// SPDX-License-Identifier: GPL-2.0-only
/* Some common code for MSG_ZEROCOPY logic
 *
 * Copyright (C) 2023 SberDevices.
 *
 * Author: Arseniy Krasnov <avkrasnov@salutedevices.com>
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/errqueue.h>

#include "msg_zerocopy_common.h"

void vsock_recv_completion(int fd, const bool *zerocopied)
{
        struct sock_extended_err *serr;
        struct msghdr msg = { 0 };
        char cmsg_data[128];
        struct cmsghdr *cm;
        ssize_t res;

        msg.msg_control = cmsg_data;
        msg.msg_controllen = sizeof(cmsg_data);

        res = recvmsg(fd, &msg, MSG_ERRQUEUE);
        if (res) {
                fprintf(stderr, "failed to read error queue: %zi\n", res);
                exit(EXIT_FAILURE);
        }

        cm = CMSG_FIRSTHDR(&msg);
        if (!cm) {
                fprintf(stderr, "cmsg: no cmsg\n");
                exit(EXIT_FAILURE);
        }

        if (cm->cmsg_level != SOL_VSOCK) {
                fprintf(stderr, "cmsg: unexpected 'cmsg_level'\n");
                exit(EXIT_FAILURE);
        }

        if (cm->cmsg_type != VSOCK_RECVERR) {
                fprintf(stderr, "cmsg: unexpected 'cmsg_type'\n");
                exit(EXIT_FAILURE);
        }

        serr = (void *)CMSG_DATA(cm);
        if (serr->ee_origin != SO_EE_ORIGIN_ZEROCOPY) {
                fprintf(stderr, "serr: wrong origin: %u\n", serr->ee_origin);
                exit(EXIT_FAILURE);
        }

        if (serr->ee_errno) {
                fprintf(stderr, "serr: wrong error code: %u\n", serr->ee_errno);
                exit(EXIT_FAILURE);
        }

        /* This flag is used for tests, to check that transmission was
         * performed as expected: zerocopy or fallback to copy. If NULL
         * - don't care.
         */
        if (!zerocopied)
                return;

        if (*zerocopied && (serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED)) {
                fprintf(stderr, "serr: was copy instead of zerocopy\n");
                exit(EXIT_FAILURE);
        }

        if (!*zerocopied && !(serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED)) {
                fprintf(stderr, "serr: was zerocopy instead of copy\n");
                exit(EXIT_FAILURE);
        }
}