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| #include <sys/socket.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
static const int CONTROL_LEN = CMSG_LEN(sizeof(int));
void send_fd(int fd, int fd_to_send)
{
struct iovec iov[1];
struct msghdr msg;
char buf[0];
iov[0].iov_base = buf;
iov[0].iov_len = 1;
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
cmsghdr cm;
cm.cmsg_len = CONTROL_LEN;
cm.cmsg_level = SOL_SOCKET;
cm.cmsg_type = SCM_RIGHTS;
*(int *)CMSG_DATA(&cm) = fd_to_send;
msg.msg_control = &cm;
msg.msg_controllen = CONTROL_LEN;
sendmsg(fd, &msg, 0);
}
int recv_fd(int fd)
{
struct iovec iov[1];
struct msghdr msg;
char buf[0];
iov[0].iov_base = buf;
iov[0].iov_len = 1;
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
cmsghdr cm;
msg.msg_control = &cm;
msg.msg_controllen = CONTROL_LEN;
recvmsg(fd, &msg, 0);
int fd_to_read = *(int *)CMSG_DATA(&cm);
return fd_to_read;
}
int main()
{
int pipefd[2];
int fd_to_pass = 0;
int ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, pipefd);
assert(ret != -1);
pid_t pid = fork();
assert(pid >= 0);
if (pid == 0)
{
close(pipefd[0]);
fd_to_pass = open("test.txt", O_RDWR, 0666);
send_fd(pipefd[1], (fd_to_pass > 0) ? fd_to_pass : 0);
close(fd_to_pass);
exit(0);
}
close(pipefd[1]);
fd_to_pass = recv_fd(pipefd[0]);
char buf[1024];
memset(buf, '\0', 1024);
read(fd_to_pass, buf, 1024);
printf("I got fd %d and data %s\n", fd_to_pass, buf);
close(fd_to_pass);
}
|