From e47b6e657aa5dda6dfb79d495ba3ee7b0534532a Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Tue, 3 Mar 2026 23:50:08 +0100
Subject: [PATCH] socketpair: clear 'err' when retrying due to EINTR

If the first write was interrupted by a signal and a subsequent write
succeeds, the function would still erroneously return EINTR.

Found by Codex Security
Closes #20809
---
 lib/socketpair.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/socketpair.c b/lib/socketpair.c
index 7fd7e30bba..76b959dd4a 100644
--- a/lib/socketpair.c
+++ b/lib/socketpair.c
@@ -317,6 +317,7 @@ int Curl_wakeup_signal(curl_socket_t socks[2])
 #endif
 
   while(1) {
+    err = 0;
     if(wakeup_write(socks[1], buf, sizeof(buf)) < 0) {
       err = SOCKERRNO;
 #ifdef USE_WINSOCK