1SD_IS_FIFO(3) sd_is_fifo SD_IS_FIFO(3)
2
6 sd_is_fifo, sd_is_socket, sd_is_socket_inet, sd_is_socket_unix - Check
7 the type of a file descriptor
8
10 #include "sd-daemon.h"
11 int sd_is_fifo(int fd, const char *path);
13 int sd_is_socket(int fd, int family, int type, int listening);
15 int sd_is_socket_inet(int fd, int family, int type, int listening,
17 uint16_t port);
18 int sd_is_socket_unix(int fd, int type, int listening,
20 const char* path, size_t length);
21
23 sd_is_fifo() may be called to check whether the specified file
24 descriptor refers to a FIFO or pipe. If the path parameter is not NULL,
25 it is checked whether the FIFO is bound to the specified file system
26 path.
27 sd_is_socket() may be called to check whether the specified file
29 descriptor refers to a socket. It the family parameter is not AF_UNSPEC
30 it is checked whether the socket is of the specified family (AF_UNIX,
31 AF_INET, ...). If the type parameter is not 0 it is checked whether the
32 socket is of the specified type (SOCK_STREAM, SOCK_DGRAM, ...). If the
33 listening parameter is positive it is checked whether the socket is in
34 accepting mode, i.e. listen() has been called for it. If listening is
35 0, it is checked whether the socket is not in this mode. If the
36 parameter is negative, no such check is made. The listening parameter
37 should only be used for stream sockets and should be set to a negative
38 value otherwise.
39 sd_is_socket_inet() is similar to sd_is_socket(), but optionally checks
41 the IPv4 or IPv6 port number the socket is bound to, unless port is
42 zero. For this call family must be passed as either AF_UNSPEC, AF_INET
43 or AF_INET6.
44 sd_is_socket_unix() is similar to sd_is_socket(), but optionally checks
46 the AF_UNIX path the socket is bound to, unless the path parameter is
47 NULL. For normal file system AF_UNIX sockets set the length parameter
48 to 0. For Linux abstract namespace sockets set the length to the size
49 of the address, including the initial 0 byte and set path to the
50 initial 0 byte of the socket address.
51
53 On failure, these calls return a negative errno-style error code. If
54 the file descriptor is of the specified type and bound to the specified
55 address a positive return value is returned, otherwise zero.
56
58 These functions are provided by the reference implementation of APIs
59 for new-style daemons and distributed with the systemd package. The
60 algorithms they implement are simple, and can easily be reimplemented
61 in daemons if it is important to support this interface without using
62 the reference implementation.
63 Internally, these function use a combination of fstat() and
65 getsockname() to check the file descriptor type and where it is bound
66 to.
67 For details about the algorithm check the liberally licensed reference
69 implementation sources:
70 http://cgit.freedesktop.org/systemd/tree/src/sd-daemon.c resp.
71 http://cgit.freedesktop.org/systemd/tree/src/sd-daemon.h
72 sd_is_fifo() and the related functions are implemented in the reference
74 implementation´s drop-in sd-daemon.c and sd-daemon.h files. It is
75 recommended that applications consuming these APIs copy the
76 implementation into their source tree. For more details about the
77 reference implementation see sd_daemon(7)
78 These functions continue to work as described, even if
80 -DDISABLE_SYSTEMD is set during compilation.
81
83 systemd(1), sd-daemon(7), sd_listen_fds(3), systemd.service(5),
84 systemd.socket(5)
85
87 Lennart Poettering <lennart@poettering.net>
88 Developer
89systemd 09/14/2010 SD_IS_FIFO(3)