From 12a7a24694dddcb96202af36774b94766532f30a Mon Sep 17 00:00:00 2001
From: Emi Tatsuo <emi@alchemi.dev>
Date: Wed, 16 Dec 2020 16:45:35 -0500
Subject: [PATCH] Split off DeserializeError into its own thing

---
 src/user_management/mod.rs | 85 +++++++++++++++++++++++++++++++-------
 1 file changed, 71 insertions(+), 14 deletions(-)

diff --git a/src/user_management/mod.rs b/src/user_management/mod.rs
index 8dd8a44..fe9141c 100644
--- a/src/user_management/mod.rs
+++ b/src/user_management/mod.rs
@@ -59,16 +59,13 @@ pub enum UserManagerError {
 
     /// There was an error deserializing from the database
     ///
-    /// This likely indicates that the database was generated with
-    /// a different version of the software than is curretly being used, either because
-    /// the UserData struct has changed, or because kochab itself has updated it's schema.
+    /// This likely indicates that the database was generated with a different version of
+    /// the software than is curretly being used, either because the UserData struct has
+    /// changed, or because kochab itself has updated it's schema.
     ///
     /// Recommended handling:  Log a visible error and exit.  Recommend seeking a database
     /// migration script or deleting the database
-    DeserializeBincodeError(bincode::Error),
-
-    /// A different version of [`UserManagerError::DeserializeBincodeError`]
-    DeserializeUtf8Error(std::str::Utf8Error),
+    DeserializeError(DeserializeError),
 
     #[cfg(feature = "user_management_advanced")]
     /// There was an error hashing or checking the user's password.
@@ -92,13 +89,13 @@ impl From<sled::transaction::TransactionError> for UserManagerError {
 
 impl From<bincode::Error> for UserManagerError {
     fn from(error: bincode::Error) -> Self {
-        Self::DeserializeBincodeError(error)
+        Self::DeserializeError(error.into())
     }
 }
 
 impl From<std::str::Utf8Error> for UserManagerError {
     fn from(error: std::str::Utf8Error) -> Self {
-        Self::DeserializeUtf8Error(error)
+        Self::DeserializeError(error.into())
     }
 }
 
@@ -114,8 +111,7 @@ impl std::error::Error for UserManagerError {
         match self {
             Self::DatabaseError(e) => Some(e),
             Self::DatabaseTransactionError(e) => Some(e),
-            Self::DeserializeBincodeError(e) => Some(e),
-            Self::DeserializeUtf8Error(e) => Some(e),
+            Self::DeserializeError(e) => Some(e),
             #[cfg(feature = "user_management_advanced")]
             Self::Argon2Error(e) => Some(e),
             _ => None
@@ -134,10 +130,8 @@ impl std::fmt::Display for UserManagerError {
                 write!(f, "Error accessing the user database: {}", e),
             Self::DatabaseTransactionError(e) =>
                 write!(f, "Error accessing the user database: {}", e),
-            Self::DeserializeBincodeError(e) =>
+            Self::DeserializeError(e) =>
                 write!(f, "Recieved messy data from database, possible corruption: {}", e),
-            Self::DeserializeUtf8Error(e) =>
-                write!(f, "Recieved invalid UTF-8 from database, possible corruption: {}", e),
             #[cfg(feature = "user_management_advanced")]
             Self::Argon2Error(e) =>
                 write!(f, "Argon2 Error, likely malformed password hash, possible database corruption: {}", e),
@@ -145,5 +139,68 @@ impl std::fmt::Display for UserManagerError {
     }
 }
 
+#[derive(Debug)]
+/// Indicates an error deserializing from the database
+///
+/// This likely indicates that the database was generated with
+/// a different version of the software than is curretly being used, either because
+/// the UserData struct has changed, or because kochab itself has updated it's schema.
+pub enum DeserializeError {
+
+    /// There was an error deserializing an entire struct
+    ///
+    /// Most likely indicates that the struct itself changed, i.e. between versions.
+    StructError(bincode::Error),
+
+    /// The was an error deserializing a userid
+    ///
+    /// Likely because too many bytes were received.  If you are getting this, you are
+    /// likely using a pre-0.1.0 version of kochab, and should update to the latest
+    /// version, or you're using a database that was created by a version of kochab that
+    /// was released after the one you're currently using.  However, as of right now, no
+    /// such release exists or is planned.
+    UidError(std::str::Utf8Error),
+
+    /// There was an error deserializing a username
+    ///
+    /// Indicates data corruption or a misaligned database version
+    UsernameError(std::str::Utf8Error),
+}
+
+impl From<bincode::Error> for DeserializeError {
+    fn from(error: bincode::Error) -> Self {
+        Self::StructError(error)
+    }
+}
+
+impl From<std::str::Utf8Error> for DeserializeError {
+    fn from(error: std::str::Utf8Error) -> Self {
+        Self::UsernameError(error)
+    }
+}
+
+impl std::error::Error for DeserializeError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::StructError(e) => Some(e),
+            Self::UidError(e) => Some(e),
+            Self::UsernameError(e) => Some(e),
+        }
+    }
+}
+
+impl std::fmt::Display for DeserializeError {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::result::Result<(), std::fmt::Error> {
+        match self {
+            Self::StructError(e) =>
+                write!(f, "Failed to deserialize struct: {}", e),
+            Self::UidError(e) =>
+                write!(f, "Got wrong number of bytes while deserializing user ID: {}", e),
+            Self::UsernameError(e) =>
+                write!(f, "Got invalid UTF-8 instead of username: {}", e),
+        }
+    }
+}
+
 /// A result type returned by many methods within the [`user_management`] module
 pub type Result<T> = std::result::Result<T, UserManagerError>;