From: Willy Tarreau <w@1wt.eu>
Date: Mon, 18 May 2026 15:18:34 +0000 (+0200)
Subject: CLEANUP: tcpcheck: mention that we're a bit far for a sync errno
X-Git-Tag: v3.4-dev13~51
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=bbc41785d9099815479808b2e49d8dccdb067815;p=thirdparty%2Fhaproxy.git

CLEANUP: tcpcheck: mention that we're a bit far for a sync errno

The collection of errno in tcpcheck_eval_connect() and tcpcheck_main()
is quite far from the production location, and the risk of having a
zero errno is definitely not null. Tests show that this works, so
better not try to fix something not broken, but at least place a
comment there indicating that it's not necessarily super-reliable.
This would need to be revisited the day we finally store errno in
the connection.
---

diff --git a/src/tcpcheck.c b/src/tcpcheck.c
index a500dbadf..d354291f1 100644
--- a/src/tcpcheck.c
+++ b/src/tcpcheck.c
@@ -1611,6 +1611,7 @@ enum tcpcheck_eval_ret tcpcheck_eval_connect(struct check *check, struct tcpchec
 	case SF_ERR_RESOURCE:
 	case SF_ERR_INTERNAL:
 		TRACE_ERROR("report connection error", CHK_EV_TCPCHK_CONN|CHK_EV_TCPCHK_ERR, check, 0, 0, (size_t[]){status});
+		/* note: errno is no longer guaranteed here */
 		chk_report_conn_err(check, errno, 0);
 		ret = TCPCHK_EVAL_STOP;
 		goto out;
@@ -2648,6 +2649,7 @@ int tcpcheck_main(struct check *check)
   out_end_tcpcheck:
 	if ((conn && conn->flags & CO_FL_ERROR) || sc_ep_test(sc, SE_FL_ERROR)) {
 		TRACE_ERROR("report connection error", CHK_EV_TCPCHK_EVAL|CHK_EV_TCPCHK_ERR, check);
+		/* note: errno is no longer guaranteed here */
 		chk_report_conn_err(check, errno, 0);
 	}