codex-rs/mcp-server/src/main.rs

use codex_arg0::arg0_dispatch_or_else;
use codex_mcp_server::run_main;

fn main() -> anyhow::Result<()> {
    arg0_dispatch_or_else(|codex_linux_sandbox_exe| async move {
        run_main(codex_linux_sandbox_exe).await?;
        Ok(())
    })
}
fix: move arg0 handling out of codex-linux-sandbox and into its own crate (#1697) 2025-07-28 08:31:24 -07:00			`use codex_arg0::arg0_dispatch_or_else;`
feat: add mcp subcommand to CLI to run Codex as an MCP server (#934) Previously, running Codex as an MCP server required a standalone binary in our Cargo workspace, but this PR makes it available as a subcommand (`mcp`) of the main CLI. Ran this with: ``` RUST_LOG=debug npx @modelcontextprotocol/inspector cargo run --bin codex -- mcp ``` and verified it worked as expected in the inspector at `http://127.0.0.1:6274/`. 2025-05-14 13:15:41 -07:00			`use codex_mcp_server::run_main;`
feat: introduce mcp-server crate (#792) This introduces the `mcp-server` crate, which contains a barebones MCP server that provides an `echo` tool that echoes the user's request back to them. To test it out, I launched [modelcontextprotocol/inspector](https://github.com/modelcontextprotocol/inspector) like so: ``` mcp-server$ npx @modelcontextprotocol/inspector cargo run -- ``` and opened up `http://127.0.0.1:6274` in my browser: ![image](https://github.com/user-attachments/assets/83fc55d4-25c2-4497-80cd-e9702283ff93) I also had to make a small fix to `mcp-types`, adding `#[serde(untagged)]` to a number of `enum`s. 2025-05-02 17:25:58 -07:00
fix: overhaul how we spawn commands under seccomp/landlock on Linux (#1086) Historically, we spawned the Seatbelt and Landlock sandboxes in substantially different ways: For Seatbelt, we would run `/usr/bin/sandbox-exec` with our policy specified as an arg followed by the original command: https://github.com/openai/codex/blob/d1de7bb383552e8fadd94be79d65d188e00fd562/codex-rs/core/src/exec.rs#L147-L219 For Landlock/Seccomp, we would do `tokio::runtime::Builder::new_current_thread()`, _invoke Landlock/Seccomp APIs to modify the permissions of that new thread_, and then spawn the command: https://github.com/openai/codex/blob/d1de7bb383552e8fadd94be79d65d188e00fd562/codex-rs/core/src/exec_linux.rs#L28-L49 While it is neat that Landlock/Seccomp supports applying a policy to only one thread without having to apply it to the entire process, it requires us to maintain two different codepaths and is a bit harder to reason about. The tipping point was https://github.com/openai/codex/pull/1061, in which we had to start building up the `env` in an unexpected way for the existing Landlock/Seccomp approach to continue to work. This PR overhauls things so that we do similar things for Mac and Linux. It turned out that we were already building our own "helper binary" comparable to Mac's `sandbox-exec` as part of the `cli` crate: https://github.com/openai/codex/blob/d1de7bb383552e8fadd94be79d65d188e00fd562/codex-rs/cli/Cargo.toml#L10-L12 We originally created this to build a small binary to include with the Node.js version of the Codex CLI to provide support for Linux sandboxing. Though the sticky bit is that, at this point, we still want to deploy the Rust version of Codex as a single, standalone binary rather than a CLI and a supporting sandboxing binary. To satisfy this goal, we use "the arg0 trick," in which we: * use `std::env::current_exe()` to get the path to the CLI that is currently running * use the CLI as the `program` for the `Command` * set `"codex-linux-sandbox"` as arg0 for the `Command` A CLI that supports sandboxing should check arg0 at the start of the program. If it is `"codex-linux-sandbox"`, it must invoke `codex_linux_sandbox::run_main()`, which runs the CLI as if it were `codex-linux-sandbox`. When acting as `codex-linux-sandbox`, we make the appropriate Landlock/Seccomp API calls and then use `execvp(3)` to spawn the original command, so do _replace_ the process rather than spawn a subprocess. Incidentally, we do this before starting the Tokio runtime, so the process should only have one thread when `execvp(3)` is called. Because the `core` crate that needs to spawn the Linux sandboxing is not a CLI in its own right, this means that every CLI that includes `core` and relies on this behavior has to (1) implement it and (2) provide the path to the sandboxing executable. While the path is almost always `std::env::current_exe()`, we needed to make this configurable for integration tests, so `Config` now has a `codex_linux_sandbox_exe: Option<PathBuf>` property to facilitate threading this through, introduced in https://github.com/openai/codex/pull/1089. This common pattern is now captured in `codex_linux_sandbox::run_with_sandbox()` and all of the `main.rs` functions that should use it have been updated as part of this PR. The `codex-linux-sandbox` crate added to the Cargo workspace as part of this PR now has the bulk of the Landlock/Seccomp logic, which makes `core` a bit simpler. Indeed, `core/src/exec_linux.rs` and `core/src/landlock.rs` were removed/ported as part of this PR. I also moved the unit tests for this code into an integration test, `linux-sandbox/tests/landlock.rs`, in which I use `env!("CARGO_BIN_EXE_codex-linux-sandbox")` as the value for `codex_linux_sandbox_exe` since `std::env::current_exe()` is not appropriate in that case. 2025-05-23 11:37:07 -07:00			`fn main() -> anyhow::Result<()> {`
