Add borsh impls for SignedEmbeddedEllipticCurveKeys

substrate/primitives/src/lib.rs

@@ -102,3 +102,39 @@ pub mod prelude {
   pub use crate::validator_sets::{Session, ValidatorSet, ExternalValidatorSet, Slash, SlashReport};
   pub use crate::instructions::*;
 }
+
+#[doc(hidden)]
+#[cfg(feature = "non_canonical_scale_derivations")]
+pub fn read_scale_as_borsh<T: borsh::BorshDeserialize, I: scale::Input>(
+  input: &mut I,
+) -> Result<T, scale::Error> {
+  struct ScaleRead<'a, I: scale::Input>(&'a mut I, Option<scale::Error>);
+  impl<I: scale::Input> borsh::io::Read for ScaleRead<'_, I> {
+    fn read(&mut self, buf: &mut [u8]) -> borsh::io::Result<usize> {
+      let remaining_len = self.0.remaining_len().map_err(|err| {
+        self.1 = Some(err);
+        #[allow(clippy::io_other_error)]
+        borsh::io::Error::new(borsh::io::ErrorKind::Other, "")
+      })?;
+      // If we're still calling `read`, we try to read at least one more byte
+      let to_read = buf.len().min(remaining_len.unwrap_or(1));
+      // This may not be _allocated_ making this over-zealous, but it's the best we can do
+      self.0.on_before_alloc_mem(to_read).map_err(|err| {
+        self.1 = Some(err);
+        #[allow(clippy::io_other_error)]
+        borsh::io::Error::new(borsh::io::ErrorKind::Other, "")
+      })?;
+      self.0.read(&mut buf[.. to_read]).map_err(|err| {
+        self.1 = Some(err);
+        #[allow(clippy::io_other_error)]
+        borsh::io::Error::new(borsh::io::ErrorKind::Other, "")
+      })?;
+      Ok(to_read)
+    }
+  }
+  let mut input = ScaleRead(input, None);
+  match T::deserialize_reader(&mut input) {
+    Ok(res) => Ok(res),
+    Err(_) => Err(input.1.unwrap()),
+  }
+}