From a684ef1e347afdd315138db547ad74b09b95db0b Mon Sep 17 00:00:00 2001
From: damocles <damocles@hyperhive.local>
Date: Sat, 24 Oct 2026 09:54:56 +0200
Subject: [PATCH] meta test: retry the fake nix exec when it hits ETXTBSY

---
 hive-c0re/src/meta.rs | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/hive-c0re/src/meta.rs b/hive-c0re/src/meta.rs
index 430c65ae..53eedd3a 100644
--- a/hive-c0re/src/meta.rs
+++ b/hive-c0re/src/meta.rs
@@ -2144,14 +2144,26 @@ mod lock_wait_tests {
         std::fs::write(&fake, "#!/bin/sh\nexec sleep 30\n").expect("write");
         std::fs::set_permissions(&fake, std::os::unix::fs::PermissionsExt::from_mode(0o755))
             .expect("chmod");
-        let err = nix_output_with(
-            fake.as_os_str(),
-            dir.path(),
-            &["flake", "update", "hyperhive"],
-            Duration::from_millis(300),
-        )
-        .await
-        .expect_err("hung nix must time out");
+        // Parallel tests fork while the script's write fd is still open, so an
+        // early exec can hit ETXTBSY. That is a race in building the fake, not
+        // in `nix_output_with`: retry it, anything else fails the test.
+        let mut tries = 0;
+        let err = loop {
+            let res = nix_output_with(
+                fake.as_os_str(),
+                dir.path(),
+                &["flake", "update", "hyperhive"],
+                Duration::from_millis(300),
+            )
+            .await;
+            match res {
+                Err(e) if tries < 20 && format!("{e:#}").contains("Text file busy") => {
+                    tries += 1;
+                    tokio::time::sleep(Duration::from_millis(50)).await;
+                }
+                other => break other.expect_err("hung nix must time out"),
+            }
+        };
         let msg = format!("{err:#}");
         assert!(
             msg.contains("nix flake update hyperhive in") && msg.contains("timed out after 0.3s"),