tests: Clean up string interpolation into QMP input (simple cases)

When you build QMP input manually like this

    cmd = g_strdup_printf("{ 'execute': 'migrate',"
                          "'arguments': { 'uri': '%s' } }",
                          uri);
    rsp = qmp(cmd);
    g_free(cmd);

you're responsible for escaping the interpolated values for JSON.  Not
done here, and therefore works only for sufficiently nice @uri.  For
instance, if @uri contained a single "'", qobject_from_vjsonf_nofail()
would abort.  A sufficiently nasty @uri could even inject unwanted
members into the arguments object.

Leaving interpolation into JSON to qmp() is more robust:

    rsp = qmp("{ 'execute': 'migrate', 'arguments': { 'uri': %s } }", uri);

It's also more concise.

Clean up the simple cases where we interpolate exactly a JSON value.

Bonus: gets rid of non-literal format strings.  A step towards
compile-time format string checking without triggering
-Wformat-nonliteral.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180806065344.7103-13-armbru@redhat.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/tests/migration-test.c b/tests/migration-test.c
index bbe9c9e95d..486059580c 100644
--- a/tests/migration-test.c
+++ b/tests/migration-test.c
@@ -532,14 +532,12 @@ static void test_migrate_end(QTestState *from, QTestState *to, bool test_dest)
 static void deprecated_set_downtime(QTestState *who, const double value)
 {
     QDict *rsp;
-    gchar *cmd;
     char *expected;
     int64_t result_int;
 
-    cmd = g_strdup_printf("{ 'execute': 'migrate_set_downtime',"
-                          "'arguments': { 'value': %g } }", value);
-    rsp = qtest_qmp(who, cmd);
-    g_free(cmd);
+    rsp = qtest_qmp(who,
+                    "{ 'execute': 'migrate_set_downtime',"
+                    " 'arguments': { 'value': %f } }", value);
     g_assert(qdict_haskey(rsp, "return"));
     qobject_unref(rsp);
     result_int = value * 1000L;