Save and restore the Windows error around TlsGetValue.

TlsGetValue clears the last error even on success, so that callers may
distinguish it successfully returning NULL or failing. This error-mangling
behavior interferes with the caller's use of GetLastError. In particular
SSL_get_error queries the error queue to determine whether the caller should
look at the OS's errors. To avoid destroying state, save and restore the
Windows error.

Fixes #6299.

Reviewed-by: Rich Salz <rsalz@openssl.org>

(cherry picked from commit 2de108dfa343c3e06eb98beb122cd06306bb12fd)

(Merged from https://github.com/openssl/openssl/pull/6349)

3 files changed, 57 insertions, 1 deletions

diff --git a/test/build.info b/test/build.info
index dcb398517c..87961bc834 100644
--- a/test/build.info
+++ b/test/build.info
@@ -18,7 +18,7 @@ IF[{- !$disabled{tests} -}]
           dtlsv1listentest ct_test threadstest afalgtest d2i_test \
           ssl_test_ctx_test ssl_test x509aux cipherlist_test asynciotest \
           bioprinttest sslapitest dtlstest sslcorrupttest bio_enc_test \
-          ocspapitest fatalerrtest x509_time_test
+          ocspapitest fatalerrtest x509_time_test errtest
 
   SOURCE[versions]=versions.c
   INCLUDE[versions]=../include
@@ -306,6 +306,10 @@ IF[{- !$disabled{tests} -}]
     SOURCE[shlibloadtest]=shlibloadtest.c
     INCLUDE[shlibloadtest]=../include
   ENDIF
+
+  SOURCE[errtest]=errtest.c testutil.c
+  INCLUDE[errtest]=../include
+  DEPEND[errtest]=../libcrypto
 ENDIF
 
 {-
diff --git a/test/errtest.c b/test/errtest.c
new file mode 100644
index 0000000000..df4cddb096
--- /dev/null
+++ b/test/errtest.c
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <openssl/opensslconf.h>
+#include <openssl/err.h>
+
+#include "testutil.h"
+
+#if defined(OPENSSL_SYS_WINDOWS)
+# include <windows.h>
+#else
+# include <errno.h>
+#endif
+
+/* Test that querying the error queue preserves the OS error. */
+static int preserves_system_error(void)
+{
+#if defined(OPENSSL_SYS_WINDOWS)
+    SetLastError(ERROR_INVALID_FUNCTION);
+    ERR_get_error();
+    return GetLastError() == ERROR_INVALID_FUNCTION;
+#else
+    errno = EINVAL;
+    ERR_get_error();
+    return errno == EINVAL;
+#endif
+}
+
+int main(int argc, char **argv)
+{
+    ADD_TEST(preserves_system_error);
+
+    return run_tests(argv[0]);
+}
diff --git a/test/recipes/04-test_err.t b/test/recipes/04-test_err.t
new file mode 100644
index 0000000000..dd7681afa4
--- /dev/null
+++ b/test/recipes/04-test_err.t
@@ -0,0 +1,12 @@
+#! /usr/bin/env perl
+# Copyright 2018 The OpenSSL Project Authors. All Rights Reserved.
+#
+# Licensed under the OpenSSL license (the "License").  You may not use
+# this file except in compliance with the License.  You can obtain a copy
+# in the file LICENSE in the source distribution or at
+# https://www.openssl.org/source/license.html
+
+
+use OpenSSL::Test::Simple;
+
+simple_test("test_err", "errtest");