basic/set: add set_ensure_consume()

This combines set_ensure_allocated() with set_consume(). The cool thing is that
because we know the hash ops, we can correctly free the item if appropriate.
Similarly to set_consume(), the goal is to simplify handling of the case where
the item needs to be freed on error and if already present in the set.

src/basic/hashmap.c

@@ -1257,6 +1257,20 @@ int _set_ensure_put(Set **s, const struct hash_ops *hash_ops, const void *key  H
         return set_put(*s, key);
 }
 
+int _set_ensure_consume(Set **s, const struct hash_ops *hash_ops, void *key  HASHMAP_DEBUG_PARAMS) {
+        int r;
+
+        r = _set_ensure_put(s, hash_ops, key  HASHMAP_DEBUG_PASS_ARGS);
+        if (r <= 0) {
+                if (hash_ops && hash_ops->free_key)
+                        hash_ops->free_key(key);
+                else
+                        free(key);
+        }
+
+        return r;
+}
+
 int hashmap_replace(Hashmap *h, const void *key, void *value) {
         struct swap_entries swap;
         struct plain_hashmap_entry *e;

src/basic/set.h

@@ -123,6 +123,9 @@ static inline char **set_get_strv(Set *s) {
 int _set_ensure_put(Set **s, const struct hash_ops *hash_ops, const void *key  HASHMAP_DEBUG_PARAMS);
 #define set_ensure_put(s, hash_ops, key) _set_ensure_put(s, hash_ops, key  HASHMAP_DEBUG_SRC_ARGS)
 
+int _set_ensure_consume(Set **s, const struct hash_ops *hash_ops, void *key  HASHMAP_DEBUG_PARAMS);
+#define set_ensure_consume(s, hash_ops, key) _set_ensure_consume(s, hash_ops, key  HASHMAP_DEBUG_SRC_ARGS)
+
 int set_consume(Set *s, void *value);
 int set_put_strdup(Set **s, const char *p);
 int set_put_strdupv(Set **s, char **l);

src/test/test-set.c

@@ -128,6 +128,28 @@ static void test_set_ensure_put(void) {
         assert_se(set_size(m) == 2);
 }
 
+static void test_set_ensure_consume(void) {
+        _cleanup_set_free_ Set *m = NULL;
+        char *s, *t;
+
+        assert_se(s = strdup("a"));
+        assert_se(set_ensure_consume(&m, &string_hash_ops_free, s) == 1);
+
+        assert_se(t = strdup("a"));
+        assert_se(set_ensure_consume(&m, &string_hash_ops_free, t) == 0);
+
+        assert_se(t = strdup("a"));
+        assert_se(set_ensure_consume(&m, &string_hash_ops_free, t) == 0);
+
+        assert_se(t = strdup("b"));
+        assert_se(set_ensure_consume(&m, &string_hash_ops_free, t) == 1);
+
+        assert_se(t = strdup("b"));
+        assert_se(set_ensure_consume(&m, &string_hash_ops_free, t) == 0);
+
+        assert_se(set_size(m) == 2);
+}
+
 int main(int argc, const char *argv[]) {
         test_set_steal_first();
         test_set_free_with_destructor();
@@ -137,6 +159,7 @@ int main(int argc, const char *argv[]) {
         test_set_put_strdupv();
         test_set_ensure_allocated();
         test_set_ensure_put();
+        test_set_ensure_consume();
 
         return 0;
 }

test/fuzz/fuzz-network-parser/dns-trust-anchor-duplicate.network

@@ -0,0 +1,2 @@
+[Network]
+DNSSECNegativeTrustAnchors=i i