src/tools/wasm2c.cc

/*
 * Copyright 2017 WebAssembly Community Group participants
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <cassert>
#include <cinttypes>
#include <cstdio>
#include <cstdlib>

#include "wabt/apply-names.h"
#include "wabt/binary-reader-ir.h"
#include "wabt/binary-reader.h"
#include "wabt/error-formatter.h"
#include "wabt/feature.h"
#include "wabt/filenames.h"
#include "wabt/generate-names.h"
#include "wabt/ir.h"
#include "wabt/option-parser.h"
#include "wabt/result.h"
#include "wabt/stream.h"
#include "wabt/validator.h"
#include "wabt/wast-lexer.h"

#include "wabt/c-writer.h"

using namespace wabt;

static int s_verbose;
static std::string s_infile;
static std::string s_outfile;
static unsigned int s_num_outputs = 1;
static Features s_features;
static WriteCOptions s_write_c_options;
static bool s_read_debug_names = true;
static std::unique_ptr<FileStream> s_log_stream;

static const char s_description[] =
    R"(  Read a file in the WebAssembly binary format, and convert it to
  a C source file and header.

examples:
  # parse binary file test.wasm and write test.c and test.h
  $ wasm2c test.wasm -o test.c

  # parse test.wasm, write test.c and test.h, but ignore the debug names, if any
  $ wasm2c test.wasm --no-debug-names -o test.c
)";

static const std::string supported_features[] = {
    "multi-memory", "multi-value", "sign-extension", "saturating-float-to-int",
    "exceptions",   "memory64",    "extended-const", "simd",
    "threads"};

static bool IsFeatureSupported(const std::string& feature) {
  return std::find(std::begin(supported_features), std::end(supported_features),
                   feature) != std::end(supported_features);
};

static void ParseOptions(int argc, char** argv) {
  OptionParser parser("wasm2c", s_description);

  parser.AddOption('v', "verbose", "Use multiple times for more info", []() {
    s_verbose++;
    s_log_stream = FileStream::CreateStderr();
  });
  parser.AddOption(
      'o', "output", "FILENAME",
      "Output file for the generated C source file, by default use stdout",
      [](const char* argument) {
        s_outfile = argument;
        ConvertBackslashToSlash(&s_outfile);
      });
  parser.AddOption(
      '\0', "num-outputs", "NUM", "Number of output files to write",
      [](const char* argument) { s_num_outputs = atoi(argument); });
  parser.AddOption(
      'n', "module-name", "MODNAME",
      "Unique name for the module being generated. This name is prefixed to\n"
      "each of the generaed C symbols. By default, the module name from the\n"
      "names section is used. If that is not present the name of the input\n"
      "file is used as the default.\n",
      [](const char* argument) { s_write_c_options.module_name = argument; });
  s_features.AddOptions(&parser);
  parser.AddOption("no-debug-names", "Ignore debug names in the binary file",
                   []() { s_read_debug_names = false; });
  parser.AddArgument("filename", OptionParser::ArgumentCount::One,
                     [](const char* argument) {
                       s_infile = argument;
                       ConvertBackslashToSlash(&s_infile);
                     });
  parser.Parse(argc, argv);

  bool any_non_supported_feature = false;
#define WABT_FEATURE(variable, flag, default_, help)   \
  any_non_supported_feature |=                         \
      (s_features.variable##_enabled() != default_) && \
      s_features.variable##_enabled() && !IsFeatureSupported(flag);
#include "wabt/feature.def"
#undef WABT_FEATURE

  if (any_non_supported_feature) {
    fprintf(stderr,
            "wasm2c currently only supports a limited set of features.\n");
    exit(1);
  }
}

// TODO(binji): copied from binary-writer-spec.cc, probably should share.
static std::string_view strip_extension(std::string_view s) {
  std::string_view ext = s.substr(s.find_last_of('.'));
  std::string_view result = s;

  if (ext == ".c")
    result.remove_suffix(ext.length());
  return result;
}

Result Wasm2cMain(Errors& errors) {
  if (s_num_outputs < 1) {
    fprintf(stderr, "Number of output files must be positive.\n");
    return Result::Error;
  }

  std::vector<uint8_t> file_data;
  CHECK_RESULT(ReadFile(s_infile.c_str(), &file_data));

  Module module;
  const bool kStopOnFirstError = true;
  const bool kFailOnCustomSectionError = true;
  ReadBinaryOptions options(s_features, s_log_stream.get(), s_read_debug_names,
                            kStopOnFirstError, kFailOnCustomSectionError);
  CHECK_RESULT(ReadBinaryIr(s_infile.c_str(), file_data.data(),
                            file_data.size(), options, &errors, &module));
  CHECK_RESULT(ValidateModule(&module, &errors, s_features));
  CHECK_RESULT(GenerateNames(&module));
  /* TODO(binji): This shouldn't fail; if a name can't be applied
   * (because the index is invalid, say) it should just be skipped. */
  ApplyNames(&module);

  if (!s_outfile.empty()) {
    std::string header_name_full =
        std::string(strip_extension(s_outfile)) + ".h";
    std::vector<FileStream> c_streams;
    if (s_num_outputs == 1) {
      c_streams.emplace_back(s_outfile.c_str());
    } else {
      std::string output_prefix{strip_extension(s_outfile)};
      for (unsigned int i = 0; i < s_num_outputs; i++) {
        c_streams.emplace_back(output_prefix + "_" + std::to_string(i) + ".c");
      }
    }
    std::vector<Stream*> c_stream_ptrs;
    for (auto& s : c_streams) {
      c_stream_ptrs.emplace_back(&s);
    }
    FileStream h_stream(header_name_full);
    std::string_view header_name = GetBasename(header_name_full);
    if (s_write_c_options.module_name.empty()) {
      s_write_c_options.module_name = module.name;
      if (s_write_c_options.module_name.empty()) {
        // In the absence of module name in the names section use the filename.
        s_write_c_options.module_name = StripExtension(GetBasename(s_infile));
      }
    }
    if (s_num_outputs == 1) {
      CHECK_RESULT(WriteC(std::move(c_stream_ptrs), &h_stream, c_stream_ptrs[0],
                          std::string(header_name).c_str(), "", &module,
                          s_write_c_options));
    } else {
      std::string header_impl_name_full =
          std::string(strip_extension(s_outfile)) + "-impl.h";
      FileStream h_impl_stream(header_impl_name_full);
      std::string_view header_impl_name = GetBasename(header_impl_name_full);
      CHECK_RESULT(WriteC(std::move(c_stream_ptrs), &h_stream, &h_impl_stream,
                          std::string(header_name).c_str(),
                          std::string(header_impl_name).c_str(), &module,
                          s_write_c_options));
    }
  } else {
    FileStream stream(stdout);
    CHECK_RESULT(WriteC({&stream}, &stream, &stream, "wasm.h", "", &module,
                        s_write_c_options));
  }

  return Result::Ok;
}

int ProgramMain(int argc, char** argv) {
  Result result;

  InitStdio();
  ParseOptions(argc, argv);

  Errors errors;
  result = Wasm2cMain(errors);
  FormatErrorsToFile(errors, Location::Type::Binary);

  return result != Result::Ok;
}

int main(int argc, char** argv) {
  WABT_TRY
  return ProgramMain(argc, argv);
  WABT_CATCH_BAD_ALLOC_AND_EXIT
}