sd_is_fifo

systemd

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

const char *

path

int

sd_is_socket

int

family

int

type

int

listening

int

sd_is_socket_inet

int

family

int

type

int

listening

uint16_t

port

int

sd_is_socket_sockaddr

int

type

const struct sockaddr *

addr

unsigned

addr_len

int

listening

int

sd_is_socket_unix

int

type

int

listening

const char *

path

size_t

length

int

sd_is_mq

int

const char *

path

int

sd_is_special

int

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 functions use a combination of fstat(2) and getsockname(2) to check the file descriptor type and where it is bound to.

History

sd_is_special() was added in version 209.

sd_is_socket_sockaddr() was added in version 233.