Older versions of gcc with -Wformat-overflow=2 don't like the usage of
fixed size char arrays in this test; gcc 7.5.0 (SUSE Linux) says:

../tests/qtest/arm-cpu-features.c: In function ‘test_query_cpu_model_expansion_kvm’:
../tests/qtest/arm-cpu-features.c:578:35: error: ‘%u’ directive writing
between 1 and 10 bytes into a region of size 5
[-Werror=format-overflow=]

These can't actually happen because of the limited size of the values
being substituted in.  However rather than require readers to check
whether the arrays really have been declared large enough, we prefer
to use g_strdup_printf() for this kind of string work.

Reported-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20260310151507.2973843-3-peter.maydell@linaro.org
---
 tests/qtest/arm-cpu-features.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/tests/qtest/arm-cpu-features.c b/tests/qtest/arm-cpu-features.c
index eb8ddebffb..5444e4d40b 100644
--- a/tests/qtest/arm-cpu-features.c
+++ b/tests/qtest/arm-cpu-features.c
@@ -519,7 +519,6 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
         bool kvm_supports_pmu;
         bool kvm_supports_steal_time;
         bool kvm_supports_sve;
-        char max_name[8], name[8];
         uint32_t max_vq, vq;
         uint64_t vls;
         QDict *resp;
@@ -573,9 +572,12 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
         }
 
         if (kvm_supports_sve) {
+            g_autofree const char *max_name = NULL;
+            g_autofree const char *name = NULL;
+
             g_assert(vls != 0);
             max_vq = 64 - __builtin_clzll(vls);
-            sprintf(max_name, "sve%u", max_vq * 128);
+            max_name = g_strdup_printf("sve%u", max_vq * 128);
 
             /* Enabling a supported length is of course fine. */
             assert_sve_vls(qts, "host", vls, "{ %s: true }", max_name);
@@ -583,6 +585,9 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
             /* Get the next supported length smaller than max-vq. */
             vq = 64 - __builtin_clzll(vls & ~BIT_ULL(max_vq - 1));
             if (vq) {
+                g_autofree const char *name2 =
+                    g_strdup_printf("sve%u", vq * 128);
+
                 /*
                  * We have at least one length smaller than max-vq,
                  * so we can disable max-vq.
@@ -595,11 +600,10 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
                  * unless all larger, supported vector lengths are also
                  * disabled.
                  */
-                sprintf(name, "sve%u", vq * 128);
-                error = g_strdup_printf("cannot disable %s", name);
+                error = g_strdup_printf("cannot disable %s", name2);
                 assert_error(qts, "host", error,
                              "{ %s: true, %s: false }",
-                             max_name, name);
+                             max_name, name2);
                 g_free(error);
             }
 
@@ -608,7 +612,7 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
              * we need at least one vector length enabled.
              */
             vq = __builtin_ffsll(vls);
-            sprintf(name, "sve%u", vq * 128);
+            name = g_strdup_printf(name, "sve%u", vq * 128);
             error = g_strdup_printf("cannot disable %s", name);
             assert_error(qts, "host", error, "{ %s: false }", name);
             g_free(error);
@@ -620,9 +624,11 @@ static void test_query_cpu_model_expansion_kvm(const void *data)
                 }
             }
             if (vq <= SVE_MAX_VQ) {
-                sprintf(name, "sve%u", vq * 128);
-                error = g_strdup_printf("cannot enable %s", name);
-                assert_error(qts, "host", error, "{ %s: true }", name);
+                g_autofree const char *name2 =
+                    g_strdup_printf("sve%u", vq * 128);
+
+                error = g_strdup_printf("cannot enable %s", name2);
+                assert_error(qts, "host", error, "{ %s: true }", name2);
                 g_free(error);
             }
         } else {
-- 
2.43.0