ENDHOSTENT(3)              POSIX Programmer's Manual             ENDHOSTENT(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
       endhostent, gethostent, sethostent -- network host database functions

SYNOPSIS
       #include <netdb.h>

       void endhostent(void);
       struct hostent *gethostent(void);
       void sethostent(int stayopen);

DESCRIPTION
       These functions shall retrieve information about hosts. This
       information is considered to be stored in a database that can be
       accessed sequentially or randomly. The implementation of this database
       is unspecified.

       Note:     In many cases this database is implemented by the Domain Name
                 System, as documented in RFC 1034, RFC 1035, and RFC 1886.

       The sethostent() function shall open a connection to the database and
       set the next entry for retrieval to the first entry in the database. If
       the stayopen argument is non-zero, the connection shall not be closed
       by a call to gethostent(), and the implementation may maintain an open
       file descriptor.

       The gethostent() function shall read the next entry in the database,
       opening and closing a connection to the database as necessary.

       Entries shall be returned in hostent structures.

       The endhostent() function shall close the connection to the database,
       releasing any open file descriptor.

       These functions need not be thread-safe.

RETURN VALUE
       Upon successful completion, the gethostent() function shall return a
       pointer to a hostent 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.

       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 gethostent().  The returned
       pointer, and pointers within the structure, might also be invalidated
       if the calling thread is terminated.

ERRORS
       No errors are defined for endhostent(), gethostent(), and sethostent().

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       endservent()

       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                        ENDHOSTENT(3)
