Support LDK's new LengthReadable trait

Because we're always reading from a fixed-length buffer anyway, we
can always support it with our existing code.

Author: TheBlueMatt

c-bindings-gen/src/main.rs

@@ -108,7 +108,7 @@ fn maybe_convert_trait_impl<W: std::io::Write>(w: &mut W, trait_path: &syn::Path
 				}
 				writeln!(w, "}}").unwrap();
 			},
-			"lightning::util::ser::Readable"|"lightning::util::ser::ReadableArgs"|"lightning::util::ser::MaybeReadable" => {
+			"lightning::util::ser::Readable"|"lightning::util::ser::LengthReadable"|"lightning::util::ser::ReadableArgs"|"lightning::util::ser::MaybeReadable" => {
 				// Create the Result<Object, DecodeError> syn::Type
 				let mut res_ty: syn::Type = parse_quote!(Result<#for_ty, lightning::ln::msgs::DecodeError>);
 

c-bindings-gen/src/types.rs

@@ -1160,7 +1160,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 			|"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
 				if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 
-			"lightning::io::Read" => Some("crate::c_types::u8slice"),
+			"lightning::util::ser::LengthLimitedRead"|"lightning::io::Read" => Some("crate::c_types::u8slice"),
 
 			_ => None,
 		}
@@ -1287,7 +1287,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 			"lightning::chain::ClaimId" if is_ref=> Some("&::lightning::chain::ClaimId( unsafe { *"),
 
 			// List of traits we map (possibly during processing of other files):
-			"lightning::io::Read" => Some("&mut "),
+			"lightning::util::ser::LengthLimitedRead"|"lightning::io::Read" => Some("&mut "),
 
 			_ => None,
 		}.map(|s| s.to_owned())
@@ -1399,7 +1399,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 				if is_ref => Some(" })"),
 
 			// List of traits we map (possibly during processing of other files):
-			"lightning::io::Read" => Some(".to_reader()"),
+			"lightning::util::ser::LengthLimitedRead"|"lightning::io::Read" => Some(".to_slice()"),
 
 			_ => None,
 		}.map(|s| s.to_owned())
@@ -1530,7 +1530,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 			|"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
 				if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
 
-			"lightning::io::Read" => Some("crate::c_types::u8slice::from_vec(&crate::c_types::reader_to_vec("),
+			"lightning::util::ser::LengthLimitedRead"|"lightning::io::Read" => Some("crate::c_types::u8slice::from_vec(&crate::c_types::reader_to_vec("),
 
 			_ => None,
 		}.map(|s| s.to_owned())
@@ -1640,7 +1640,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 			|"lightning::sign::KeyMaterial"|"lightning::chain::ClaimId"
 				if !is_ref => Some(".0 }"),
 
-			"lightning::io::Read" => Some("))"),
+			"lightning::util::ser::LengthLimitedRead"|"lightning::io::Read" => Some("))"),
 
 			_ => None,
 		}.map(|s| s.to_owned())
@@ -1661,7 +1661,7 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 	/// TODO: We should never need to use this!
 	fn real_rust_type_mapping<'equiv>(&self, thing: &'equiv str) -> &'equiv str {
 		match thing {
-			"lightning::io::Read" => "crate::c_types::io::Read",
+			"lightning::util::ser::LengthLimitedRead"|"lightning::io::Read" => "crate::c_types::io::Read",
 			_ => thing,
 		}
 	}

lightning-c-bindings/src/c_types/mod.rs

@@ -880,8 +880,8 @@ pub(crate) fn serialize_obj<I: lightning::util::ser::Writeable>(i: &I) -> derive
 	i.write(&mut out).unwrap();
 	derived::CVec_u8Z::from(out.0)
 }
-pub(crate) fn deserialize_obj<I: lightning::util::ser::Readable>(s: u8slice) -> Result<I, lightning::ln::msgs::DecodeError> {
-	I::read(&mut s.to_slice())
+pub(crate) fn deserialize_obj<I: lightning::util::ser::LengthReadable>(s: u8slice) -> Result<I, lightning::ln::msgs::DecodeError> {
+	I::read_from_fixed_length_buffer(&mut s.to_slice())
 }
 pub(crate) fn maybe_deserialize_obj<I: lightning::util::ser::MaybeReadable>(s: u8slice) -> Result<Option<I>, lightning::ln::msgs::DecodeError> {
 	I::read(&mut s.to_slice())