fix(wsl): normalize Windows paths during update (#6086) (#6097)

When running under WSL, the update command could receive Windows-style
absolute paths (e.g., `C:\...`) and pass them to Linux processes
unchanged, which fails because WSL expects those paths in
`/mnt/<drive>/...` form.

This patch adds a tiny helper in the CLI (`cli/src/wsl_paths.rs`) that:
- Detects WSL (`WSL_DISTRO_NAME` or `"microsoft"` in `/proc/version`)  
- Converts `X:\...` → `/mnt/x/...`  

`run_update_action` now normalizes the package-manager command and
arguments under WSL before spawning.
Non-WSL platforms are unaffected.  

Includes small unit tests for the converter.  

**Fixes:** #6086, #6084

Co-authored-by: Eric Traut <etraut@openai.com>

codex-rs/cli/src/main.rs

@@ -26,8 +26,10 @@ use std::path::PathBuf;
 use supports_color::Stream;
 
 mod mcp_cmd;
+mod wsl_paths;
 
 use crate::mcp_cmd::McpCli;
+use crate::wsl_paths::normalize_for_wsl;
 use codex_core::config::Config;
 use codex_core::config::ConfigOverrides;
 use codex_core::features::is_known_feature_key;
@@ -270,7 +272,11 @@ fn run_update_action(action: UpdateAction) -> anyhow::Result<()> {
     let (cmd, args) = action.command_args();
     let cmd_str = action.command_str();
     println!("Updating Codex via `{cmd_str}`...");
-    let status = std::process::Command::new(cmd).args(args).status()?;
+    let command_path = normalize_for_wsl(cmd);
+    let normalized_args: Vec<String> = args.iter().map(normalize_for_wsl).collect();
+    let status = std::process::Command::new(&command_path)
+        .args(&normalized_args)
+        .status()?;
     if !status.success() {
         anyhow::bail!("`{cmd_str}` failed with status {status}");
     }

codex-rs/cli/src/wsl_paths.rs

@@ -0,0 +1,76 @@
+use std::ffi::OsStr;
+
+/// WSL-specific path helpers used by the updater logic.
+///
+/// See https://github.com/openai/codex/issues/6086.
+pub fn is_wsl() -> bool {
+    #[cfg(target_os = "linux")]
+    {
+        if std::env::var_os("WSL_DISTRO_NAME").is_some() {
+            return true;
+        }
+        match std::fs::read_to_string("/proc/version") {
+            Ok(version) => version.to_lowercase().contains("microsoft"),
+            Err(_) => false,
+        }
+    }
+    #[cfg(not(target_os = "linux"))]
+    {
+        false
+    }
+}
+
+/// Convert a Windows absolute path (`C:\foo\bar` or `C:/foo/bar`) to a WSL mount path (`/mnt/c/foo/bar`).
+/// Returns `None` if the input does not look like a Windows drive path.
+pub fn win_path_to_wsl(path: &str) -> Option<String> {
+    let bytes = path.as_bytes();
+    if bytes.len() < 3
+        || bytes[1] != b':'
+        || !(bytes[2] == b'\\' || bytes[2] == b'/')
+        || !bytes[0].is_ascii_alphabetic()
+    {
+        return None;
+    }
+    let drive = (bytes[0] as char).to_ascii_lowercase();
+    let tail = path[3..].replace('\\', "/");
+    if tail.is_empty() {
+        return Some(format!("/mnt/{drive}"));
+    }
+    Some(format!("/mnt/{drive}/{tail}"))
+}
+
+/// If under WSL and given a Windows-style path, return the equivalent `/mnt/<drive>/…` path.
+/// Otherwise returns the input unchanged.
+pub fn normalize_for_wsl<P: AsRef<OsStr>>(path: P) -> String {
+    let value = path.as_ref().to_string_lossy().to_string();
+    if !is_wsl() {
+        return value;
+    }
+    if let Some(mapped) = win_path_to_wsl(&value) {
+        return mapped;
+    }
+    value
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn win_to_wsl_basic() {
+        assert_eq!(
+            win_path_to_wsl(r"C:\Temp\codex.zip").as_deref(),
+            Some("/mnt/c/Temp/codex.zip")
+        );
+        assert_eq!(
+            win_path_to_wsl("D:/Work/codex.tgz").as_deref(),
+            Some("/mnt/d/Work/codex.tgz")
+        );
+        assert!(win_path_to_wsl("/home/user/codex").is_none());
+    }
+
+    #[test]
+    fn normalize_is_noop_on_unix_paths() {
+        assert_eq!(normalize_for_wsl("/home/u/x"), "/home/u/x");
+    }
+}