🚧 some changes to the BSON code

- added fuzz testers
- added some reference files
- made an exception text more clear

Makefile

@@ -48,6 +48,7 @@ all:
 	@echo "cppcheck - analyze code with cppcheck"
 	@echo "doctest - compile example files and check their output"
 	@echo "fuzz_testing - prepare fuzz testing of the JSON parser"
+	@echo "fuzz_testing_bson - prepare fuzz testing of the BSON parser"
 	@echo "fuzz_testing_cbor - prepare fuzz testing of the CBOR parser"
 	@echo "fuzz_testing_msgpack - prepare fuzz testing of the MessagePack parser"
 	@echo "fuzz_testing_ubjson - prepare fuzz testing of the UBJSON parser"
@@ -220,6 +221,14 @@ fuzz_testing:
 	find test/data/json_tests -size -5k -name *json | xargs -I{} cp "{}" fuzz-testing/testcases
 	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
 
+fuzz_testing_bson:
+	rm -fr fuzz-testing
+	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
+	$(MAKE) parse_bson_fuzzer -C test CXX=afl-clang++
+	mv test/parse_bson_fuzzer fuzz-testing/fuzzer
+	find test/data -size -5k -name *.bson | xargs -I{} cp "{}" fuzz-testing/testcases
+	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
+
 fuzz_testing_cbor:
 	rm -fr fuzz-testing
 	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out

include/nlohmann/detail/meta/type_traits.hpp

@@ -193,13 +193,13 @@ struct is_constructible_object_type_impl <
     static constexpr bool value =
         std::is_constructible<typename ConstructibleObjectType::key_type,
         typename object_t::key_type>::value and
-        std::is_same<typename object_t::mapped_type,
+        (std::is_same<typename object_t::mapped_type,
-        typename ConstructibleObjectType::mapped_type>::value or
-        (has_from_json<BasicJsonType,
          typename ConstructibleObjectType::mapped_type>::value or
-         has_non_default_from_json <
+         (has_from_json<BasicJsonType,
-         BasicJsonType,
+          typename ConstructibleObjectType::mapped_type>::value or
-         typename ConstructibleObjectType::mapped_type >::value);
+          has_non_default_from_json <
+          BasicJsonType,
+          typename ConstructibleObjectType::mapped_type >::value));
 };
 
 template <typename BasicJsonType, typename ConstructibleObjectType>

include/nlohmann/detail/output/binary_writer.hpp

@@ -976,14 +976,22 @@ class binary_writer
     {
         switch (j.type())
         {
-            default:
-                JSON_THROW(type_error::create(317, "JSON value of type " + std::to_string(static_cast<std::uint8_t>(j.type())) + " cannot be serialized to requested format"));
-                break;
-            case value_t::discarded:
-                break;
             case value_t::object:
+            {
                 write_bson_object(*j.m_value.object);
                 break;
+            }
+
+            case value_t::discarded:
+            {
+                break;
+            }
+
+            default:
+            {
+                JSON_THROW(type_error::create(317, "to serialize to BSON, top-level type must be object, but is " + std::string(j.type_name())));
+                break;
+            }
         }
     }
 
@@ -1009,7 +1017,7 @@ class binary_writer
         std::memcpy(vec.data(), &n, sizeof(NumberType));
 
         // step 2: write array to output (with possible reordering)
-        if (is_little_endian && !OutputIsLittleEndian)
+        if (is_little_endian and not OutputIsLittleEndian)
         {
             // reverse byte order prior to conversion if necessary
             std::reverse(vec.begin(), vec.end());

single_include/nlohmann/json.hpp

@@ -553,13 +553,13 @@ struct is_constructible_object_type_impl <
     static constexpr bool value =
         std::is_constructible<typename ConstructibleObjectType::key_type,
         typename object_t::key_type>::value and
-        std::is_same<typename object_t::mapped_type,
+        (std::is_same<typename object_t::mapped_type,
-        typename ConstructibleObjectType::mapped_type>::value or
-        (has_from_json<BasicJsonType,
          typename ConstructibleObjectType::mapped_type>::value or
-         has_non_default_from_json <
+         (has_from_json<BasicJsonType,
-         BasicJsonType,
+          typename ConstructibleObjectType::mapped_type>::value or
-         typename ConstructibleObjectType::mapped_type >::value);
+          has_non_default_from_json <
+          BasicJsonType,
+          typename ConstructibleObjectType::mapped_type >::value));
 };
 
 template <typename BasicJsonType, typename ConstructibleObjectType>
@@ -9234,14 +9234,22 @@ class binary_writer
     {
         switch (j.type())
         {
-            default:
-                JSON_THROW(type_error::create(317, "JSON value of type " + std::to_string(static_cast<std::uint8_t>(j.type())) + " cannot be serialized to requested format"));
-                break;
-            case value_t::discarded:
-                break;
             case value_t::object:
+            {
                 write_bson_object(*j.m_value.object);
                 break;
+            }
+
+            case value_t::discarded:
+            {
+                break;
+            }
+
+            default:
+            {
+                JSON_THROW(type_error::create(317, "to serialize to BSON, top-level type must be object, but is " + std::string(j.type_name())));
+                break;
+            }
         }
     }
 
