commit 766be1f8f4ea2f22cbb004f4c8c2341f789ea97f
author Felix Conway <felix.conway@arm.com> Thu Jun 12 10:52:36 2025 +0100
committer Felix Conway <felix.conway@arm.com> Thu Jun 12 11:13:33 2025 +0100
tree a4d5648c4c196a8eda60d1e11fa4384e5489b001
parent 2e1399f1e1ed6fa1072cf9584f5771322b0d001b

Replace __attribute__((nonstring)) with macro MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING

This macro applies __attribute__((nonstring)) when the compiler supports
it

Signed-off-by: Felix Conway <felix.conway@arm.com>

library/common.h

diff --git a/library/common.h b/library/common.h
index 7bb2674..50f2a29 100644
--- a/library/common.h
+++ b/library/common.h
@@ -434,4 +434,20 @@
 #    define MBEDTLS_MAYBE_UNUSED
 #endif
 
+/* GCC >= 15 has a warning 'unterminated-string-initialization' which complains if you initialize
+ * a string into an array without space for a terminating NULL character. In some places in the
+ * codebase this behaviour is intended, so we add the macro MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING
+ * to suppress the warning in these places.
+ */
+#if defined(__has_attribute)
+#if __has_attribute(nonstring)
+#define MBEDTLS_HAS_ATTRIBUTE_NONSTRING
+#endif /* __has_attribute(nonstring) */
+#endif /* __has_attribute */
+#if defined(MBEDTLS_HAS_ATTRIBUTE_NONSTRING)
+#define MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING __attribute__((nonstring))
+#else
+#define MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING
+#endif /* MBEDTLS_HAS_ATTRIBUTE_NONSTRING */
+
 #endif /* MBEDTLS_LIBRARY_COMMON_H */

library/ssl_tls13_keys.c

diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index dcbfcf0..1967883 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -83,7 +83,7 @@
  */
 
 /* We need to tell the compiler that we meant to leave out the null character. */
-static const char tls13_label_prefix[6] __attribute__ ((nonstring)) = "tls13 ";
+static const char tls13_label_prefix[6] MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING = "tls13 ";
 
 #define SSL_TLS1_3_KEY_SCHEDULE_HKDF_LABEL_LEN(label_len, context_len) \
     (2                     /* expansion length           */ \

library/ssl_tls13_keys.h

diff --git a/library/ssl_tls13_keys.h b/library/ssl_tls13_keys.h
index f6d02b5..1509e9a 100644
--- a/library/ssl_tls13_keys.h
+++ b/library/ssl_tls13_keys.h
@@ -42,7 +42,7 @@
 
 /* We need to tell the compiler that we meant to leave out the null character. */
 #define MBEDTLS_SSL_TLS1_3_LABEL(name, string)       \
-    const unsigned char name    [sizeof(string) - 1] __attribute__ ((nonstring));
+    const unsigned char name    [sizeof(string) - 1] MBEDTLS_ATTRIBUTE_UNTERMINATED_STRING;
 
 union mbedtls_ssl_tls13_labels_union {
     MBEDTLS_SSL_TLS1_3_LABEL_LIST