From 9102255854eab4310d7d90ab64215bf3f2e06850 Mon Sep 17 00:00:00 2001
From: Michael Bolin <mbolin@openai.com>
Date: Mon, 28 Jul 2025 08:31:24 -0700
Subject: [PATCH] fix: move arg0 handling out of codex-linux-sandbox and into
 its own crate (#1697)

---
 codex-rs/Cargo.lock               | 20 ++++++---
 codex-rs/Cargo.toml               |  1 +
 codex-rs/arg0/Cargo.toml          | 18 ++++++++
 codex-rs/arg0/src/lib.rs          | 68 +++++++++++++++++++++++++++++++
 codex-rs/cli/Cargo.toml           |  2 +-
 codex-rs/cli/src/main.rs          |  3 +-
 codex-rs/exec/Cargo.toml          |  2 +-
 codex-rs/exec/src/main.rs         |  3 +-
 codex-rs/linux-sandbox/Cargo.toml | 14 +++----
 codex-rs/linux-sandbox/src/lib.rs | 65 +----------------------------
 codex-rs/mcp-server/Cargo.toml    |  2 +-
 codex-rs/mcp-server/src/main.rs   |  3 +-
 codex-rs/tui/Cargo.toml           |  2 +-
 codex-rs/tui/src/main.rs          |  3 +-
 14 files changed, 121 insertions(+), 85 deletions(-)
 create mode 100644 codex-rs/arg0/Cargo.toml
 create mode 100644 codex-rs/arg0/src/lib.rs

diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index da3bd50a..f3903d6e 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -605,6 +605,17 @@ dependencies = [
  "tree-sitter-bash",
 ]
 
