From 5ccd15517787ba273623cc1c1d7333f758ad2ee9 Mon Sep 17 00:00:00 2001
From: Johannes Altmanninger <aclopte@gmail.com>
Date: Tue, 20 May 2025 15:21:00 +0200
Subject: [PATCH] Retry history file flock() on EINTR

When locking the uvar file, we retry whenever flock() fails with EINTR
(e.g. due to ctrl-c).

But not when locking the history file.  This seems wrong; all other libc
functions in the "history_file" code path do retry.

Fix that. In future we should extract a function.

Note that there are other inconsistencies; flock_uvar_file() does not
shy away from remote file systems and does not respect ABANDONED_LOCKING.
This means that empirically probably neither are necessary; let's make things
consistent in future.

See https://github.com/fish-shell/fish-shell/pull/11492#discussion_r2095096200
Might help #10300

(cherry picked from commit 4d84e68dd4f8d4c15a36b8d91c6562b8e93ecdee)
---
 src/history.rs | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/history.rs b/src/history.rs
index 565c83f53..1c6e9747a 100644
--- a/src/history.rs
+++ b/src/history.rs
@@ -44,7 +44,7 @@
 };
 
 use bitflags::bitflags;
-use libc::{fchmod, fchown, flock, LOCK_EX, LOCK_SH, LOCK_UN};
+use libc::{fchmod, fchown, flock, EINTR, LOCK_EX, LOCK_SH, LOCK_UN};
 use lru::LruCache;
 use nix::{fcntl::OFlag, sys::stat::Mode};
 use rand::Rng;
@@ -1353,8 +1353,15 @@ unsafe fn maybe_lock_file(file: &mut File, lock_type: libc::c_int) -> bool {
             return false;
         }
 
-        let start_time = SystemTime::now();
-        let retval = unsafe { flock(raw_fd, lock_type) };
+        let (ok, start_time) = loop {
+            let start_time = SystemTime::now();
+            if unsafe { flock(raw_fd, lock_type) } == -1 {
+                if errno::errno().0 != EINTR {
+                    break (false, start_time);
+                }
+            }
+            break (true, start_time);
+        };
         if let Ok(duration) = start_time.elapsed() {
             if duration > Duration::from_millis(250) {
                 FLOG!(
@@ -1367,7 +1374,7 @@ unsafe fn maybe_lock_file(file: &mut File, lock_type: libc::c_int) -> bool {
                 ABANDONED_LOCKING.store(true);
             }
         }
-        retval != -1
+        ok
     }
 
     /// Unlock a history file.