GETSERVENT(3) | Library Functions Manual | GETSERVENT(3) |
getservent
,
getservbyport
,
getservbyname
, setservent
,
endservent
— get service
entry
Standard C Library (libc, -lc)
#include
<netdb.h>
struct servent *
getservent
();
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
(),
getservbyname
(), and
getservbyport
() functions each return a pointer to
an object with the following structure containing the broken-out fields of a
line in the network services data base,
/etc/services.
struct servent { char *s_name; /* official name of service */ char **s_aliases; /* alias list */ int s_port; /* port service resides at */ char *s_proto; /* protocol to use */ };
The members of this structure are:
The
getservent
()
function reads the next line of the file, opening the file if necessary.
The
setservent
()
function opens and rewinds the file. If the stayopen
flag is non-zero, the net data base will not be closed after each call to
getservbyname
() or
getservbyport
().
The
endservent
()
function closes the file.
The
getservbyname
()
and
getservbyport
()
functions sequentially search from the beginning of the file until a
matching protocol name or port number (which must be specified in network
byte order) is found, or until EOF
is encountered.
If a protocol name is also supplied (non- NULL
),
searches must also match the protocol.
Null pointer (0) returned on EOF
or
error.
The getservent
(),
getservbyport
(),
getservbyname
(),
setservent
(), and
endservent
() functions appeared in
4.2BSD.
These functions use a thread-specific data storage; if the data is needed for future use, it should be copied before any subsequent calls overwrite it. Expecting port numbers to fit in a 32 bit quantity is probably naive.
July 9, 1995 | macOS 14.6 |