@@ -9267,7 +9275,7 @@ class binary_writer
         std::memcpy(vec.data(), &n, sizeof(NumberType));
 
         // step 2: write array to output (with possible reordering)
-        if (is_little_endian && !OutputIsLittleEndian)
+        if (is_little_endian and not OutputIsLittleEndian)
         {
             // reverse byte order prior to conversion if necessary
             std::reverse(vec.begin(), vec.end());

test/Makefile

@@ -10,6 +10,7 @@ SOURCES = src/unit.cpp \
           src/unit-algorithms.cpp \
           src/unit-allocator.cpp \
           src/unit-alt-string.cpp \
+          src/unit-bson.cpp \
           src/unit-capacity.cpp \
           src/unit-cbor.cpp \
           src/unit-class_const_iterator.cpp \
@@ -90,12 +91,15 @@ check: $(OBJECTS) $(TESTCASES)
 ##############################################################################
 
 FUZZER_ENGINE = src/fuzzer-driver_afl.cpp
-FUZZERS = parse_afl_fuzzer parse_cbor_fuzzer parse_msgpack_fuzzer parse_ubjson_fuzzer
+FUZZERS = parse_afl_fuzzer parse_bson_fuzzer parse_cbor_fuzzer parse_msgpack_fuzzer parse_ubjson_fuzzer
 fuzzers: $(FUZZERS)
 
 parse_afl_fuzzer:
 	$(CXX) $(CXXFLAGS) $(CPPFLAGS) $(FUZZER_ENGINE) src/fuzzer-parse_json.cpp -o $@
 
+parse_bson_fuzzer:
+	$(CXX) $(CXXFLAGS) $(CPPFLAGS) $(FUZZER_ENGINE) src/fuzzer-parse_bson.cpp -o $@
+
 parse_cbor_fuzzer:
 	$(CXX) $(CXXFLAGS) $(CPPFLAGS) $(FUZZER_ENGINE) src/fuzzer-parse_cbor.cpp -o $@
 

test/src/fuzzer-parse_bson.cpp

@@ -0,0 +1,68 @@
+/*
+    __ _____ _____ _____
+ __|  |   __|     |   | |  JSON for Modern C++ (fuzz test support)
+|  |  |__   |  |  | | | |  version 3.3.0
+|_____|_____|_____|_|___|  https://github.com/nlohmann/json
+
+This file implements a parser test suitable for fuzz testing. Given a byte
+array data, it performs the following steps:
+
+- j1 = from_bson(data)
+- vec = to_bson(j1)
+- j2 = from_bson(vec)
+- assert(j1 == j2)
+
+The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
+drivers.
+
+Licensed under the MIT License <http://opensource.org/licenses/MIT>.
+*/
+
+#include <iostream>
+#include <sstream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+// see http://llvm.org/docs/LibFuzzer.html
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
+{
+    try
+    {
+        // step 1: parse input
+        std::vector<uint8_t> vec1(data, data + size);
+        json j1 = json::from_bson(vec1);
+
+        try
+        {
+            // step 2: round trip
+            std::vector<uint8_t> vec2 = json::to_bson(j1);
+
+            // parse serialization
+            json j2 = json::from_bson(vec2);
+
+            // serializations must match
+            assert(json::to_bson(j2) == vec2);
+        }
+        catch (const json::parse_error&)
+        {
+            // parsing a CBOR serialization must not fail
+            assert(false);
+        }
+    }
+    catch (const json::parse_error&)
+    {
+        // parse errors are ok, because input may be random bytes
+    }
+    catch (const json::type_error&)
+    {
+        // type errors can occur during parsing, too
+    }
+    catch (const json::out_of_range&)
+    {
+        // out of range errors can occur during parsing, too
+    }
+
+    // return 0 - non-zero return values are reserved for future use
+    return 0;
+}

test/src/unit-bson.cpp

@@ -49,7 +49,7 @@ TEST_CASE("BSON")
         {
             json j = nullptr;
             REQUIRE_THROWS_AS(json::to_bson(j), json::type_error&);
-            CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] JSON value of type 0 cannot be serialized to requested format");
+            CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] to serialize to BSON, top-level type must be object, but is null");
         }
 