+[[package]]
+name = "codex-arg0"
+version = "0.0.0"
+dependencies = [
+ "anyhow",
+ "codex-core",
+ "codex-linux-sandbox",
+ "dotenvy",
+ "tokio",
+]
+
 [[package]]
 name = "codex-chatgpt"
 version = "0.0.0"
@@ -628,11 +639,11 @@ dependencies = [
  "anyhow",
  "clap",
  "clap_complete",
+ "codex-arg0",
  "codex-chatgpt",
  "codex-common",
  "codex-core",
  "codex-exec",
- "codex-linux-sandbox",
  "codex-login",
  "codex-mcp-server",
  "codex-tui",
@@ -709,9 +720,9 @@ dependencies = [
  "anyhow",
  "chrono",
  "clap",
+ "codex-arg0",
  "codex-common",
  "codex-core",
- "codex-linux-sandbox",
  "owo-colors",
  "serde_json",
  "shlex",
@@ -761,7 +772,6 @@ dependencies = [
  "clap",
  "codex-common",
  "codex-core",
- "dotenvy",
  "landlock",
  "libc",
  "seccompiler",
@@ -799,8 +809,8 @@ version = "0.0.0"
 dependencies = [
  "anyhow",
  "assert_cmd",
+ "codex-arg0",
  "codex-core",
- "codex-linux-sandbox",
  "mcp-types",
  "mcp_test_support",
  "pretty_assertions",
@@ -826,10 +836,10 @@ dependencies = [
  "base64 0.22.1",
  "clap",
  "codex-ansi-escape",
+ "codex-arg0",
  "codex-common",
  "codex-core",
  "codex-file-search",
- "codex-linux-sandbox",
  "codex-login",
  "color-eyre",
  "crossterm",
diff --git a/codex-rs/Cargo.toml b/codex-rs/Cargo.toml
index 6f89e8fa..51b2b5cc 100644
--- a/codex-rs/Cargo.toml
+++ b/codex-rs/Cargo.toml
@@ -3,6 +3,7 @@ resolver = "2"
 members = [
     "ansi-escape",
     "apply-patch",
+    "arg0",
     "cli",
     "common",
     "core",
diff --git a/codex-rs/arg0/Cargo.toml b/codex-rs/arg0/Cargo.toml
new file mode 100644
index 00000000..9ad18967
--- /dev/null
+++ b/codex-rs/arg0/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "codex-arg0"
+version = { workspace = true }
+edition = "2024"
+
+[lib]
+name = "codex_arg0"
+path = "src/lib.rs"
+
+[lints]
+workspace = true
+
+[dependencies]
+anyhow = "1"
+codex-core = { path = "../core" }
+codex-linux-sandbox = { path = "../linux-sandbox" }
+dotenvy = "0.15.7"
+tokio = { version = "1", features = ["rt-multi-thread"] }
diff --git a/codex-rs/arg0/src/lib.rs b/codex-rs/arg0/src/lib.rs
new file mode 100644
index 00000000..86b98c7d
--- /dev/null
+++ b/codex-rs/arg0/src/lib.rs
@@ -0,0 +1,68 @@
+use std::future::Future;
+use std::path::Path;
+use std::path::PathBuf;
+
+/// While we want to deploy the Codex CLI as a single executable for simplicity,
+/// we also want to expose some of its functionality as distinct CLIs, so we use
+/// the "arg0 trick" to determine which CLI to dispatch. This effectively allows
+/// us to simulate deploying multiple executables as a single binary on Mac and
+/// Linux (but not Windows).
+///
+/// When the current executable is invoked through the hard-link or alias named
+/// `codex-linux-sandbox` we *directly* execute
+/// [`codex_linux_sandbox::run_main`] (which never returns). Otherwise we:
+///
+/// 1.  Use [`dotenvy::from_path`] and [`dotenvy::dotenv`] to modify the
+///     environment before creating any threads.
+/// 2.  Construct a Tokio multi-thread runtime.
+/// 3.  Derive the path to the current executable (so children can re-invoke the
+///     sandbox) when running on Linux.
+/// 4.  Execute the provided async `main_fn` inside that runtime, forwarding any
+///     error. Note that `main_fn` receives `codex_linux_sandbox_exe:
+///     Option<PathBuf>`, as an argument, which is generally needed as part of
+///     constructing [`codex_core::config::Config`].
+///
+/// This function should be used to wrap any `main()` function in binary crates
+/// in this workspace that depends on these helper CLIs.
+pub fn arg0_dispatch_or_else<F, Fut>(main_fn: F) -> anyhow::Result<()>
+where
+    F: FnOnce(Option<PathBuf>) -> Fut,
+    Fut: Future<Output = anyhow::Result<()>>,
+{
+    // Determine if we were invoked via the special alias.
+    let argv0 = std::env::args().next().unwrap_or_default();
+    let exe_name = Path::new(&argv0)
+        .file_name()
+        .and_then(|s| s.to_str())
+        .unwrap_or("");
+
+    if exe_name == "codex-linux-sandbox" {
+        // Safety: [`run_main`] never returns.
+        codex_linux_sandbox::run_main();
+    }
+
+    // This modifies the environment, which is not thread-safe, so do this
+    // before creating any threads/the Tokio runtime.
+    load_dotenv();
+
+    // Regular invocation – create a Tokio runtime and execute the provided
+    // async entry-point.
+    let runtime = tokio::runtime::Runtime::new()?;
+    runtime.block_on(async move {
+        let codex_linux_sandbox_exe: Option<PathBuf> = if cfg!(target_os = "linux") {
+            std::env::current_exe().ok()
+        } else {
+            None
+        };
+
+        main_fn(codex_linux_sandbox_exe).await
+    })
+}
+
+/// Load env vars from ~/.codex/.env and `$(pwd)/.env`.
+fn load_dotenv() {
+    if let Ok(codex_home) = codex_core::config::find_codex_home() {
+        dotenvy::from_path(codex_home.join(".env")).ok();
+    }
+    dotenvy::dotenv().ok();
+}
diff --git a/codex-rs/cli/Cargo.toml b/codex-rs/cli/Cargo.toml
index 94378815..ab98764b 100644
--- a/codex-rs/cli/Cargo.toml
+++ b/codex-rs/cli/Cargo.toml
@@ -18,12 +18,12 @@ workspace = true
 anyhow = "1"
 clap = { version = "4", features = ["derive"] }
 clap_complete = "4"
+codex-arg0 = { path = "../arg0" }
 codex-chatgpt = { path = "../chatgpt" }
 codex-core = { path = "../core" }
 codex-common = { path = "../common", features = ["cli"] }
 codex-exec = { path = "../exec" }
 codex-login = { path = "../login" }
-codex-linux-sandbox = { path = "../linux-sandbox" }
 codex-mcp-server = { path = "../mcp-server" }
 codex-tui = { path = "../tui" }
 serde_json = "1"
diff --git a/codex-rs/cli/src/main.rs b/codex-rs/cli/src/main.rs
index 7916a7dc..efda03bd 100644
--- a/codex-rs/cli/src/main.rs
+++ b/codex-rs/cli/src/main.rs
@@ -2,6 +2,7 @@ use clap::CommandFactory;
 use clap::Parser;
 use clap_complete::Shell;
 use clap_complete::generate;
+use codex_arg0::arg0_dispatch_or_else;
 use codex_chatgpt::apply_command::ApplyCommand;
 use codex_chatgpt::apply_command::run_apply_command;
 use codex_cli::LandlockCommand;
@@ -92,7 +93,7 @@ struct LoginCommand {
 }
 
