size_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read) { size_t offset = 0; if (qemu_in_coroutine()) { if (do_read) { return qemu_co_recv(fd, buffer, size); } else { return qemu_co_send(fd, buffer, size); } } while (offset < size) { ssize_t len; if (do_read) { len = qemu_recv(fd, buffer + offset, size - offset, 0); } else { len = send(fd, buffer + offset, size - offset, 0); } if (len == -1) errno = socket_error(); /* recoverable error */ if (len == -1 && (errno == EAGAIN || errno == EINTR)) { continue; } /* eof */ if (len == 0) { break; } /* unrecoverable error */ if (len == -1) { return 0; } offset += len; } return offset; }