            }
+        }
+    }
+
+    /// Read a null terminated string at an offset.
+    ///
+    /// Does not assume any encoding. Does not return the null byte.
+    #[inline]
+    pub fn read_string_at(mut self, offset: usize) -> Result<&'data [u8], ()> {
+        self.skip(offset)?;
+        self.read_string()
+    }
+
+    /// Read an unsigned LEB128 number.
+    pub fn read_uleb128(&mut self) -> Result<u64, ()> {
+        let mut result = 0;
+        let mut shift = 0;
+
+        loop {
+            let byte = *self.read::<u8>()?;
+            if shift == 63 && byte != 0x00 && byte != 0x01 {
+                return Err(());
+            }
+            result |= u64::from(byte & 0x7f) << shift;
+            shift += 7;
+
+            if byte & 0x80 == 0 {
+                return Ok(result);
+            }
+        }
+    }
+
+    /// Read a signed LEB128 number.
+    pub fn read_sleb128(&mut self) -> Result<i64, ()> {
+        let mut result = 0;
+        let mut shift = 0;
+
+        loop {
+            let byte = *self.read::<u8>()?;
+            if shift == 63 && byte != 0x00 && byte != 0x7f {
+                return Err(());
+            }
+            result |= i64::from(byte & 0x7f) << shift;
+            shift += 7;
+
+            if byte & 0x80 == 0 {
+                if shift < 64 && (byte & 0x40) != 0 {
+                    // Sign extend the result.
+                    result |= !0 << shift;
+                }
+                return Ok(result);
+            }
+        }
+    }
+}
+
+// Only for Debug impl of `Bytes`.
+fn debug_list_bytes(bytes: &[u8], fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+    let mut list = fmt.debug_list();
+    list.entries(bytes.iter().take(8).copied().map(DebugByte));
+    if bytes.len() > 8 {
+        list.entry(&DebugLen(bytes.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)
+    }
+}
+
+/// A newtype for byte strings.
+///
+/// For byte slices that are strings of an unknown encoding.
+///
+/// Provides a `Debug` implementation that interprets the bytes as UTF-8.
+#[derive(Default, Clone, Copy, PartialEq, Eq)]
+pub(crate) struct ByteString<'data>(pub &'data [u8]);
+
+impl<'data> fmt::Debug for ByteString<'data> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "\"{}\"", String::from_utf8_lossy(self.0))
+    }
+}
+
+#[allow(dead_code)]
+#[inline]
+pub(crate) fn align(offset: usize, size: usize) -> usize {
+    (offset + (size - 1)) & !(size - 1)
+}
+
+#[allow(dead_code)]
+pub(crate) fn data_range(
+    data: &[u8],
+    data_address: u64,
+    range_address: u64,
+    size: u64,
+) -> Option<&[u8]> {
+    let offset = range_address.checked_sub(data_address)?;
+    data.get(offset.try_into().ok()?..)?
+        .get(..size.try_into().ok()?)
+}
+
+/// A table of zero-terminated strings.
+///
+/// This is used by most file formats for strings such as section names and symbol names.
+#[derive(Debug, Clone, Copy)]
+pub struct StringTable<'data, R = &'data [u8]>
+where
+    R: ReadRef<'data>,
+{
+    data: Option<R>,
+    start: u64,
+    end: u64,
+    marker: PhantomData<&'data ()>,
+}
+
+impl<'data, R: ReadRef<'data>> StringTable<'data, R> {
+    /// Interpret the given data as a string table.
+    pub fn new(data: R, start: u64, end: u64) -> Self {
+        StringTable {
+            data: Some(data),
+            start,
+            end,
+            marker: PhantomData,
+        }
+    }
+
+    /// Return the string at the given offset.
