Merge "base: support optional flags in android::base::Pipe."

// Inline functions, so that they can be used header-only.

template <typename Closer>

inline bool Pipe(unique_fd_impl<Closer>* read, unique_fd_impl<Closer>* write) {

inline bool Pipe(unique_fd_impl<Closer>* read, unique_fd_impl<Closer>* write,

                 int flags = O_CLOEXEC) {

  int pipefd[2];

#if defined(__linux__)

  if (pipe2(pipefd, O_CLOEXEC) != 0) {

  if (pipe2(pipefd, flags) != 0) {

    return false;

  }

#else  // defined(__APPLE__)

  if (flags & ~(O_CLOEXEC | O_NONBLOCK)) {

    return false;

  }

  if (pipe(pipefd) != 0) {

    return false;

  }

  if (flags & O_CLOEXEC) {

    if (fcntl(pipefd[0], F_SETFD, FD_CLOEXEC) != 0 || fcntl(pipefd[1], F_SETFD, FD_CLOEXEC) != 0) {

      close(pipefd[0]);

      close(pipefd[1]);

      return false;

    }

  }

  if (flags & O_NONBLOCK) {

    if (fcntl(pipefd[0], F_SETFL, O_NONBLOCK) != 0 || fcntl(pipefd[1], F_SETFL, O_NONBLOCK) != 0) {

      close(pipefd[0]);

      close(pipefd[1]);

      return false;

    }

  }

#endif

  read->reset(pipefd[0]);