sd_is_fifo

systemd
sd_is_fifo 3
sd_is_fifo sd_is_socket sd_is_socket_inet sd_is_socket_unix sd_is_socket_sockaddr sd_is_mq sd_is_special Check the type of a file descriptor

    #include <systemd/sd-daemon.h>

int `sd_is_fifo` int fd const char *path int `sd_is_socket` int fd int family int type int listening int `sd_is_socket_inet` int fd int family int type int listening uint16_t port int `sd_is_socket_sockaddr` int fd int type const struct sockaddr *addr unsigned addr_len int listening int `sd_is_socket_unix` int fd int type int listening const char *path size_t length int `sd_is_mq` int fd const char *path int `sd_is_special` int fd const char *path

## Description

`sd_is_fifo()` may be called to check whether the specified file descriptor refers to a FIFO or pipe. If the path parameter is not `NULL`, it is checked whether the FIFO is bound to the specified file system path.

`sd_is_socket()` may be called to check whether the specified file descriptor refers to a socket. If the family parameter is not `AF_UNSPEC`, it is checked whether the socket is of the specified family (`AF_UNIX`, `AF_INET`, …). If the type parameter is not 0, it is checked whether the socket is of the specified type (`SOCK_STREAM`, `SOCK_DGRAM`, …). If the listening parameter is positive, it is checked whether the socket is in accepting mode, i.e. `listen()` has been called for it. If listening is 0, it is checked whether the socket is not in this mode. If the parameter is negative, no such check is made. The listening parameter should only be used for stream sockets and should be set to a negative value otherwise.

`sd_is_socket_inet()` is similar to `sd_is_socket()`, but optionally checks the IPv4 or IPv6 port number the socket is bound to, unless port is zero. For this call family must be passed as either `AF_UNSPEC`, `AF_INET`, or `AF_INET6`.

`sd_is_socket_sockaddr()` is similar to `sd_is_socket_inet()`, but checks if the socket is bound to the address specified by addr. The family specified by addr must be either `AF_INET` or `AF_INET6` and addr_len must be large enough for that family. If addr specifies a non-zero port, it is also checked if the socket is bound to this port. In addition, for IPv6, if addr specifies non-zero sin6_flowinfo or sin6_scope_id, it is checked if the socket has the same values.

`sd_is_socket_unix()` is similar to `sd_is_socket()` but optionally checks the `AF_UNIX` path the socket is bound to, unless the path parameter is `NULL`. For normal file system `AF_UNIX` sockets, set the length parameter to 0. For Linux abstract namespace sockets, set the length to the size of the address, including the initial 0 byte, and set the path to the initial 0 byte of the socket address.

`sd_is_mq()` may be called to check whether the specified file descriptor refers to a POSIX message queue. If the path parameter is not `NULL`, it is checked whether the message queue is bound to the specified name.

`sd_is_special()` may be called to check whether the specified file descriptor refers to a special file. If the path parameter is not `NULL`, it is checked whether the file descriptor is bound to the specified filename. Special files in this context are character device nodes and files in `/proc` or `/sys`.

## Return Value

On failure, these calls return a negative errno-style error code. If the file descriptor is of the specified type and bound to the specified address, a positive return value is returned, otherwise zero.

## Notes

Internally, these function use a combination of `fstat()` and `getsockname()` to check the file descriptor type and where it is bound to.

## See Also

systemd 1, sd-daemon 3, sd_listen_fds 3, systemd.service 5, systemd.socket 5, ip 7, ipv6 7, unix 7, fifo 7, mq_overview 7, socket 7.