utils.c

/*
 * Copyright 2021 Max Planck Institute for Software Systems, and
 * National University of Singapore
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <fcntl.h>
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/un.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <unistd.h>

#include "internal.h"

int uxsocket_connect(const char *path)
{
    int fd;
    struct sockaddr_un saun;

    /* prepare and connect socket */
    memset(&saun, 0, sizeof(saun));
    saun.sun_family = AF_UNIX;
    strcpy(saun.sun_path, path);

    if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
        perror("socket failed");
        return -1;
    }

    if (connect(fd, (struct sockaddr *) &saun, sizeof(saun)) != 0) {
        perror("connect failed");
        return -1;
    }

    return fd;
}

int uxsocket_recv(int fd, void *data, size_t len, int *pfd)
{
    int *ppfd;
    ssize_t ret;
    struct cmsghdr *cmsg;
    union {
        char buf[CMSG_SPACE(sizeof(int))];
        struct cmsghdr align;
    } u;
    struct iovec iov = {
        .iov_base = data,
        .iov_len = len,
    };
    struct msghdr msg = {
        .msg_name = NULL,
        .msg_namelen = 0,
        .msg_iov = &iov,
        .msg_iovlen = 1,
        .msg_control = u.buf,
        .msg_controllen = sizeof(u.buf),
        .msg_flags = 0,
    };

    if ((ret = recvmsg(fd, &msg, 0)) != (ssize_t) len) {
        perror("recvmsg failed");
        return -1;
    }

    cmsg = CMSG_FIRSTHDR(&msg);
    ppfd = (int *) CMSG_DATA(cmsg);
    if (msg.msg_controllen <= 0 || cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
        fprintf(stderr, "accessing ancillary data failed\n");
        return -1;
    }

    *pfd = *ppfd;
    return 0;
}

void *shm_map(int shm_fd)
{
    void *p;
    struct stat statbuf;

    if (fstat(shm_fd, &statbuf) != 0) {
        perror("shm_map: fstat failed");
        return NULL;
    }

    p = mmap(NULL, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd,
            0);
    if (p == MAP_FAILED) {
        perror("shm_map: mmap failed");
        return NULL;
    }

    return p;
}