flatbuffers_codegen_fuzzer.cc

#include <stddef.h>
#include <stdint.h>
#include <string>
#include "flatbuffers/idl.h"  // For Parser and generation functions
#include "test_init.h"
#include <memory>
#include <flatbuffers/flatc.h>
#include "idl_gen_cpp.h"  // For C++ generator
#include <idl_gen_csharp.h>
#include <iostream>
#include "flatbuffers/code_generator.h"
#include <idl_gen_binary.h>
#include <idl_gen_dart.h>
#include <idl_gen_fbs.h>
#include <idl_gen_go.h>
#include <idl_gen_java.h>
#include <idl_gen_json_schema.h>
#include <idl_gen_kotlin.h>
#include <idl_gen_kotlin.h>
#include <idl_gen_lobster.h>
#include <bfbs_gen_lua.h>
#include <bfbs_gen_nim.h>
#include <idl_gen_python.h>
#include <idl_gen_php.h>
#include <idl_gen_rust.h>
#include <idl_gen_text.h>
#include <idl_gen_swift.h>
#include <idl_gen_ts.h>

static constexpr size_t kMinInputLength = 1;
static constexpr size_t kMaxInputLength = 16384;

static constexpr uint8_t flags_strict_json = 0x80;
static constexpr uint8_t flags_skip_unexpected_fields_in_json = 0x40;
static constexpr uint8_t flags_allow_non_utf8 = 0x20;

// Utility for test run.
OneTimeTestInit OneTimeTestInit::one_time_init_;

static const char* g_program_name = nullptr;

static void Warn(const flatbuffers::FlatCompiler* flatc,
                 const std::string& warn, bool show_exe_name) {
  (void)flatc;
  if (show_exe_name) {
    printf("%s: ", g_program_name);
  }
  fprintf(stderr, "\nwarning:\n  %s\n\n", warn.c_str());
}

static void Error(const flatbuffers::FlatCompiler* flatc,
                  const std::string& err, bool usage, bool show_exe_name) {
  if (show_exe_name) {
    printf("%s: ", g_program_name);
  }
  if (usage && flatc) {
    fprintf(stderr, "%s\n", flatc->GetShortUsageString(g_program_name).c_str());
  }
  fprintf(stderr, "\nerror:\n  %s\n\n", err.c_str());
  exit(1);
}

namespace flatbuffers {
void LogCompilerWarn(const std::string& warn) {
  Warn(static_cast<const flatbuffers::FlatCompiler*>(nullptr), warn, true);
}
void LogCompilerError(const std::string& err) {
  Error(static_cast<const flatbuffers::FlatCompiler*>(nullptr), err, false,
        true);
}
}  // namespace flatbuffers

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
  // Reserve one byte for Parser flags and one byte for repetition counter.
  if (size < 3) return 0;
  const uint8_t flags = data[0];
  (void)data[1];  //  reserved
  data += 2;
  size -= 2;  // bypass

  const std::string original(reinterpret_cast<const char*>(data), size);
  auto input = std::string(original.c_str());  // until '\0'
  if (input.size() < kMinInputLength || input.size() > kMaxInputLength)
    return 0;

  flatbuffers::IDLOptions opts;
  opts.strict_json = (flags & flags_strict_json);
  opts.skip_unexpected_fields_in_json =
      (flags & flags_skip_unexpected_fields_in_json);
  opts.allow_non_utf8 = (flags & flags_allow_non_utf8);

  flatbuffers::Parser parser(opts);

  // Guarantee 0-termination in the input.
  auto parse_input = input.c_str();

  // Parse the input schema
  if (parser.Parse(parse_input)) {
    parser.Serialize();
    const uint8_t* buf = parser.builder_.GetBufferPointer();
    flatbuffers::Verifier verifier(buf,
                                   parser.builder_.GetSize());
    TEST_EQ(true, reflection::VerifySchemaBuffer(verifier));

    auto root = flatbuffers::GetRoot<flatbuffers::Table>(buf);
    if (verifier.VerifyTableStart(buf) && root->VerifyTableStart(verifier)) {
      if (parser.root_struct_def_) {
        std::string json_output;
        flatbuffers::GenText(parser, parser.builder_.GetBufferPointer(),
                             &json_output);
      }
    }

    std::string temp_filename = "fuzzer_generated";

    const std::string flatbuffers_version(flatbuffers::FLATBUFFERS_VERSION());
    std::vector<std::unique_ptr<flatbuffers::CodeGenerator>> generators;
    generators.emplace_back(flatbuffers::NewBinaryCodeGenerator());
    generators.emplace_back(flatbuffers::NewCppCodeGenerator());
    generators.emplace_back(flatbuffers::NewCSharpCodeGenerator());
    generators.emplace_back(flatbuffers::NewDartCodeGenerator());
    generators.emplace_back(flatbuffers::NewFBSCodeGenerator());
    generators.emplace_back(flatbuffers::NewGoCodeGenerator());
    generators.emplace_back(flatbuffers::NewJavaCodeGenerator());
    generators.emplace_back(flatbuffers::NewJsonSchemaCodeGenerator());
    generators.emplace_back(flatbuffers::NewKotlinCodeGenerator());
    generators.emplace_back(flatbuffers::NewKotlinKMPCodeGenerator());
    generators.emplace_back(flatbuffers::NewLobsterCodeGenerator());
    generators.emplace_back(flatbuffers::NewLuaBfbsGenerator(flatbuffers_version));
    generators.emplace_back(flatbuffers::NewNimBfbsGenerator(flatbuffers_version));
    generators.emplace_back(flatbuffers::NewPythonCodeGenerator());
    generators.emplace_back(flatbuffers::NewPhpCodeGenerator());
    generators.emplace_back(flatbuffers::NewRustCodeGenerator());
    generators.emplace_back(flatbuffers::NewTextCodeGenerator());
    generators.emplace_back(flatbuffers::NewSwiftCodeGenerator());
    generators.emplace_back(flatbuffers::NewTsCodeGenerator());

    for (auto& gen : generators) {
      auto p = gen.get();
      std::string temp_path = "/tmp/";
      auto status = p->GenerateCode(parser, temp_path, "fuzzer_generated");
      if (status != flatbuffers::CodeGenerator::Status::OK) {
        TEST_OUTPUT_LINE("GenerateCode failed %d", status);
      }

      // test gRPC code generation
      auto grpc_status =
          p->GenerateGrpcCode(parser, temp_path, "fuzzer_generated");
      if (grpc_status != flatbuffers::CodeGenerator::Status::OK) {
        TEST_OUTPUT_LINE("GenerateGrpcCode failed %d", grpc_status);
      }
    }
  }

  return 0;
}