getservent, getservbyname, getservbyport, setservent, endservent - get service
entry
#include <netdb.h>
struct servent *getservent(void);
struct servent *getservbyname(const char *name, const char *proto);
struct servent *getservbyport(int port, const char *proto);
void setservent(int stayopen);
void endservent(void);
The
getservent() function reads the next entry from the services database
(see
services(5)) and returns a
servent structure containing the
broken-out fields from the entry. A connection is opened to the database if
necessary.
The
getservbyname() function returns a
servent structure for the
entry from the database that matches the service
name using protocol
proto. If
proto is NULL, any protocol will be matched. A
connection is opened to the database if necessary.
The
getservbyport() function returns a
servent structure for the
entry from the database that matches the port
port (given in network
byte order) using protocol
proto. If
proto is NULL, any protocol
will be matched. A connection is opened to the database if necessary.
The
setservent() function opens a connection to the database, and sets
the next entry to the first entry. If
stayopen is nonzero, then the
connection to the database will not be closed between calls to one of the
getserv*() functions.
The
endservent() function closes the connection to the database.
The
servent structure is defined in
<netdb.h> as follows:
struct servent {
char *s_name; /* official service name */
char **s_aliases; /* alias list */
int s_port; /* port number */
char *s_proto; /* protocol to use */
}
The members of the
servent structure are:
- s_name
- The official name of the service.
- s_aliases
- A NULL-terminated list of alternative names for the service.
- s_port
- The port number for the service given in network byte order.
- s_proto
- The name of the protocol to use with this service.
The
getservent(),
getservbyname() and
getservbyport()
functions return a pointer to a statically allocated
servent structure,
or NULL if an error occurs or the end of the file is reached.
- /etc/services
- services database file
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
getservent () |
Thread safety |
MT-Unsafe race:servent race:serventbuf locale |
getservbyname () |
Thread safety |
MT-Unsafe race:servbyname locale |
getservbyport () |
Thread safety |
MT-Unsafe race:servbyport locale |
setservent (), endservent () |
Thread safety |
MT-Unsafe race:servent locale |
In the above table,
servent in
race:servent signifies that if any
of the functions
setservent(),
getservent(), or
endservent() are used in parallel in different threads of a program,
then data races could occur.
POSIX.1-2001, POSIX.1-2008, 4.3BSD.
getnetent(3),
getprotoent(3),
getservent_r(3),
services(5)