Improve Cognito Login Pair Array

Source/AwsCommonRuntimeKit/auth/credentials/CredentialsProvider.swift

@@ -11,7 +11,7 @@ public protocol CredentialsProviding {
 }
 
 /// A pair defining an identity provider and a valid login token sourced from it.
-public struct CognitoLoginPair: CStruct {
+public class CognitoLoginPair: CStruct {
     public var IdentityProviderName: String
     public var IdentityProviderToken: String
 
@@ -20,17 +20,20 @@ public struct CognitoLoginPair: CStruct {
         self.IdentityProviderName = identityProviderName
         self.IdentityProviderToken = identityProviderToken
     }
-
+
+    private var name_buffer: aws_byte_buf = aws_byte_buf()
+    private var token_buffer: aws_byte_buf = aws_byte_buf()
     typealias RawType = aws_cognito_identity_provider_token_pair
     func withCStruct<Result>(_ body: (aws_cognito_identity_provider_token_pair) -> Result) -> Result {
         var token_pair = aws_cognito_identity_provider_token_pair()
-
-        return withByteCursorFromStrings(IdentityProviderName,
-                                         IdentityProviderToken) { identityProviderNameCursor, IdentityProviderTokenCursor in
-            token_pair.identity_provider_name = identityProviderNameCursor
-            token_pair.identity_provider_token = IdentityProviderTokenCursor
-            return body(token_pair)
-        }
+        token_pair.identity_provider_name = aws_byte_cursor_from_buf(&self.name_buffer)
+        token_pair.identity_provider_token = aws_byte_cursor_from_buf(&self.token_buffer)
+        return body(token_pair)
+    }
+
+    deinit{
+        aws_byte_buf_clean_up(&self.name_buffer)
+        aws_byte_buf_clean_up(&self.token_buffer)
     }
 }
 

Source/AwsCommonRuntimeKit/crt/CStruct.swift

@@ -20,8 +20,8 @@ extension CStruct {
 }
 
 extension Array where Element: CStruct {
-    /// Convert a CStruct Array into raw c pointer. The function would not do a deep copy of the CStruct element. If you required a deep copy
-    /// make sure to clean up the memory underneath. 
+    /// Convert a CStruct Array into raw c pointer. However, as the conversion made by withCPointer will be unavailable out of 
+    /// the scope, we need to make sure that we have a copy of the underlying memory. 
     func withAWSArrayList<Result>(_ body: (OpaquePointer?) throws -> Result) rethrows -> Result {
         guard capacity != 0 else {
             return try body(nil)
@@ -42,9 +42,11 @@ extension Array where Element: CStruct {
         forEach {
             $0.withCPointer {
                 // `aws_array_list_push_back` will do a memory copy of $0 into array_list, but it would
-                // not do a deep copy there.
+                // not do a deep copy there. For example, if the c struct contains a aws_byte_cursor, it
+                // would only copy the cursor, not the underlying memory it points to, it is possible that
+                // the memory will be unavailable out of the scope.
                 guard aws_array_list_push_back(array_list, $0) == AWS_OP_SUCCESS else {
-                    fatalError("Unable to add user property")
+                    fatalError("Unable to add array element")
                 }
             }
         }