fix: move arg0 handling out of codex-linux-sandbox and into its own crate (#1697) 2025-07-28 08:31:24 -07:00			`arg0_dispatch_or_else(\|codex_linux_sandbox_exe\| async move {`
fix: overhaul how we spawn commands under seccomp/landlock on Linux (#1086) Historically, we spawned the Seatbelt and Landlock sandboxes in substantially different ways: For Seatbelt, we would run `/usr/bin/sandbox-exec` with our policy specified as an arg followed by the original command: https://github.com/openai/codex/blob/d1de7bb383552e8fadd94be79d65d188e00fd562/codex-rs/core/src/exec.rs#L147-L219 For Landlock/Seccomp, we would do `tokio::runtime::Builder::new_current_thread()`, _invoke Landlock/Seccomp APIs to modify the permissions of that new thread_, and then spawn the command: https://github.com/openai/codex/blob/d1de7bb383552e8fadd94be79d65d188e00fd562/codex-rs/core/src/exec_linux.rs#L28-L49 While it is neat that Landlock/Seccomp supports applying a policy to only one thread without having to apply it to the entire process, it requires us to maintain two different codepaths and is a bit harder to reason about. The tipping point was https://github.com/openai/codex/pull/1061, in which we had to start building up the `env` in an unexpected way for the existing Landlock/Seccomp approach to continue to work. This PR overhauls things so that we do similar things for Mac and Linux. It turned out that we were already building our own "helper binary" comparable to Mac's `sandbox-exec` as part of the `cli` crate: https://github.com/openai/codex/blob/d1de7bb383552e8fadd94be79d65d188e00fd562/codex-rs/cli/Cargo.toml#L10-L12 We originally created this to build a small binary to include with the Node.js version of the Codex CLI to provide support for Linux sandboxing. Though the sticky bit is that, at this point, we still want to deploy the Rust version of Codex as a single, standalone binary rather than a CLI and a supporting sandboxing binary. To satisfy this goal, we use "the arg0 trick," in which we: * use `std::env::current_exe()` to get the path to the CLI that is currently running * use the CLI as the `program` for the `Command` * set `"codex-linux-sandbox"` as arg0 for the `Command` A CLI that supports sandboxing should check arg0 at the start of the program. If it is `"codex-linux-sandbox"`, it must invoke `codex_linux_sandbox::run_main()`, which runs the CLI as if it were `codex-linux-sandbox`. When acting as `codex-linux-sandbox`, we make the appropriate Landlock/Seccomp API calls and then use `execvp(3)` to spawn the original command, so do _replace_ the process rather than spawn a subprocess. Incidentally, we do this before starting the Tokio runtime, so the process should only have one thread when `execvp(3)` is called. Because the `core` crate that needs to spawn the Linux sandboxing is not a CLI in its own right, this means that every CLI that includes `core` and relies on this behavior has to (1) implement it and (2) provide the path to the sandboxing executable. While the path is almost always `std::env::current_exe()`, we needed to make this configurable for integration tests, so `Config` now has a `codex_linux_sandbox_exe: Option<PathBuf>` property to facilitate threading this through, introduced in https://github.com/openai/codex/pull/1089. This common pattern is now captured in `codex_linux_sandbox::run_with_sandbox()` and all of the `main.rs` functions that should use it have been updated as part of this PR. The `codex-linux-sandbox` crate added to the Cargo workspace as part of this PR now has the bulk of the Landlock/Seccomp logic, which makes `core` a bit simpler. Indeed, `core/src/exec_linux.rs` and `core/src/landlock.rs` were removed/ported as part of this PR. I also moved the unit tests for this code into an integration test, `linux-sandbox/tests/landlock.rs`, in which I use `env!("CARGO_BIN_EXE_codex-linux-sandbox")` as the value for `codex_linux_sandbox_exe` since `std::env::current_exe()` is not appropriate in that case. 2025-05-23 11:37:07 -07:00			`run_main(codex_linux_sandbox_exe).await?;`
			`Ok(())`
			`})`
feat: introduce mcp-server crate (#792) This introduces the `mcp-server` crate, which contains a barebones MCP server that provides an `echo` tool that echoes the user's request back to them. To test it out, I launched [modelcontextprotocol/inspector](https://github.com/modelcontextprotocol/inspector) like so: ``` mcp-server$ npx @modelcontextprotocol/inspector cargo run -- ``` and opened up `http://127.0.0.1:6274` in my browser: ![image](https://github.com/user-attachments/assets/83fc55d4-25c2-4497-80cd-e9702283ff93) I also had to make a small fix to `mcp-types`, adding `#[serde(untagged)]` to a number of `enum`s. 2025-05-02 17:25:58 -07:00			`}`