From b557c9887f06b6429b77e81e4972538567db36ad Mon Sep 17 00:00:00 2001
From: reverse <mike.chevronnet@gmail.com>
Date: Wed, 19 Aug 2026 01:28:42 +0000
Subject: [PATCH] =?UTF-8?q?log=5Fjson:=20cache=20an=20open=20failure=20so?=
 =?UTF-8?q?=20a=20misconfigured=20path=20doesn't=20re-issue=20an=20open()?=
 =?UTF-8?q?=20syscall=20(and=20silently=20drop)=20on=20every=20notice=20?=
 =?UTF-8?q?=E2=80=94=20the=20error=20is=20now=20surfaced=20once=20via=20st?=
 =?UTF-8?q?derr=20and=20not=20retried=20until=20the=20path=20changes;=20th?=
 =?UTF-8?q?e=20write-failure=20reopen=20(for=20logrotate)=20is=20preserved?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/modules/log_json.rs | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/modules/log_json.rs b/src/modules/log_json.rs
index cd4d7ad..2541c6a 100644
--- a/src/modules/log_json.rs
+++ b/src/modules/log_json.rs
@@ -11,8 +11,10 @@ use std::io::Write;
 use crate::server::Server;
 
 thread_local! {
-    /// (configured path, open append handle) cached for reuse.
-    static SINK: RefCell<Option<(String, File)>> = const { RefCell::new(None) };
+    /// (configured path, open append handle or `None` if opening it failed) cached
+    /// for reuse. Caching the failure stops us re-issuing an `open` syscall — and a
+    /// silent drop — on every single notice when the path is misconfigured.
+    static SINK: RefCell<Option<(String, Option<File>)>> = const { RefCell::new(None) };
 }
 
 /// Append `msg` as a JSON line to the configured log file. Called at the tail of
@@ -30,16 +32,19 @@ pub fn tee(s: &Server, msg: &str) {
             None => true,
         };
         if need_open {
-            *slot = OpenOptions::new()
-                .create(true)
-                .append(true)
-                .open(path)
-                .ok()
-                .map(|f| (path.to_string(), f));
+            match OpenOptions::new().create(true).append(true).open(path) {
+                Ok(f) => *slot = Some((path.to_string(), Some(f))),
+                Err(e) => {
+                    // surface once (this branch only runs when the path changes),
+                    // then remember the failure so we don't retry every notice
+                    eprintln!("echoircd: log_json cannot open {path}: {e}");
+                    *slot = Some((path.to_string(), None));
+                }
+            }
         }
-        if let Some((_, f)) = slot.as_mut() {
+        if let Some((_, Some(f))) = slot.as_mut() {
             if writeln!(f, "{line}").is_err() {
-                *slot = None; // reopen next time
+                *slot = None; // reopen next time (e.g. after a logrotate rename)
             }
         }
     });