json: introduce json_append()

3 files changed, 42 insertions, 0 deletions

diff --git a/src/shared/json.c b/src/shared/json.c
index f0416e66dc..d541eb1036 100644
--- a/src/shared/json.c
+++ b/src/shared/json.c
@@ -4120,6 +4120,30 @@ int json_build(JsonVariant **ret, ...) {
         return r;
 }
 
+int json_appendv(JsonVariant **v, va_list ap) {
+        _cleanup_(json_variant_unrefp) JsonVariant *w = NULL;
+        int r;
+
+        assert(v);
+
+        r = json_buildv(&w, ap);
+        if (r < 0)
+                return r;
+
+        return json_variant_merge(v, w);
+}
+
+int json_append(JsonVariant **v, ...) {
+        va_list ap;
+        int r;
+
+        va_start(ap, v);
+        r = json_appendv(v, ap);
+        va_end(ap);
+
+        return r;
+}
+
 int json_log_internal(
                 JsonVariant *variant,
                 int level,
diff --git a/src/shared/json.h b/src/shared/json.h
index 98d184c309..c75dfe8741 100644
--- a/src/shared/json.h
+++ b/src/shared/json.h
@@ -327,6 +327,9 @@ enum {
 
 int json_build(JsonVariant **ret, ...);
 int json_buildv(JsonVariant **ret, va_list ap);
+ /* These two functions below are equivalent to json_build() (or json_buildv()) and json_variant_merge(). */
+int json_append(JsonVariant **v, ...);
+int json_appendv(JsonVariant **v, va_list ap);
 
 /* A bitmask of flags used by the dispatch logic. Note that this is a combined bit mask, that is generated from the bit
  * mask originally passed into json_dispatch(), the individual bitmask associated with the static JsonDispatch callout
diff --git a/src/test/test-json.c b/src/test/test-json.c
index d22485630a..3563d004c8 100644
--- a/src/test/test-json.c
+++ b/src/test/test-json.c
@@ -631,4 +631,19 @@ TEST(variant) {
         test_variant_one("[ 0, -0, 0.0, -0.0, 0.000, -0.000, 0e0, -0e0, 0e+0, -0e-0, 0e-0, -0e000, 0e+000 ]", test_zeroes);
 }
 
+TEST(json_append) {
+        _cleanup_(json_variant_unrefp) JsonVariant *v = NULL, *w = NULL;
+
+        assert_se(json_build(&v, JSON_BUILD_OBJECT(
+                                             JSON_BUILD_PAIR("b", JSON_BUILD_STRING("x")),
+                                             JSON_BUILD_PAIR("c", JSON_BUILD_CONST_STRING("y")),
+                                             JSON_BUILD_PAIR("a", JSON_BUILD_CONST_STRING("z")))) >= 0);
+
+        assert_se(json_append(&w, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("b", JSON_BUILD_STRING("x")))) >= 0);
+        assert_se(json_append(&w, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("c", JSON_BUILD_STRING("y")))) >= 0);
+        assert_se(json_append(&w, JSON_BUILD_OBJECT(JSON_BUILD_PAIR("a", JSON_BUILD_STRING("z")))) >= 0);
+
+        assert_se(json_variant_equal(v, w));
+}
+
 DEFINE_TEST_MAIN(LOG_DEBUG);