#Name

sendfd - send a file descriptor to a local socket peer

#Synopsis

#include <sys/socket.h>

int sendfd(int sockfd, int fd);

#Description

Send an open file descriptor to a local socket peer connected via sockfd. This is a non-blocking call that will fail if there are too many file descriptors already waiting to be received by the peer.

File descriptors are sent out-of-band and do not affect the regular data streams.

#Return value

If a file descriptor is successfully sent, sendfd() returns 0. Otherwise, -1 is returned and errno is set to indicate the error.

#Errors

• EBADF: sockfd or fd is not an open file descriptor.
• ENOTSOCK: sockfd does not refer to a socket.
• EAFNOSUPPORT: sockfd does not refer to a local domain socket.
• ENOTCONN: sockfd refers to a socket which is not connected.
• EINVAL: sockfd does not refer to a connected or accepted socket.
• EBUSY: There are too many file descriptors already waiting to be received by the peer.

#History

sendfd() was first introduced in Plan 9 from User Space.

#See also

• recvfd(2)