log sandbox commands to $CODEX_HOME instead of cwd (#6171)

Logging commands in the Windows Sandbox is temporary, but while we are
doing it, let's always write to CODEX_HOME instead of dirtying the cwd.

codex-rs/windows-sandbox-rs/src/logging.rs

@@ -1,5 +1,7 @@
 use std::fs::OpenOptions;
 use std::io::Write;
+use std::path::Path;
+use std::path::PathBuf;
 
 const LOG_COMMAND_PREVIEW_LIMIT: usize = 200;
 pub const LOG_FILE_NAME: &str = "sandbox_commands.rust.log";
@@ -13,35 +15,43 @@ fn preview(command: &[String]) -> String {
     }
 }
 
-fn append_line(line: &str) {
-    if let Ok(mut f) = OpenOptions::new()
-        .create(true)
-        .append(true)
-        .open(LOG_FILE_NAME)
-    {
-        let _ = writeln!(f, "{}", line);
+fn log_file_path(base_dir: &Path) -> Option<PathBuf> {
+    if base_dir.is_dir() {
+        Some(base_dir.join(LOG_FILE_NAME))
+    } else {
+        None
     }
 }
 
-pub fn log_start(command: &[String]) {
-    let p = preview(command);
-    append_line(&format!("START: {}", p));
+fn append_line(line: &str, base_dir: Option<&Path>) {
+    if let Some(dir) = base_dir {
+        if let Some(path) = log_file_path(dir) {
+            if let Ok(mut f) = OpenOptions::new().create(true).append(true).open(path) {
+                let _ = writeln!(f, "{}", line);
+            }
+        }
+    }
 }
 
-pub fn log_success(command: &[String]) {
+pub fn log_start(command: &[String], base_dir: Option<&Path>) {
     let p = preview(command);
-    append_line(&format!("SUCCESS: {}", p));
+    append_line(&format!("START: {p}"), base_dir);
 }
 
-pub fn log_failure(command: &[String], detail: &str) {
+pub fn log_success(command: &[String], base_dir: Option<&Path>) {
     let p = preview(command);
-    append_line(&format!("FAILURE: {} ({})", p, detail));
+    append_line(&format!("SUCCESS: {p}"), base_dir);
+}
+
+pub fn log_failure(command: &[String], detail: &str, base_dir: Option<&Path>) {
+    let p = preview(command);
+    append_line(&format!("FAILURE: {p} ({detail})"), base_dir);
 }
 
 // Debug logging helper. Emits only when SBX_DEBUG=1 to avoid noisy logs.
-pub fn debug_log(msg: &str) {
+pub fn debug_log(msg: &str, base_dir: Option<&Path>) {
     if std::env::var("SBX_DEBUG").ok().as_deref() == Some("1") {
-        append_line(&format!("DEBUG: {}", msg));
-        eprintln!("{}", msg);
+        append_line(&format!("DEBUG: {msg}"), base_dir);
+        eprintln!("{msg}");
     }
 }