content/shell/app/shell_main_mac.cc

// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <dlfcn.h>
#include <errno.h>
#include <libgen.h>
#include <mach-o/dyld.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <memory>

#if defined(HELPER_EXECUTABLE)
#include "sandbox/mac/seatbelt_exec.h"  // nogncheck
#endif                                  // defined(HELPER_EXECUTABLE)

namespace {

using ContentMainPtr = int (*)(int, char**);

}  // namespace

int main(int argc, char* argv[]) {
  uint32_t exec_path_size = 0;
  int rv = _NSGetExecutablePath(NULL, &exec_path_size);
  if (rv != -1) {
    fprintf(stderr, "_NSGetExecutablePath: get length failed\n");
    abort();
  }

  std::unique_ptr<char[]> exec_path(new char[exec_path_size]);
  rv = _NSGetExecutablePath(exec_path.get(), &exec_path_size);
  if (rv != 0) {
    fprintf(stderr, "_NSGetExecutablePath: get path failed\n");
    abort();
  }

#if defined(HELPER_EXECUTABLE)
  sandbox::SeatbeltExecServer::CreateFromArgumentsResult seatbelt =
      sandbox::SeatbeltExecServer::CreateFromArguments(exec_path.get(), argc,
                                                       argv);
  if (seatbelt.sandbox_required) {
    if (!seatbelt.server) {
      fprintf(stderr, "Failed to create seatbelt sandbox server.\n");
      abort();
    }
    if (!seatbelt.server->InitializeSandbox()) {
      fprintf(stderr, "Failed to initialize sandbox.\n");
      abort();
    }
  }

  // The Helper app is in the versioned framework directory, so just go up to
  // the version folder to locate the dylib.
  const char rel_path[] = "../../../../" SHELL_PRODUCT_NAME " Framework";
#else
  const char rel_path[] =
      "../Frameworks/" SHELL_PRODUCT_NAME
      " Framework.framework/" SHELL_PRODUCT_NAME " Framework";
#endif  // defined(HELPER_EXECUTABLE)

  // Slice off the last part of the main executable path, and append the
  // version framework information.
  const char* parent_dir = dirname(exec_path.get());
  if (!parent_dir) {
    fprintf(stderr, "dirname %s: %s\n", exec_path.get(), strerror(errno));
    abort();
  }

  const size_t parent_dir_len = strlen(parent_dir);
  const size_t rel_path_len = strlen(rel_path);
  // 2 accounts for a trailing NUL byte and the '/' in the middle of the paths.
  const size_t framework_path_size = parent_dir_len + rel_path_len + 2;
  std::unique_ptr<char[]> framework_path(new char[framework_path_size]);
  snprintf(framework_path.get(), framework_path_size, "%s/%s", parent_dir,
           rel_path);

  void* library =
      dlopen(framework_path.get(), RTLD_LAZY | RTLD_LOCAL | RTLD_FIRST);
  if (!library) {
    fprintf(stderr, "dlopen %s: %s\n", framework_path.get(), dlerror());
    abort();
  }

  const ContentMainPtr content_main =
      reinterpret_cast<ContentMainPtr>(dlsym(library, "ContentMain"));
  if (!content_main) {
    fprintf(stderr, "dlsym ContentMain: %s\n", dlerror());
    abort();
  }
  rv = content_main(argc, argv);

  // exit, don't return from main, to avoid the apparent removal of main from
  // stack backtraces under tail call optimization.
  exit(rv);
}