Merge "Prevent app fuse from indefinitely trying if it gets ENOBUFS" into main

namespace {

constexpr useconds_t kRetrySleepForWriting = 1000;  // 1 ms

// This makes the total wait time to allocate a buffer 5 seconds

const int kNumberOfRetriesForWriting = 5000;

template <typename T>

bool CheckHeaderLength(const FuseMessage<T>* self, const char* name, size_t max_size) {

    const char* const buf = reinterpret_cast<const char*>(self);

    const auto& header = static_cast<const T*>(self)->header;

    int retry = kNumberOfRetriesForWriting;

    while (true) {

        int result;

                case ENOBUFS:

                    // When returning ENOBUFS, epoll still reports the FD is writable. Just usleep

                    // and retry again.

                    if (retry > 0) {

                        usleep(kRetrySleepForWriting);

                        retry--;

                        continue;

                    } else {

                        LOG(ERROR) << "Failed to write a FUSE message: ENOBUFS retries are failed";

                        return ResultOrAgain::kFailure;

                    }

                case EAGAIN:

                    return ResultOrAgain::kAgain;

                default: