json: Encode NULL strings as null

This is the only nullable thing we have here.

2 files changed, 12 insertions, 1 deletions

diff --git a/apt-private/private-json-hooks.cc b/apt-private/private-json-hooks.cc
index ce1665b18..7991a7d77 100644
--- a/apt-private/private-json-hooks.cc
+++ b/apt-private/private-json-hooks.cc
@@ -141,7 +141,10 @@ class APT_HIDDEN JsonWriter
    JsonWriter &value(const char *value)
    {
       maybeComma();
-      encodeString(os, value);
+      if (value == nullptr)
+	 os << "null";
+      else
+	 encodeString(os, value);
       return *this;
    }
    JsonWriter &value(int value)
diff --git a/test/libapt/json_test.cc b/test/libapt/json_test.cc
index 9c29936f6..ee8f3cebe 100644
--- a/test/libapt/json_test.cc
+++ b/test/libapt/json_test.cc
@@ -59,3 +59,11 @@ TEST(JsonTest, JsonStackRegression)
 
    EXPECT_EQ("{\"a\":[{}],\"b\":[{}]}", os.str());
 }
+TEST(JsonTest, JsonNull)
+{
+   std::ostringstream os;
+
+   JsonWriter(os).value(nullptr);
+
+   EXPECT_EQ("null", os.str());
+}