From 69f44d9301c54168e9eaaf046db3d478e6739173 Mon Sep 17 00:00:00 2001
From: Tobin Harding <me@tobin.cc>
Date: Fri, 7 Jan 2022 10:31:15 +1100
Subject: [PATCH] Manually implement Debug for SerializedSignature

Currently we have an implementation of `Debug` (also used by `Display`)
for `Signature` that first converts the sig to a `SerializedSignature`
then prints it as hex.

We would like to have an implementation of `Debug` for
`SerializedSignature`, this cannot be derived because of the `data: [u8;
field]`. We can manually implement `Debug` for `SerializedSignature`
exactly as it is currently done for `Signature` and call this new
implementation from `Signature::fmt()`.

This code path is already tested in `lib.rs` in the test function
`signature_display`.
---
 src/ecdsa/mod.rs | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/ecdsa/mod.rs b/src/ecdsa/mod.rs
index cedd844..52b276c 100644
--- a/src/ecdsa/mod.rs
+++ b/src/ecdsa/mod.rs
@@ -32,7 +32,19 @@ impl fmt::Debug for Signature {
 impl fmt::Display for Signature {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let sig = self.serialize_der();
-        for v in sig.iter() {
+        sig.fmt(f)
+    }
+}
+
+impl fmt::Debug for SerializedSignature {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(self, f)
+    }
+}
+
+impl fmt::Display for SerializedSignature {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        for v in self.data.iter().take(self.len) {
             write!(f, "{:02x}", v)?;
         }
         Ok(())