Save errno before printing in case printing fails and clobbers it

diff --git a/pdns/test-mplexer.cc b/pdns/test-mplexer.cc
index f2ac639afc5ccf1b7b6391cfc6aac75c3b1106c2..b35c54d1892c8d9a3b49f160a3b8829b558ec289 100644 (file)
--- 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);