1 /* CC0 license (public domain) - see LICENSE file for details */
2 #include <ccan/fdpass/fdpass.h>
3 #include <sys/socket.h>
7 bool fdpass_send(int sockout, int fd)
9 /* From the cmsg(3) manpage: */
10 struct msghdr msg = { 0 };
14 union { /* Ancillary data buffer, wrapped in a union
15 in order to ensure it is suitably aligned */
16 char buf[CMSG_SPACE(sizeof(fd))];
20 msg.msg_control = u.buf;
21 msg.msg_controllen = sizeof(u.buf);
22 memset(&u, 0, sizeof(u));
23 cmsg = CMSG_FIRSTHDR(&msg);
24 cmsg->cmsg_level = SOL_SOCKET;
25 cmsg->cmsg_type = SCM_RIGHTS;
26 cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
27 memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
35 /* Keith Packard reports that 0-length sends don't work, so we
36 * always send 1 byte. */
40 return sendmsg(sockout, &msg, 0) == 1;
43 int fdpass_recv(int sockin)
45 /* From the cmsg(3) manpage: */
46 struct msghdr msg = { 0 };
51 union { /* Ancillary data buffer, wrapped in a union
52 in order to ensure it is suitably aligned */
53 char buf[CMSG_SPACE(sizeof(fd))];
57 msg.msg_control = u.buf;
58 msg.msg_controllen = sizeof(u.buf);
69 if (recvmsg(sockin, &msg, 0) < 0)
72 cmsg = CMSG_FIRSTHDR(&msg);
74 || cmsg->cmsg_len != CMSG_LEN(sizeof(fd))
75 || cmsg->cmsg_level != SOL_SOCKET
76 || cmsg->cmsg_type != SCM_RIGHTS) {
81 memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd));