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endservent.3p (5063B)

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.TH ENDSERVENT "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH 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.
.\"
.SH NAME
endservent,
getservbyname,
getservbyport,
getservent,
setservent
\(em network services database functions
.SH SYNOPSIS
.LP
.nf
#include <netdb.h>
.P
void endservent(void);
struct servent *getservbyname(const char *\fIname\fP, const char *\fIproto\fP);
struct servent *getservbyport(int \fIport\fP, const char *\fIproto\fP);
struct servent *getservent(void);
void setservent(int \fIstayopen\fP);
.fi
.SH 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.
.P
The
\fIsetservent\fR()
function shall open a connection to the database, and set the next
entry to the first entry. If the
.IR stayopen
argument is non-zero, the
.IR net
database shall not be closed after each call to the
\fIgetservent\fR()
function (either directly, or indirectly through one of the other
.IR getserv* (\|)
functions), and the implementation may maintain an open file descriptor
for the database.
.P
The
\fIgetservent\fR()
function shall read the next entry of the database, opening and closing
a connection to the database as necessary.
.P
The
\fIgetservbyname\fR()
function shall search the database from the beginning and find the
first entry for which the service name specified by
.IR name
matches the
.IR s_name
member and the protocol name specified by
.IR proto
matches the
.IR s_proto
member, opening and closing a connection to the database as necessary.
If
.IR proto
is a null pointer, any value of the
.IR s_proto
member shall be matched.
.P
The
\fIgetservbyport\fR()
function shall search the database from the beginning and find the
first entry for which the port specified by
.IR port
matches the
.IR s_port
member and the protocol name specified by
.IR proto
matches the
.IR s_proto
member, opening and closing a connection to the database as necessary.
If
.IR proto
is a null pointer, any value of the
.IR s_proto
member shall be matched. The
.IR port
argument shall be a value obtained by converting a
.BR uint16_t
in network byte order to
.BR int .
.P
The
\fIgetservbyname\fR(),
\fIgetservbyport\fR(),
and
\fIgetservent\fR()
functions shall each return a pointer to a
.BR servent
structure, the members of which shall contain the fields of an entry in
the network services database.
.P
The
\fIendservent\fR()
function shall close the database, releasing any open file descriptor.
.P
These functions need not be thread-safe.
.SH "RETURN VALUE"
Upon successful completion,
\fIgetservbyname\fR(),
\fIgetservbyport\fR(),
and
\fIgetservent\fR()
return a pointer to a
.BR 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.
.P
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
\fIgetservbyname\fR(),
\fIgetservbyport\fR(),
or
\fIgetservent\fR().
The returned pointer, and pointers within the structure, might also be
invalidated if the calling thread is terminated.
.SH ERRORS
No errors are defined.
.LP
.IR "The following sections are informative."
.SH "EXAMPLES"
None.
.SH "APPLICATION USAGE"
The
.IR port
argument of
\fIgetservbyport\fR()
need not be compatible with the port values of all address families.
.SH "RATIONALE"
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIendhostent\fR\^(\|)",
.IR "\fIendprotoent\fR\^(\|)",
.IR "\fIhtonl\fR\^(\|)",
.IR "\fIinet_addr\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<netdb.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, 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 .
.PP
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/man-pages/reporting_bugs.html .