io\_uring\_prep\_socket(3) liburing Manual io\_uring\_prep\_socket(3)

# [NAME](#NAME)

io\_uring\_prep\_socket - prepare a socket creation request

# [SYNOPSIS](#SYNOPSIS)

```
#include <sys/socket.h>
#include <liburing.h>
```

```
void io_uring_prep_socket(struct io_uring_sqe *sqe,
                          int domain,
                          int type,
                          int protocol,
                          unsigned int flags);
```

```
void io_uring_prep_socket_direct(struct io_uring_sqe *sqe,
                                 int domain,
                                 int type,
                                 int protocol,
                                 unsigned int file_index,
                                 unsigned int flags);
```

```
void io_uring_prep_socket_direct_alloc(struct io_uring_sqe *sqe,
                                 int domain,
                                 int type,
                                 int protocol,
                                 unsigned int flags);
```

# [DESCRIPTION](#DESCRIPTION)

The [**io\_uring\_prep\_socket**(3)](/man/os/liburing/io_uring_prep_socket.3) function prepares a socket creation request. The submission queue entry *sqe* is setup to use the communication domain defined by *domain* and use the communication type defined by *type* and the protocol set by *protocol*. The *flags* argument are currently unused.

The [**io\_uring\_prep\_socket\_direct**(3)](/man/os/liburing/io_uring_prep_socket_direct.3) helper works just like [**io\_uring\_prep\_socket**(3)](/man/os/liburing/io_uring_prep_socket.3), except it maps the socket to a direct descriptor rather than return a normal file descriptor. The *file\_index* argument should be set to the slot that should be used for this socket.

The [**io\_uring\_prep\_socket\_direct\_alloc**(3)](/man/os/liburing/io_uring_prep_socket_direct_alloc.3) helper works just like [**io\_uring\_prep\_socket\_direct**(3)](/man/os/liburing/io_uring_prep_socket_direct.3), except it allocates a new direct descriptor rather than pass a free slot in. It is equivalent to using [**io\_uring\_prep\_socket\_direct**(3)](/man/os/liburing/io_uring_prep_socket_direct.3) with **IORING\_FILE\_INDEX\_ALLOC** as the *file\_index .* Upon completion, the *res* field of the CQE will return the direct slot that was allocated for the socket.

If the direct variants are used, the application must first have registered a file table using [**io\_uring\_register\_files**(3)](/man/os/liburing/io_uring_register_files.3) of the appropriate size. Once registered, a direct socket request may use any entry in that table, as long as it is within the size of the registered table. If a specified entry already contains a file, the file will first be removed from the table and closed. It's consistent with the behavior of updating an existing file with [**io\_uring\_register\_files\_update**(3)](/man/os/liburing/io_uring_register_files_update.3).

For a direct descriptor socket request, the *file\_index* argument can be set to **IORING\_FILE\_INDEX\_ALLOC**, In this case a free entry in io\_uring file table will be used automatically and the file index will be returned as CQE *res*. **-ENFILE** is otherwise returned if there is no free entries in the io\_uring file table.

These functions prepare an async [**socket**(2)](/man/os/liburing/socket.2) request. See that man page for details.

# [RETURN VALUE](#RETURN_VALUE)

None

# [ERRORS](#ERRORS)

The CQE *res* field will contain the result of the operation. See the related man page for details on possible values. Note that where synchronous system calls will return **-1** on failure and set *errno* to the actual error value, io\_uring never uses *errno*. Instead it returns the negated *errno* directly in the CQE *res* field.

# [SEE ALSO](#SEE_ALSO)

[**io\_uring\_get\_sqe**(3)](/man/os/liburing/io_uring_get_sqe.3), [**io\_uring\_submit**(3)](/man/os/liburing/io_uring_submit.3), [**socket**(2)](/man/os/liburing/socket.2)

May 27, 2022 liburing-2.2

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Document: io_uring_prep_socket(3) from liburing 2.15-r5 (Chainguard OS)
Source: https://github.com/axboe/liburing.git