static void LLVM_ATTRIBUTE_NORETURN ChildFunc(int error_fd,
                                              const ProcessLaunchInfo &info) {
  if (info.GetFlags().Test(eLaunchFlagLaunchInSeparateProcessGroup)) {
    if (setpgid(0, 0) != 0)
      ExitWithError(error_fd, "setpgid");
  }

  for (size_t i = 0; i < info.GetNumFileActions(); ++i) {
    const FileAction &action = *info.GetFileActionAtIndex(i);
    switch (action.GetAction()) {
    case FileAction::eFileActionClose:
      if (close(action.GetFD()) != 0)
        ExitWithError(error_fd, "close");
      break;
    case FileAction::eFileActionDuplicate:
      if (dup2(action.GetFD(), action.GetActionArgument()) == -1)
        ExitWithError(error_fd, "dup2");
      break;
    case FileAction::eFileActionOpen:
      DupDescriptor(error_fd, action.GetFileSpec(), action.GetFD(),
                    action.GetActionArgument());
      break;
    case FileAction::eFileActionNone:
      break;
    }
  }

  const char **argv = info.GetArguments().GetConstArgumentVector();

  // Change working directory
  if (info.GetWorkingDirectory() &&
      0 != ::chdir(info.GetWorkingDirectory().GetCString()))
    ExitWithError(error_fd, "chdir");

  DisableASLRIfRequested(error_fd, info);
  Environment env = info.GetEnvironment();
  FixupEnvironment(env);
  Environment::Envp envp = env.getEnvp();

  // Clear the signal mask to prevent the child from being affected by any
  // masking done by the parent.
  sigset_t set;
  if (sigemptyset(&set) != 0 ||
      pthread_sigmask(SIG_SETMASK, &set, nullptr) != 0)
    ExitWithError(error_fd, "pthread_sigmask");

  if (info.GetFlags().Test(eLaunchFlagDebug)) {
    // Do not inherit setgid powers.
    if (setgid(getgid()) != 0)
      ExitWithError(error_fd, "setgid");

    // HACK:
    // Close everything besides stdin, stdout, and stderr that has no file
    // action to avoid leaking. Only do this when debugging, as elsewhere we
    // actually rely on passing open descriptors to child processes.
    for (int fd = 3; fd < sysconf(_SC_OPEN_MAX); ++fd)
      if (!info.GetFileActionForFD(fd) && fd != error_fd)
        close(fd);

    // Start tracing this child that is about to exec.
    if (ptrace(PT_TRACE_ME, 0, nullptr, 0) == -1)
      ExitWithError(error_fd, "ptrace");
  }

  // Execute.  We should never return...
  execve(argv[0], const_cast<char *const *>(argv), envp);

#if defined(__linux__)
  if (errno == ETXTBSY) {
    // On android M and earlier we can get this error because the adb daemon
    // can hold a write handle on the executable even after it has finished
    // uploading it. This state lasts only a short time and happens only when
    // there are many concurrent adb commands being issued, such as when
    // running the test suite. (The file remains open when someone does an "adb
    // shell" command in the fork() child before it has had a chance to exec.)
    // Since this state should clear up quickly, wait a while and then give it
    // one more go.
    usleep(50000);
    execve(argv[0], const_cast<char *const *>(argv), envp);
  }
#endif

  // ...unless exec fails.  In which case we definitely need to end the child
  // here.
  ExitWithError(error_fd, "execve");
}
Exemplo n.º 2
0
Status ProcessFreeBSD::DoLaunch(Module *module,
                                ProcessLaunchInfo &launch_info) {
  Status error;
  assert(m_monitor == NULL);

  FileSpec working_dir = launch_info.GetWorkingDirectory();
  if (working_dir) {
    FileSystem::Instance().Resolve(working_dir);
    if (!FileSystem::Instance().IsDirectory(working_dir.GetPath())) {
      error.SetErrorStringWithFormat("No such file or directory: %s",
                                   working_dir.GetCString());
      return error;
    }
  }

  SetPrivateState(eStateLaunching);

  const lldb_private::FileAction *file_action;

  // Default of empty will mean to use existing open file descriptors
  FileSpec stdin_file_spec{};
  FileSpec stdout_file_spec{};
  FileSpec stderr_file_spec{};

  const FileSpec dbg_pts_file_spec{launch_info.GetPTY().GetSlaveName(NULL, 0)};

  file_action = launch_info.GetFileActionForFD(STDIN_FILENO);
  stdin_file_spec =
      GetFileSpec(file_action, stdin_file_spec, dbg_pts_file_spec);

  file_action = launch_info.GetFileActionForFD(STDOUT_FILENO);
  stdout_file_spec =
      GetFileSpec(file_action, stdout_file_spec, dbg_pts_file_spec);

  file_action = launch_info.GetFileActionForFD(STDERR_FILENO);
  stderr_file_spec =
      GetFileSpec(file_action, stderr_file_spec, dbg_pts_file_spec);

  m_monitor = new ProcessMonitor(
      this, module, launch_info.GetArguments().GetConstArgumentVector(),
      launch_info.GetEnvironment(), stdin_file_spec, stdout_file_spec,
      stderr_file_spec, working_dir, launch_info, error);

  m_module = module;

  if (!error.Success())
    return error;

  int terminal = m_monitor->GetTerminalFD();
  if (terminal >= 0) {
// The reader thread will close the file descriptor when done, so we pass it a
// copy.
#ifdef F_DUPFD_CLOEXEC
    int stdio = fcntl(terminal, F_DUPFD_CLOEXEC, 0);
    if (stdio == -1) {
      error.SetErrorToErrno();
      return error;
    }
#else
    // Special case when F_DUPFD_CLOEXEC does not exist (Debian kFreeBSD)
    int stdio = fcntl(terminal, F_DUPFD, 0);
    if (stdio == -1) {
      error.SetErrorToErrno();
      return error;
    }
    stdio = fcntl(terminal, F_SETFD, FD_CLOEXEC);
    if (stdio == -1) {
      error.SetErrorToErrno();
      return error;
    }
#endif
    SetSTDIOFileDescriptor(stdio);
  }

  SetID(m_monitor->GetPID());
  return error;
}