ENDSERVENT(3)              POSIX Programmer's Manual             ENDSERVENT(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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 non-
       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 thread-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 1003.1-2017, 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 .

       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 .



IEEE/The Open Group                  2017                        ENDSERVENT(3)