 fn main() -> anyhow::Result<()> {
-    codex_linux_sandbox::run_with_sandbox(|codex_linux_sandbox_exe| async move {
+    arg0_dispatch_or_else(|codex_linux_sandbox_exe| async move {
         cli_main(codex_linux_sandbox_exe).await?;
         Ok(())
     })
diff --git a/codex-rs/exec/Cargo.toml b/codex-rs/exec/Cargo.toml
index ed01b78e..c9d94deb 100644
--- a/codex-rs/exec/Cargo.toml
+++ b/codex-rs/exec/Cargo.toml
@@ -18,13 +18,13 @@ workspace = true
 anyhow = "1"
 chrono = "0.4.40"
 clap = { version = "4", features = ["derive"] }
+codex-arg0 = { path = "../arg0" }
 codex-core = { path = "../core" }
 codex-common = { path = "../common", features = [
     "cli",
     "elapsed",
     "sandbox_summary",
 ] }
-codex-linux-sandbox = { path = "../linux-sandbox" }
 owo-colors = "4.2.0"
 serde_json = "1"
 shlex = "1.3.0"
diff --git a/codex-rs/exec/src/main.rs b/codex-rs/exec/src/main.rs
index 3a8e1f94..03ee533e 100644
--- a/codex-rs/exec/src/main.rs
+++ b/codex-rs/exec/src/main.rs
@@ -10,6 +10,7 @@
 //! This allows us to ship a completely separate set of functionality as part
 //! of the `codex-exec` binary.
 use clap::Parser;
+use codex_arg0::arg0_dispatch_or_else;
 use codex_common::CliConfigOverrides;
 use codex_exec::Cli;
 use codex_exec::run_main;
@@ -24,7 +25,7 @@ struct TopCli {
 }
 
 fn main() -> anyhow::Result<()> {
-    codex_linux_sandbox::run_with_sandbox(|codex_linux_sandbox_exe| async move {
+    arg0_dispatch_or_else(|codex_linux_sandbox_exe| async move {
         let top_cli = TopCli::parse();
         // Merge root-level overrides into inner CLI struct so downstream logic remains unchanged.
         let mut inner = top_cli.inner;
diff --git a/codex-rs/linux-sandbox/Cargo.toml b/codex-rs/linux-sandbox/Cargo.toml
index 5c2dea60..4b173ea1 100644
--- a/codex-rs/linux-sandbox/Cargo.toml
+++ b/codex-rs/linux-sandbox/Cargo.toml
@@ -14,15 +14,16 @@ path = "src/lib.rs"
 [lints]
 workspace = true
 
-[dependencies]
+[target.'cfg(target_os = "linux")'.dependencies]
 anyhow = "1"
 clap = { version = "4", features = ["derive"] }
 codex-common = { path = "../common", features = ["cli"] }
 codex-core = { path = "../core" }
-dotenvy = "0.15.7"
-tokio = { version = "1", features = ["rt-multi-thread"] }
+libc = "0.2.172"
+landlock = "0.4.1"
+seccompiler = "0.5.0"
 
-[dev-dependencies]
+[target.'cfg(target_os = "linux")'.dev-dependencies]
 tempfile = "3"
 tokio = { version = "1", features = [
     "io-std",
@@ -31,8 +32,3 @@ tokio = { version = "1", features = [
     "rt-multi-thread",
     "signal",
 ] }
-
-[target.'cfg(target_os = "linux")'.dependencies]
-libc = "0.2.172"
-landlock = "0.4.1"
-seccompiler = "0.5.0"
diff --git a/codex-rs/linux-sandbox/src/lib.rs b/codex-rs/linux-sandbox/src/lib.rs
index 96067846..80453c7f 100644
--- a/codex-rs/linux-sandbox/src/lib.rs
+++ b/codex-rs/linux-sandbox/src/lib.rs
@@ -4,72 +4,11 @@ mod landlock;
 mod linux_run_main;
 
 #[cfg(target_os = "linux")]
-pub use linux_run_main::run_main;
-
-use std::future::Future;
-use std::path::PathBuf;
-
-/// Helper that consolidates the common boilerplate found in several Codex
-/// binaries (`codex`, `codex-exec`, `codex-tui`) around dispatching to the
-/// `codex-linux-sandbox` sub-command.
-///
-/// When the current executable is invoked through the hard-link or alias
-/// named `codex-linux-sandbox` we *directly* execute [`run_main`](crate::run_main)
-/// (which never returns). Otherwise we:
-/// 1.  Construct a Tokio multi-thread runtime.
-/// 2.  Derive the path to the current executable (so children can re-invoke
-///     the sandbox) when running on Linux.
-/// 3.  Execute the provided async `main_fn` inside that runtime, forwarding
-///     any error.
-///
-/// This function eliminates duplicated code across the various `main.rs`
-/// entry-points.
-pub fn run_with_sandbox<F, Fut>(main_fn: F) -> anyhow::Result<()>
-where
-    F: FnOnce(Option<PathBuf>) -> Fut,
-    Fut: Future<Output = anyhow::Result<()>>,
-{
-    use std::path::Path;
-
-    // Determine if we were invoked via the special alias.
-    let argv0 = std::env::args().next().unwrap_or_default();
-    let exe_name = Path::new(&argv0)
-        .file_name()
-        .and_then(|s| s.to_str())
-        .unwrap_or("");
-
-    if exe_name == "codex-linux-sandbox" {
-        // Safety: [`run_main`] never returns.
-        crate::run_main();
-    }
-
-    // This modifies the environment, which is not thread-safe, so do this
-    // before creating any threads/the Tokio runtime.
-    load_dotenv();
-
-    // Regular invocation – create a Tokio runtime and execute the provided
-    // async entry-point.
-    let runtime = tokio::runtime::Runtime::new()?;
-    runtime.block_on(async move {
-        let codex_linux_sandbox_exe: Option<PathBuf> = if cfg!(target_os = "linux") {
-            std::env::current_exe().ok()
-        } else {
-            None
-        };
-
-        main_fn(codex_linux_sandbox_exe).await
-    })
+pub fn run_main() -> ! {
+    linux_run_main::run_main();
 }
 
