Add rand() for TA usage

Adds rand() by declaring it in stdlib.h where it's expected to be found.
Implementation is provided in libutee since it depends on
TEE_GenerateRandom().

Reviewed-by: Joakim Bech <joakim.bech@linaro.org>
Acked-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/lib/libutee/tee_api_operations.c b/lib/libutee/tee_api_operations.c
index 1f214fc3..42d47b66 100644
--- a/lib/libutee/tee_api_operations.c
+++ b/lib/libutee/tee_api_operations.c
@@ -1791,3 +1791,16 @@ void TEE_GenerateRandom(void *randomBuffer, uint32_t randomBufferLen)
 	if (res != TEE_SUCCESS)
 		TEE_Panic(res);
 }
+
+int rand(void)
+{
+	int rc;
+
+	TEE_GenerateRandom(&rc, sizeof(rc));
+
+	/*
+	 * RAND_MAX is the larges int, INT_MAX which is all bits but the
+	 * highest bit set.
+	 */
+	return rc & RAND_MAX;
+}