feat(rdma): add optional object transfer integration

.gitignore

@@ -27,3 +27,7 @@ coverage/
 # Cargo lock for library crates (keep for binary)
 # Cargo.lock
 CLAUDE.md
+
+# The independent opt-in build owns its artifacts and lockfile.
+/rdma/target/
+/rdma/Cargo.lock

.gitmodules

@@ -0,0 +1,4 @@
+[submodule "vendor/rustfs-ucx"]
+	path = vendor/rustfs-ucx
+	url = git@github.com:rustfs/rustfs-ucx.git
+	branch = s3-rdma

Cargo.toml

@@ -1,4 +1,5 @@
 [workspace]
+exclude = ["rdma", "vendor/rustfs-ucx"]
 resolver = "3"
 members = ["crates/cli", "crates/core", "crates/s3"]
 

README.md

@@ -71,6 +71,9 @@ cd cli
 cargo build --release
 ```
 
+Optional object-data interfaces and the explicit private build are documented
+in [RDMA builds](docs/rdma-build.md). The ordinary build requires no private source.
+
 ## Quick Start
 
 ### Configure Aliases

crates/cli/src/commands/mod.rs

@@ -8,7 +8,10 @@ use std::io::{IsTerminal, stderr, stdout};
 
 use clap::{Parser, Subcommand, ValueEnum};
 use rc_core::config::Defaults;
-use rc_core::{ConfigManager, RequestHeader, set_global_request_headers};
+use rc_core::{
+    ConfigManager, DataTransportMode, RequestHeader, set_global_data_transport_mode,
+    set_global_request_headers,
+};
 
 use crate::exit_code::ExitCode;
 use crate::output::{Formatter, OutputConfig};
@@ -90,6 +93,10 @@ fn validate_version_selector(version_id: Option<&str>, rewind: Option<&str>) ->
 #[command(after_help = COMPATIBILITY_AFTER_HELP)]
 #[command(propagate_version = true)]
 pub struct Cli {
+    /// Object data transport: http, auto, or rdma (requires an installed provider)
+    #[arg(long, global = true, default_value = "http")]
+    pub data_transport: DataTransportMode,
+
     /// Output format: auto-detect, human-readable, or JSON
     #[arg(long, global = true, value_enum)]
     pub format: Option<OutputFormat>,
@@ -357,6 +364,7 @@ pub enum Commands {
 
 /// Execute the CLI command and return an exit code
 pub async fn execute(cli: Cli) -> ExitCode {
+    set_global_data_transport_mode(cli.data_transport);
     set_global_request_headers(cli.request_headers.clone());
     let cli_output_options = GlobalOutputOptions::from_cli(&cli);
     let defaults = match ConfigManager::new() {
@@ -564,6 +572,16 @@ pub async fn execute(cli: Cli) -> ExitCode {
 #[cfg(test)]
 mod tests {
     use super::*;
+
+    #[test]
+    fn data_transport_selection_is_explicit_and_http_is_default() {
+        let cli = Cli::try_parse_from(["rc", "alias", "list"]).expect("default CLI");
+        assert_eq!(cli.data_transport, DataTransportMode::Http);
+        let cli = Cli::try_parse_from(["rc", "--data-transport", "rdma", "alias", "list"])
+            .expect("explicit external data transport");
+        assert_eq!(cli.data_transport, DataTransportMode::Rdma);
+        assert!(Cli::try_parse_from(["rc", "--data-transport", "udp", "alias", "list"]).is_err());
+    }
     use clap::Parser;
 
     #[test]

crates/cli/src/commands/rb.rs

@@ -862,6 +862,9 @@ fn bucket_delete_message(error: &Error, bucket: &str) -> String {
 
 fn exit_code_for_error(error: &Error) -> ExitCode {
     match error {
+        Error::DataTransfer { .. } => {
+            ExitCode::from_i32(error.exit_code()).unwrap_or(ExitCode::GeneralError)
+        }
         Error::InvalidPath(_) | Error::Config(_) => ExitCode::UsageError,
         Error::Network(_) => ExitCode::NetworkError,
         Error::Auth(_) => ExitCode::AuthError,