Message.cpp 2.1 KB

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  1. /*
  2. * Copyright (c) 2024, Tim Flynn <trflynn89@serenityos.org>
  3. *
  4. * SPDX-License-Identifier: BSD-2-Clause
  5. */
  6. #include <LibCore/Socket.h>
  7. #include <LibIPC/Message.h>
  8. #include <sched.h>
  9. namespace IPC {
  10. using MessageSizeType = u32;
  11. ErrorOr<void> MessageBuffer::transfer_message(Core::LocalSocket& fd_passing_socket, Core::LocalSocket& data_socket)
  12. {
  13. MessageSizeType message_size = data.size();
  14. TRY(data.try_prepend(reinterpret_cast<u8 const*>(&message_size), sizeof(message_size)));
  15. for (auto const& fd : fds)
  16. TRY(fd_passing_socket.send_fd(fd->value()));
  17. ReadonlyBytes bytes_to_write { data.span() };
  18. size_t writes_done = 0;
  19. while (!bytes_to_write.is_empty()) {
  20. auto maybe_nwritten = data_socket.write_some(bytes_to_write);
  21. ++writes_done;
  22. if (maybe_nwritten.is_error()) {
  23. if (auto error = maybe_nwritten.release_error(); error.is_errno()) {
  24. // FIXME: This is a hacky way to at least not crash on large messages
  25. // The limit of 100 writes is arbitrary, and there to prevent indefinite spinning on the EventLoop
  26. if (error.code() == EAGAIN && writes_done < 100) {
  27. sched_yield();
  28. continue;
  29. }
  30. switch (error.code()) {
  31. case EPIPE:
  32. return Error::from_string_literal("IPC::transfer_message: Disconnected from peer");
  33. case EAGAIN:
  34. return Error::from_string_literal("IPC::transfer_message: Peer buffer overflowed");
  35. default:
  36. return Error::from_syscall("IPC::transfer_message write"sv, -error.code());
  37. }
  38. } else {
  39. return error;
  40. }
  41. }
  42. bytes_to_write = bytes_to_write.slice(maybe_nwritten.value());
  43. }
  44. if (writes_done > 1) {
  45. dbgln("LibIPC::transfer_message FIXME Warning, needed {} writes needed to send message of size {}B, this is pretty bad, as it spins on the EventLoop", writes_done, data.size());
  46. }
  47. return {};
  48. }
  49. }