ENDSERVENT
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Index
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PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
NAME
endservent,
getservbyname,
getservbyport,
getservent,
setservent
- network services database functions
SYNOPSIS
#include <netdb.h>
void endservent(void);
struct servent *getservbyname(const char *name, const char *proto);
struct servent *getservbyport(int port, const char *proto);
struct servent *getservent(void);
void setservent(int stayopen);
DESCRIPTION
These functions shall retrieve information about network services. This
information is considered to be stored in a database that can be
accessed sequentially or randomly. The implementation of this database
is unspecified.
The
setservent()
function shall open a connection to the database, and set the next
entry to the first entry. If the
stayopen
argument is no-zero, the
net
database shall not be closed after each call to the
getservent()
function (either directly, or indirectly through one of the other
getserv*()
functions), and the implementation may maintain an open file descriptor
for the database.
The
getservent()
function shall read the next entry of the database, opening and closing
a connection to the database as necessary.
The
getservbyname()
function shall search the database from the beginning and find the
first entry for which the service name specified by
name
matches the
s_name
member and the protocol name specified by
proto
matches the
s_proto
member, opening and closing a connection to the database as necessary.
If
proto
is a null pointer, any value of the
s_proto
member shall be matched.
The
getservbyport()
function shall search the database from the beginning and find the
first entry for which the port specified by
port
matches the
s_port
member and the protocol name specified by
proto
matches the
s_proto
member, opening and closing a connection to the database as necessary.
If
proto
is a null pointer, any value of the
s_proto
member shall be matched. The
port
argument shall be a value obtained by converting a
uint16_t
in network byte order to
int.
The
getservbyname(),
getservbyport(),
and
getservent()
functions shall each return a pointer to a
servent
structure, the members of which shall contain the fields of an entry in
the network services database.
The
endservent()
function shall close the database, releasing any open file descriptor.
These functions need not be threa-safe.
RETURN VALUE
Upon successful completion,
getservbyname(),
getservbyport(),
and
getservent()
return a pointer to a
servent
structure if the requested entry was found, and a null pointer if the
end of the database was reached or the requested entry was not found.
Otherwise, a null pointer is returned.
The application shall not modify the structure to which the return
value points, nor any storage areas pointed to by pointers within the
structure. The returned pointer, and pointers within the structure,
might be invalidated or the structure or the storage areas might be
overwritten by a subsequent call to
getservbyname(),
getservbyport(),
or
getservent().
The returned pointer, and pointers within the structure, might also be
invalidated if the calling thread is terminated.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The
port
argument of
getservbyport()
need not be compatible with the port values of all address families.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
endhostent(),
endprotoent(),
htonl(),
inet_addr()
The Base Definitions volume of POSIX.1-2017,
<netdb.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.-2017, Standard for Information Technology- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/ma-pages/reporting_bugs.html .
Index
- PROLOG
-
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- EXAMPLES
-
- APPLICATION USAGE
-
- RATIONALE
-
- FUTURE DIRECTIONS
-
- SEE ALSO
-
- COPYRIGHT
-
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