From 6a7674a1464395e0b2b5b0acb429ff33c6a6bf62 Mon Sep 17 00:00:00 2001
From: Daniel Pouzzner <douzzer@wolfssl.com>
Date: Wed, 1 Mar 2023 17:50:00 -0600
Subject: [PATCH] wolfcrypt/test/test.c: improve strerror_r() flavor sensing
 (simpler gate randomly provoked cppcheck-all-async-quic).

---
 wolfcrypt/test/test.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/wolfcrypt/test/test.c b/wolfcrypt/test/test.c
index 3e97f1b8d..319602ead 100644
--- a/wolfcrypt/test/test.c
+++ b/wolfcrypt/test/test.c
@@ -643,22 +643,35 @@ static void render_error_message(const char* msg, int es)
         break;
     case WC_TEST_RET_TAG_ERRNO:
     {
-#if defined(_GNU_SOURCE) || \
-    (defined(_POSIX_C_SOURCE) && (_POSIX_C_SOURCE >= 200112L))
+
+/* strerror_r() comes in two mutually incompatible flavors, a native glibc
+ * flavor that always returns a non-null char pointer that must be used
+ * directly, and a POSIX flavor that returns an error int, and iff success,
+ * stores an error string in the supplied buffer.  this is all most
+ * infelicitous...
+ */
+#if !defined(STRING_USER) && !defined(NO_ERROR_STRINGS) &&      \
+    (defined(_GNU_SOURCE) || defined(__USE_GNU) ||              \
+     (defined(__USE_XOPEN2K) &&                                 \
+      defined(_POSIX_C_SOURCE) &&                               \
+      (_POSIX_C_SOURCE >= 200112L)))
+
         char errno_buf[64], *errno_string;
-#if defined(_GNU_SOURCE)
-        errno_string = strerror_r(WC_TEST_RET_DEC_I(es),
-                                  errno_buf, sizeof(errno_buf));
-#else
+        /* precisely mirror the gate used in glibc string.h */
+#if defined __USE_XOPEN2K && !defined __USE_GNU
         if (strerror_r(WC_TEST_RET_DEC_I(es),
                        errno_buf, sizeof(errno_buf)) != 0)
             XSTRLCPY(errno_buf, "?", sizeof(errno_buf));
         errno_string = errno_buf;
+#else
+        errno_string = strerror_r(WC_TEST_RET_DEC_I(es),
+                                  errno_buf, sizeof(errno_buf));
 #endif
         err_sys_printf("%s error L=%d errno=%d (%s)\n", msg,
                        WC_TEST_RET_DEC_LN(es), WC_TEST_RET_DEC_I(es),
                        errno_string);
-#else
+
+#else /* can't figure out how to strerror_r(), or don't want error strings */
         err_sys_printf("%s error L=%d errno=%d\n", msg,
                        WC_TEST_RET_DEC_LN(es), WC_TEST_RET_DEC_I(es));
 #endif