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#define _GNU_SOURCE
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <err.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define die(...) err(EXIT_FAILURE, __VA_ARGS__)
typedef uint8_t u8;
int
main(int argc, char **argv)
{
int fd, sfd;
void *shm;
socklen_t saddrlen = sizeof(struct sockaddr_un);
struct stat sb;
struct sockaddr_un saddr = {
.sun_family = AF_UNIX,
.sun_path = "foo.sock",
};
*argv = basename(*argv);
if (argc != 2) {
fprintf(stderr, "Usage: %s file\n", *argv);
exit(EXIT_FAILURE);
}
if ((fd = open(argv[1], O_RDONLY)) == -1)
die("open: %s", argv[1]);
if (fstat(fd, &sb) == -1)
die("fstat: %s", argv[1]);
shm = mmap(NULL, sb.st_size, PROT_READ, MAP_SHARED, fd, 0);
if (shm == MAP_FAILED)
die("mmap: %s", argv[1]);
if ((sfd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1)
die("socket");
if (connect(sfd, &saddr, saddrlen) == -1)
die("connect");
u8 msg[sizeof(size_t) * 2 + sizeof("hello world") - 1];
char buf[CMSG_SPACE(sizeof(int))];
struct iovec iov = {
.iov_base = msg,
.iov_len = sizeof(msg) - 1,
};
struct msghdr hdr = {
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = buf,
.msg_controllen = CMSG_SPACE(sizeof(int)),
};
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&hdr);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
*(int *)CMSG_DATA(cmsg) = fd;
size_t len = sb.st_size;
size_t len2 = 11;
memcpy(msg, &len, sizeof(size_t));
memcpy(msg + sizeof(size_t), &len2, sizeof(size_t));
memcpy(msg + sizeof(size_t) * 2, "hello, world", 11);
if (sendmsg(sfd, &hdr, 0) == -1)
die("sendmsg");
munmap(shm, sb.st_size);
close(fd);
close(sfd);
return EXIT_SUCCESS;
}
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