chrome/app/chrome_exe_main_mac.cc

// Copyright 2015 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.

// The entry point for all Mac Chromium processes, including the outer app
// bundle (browser) and helper app (renderer, plugin, and friends).

#include <dlfcn.h>
#include <errno.h>
#include <libgen.h>
#include <mach-o/dyld.h>
#include <os/availability.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <memory>

#include "chrome/common/chrome_version.h"

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

extern "C" {
// abort_report_np() records the message in a special section that both the
// system CrashReporter and Crashpad collect in crash reports. Using a Crashpad
// Annotation would be preferable, but this executable cannot depend on
// Crashpad directly.
void abort_report_np(const char* fmt, ...) API_AVAILABLE(macos(10.11));
}

namespace {

typedef int (*ChromeMainPtr)(int, char**);

[[noreturn]] void FatalError(const char* format, ...) {
  va_list valist;
  va_start(valist, format);
  char message[4096];
  if (vsnprintf(message, sizeof(message), format, valist) >= 0) {
    if (__builtin_available(macOS 10.11, *)) {
      abort_report_np("%s", message);
    }
  }
  va_end(valist);
  abort();
}

}  // namespace

__attribute__((visibility("default"))) int main(int argc, char* argv[]) {
  uint32_t exec_path_size = 0;
  int rv = _NSGetExecutablePath(NULL, &exec_path_size);
  if (rv != -1) {
    FatalError("_NSGetExecutablePath: get length failed.");
  }

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

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

  // The helper lives within the versioned framework directory, so simply
  // go up to find the main dylib.
  const char rel_path[] = "../../../../" PRODUCT_FULLNAME_STRING " Framework";
#else
  const char rel_path[] = "../Frameworks/" PRODUCT_FULLNAME_STRING
                          " Framework.framework/Versions/" CHROME_VERSION_STRING
                          "/" PRODUCT_FULLNAME_STRING " 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) {
    FatalError("dirname %s: %s.", exec_path.get(), strerror(errno));
  }

  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) {
    FatalError("dlopen %s: %s.", framework_path.get(), dlerror());
  }

  const ChromeMainPtr chrome_main =
      reinterpret_cast<ChromeMainPtr>(dlsym(library, "ChromeMain"));
  if (!chrome_main) {
    FatalError("dlsym ChromeMain: %s.", dlerror());
  }
  rv = chrome_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);
}