From 7b8571fcb54ce4115076451c5a69cb0f8e1b99be Mon Sep 17 00:00:00 2001
From: Gilles Peskine <Gilles.Peskine@arm.com>
Date: Wed, 7 Jul 2021 21:02:36 +0200
Subject: [PATCH] New macro MBEDTLS_CHECK_RETURN

Put this macro before a function declaration to indicate that its result
must be checked. This commit supports GCC-like compilers and MSVC >=2012.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
---
 include/mbedtls/aes.h           |  1 +
 include/mbedtls/des.h           |  1 +
 include/mbedtls/platform_util.h | 20 ++++++++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index ab8793cb5..a74e41343 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -45,6 +45,7 @@
 #else
 #include MBEDTLS_CONFIG_FILE
 #endif
+#include "mbedtls/platform_util.h"
 
 #include <stddef.h>
 #include <stdint.h>
diff --git a/include/mbedtls/des.h b/include/mbedtls/des.h
index 6bfe65491..29b96dbb2 100644
--- a/include/mbedtls/des.h
+++ b/include/mbedtls/des.h
@@ -32,6 +32,7 @@
 #else
 #include MBEDTLS_CONFIG_FILE
 #endif
+#include "mbedtls/platform_util.h"
 
 #include <stddef.h>
 #include <stdint.h>
diff --git a/include/mbedtls/platform_util.h b/include/mbedtls/platform_util.h
index fbc2a0d1c..b4ffb471e 100644
--- a/include/mbedtls/platform_util.h
+++ b/include/mbedtls/platform_util.h
@@ -132,6 +132,26 @@ MBEDTLS_DEPRECATED typedef int mbedtls_deprecated_numeric_constant_t;
 #endif /* MBEDTLS_DEPRECATED_WARNING */
 #endif /* MBEDTLS_DEPRECATED_REMOVED */
 
+/** \def MBEDTLS_CHECK_RETURN
+ *
+ * This macro appearing at the beginning of the declaration of a function
+ * indicates that its return value should be checked.
+ *
+ * This should appear before most functions returning an error code
+ * (as \c int in the \c mbedtls_xxx API or
+ * as ::psa_status_t in the \c psa_xxx API).
+ */
+#if !defined(MBEDTLS_CHECK_RETURN)
+#if defined(__GNUC__)
+#define MBEDTLS_CHECK_RETURN __attribute__((warn_unused_result))
+#elif defined(_MSC_VER) && _MSC_VER >= 1700
+#include <sal.h>
+#define MBEDTLS_CHECK_RETURN _Check_return_
+#else
+#define MBEDTLS_CHECK_RETURN
+#endif
+#endif
+
 /**
  * \brief       Securely zeroize a buffer
  *