 #[cfg(not(target_os = "linux"))]
 pub fn run_main() -> ! {
     panic!("codex-linux-sandbox is only supported on Linux");
 }
-
-/// Load env vars from ~/.codex/.env and `$(pwd)/.env`.
-fn load_dotenv() {
-    if let Ok(codex_home) = codex_core::config::find_codex_home() {
-        dotenvy::from_path(codex_home.join(".env")).ok();
-    }
-    dotenvy::dotenv().ok();
-}
diff --git a/codex-rs/mcp-server/Cargo.toml b/codex-rs/mcp-server/Cargo.toml
index 1088b924..488ee6a6 100644
--- a/codex-rs/mcp-server/Cargo.toml
+++ b/codex-rs/mcp-server/Cargo.toml
@@ -16,8 +16,8 @@ workspace = true
 
 [dependencies]
 anyhow = "1"
+codex-arg0 = { path = "../arg0" }
 codex-core = { path = "../core" }
-codex-linux-sandbox = { path = "../linux-sandbox" }
 mcp-types = { path = "../mcp-types" }
 schemars = "0.8.22"
 serde = { version = "1", features = ["derive"] }
diff --git a/codex-rs/mcp-server/src/main.rs b/codex-rs/mcp-server/src/main.rs
index 51c46c44..60ddeeab 100644
--- a/codex-rs/mcp-server/src/main.rs
+++ b/codex-rs/mcp-server/src/main.rs
@@ -1,7 +1,8 @@
+use codex_arg0::arg0_dispatch_or_else;
 use codex_mcp_server::run_main;
 
 fn main() -> anyhow::Result<()> {
-    codex_linux_sandbox::run_with_sandbox(|codex_linux_sandbox_exe| async move {
+    arg0_dispatch_or_else(|codex_linux_sandbox_exe| async move {
         run_main(codex_linux_sandbox_exe).await?;
         Ok(())
     })
diff --git a/codex-rs/tui/Cargo.toml b/codex-rs/tui/Cargo.toml
index b88ac8a0..2f150921 100644
--- a/codex-rs/tui/Cargo.toml
+++ b/codex-rs/tui/Cargo.toml
@@ -19,6 +19,7 @@ anyhow = "1"
 base64 = "0.22.1"
 clap = { version = "4", features = ["derive"] }
 codex-ansi-escape = { path = "../ansi-escape" }
+codex-arg0 = { path = "../arg0" }
 codex-core = { path = "../core" }
 codex-common = { path = "../common", features = [
     "cli",
@@ -26,7 +27,6 @@ codex-common = { path = "../common", features = [
     "sandbox_summary",
 ] }
 codex-file-search = { path = "../file-search" }
-codex-linux-sandbox = { path = "../linux-sandbox" }
 codex-login = { path = "../login" }
 color-eyre = "0.6.3"
 crossterm = { version = "0.28.1", features = ["bracketed-paste"] }
diff --git a/codex-rs/tui/src/main.rs b/codex-rs/tui/src/main.rs
index fdb3cdaf..480e56e8 100644
--- a/codex-rs/tui/src/main.rs
+++ b/codex-rs/tui/src/main.rs
@@ -1,4 +1,5 @@
 use clap::Parser;
+use codex_arg0::arg0_dispatch_or_else;
 use codex_common::CliConfigOverrides;
 use codex_tui::Cli;
 use codex_tui::run_main;
@@ -13,7 +14,7 @@ struct TopCli {
 }
 
 fn main() -> anyhow::Result<()> {
-    codex_linux_sandbox::run_with_sandbox(|codex_linux_sandbox_exe| async move {
+    arg0_dispatch_or_else(|codex_linux_sandbox_exe| async move {
         let top_cli = TopCli::parse();
         let mut inner = top_cli.inner;
         inner