From 61e4d52d8c86446ad45e1c7b5b01bd2dc6a3e97b Mon Sep 17 00:00:00 2001
From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Mon, 17 Jun 2019 17:34:56 +0200
Subject: [PATCH] Save errno before printing in case printing fails and
 clobbers it

---
 pdns/test-mplexer.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pdns/test-mplexer.cc b/pdns/test-mplexer.cc
index f2ac639afc..b35c54d189 100644
--- a/pdns/test-mplexer.cc
+++ b/pdns/test-mplexer.cc
@@ -133,14 +133,16 @@ BOOST_AUTO_TEST_CASE(test_MPlexer) {
     cerr<<"The file descripttor returned as ready is "<<readyFDs.at(0)<<endl;
     char buffer[2];
     ssize_t res = read(pipes[0], &buffer[0], sizeof(buffer));
+    int saved = errno;
     cerr<<"Reading from pipes[0] returns "<<res<<endl;
     if (res == -1) {
-      cerr<<"errno is "<<errno<<endl;
+      cerr<<"errno is "<<saved<<endl;
     }
     res = write(pipes[1], "0", 1);
+    saved = errno;
     cerr<<"Writing to pipes[1] returns "<<res<<endl;
     if (res == -1) {
-      cerr<<"errno is "<<errno<<endl;
+      cerr<<"errno is "<<saved<<endl;
     }
   }
   BOOST_REQUIRE_EQUAL(readyFDs.size(), 2);
-- 
2.47.2