Support NUL inside string values (issue #1646)

extras/tests/Cpp17/string_view.cpp

@@ -8,7 +8,7 @@
 #endif
 
 TEST_CASE("string_view") {
-  StaticJsonDocument<128> doc;
+  StaticJsonDocument<256> doc;
   JsonVariant variant = doc.to<JsonVariant>();
 
   SECTION("deserializeJson()") {
@@ -57,6 +57,12 @@ TEST_CASE("string_view") {
 
     doc.add(std::string_view("example two", 7));
     REQUIRE(doc.memoryUsage() == JSON_ARRAY_SIZE(2) + 8);
+
+    doc.add(std::string_view("example\0tree", 12));
+    REQUIRE(doc.memoryUsage() == JSON_ARRAY_SIZE(3) + 21);
+
+    doc.add(std::string_view("example\0tree and a half", 12));
+    REQUIRE(doc.memoryUsage() == JSON_ARRAY_SIZE(4) + 21);
   }
 
   SECTION("as<std::string_view>()") {
@@ -72,6 +78,12 @@ TEST_CASE("string_view") {
     REQUIRE(doc["s"].is<std::string_view>() == true);
     REQUIRE(doc["i"].is<std::string_view>() == false);
   }
+
+  SECTION("String containing NUL") {
+    doc.set(std::string("hello\0world", 11));
+    REQUIRE(doc.as<std::string_view>().size() == 11);
+    REQUIRE(doc.as<std::string_view>() == std::string_view("hello\0world", 11));
+  }
 }
 
 using ARDUINOJSON_NAMESPACE::adaptString;

extras/tests/JsonDeserializer/string.cpp

@@ -60,9 +60,8 @@ TEST_CASE("\\u0000") {
   CHECK(result[4] == 'z');
   CHECK(result[5] == 0);
 
-  // ArduinoJson strings doesn't store string length, so the following returns 2
-  // instead of 5 (issue #1646)
-  CHECK(doc.as<std::string>().size() == 2);
+  CHECK(doc.as<JsonString>().size() == 5);
+  CHECK(doc.as<std::string>().size() == 5);
 }
 
 TEST_CASE("Truncated JSON string") {

extras/tests/JsonSerializer/JsonVariant.cpp

@@ -63,6 +63,10 @@ TEST_CASE("serializeJson(JsonVariant)") {
     SECTION("Escape tab") {
       check(std::string("hello\tworld"), "\"hello\\tworld\"");
     }
+
+    SECTION("NUL char") {
+      check(std::string("hello\0world", 11), "\"hello\\u0000world\"");
+    }
   }
 
   SECTION("SerializedValue<const char*>") {

extras/tests/JsonSerializer/std_string.cpp

@@ -45,3 +45,13 @@ TEST_CASE("serialize JsonObject to std::string") {
     REQUIRE("{\r\n  \"key\": \"value\"\r\n}" == json);
   }
 }
+
+TEST_CASE("serialize an std::string containing a NUL") {
+  StaticJsonDocument<256> doc;
+  doc.set(std::string("hello\0world", 11));
+  CHECK(doc.memoryUsage() == 12);
+
+  std::string json;
+  serializeJson(doc, json);
+  CHECK("\"hello\\u0000world\"" == json);
+}

extras/tests/MemoryPool/saveString.cpp

@@ -12,6 +12,10 @@ static const char *saveString(MemoryPool &pool, const char *s) {
   return pool.saveString(adaptString(const_cast<char *>(s)));
 }
 
+static const char *saveString(MemoryPool &pool, const char *s, size_t n) {
+  return pool.saveString(adaptString(s, n));
+}
+
 TEST_CASE("MemoryPool::saveString()") {
   char buffer[32];
   MemoryPool pool(buffer, 32);
@@ -30,6 +34,27 @@ TEST_CASE("MemoryPool::saveString()") {
     REQUIRE(pool.size() == 6);
   }
 
+  SECTION("Deduplicates identical strings that contain NUL") {
+    const char *a = saveString(pool, "hello\0world", 11);
+    const char *b = saveString(pool, "hello\0world", 11);
+    REQUIRE(a == b);
+    REQUIRE(pool.size() == 12);
+  }
+
+  SECTION("Reuse part of a string if it ends with NUL") {
+    const char *a = saveString(pool, "hello\0world", 11);
+    const char *b = saveString(pool, "hello");
+    REQUIRE(a == b);
+    REQUIRE(pool.size() == 12);
+  }
+
+  SECTION("Don't stop on first NUL") {
+    const char *a = saveString(pool, "hello");
+    const char *b = saveString(pool, "hello\0world", 11);
+    REQUIRE(a != b);
+    REQUIRE(pool.size() == 18);
+  }
+
   SECTION("Returns NULL when full") {
     REQUIRE(pool.capacity() == 32);