Improve error message for a malformed packet

Suggested by Neal Walfield.

Found by clippy lint useless_format:
https://rust-lang.github.io/rust-clippy/master/index.html#useless_format

2 files changed, 5 insertions, 4 deletions

diff --git a/openpgp/src/packet/pkesk.rs b/openpgp/src/packet/pkesk.rs
index 40e7bc37..50ec187a 100644
--- a/openpgp/src/packet/pkesk.rs
+++ b/openpgp/src/packet/pkesk.rs
@@ -161,7 +161,8 @@ impl PKESK3 {
 
         if key_rgn.len() != sym_algo.key_size()? {
             return Err(Error::MalformedPacket(
-                format!("session key has the wrong size")).into());
+                format!("session key has the wrong size (got: {}, expected: {})",
+                        key_rgn.len(), sym_algo.key_size()?)).into())
         }
 
         key.copy_from_slice(&plain[key_rgn]);
@@ -174,7 +175,7 @@ impl PKESK3 {
         if their_checksum == our_checksum {
             Ok((sym_algo, key))
         } else {
-            Err(Error::MalformedPacket(format!("key checksum wrong"))
+            Err(Error::MalformedPacket("key checksum wrong".to_string())
                 .into())
         }
     }
diff --git a/openpgp/src/parse.rs b/openpgp/src/parse.rs
index 549b94f2..eacded35 100644
--- a/openpgp/src/parse.rs
+++ b/openpgp/src/parse.rs
@@ -5185,11 +5185,11 @@ impl<'a> PacketParser<'a> {
 
         if self.content_was_read {
             return Err(Error::InvalidOperation(
-                format!("Packet's content has already been read.")).into());
+                "Packet's content has already been read.".to_string()).into());
         }
         if ! self.encrypted {
             return Err(Error::InvalidOperation(
-                format!("Packet not encrypted.")).into());
+                "Packet not encrypted.".to_string()).into());
         }
 
         if algo.key_size()? != key.len () {