38 lines
1.1 KiB
Markdown
38 lines
1.1 KiB
Markdown
## Name
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sendfd - send a file descriptor to a local socket peer
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## Synopsis
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```**c++
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#include <sys/socket.h>
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int sendfd(int sockfd, int fd);
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```
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## Description
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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.
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File descriptors are sent out-of-band and do not affect the regular data streams.
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## Return value
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If a file descriptor is successfully received, it is returned as a positive integer. Otherwise, -1 is returned and `errno` is set to indicate the error.
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## Errors
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* `EBADF`: `sockfd` or `fd` is not an open file descriptor.
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* `ENOTSOCK`: `sockfd` does not refer to a socket.
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* `EAFNOSUPPORT`: `sockfd` does not refer to a local domain socket.
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* `ENOTCONN`: `sockfd` refers to a socket which is not connected.
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* `EINVAL`: `sockfd` does not refer to a connected or accepted socket.
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* `EBUSY`: There are too many file descriptors already waiting to be received by the peer.
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## History
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`sendfd()` was first introduced in Plan 9 from User Space.
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## See also
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* [`recvfd`(2)](recvfd.md)
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