1 files changed, 55 insertions, 0 deletions
diff --git a/vendor/der/src/asn1/integer/int.rs b/vendor/der/src/asn1/integer/int.rs
new file mode 100644
index 000000000..a9fe43890
--- /dev/null
+++ b/vendor/der/src/asn1/integer/int.rs
@@ -0,0 +1,55 @@
+//! Support for encoding negative integers
+
+use super::is_highest_bit_set;
+use crate::{ErrorKind, Length, Result, Writer};
+
+/// Decode an unsigned integer of the specified size.
+///
+/// Returns a byte array of the requested size containing a big endian integer.
+pub(super) fn decode_to_array<const N: usize>(bytes: &[u8]) -> Result<[u8; N]> {
+    match N.checked_sub(bytes.len()) {
+        Some(offset) => {
+            let mut output = [0xFFu8; N];
+            output[offset..].copy_from_slice(bytes);
+            Ok(output)
+        }
+        None => {
+            let expected_len = Length::try_from(N)?;
+            let actual_len = Length::try_from(bytes.len())?;
+
+            Err(ErrorKind::Incomplete {
+                expected_len,
+                actual_len,
+            }
+            .into())
+        }
+    }
+}
+
+/// Encode the given big endian bytes representing an integer as ASN.1 DER.
+pub(super) fn encode_bytes<W>(writer: &mut W, bytes: &[u8]) -> Result<()>
+where
+    W: Writer + ?Sized,
+{
+    writer.write(strip_leading_ones(bytes))
+}
+
+/// Get the encoded length for the given unsigned integer serialized as bytes.
+#[inline]
+pub(super) fn encoded_len(bytes: &[u8]) -> Result<Length> {
+    Length::try_from(strip_leading_ones(bytes).len())
+}
+
+/// Strip the leading all-ones bytes from the given byte slice.
+fn strip_leading_ones(mut bytes: &[u8]) -> &[u8] {
+    while let Some((byte, rest)) = bytes.split_first() {
+        if *byte == 0xFF && is_highest_bit_set(rest) {
+            bytes = rest;
+            continue;
+        }
+
+        break;
+    }
+
+    bytes
+}