         SECTION("boolean")
@@ -58,14 +58,14 @@ TEST_CASE("BSON")
             {
                 json j = true;
                 REQUIRE_THROWS_AS(json::to_bson(j), json::type_error&);
-                CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] JSON value of type 4 cannot be serialized to requested format");
+                CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] to serialize to BSON, top-level type must be object, but is boolean");
             }
 
             SECTION("false")
             {
                 json j = false;
                 REQUIRE_THROWS_AS(json::to_bson(j), json::type_error&);
-                CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] JSON value of type 4 cannot be serialized to requested format");
+                CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] to serialize to BSON, top-level type must be object, but is boolean");
             }
         }
 
@@ -73,28 +73,28 @@ TEST_CASE("BSON")
         {
             json j = 42;
             REQUIRE_THROWS_AS(json::to_bson(j), json::type_error&);
-            CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] JSON value of type 5 cannot be serialized to requested format");
+                CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] to serialize to BSON, top-level type must be object, but is number");
         }
 
         SECTION("float")
         {
             json j = 4.2;
             REQUIRE_THROWS_AS(json::to_bson(j), json::type_error&);
-            CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] JSON value of type 7 cannot be serialized to requested format");
+                CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] to serialize to BSON, top-level type must be object, but is number");
         }
 
         SECTION("string")
         {
             json j = "not supported";
             REQUIRE_THROWS_AS(json::to_bson(j), json::type_error&);
-            CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] JSON value of type 3 cannot be serialized to requested format");
+                CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] to serialize to BSON, top-level type must be object, but is string");
         }
 
         SECTION("array")
         {
             json j = std::vector<int> {1, 2, 3, 4, 5, 6, 7};
             REQUIRE_THROWS_AS(json::to_bson(j), json::type_error&);
-            CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] JSON value of type 2 cannot be serialized to requested format");
+                CHECK_THROWS_WITH(json::to_bson(j), "[json.exception.type_error.317] to serialize to BSON, top-level type must be object, but is array");
         }
     }
 
@@ -1126,3 +1126,92 @@ TEST_CASE("BSON numerical data")
         }
     }
 }
+
+TEST_CASE("BSON roundtrips", "[hide]")
+{
+    SECTION("reference files")
+    {
+        for (std::string filename :
+                {
+                    "test/data/json.org/1.json",
+                    "test/data/json.org/2.json",
+                    "test/data/json.org/3.json",
+                    "test/data/json.org/4.json",
+                    "test/data/json.org/5.json"
+                })
+        {
+            CAPTURE(filename);
+
+            SECTION(filename + ": std::vector<uint8_t>")
+            {
+                // parse JSON file
+                std::ifstream f_json(filename);
+                json j1 = json::parse(f_json);
+
+                // parse BSON file
+                std::ifstream f_bson(filename + ".bson", std::ios::binary);
+                std::vector<uint8_t> packed(
+                    (std::istreambuf_iterator<char>(f_bson)),
+                    std::istreambuf_iterator<char>());
+                json j2;
+                CHECK_NOTHROW(j2 = json::from_bson(packed));
+
+                // compare parsed JSON values
+                CHECK(j1 == j2);
+            }
+
+            SECTION(filename + ": std::ifstream")
+            {
+                // parse JSON file
+                std::ifstream f_json(filename);
+                json j1 = json::parse(f_json);
+
+                // parse BSON file
+                std::ifstream f_bson(filename + ".bson", std::ios::binary);
+                json j2;
+                CHECK_NOTHROW(j2 = json::from_bson(f_bson));
+
+                // compare parsed JSON values
+                CHECK(j1 == j2);
+            }
+
+            SECTION(filename + ": uint8_t* and size")
+            {
+                // parse JSON file
+                std::ifstream f_json(filename);
+                json j1 = json::parse(f_json);
+
+                // parse BSON file
+                std::ifstream f_bson(filename + ".bson", std::ios::binary);
+                std::vector<uint8_t> packed(
+                    (std::istreambuf_iterator<char>(f_bson)),
+                    std::istreambuf_iterator<char>());
+                json j2;
+                CHECK_NOTHROW(j2 = json::from_bson({packed.data(), packed.size()}));
+
+                // compare parsed JSON values
+                CHECK(j1 == j2);
+            }
+
+            SECTION(filename + ": output to output adapters")
+            {
+                // parse JSON file
+                std::ifstream f_json(filename);
+                json j1 = json::parse(f_json);
+
+                // parse BSON file
+                std::ifstream f_bson(filename + ".bson", std::ios::binary);
+                std::vector<uint8_t> packed(
+                    (std::istreambuf_iterator<char>(f_bson)),
+                    std::istreambuf_iterator<char>());
+
+                    SECTION(filename + ": output adapters: std::vector<uint8_t>")
+                    {
+                        std::vector<uint8_t> vec;
+                        json::to_bson(j1, vec);
+                        CHECK(vec == packed);
+                    }
+            }
+        }
+    }
+}