+    pub fn get(&self, offset: u32) -> Result<&'data [u8], ()> {
+        match self.data {
+            Some(data) => {
+                let r_start = self.start.checked_add(offset.into()).ok_or(())?;
+                data.read_bytes_at_until(r_start..self.end, 0)
+            }
+            None => Err(()),
+        }
+    }
+}
+
+impl<'data, R: ReadRef<'data>> Default for StringTable<'data, R> {
+    fn default() -> Self {
+        StringTable {
+            data: None,
+            start: 0,
+            end: 0,
+            marker: PhantomData,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::pod::bytes_of;
+
+    #[test]
+    fn bytes() {
+        let x = u32::to_be(0x0123_4567);
+        let data = Bytes(bytes_of(&x));
+
+        let mut bytes = data;
+        assert_eq!(bytes.skip(0), Ok(()));
+        assert_eq!(bytes, data);
+
+        let mut bytes = data;
+        assert_eq!(bytes.skip(4), Ok(()));
+        assert_eq!(bytes, Bytes(&[]));
+
+        let mut bytes = data;
+        assert_eq!(bytes.skip(5), Err(()));
+        assert_eq!(bytes, Bytes(&[]));
+
+        let mut bytes = data;
+        assert_eq!(bytes.read_bytes(0), Ok(Bytes(&[])));
+        assert_eq!(bytes, data);
+
+        let mut bytes = data;
+        assert_eq!(bytes.read_bytes(4), Ok(data));
+        assert_eq!(bytes, Bytes(&[]));
+
+        let mut bytes = data;
+        assert_eq!(bytes.read_bytes(5), Err(()));
+        assert_eq!(bytes, Bytes(&[]));
+
+        assert_eq!(data.read_bytes_at(0, 0), Ok(Bytes(&[])));
+        assert_eq!(data.read_bytes_at(4, 0), Ok(Bytes(&[])));
+        assert_eq!(data.read_bytes_at(0, 4), Ok(data));
+        assert_eq!(data.read_bytes_at(1, 4), Err(()));
+
+        let mut bytes = data;
+        assert_eq!(bytes.read::<u16>(), Ok(&u16::to_be(0x0123)));
+        assert_eq!(bytes, Bytes(&[0x45, 0x67]));
+        assert_eq!(data.read_at::<u16>(2), Ok(&u16::to_be(0x4567)));
+        assert_eq!(data.read_at::<u16>(3), Err(()));
+        assert_eq!(data.read_at::<u16>(4), Err(()));
+
+        let mut bytes = data;
+        assert_eq!(bytes.read::<u32>(), Ok(&x));
+        assert_eq!(bytes, Bytes(&[]));
+
+        let mut bytes = data;
+        assert_eq!(bytes.read::<u64>(), Err(()));
+        assert_eq!(bytes, Bytes(&[]));
+
+        let mut bytes = data;
+        assert_eq!(bytes.read_slice::<u8>(0), Ok(&[][..]));
+        assert_eq!(bytes, data);
+
+        let mut bytes = data;
+        assert_eq!(bytes.read_slice::<u8>(4), Ok(data.0));
+        assert_eq!(bytes, Bytes(&[]));
+
+        let mut bytes = data;
+        assert_eq!(bytes.read_slice::<u8>(5), Err(()));
+        assert_eq!(bytes, Bytes(&[]));
+
+        assert_eq!(data.read_slice_at::<u8>(0, 0), Ok(&[][..]));
+        assert_eq!(data.read_slice_at::<u8>(4, 0), Ok(&[][..]));
+        assert_eq!(data.read_slice_at::<u8>(0, 4), Ok(data.0));
+        assert_eq!(data.read_slice_at::<u8>(1, 4), Err(()));
+
+        let data = Bytes(&[0x01, 0x02, 0x00, 0x04]);
+
+        let mut bytes = data;
+        assert_eq!(bytes.read_string(), Ok(&data.0[..2]));
+        assert_eq!(bytes.0, &data.0[3..]);
+
+        let mut bytes = data;
+        bytes.skip(3).unwrap();
+        assert_eq!(bytes.read_string(), Err(()));
+        assert_eq!(bytes.0, &[]);
+
+        assert_eq!(data.read_string_at(0), Ok(&data.0[..2]));
+        assert_eq!(data.read_string_at(1), Ok(&data.0[1..2]));
+        assert_eq!(data.read_string_at(2), Ok(&[][..]));
+        assert_eq!(data.read_string_at(3), Err(()));
+    }
+
+    #[test]
+    fn bytes_debug() {
+        assert_eq!(format!("{:?}", Bytes(&[])), "[]");
+        assert_eq!(format!("{:?}", Bytes(&[0x01])), "[0x01]");
+        assert_eq!(
+            format!(
+                "{:?}",
+                Bytes(&[0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08])
+            ),
+            "[0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08]"
+        );
+        assert_eq!(
+            format!(
+                "{:?}",
+                Bytes(&[0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09])
+            ),
+            "[0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, ...; 9]"
+        );
+    }
+}