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io/fdpass
IO helper for passing file descriptors across local sockets
Rusty Russell <[email protected]>
This code adds the ability to pass file descriptors to ccan/io.
// Given "hello" outputs hello
#include <ccan/io/fdpass/fdpass.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
// Child reads stdin into the buffer, prints it out.
struct buf {
size_t used;
char c[100];
};
static struct io_plan *read_more(struct io_conn *conn, struct buf *buf)
{
printf("%.*s", (int)buf->used, buf->c);
return io_read_partial(conn, buf->c, sizeof(buf->c), &buf->used,
read_more, buf);
}
// Child has received fd, start reading loop.
static struct io_plan *got_infd(struct io_conn *conn, int *infd)
{
struct buf *buf = calloc(1, sizeof(*buf));
io_new_conn(NULL, *infd, read_more, buf);
return io_close(conn);
}
// Child is receiving the fd to read into.
static struct io_plan *recv_infd(struct io_conn *conn, int *infd)
{
return io_recv_fd(conn, infd, got_infd, infd);
}
// Gets passed fd (stdin), which it reads from.
static void child(int sockfd)
{
int infd;
io_new_conn(NULL, sockfd, recv_infd, &infd);
io_loop(NULL, NULL);
exit(0);
}
static struct io_plan *send_stdin(struct io_conn *conn, void *unused)
{
return io_send_fd(conn, STDIN_FILENO, false, io_close_cb, NULL);
}
static void parent(int sockfd)
{
io_new_conn(NULL, sockfd, send_stdin, NULL);
io_loop(NULL, NULL);
exit(0);
}
int main(void)
{
int sv[2];
socketpair(AF_UNIX, SOCK_STREAM, 0, sv);
if (fork() == 0)
child(sv[0]);
else
parent(sv[1]);
}
LGPL (v2.1 or any later version)