From 468acda2d09bc4cf1f63d01d4ac083ccc27f8801 Mon Sep 17 00:00:00 2001
From: Gilles Peskine <Gilles.Peskine@arm.com>
Date: Wed, 15 Jan 2025 17:44:06 +0100
Subject: [PATCH] New helper function mbedtls_test_buffer_is_all_zero()

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
---
 tests/include/test/helpers.h | 24 ++++++++++++++++++++++++
 tests/src/helpers.c          | 10 ++++++++++
 2 files changed, 34 insertions(+)

diff --git a/tests/include/test/helpers.h b/tests/include/test/helpers.h
index d08100f15..aff84748f 100644
--- a/tests/include/test/helpers.h
+++ b/tests/include/test/helpers.h
@@ -166,6 +166,30 @@ const char *mbedtls_test_get_mutex_usage_error(void);
 void mbedtls_test_set_mutex_usage_error(const char *msg);
 #endif
 
+/**
+ * \brief           Check whether the given buffer is all-bits-zero.
+ *
+ * \param[in] buf   Pointer to the buffer to check.
+ * \param size      Buffer size in bytes.
+ *
+ * \retval 0        The given buffer has a nonzero byte.
+ * \retval 1        The given buffer is all-bits-zero (this includes the case
+ *                  of an empty buffer).
+ */
+int mbedtls_test_buffer_is_all_zero(const uint8_t *buf, size_t size);
+
+/** Check whether the object at the given address is all-bits-zero.
+ *
+ * \param[in] ptr   A pointer to the object to check.
+ *                  This macro parameter may be evaluated more than once.
+ *
+ * \retval 0        The given object has a nonzero byte.
+ * \retval 1        The given object is all-bits-zero (this includes the case
+ *                  of an empty buffer).
+ */
+#define MBEDTLS_TEST_OBJECT_IS_ALL_ZERO(ptr)    \
+    (mbedtls_test_buffer_is_all_zero((const uint8_t *) (ptr), sizeof(*(ptr))))
+
 #if defined(MBEDTLS_BIGNUM_C)
 
 /**
diff --git a/tests/src/helpers.c b/tests/src/helpers.c
index 1a157331b..963897bdc 100644
--- a/tests/src/helpers.c
+++ b/tests/src/helpers.c
@@ -265,6 +265,16 @@ void mbedtls_test_set_mutex_usage_error(const char *msg)
 }
 #endif // #if defined(MBEDTLS_TEST_MUTEX_USAGE)
 
+int mbedtls_test_buffer_is_all_zero(const uint8_t *buf, size_t size)
+{
+    for (size_t i = 0; i < size; i++) {
+        if (buf[i] != 0) {
+            return 0;
+        }
+    }
+    return 1;
+}
+
 #if defined(MBEDTLS_BIGNUM_C)
 
 unsigned mbedtls_test_get_case_uses_negative_0(void)