endservent(3p) — Linux manual page

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

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 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(3p), endprotoent(3p), htonl(3p), inet_addr(3p)

       The Base Definitions volume of POSIX.1‐2017, netdb.h(0p)

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(3P)

Pages that refer to this page: netdb.h(0p), endhostent(3p), freeaddrinfo(3p), getnameinfo(3p), getservbyname(3p), htonl(3p), setservent(3p)

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