FAIL: try to make the transport configurable after being boxed, but… (#450)

…that would force it to be 'static, which is something we excplicitly
cannot have. We need references to be contained within, if I remember
correctly.

Author: Byron

git-repository/src/remote/connection/mod.rs

@@ -24,6 +24,7 @@ mod access {
         remote::{connection::CredentialsFn, Connection},
         Remote,
     };
+    use std::any::Any;
 
     /// Builder
     impl<'a, 'repo, T, P> Connection<'a, 'repo, T, P> {
@@ -62,6 +63,31 @@ mod access {
         pub fn remote(&self) -> &Remote<'repo> {
             self.remote
         }
+
+        /// Return the connection's transport.
+        pub fn transport(&self) -> &T {
+            &self.transport
+        }
+    }
+
+    /// Access to the transport if it can be downcast to a particular type.
+    impl<'a, 'repo, T, P> Connection<'a, 'repo, T, P>
+    where
+        T: crate::protocol::transport::client::Transport + 'static,
+    {
+        /// Try to cast our transport `T` into `U`, and pass it to `f` to allow any kind of configuration.
+        ///
+        /// Note that if the case fails and `f` is not called at all, `false` is returned.
+        pub fn configure_transport<U: 'static, E>(
+            &mut self,
+            f: impl FnOnce(&mut U) -> Result<(), E>,
+        ) -> Result<bool, E> {
+            let transport = (&mut self.transport) as &mut dyn Any;
+            match transport.downcast_mut::<U>() {
+                Some(transport) => f(transport).map(|_| true),
+                None => Ok(false),
+            }
+        }
     }
 }
 

git-repository/src/remote/connection/ref_map.rs

@@ -134,15 +134,15 @@ where
                 &mut credentials_storage
             }
         };
+        let transport = &mut self.transport;
         let mut outcome =
-            git_protocol::fetch::handshake(&mut self.transport, authenticate, extra_parameters, &mut self.progress)
-                .await?;
+            git_protocol::fetch::handshake(&mut *transport, authenticate, extra_parameters, &mut self.progress).await?;
         let refs = match outcome.refs.take() {
             Some(refs) => refs,
             None => {
                 let specs = &self.remote.fetch_specs;
                 git_protocol::fetch::refs(
-                    &mut self.transport,
+                    transport,
                     outcome.server_protocol_version,
                     &outcome.capabilities,
                     |_capabilities, arguments, _features| {

git-transport/src/client/blocking_io/file.rs

@@ -1,3 +1,4 @@
+use std::any::Any;
 use std::process::{self, Command, Stdio};
 
 use bstr::{BString, ByteSlice};
@@ -83,6 +84,10 @@ impl SpawnProcessOnDemand {
 }
 
 impl client::TransportWithoutIO for SpawnProcessOnDemand {
+    fn as_any_mut(&mut self) -> &mut dyn Any {
+        self
+    }
+
     fn request(
         &mut self,
         write_mode: WriteMode,

git-transport/src/client/blocking_io/http/mod.rs

@@ -1,3 +1,4 @@
+use std::any::Any;
 use std::{
     borrow::Cow,
     convert::Infallible,
@@ -99,6 +100,10 @@ fn append_url(base: &str, suffix: &str) -> String {
 }
 
 impl<H: Http> client::TransportWithoutIO for Transport<H> {
+    fn as_any_mut(&mut self) -> &mut dyn Any {
+        self
+    }
+
     fn set_identity(&mut self, identity: git_sec::identity::Account) -> Result<(), client::Error> {
         self.identity = Some(identity);
         Ok(())

git-transport/src/client/git/blocking_io.rs

@@ -1,3 +1,4 @@
+use std::any::Any;
 use std::io::Write;
 
 use bstr::BString;
@@ -13,6 +14,10 @@ where
     R: std::io::Read,
     W: std::io::Write,
 {
+    fn as_any_mut(&mut self) -> &mut dyn Any {
+        self
+    }
+
     fn request(
         &mut self,
         write_mode: client::WriteMode,

git-transport/src/client/traits.rs

@@ -1,3 +1,4 @@
+use std::any::Any;
 use std::ops::{Deref, DerefMut};
 
 #[cfg(any(feature = "blocking-client", feature = "async-client"))]
@@ -7,6 +8,11 @@ use crate::{client::Error, Protocol};
 /// This trait represents all transport related functions that don't require any input/output to be done which helps
 /// implementation to share more code across blocking and async programs.
 pub trait TransportWithoutIO {
+    /// Cast this type as dyn trait to allow casting it back to a known concrete type.
+    ///
+    /// This is useful for configuration after a boxed transport implementation has been crated.
+    fn as_any_mut(&mut self) -> &mut dyn std::any::Any;
+
     /// If the handshake or subsequent reads failed with [std::io::ErrorKind::PermissionDenied], use this method to
     /// inform the transport layer about the identity to use for subsequent calls.
     /// If authentication continues to fail even with an identity set, consider communicating this to the provider
@@ -50,6 +56,10 @@ pub trait TransportWithoutIO {
 
 // Would be nice if the box implementation could auto-forward to all implemented traits.
 impl<T: TransportWithoutIO + ?Sized> TransportWithoutIO for Box<T> {
+    fn as_any_mut(&mut self) -> &mut dyn Any {
+        self
+    }
+
     fn set_identity(&mut self, identity: git_sec::identity::Account) -> Result<(), Error> {
         self.deref_mut().set_identity(identity)
     }
@@ -73,6 +83,10 @@ impl<T: TransportWithoutIO + ?Sized> TransportWithoutIO for Box<T> {
 }
 
 impl<T: TransportWithoutIO + ?Sized> TransportWithoutIO for &mut T {
+    fn as_any_mut(&mut self) -> &mut dyn Any {
+        self
+    }
+
     fn set_identity(&mut self, identity: git_sec::identity::Account) -> Result<(), Error> {
         self.deref_mut().set_identity(identity)
     }