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



PPRROOLLOOGG
       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.

NNAAMMEE
       endprotoent, getprotobyname, getprotobynumber, getprotoent, setprotoent
       -- network protocol database functions

SSYYNNOOPPSSIISS
       #include <netdb.h>

       void endprotoent(void);
       struct protoent *getprotobyname(const char *_n_a_m_e);
       struct protoent *getprotobynumber(int _p_r_o_t_o);
       struct protoent *getprotoent(void);
       void setprotoent(int _s_t_a_y_o_p_e_n);

DDEESSCCRRIIPPTTIIOONN
       These functions shall retrieve information about protocols. 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 _s_e_t_p_r_o_t_o_e_n_t() function shall open a connection to the database, and
       set the next entry to the first entry. If the _s_t_a_y_o_p_e_n argument is non-
       zero, the connection to the network protocol database shall not be
       closed after each call to _g_e_t_p_r_o_t_o_e_n_t() (either directly, or indirectly
       through one of the other _g_e_t_p_r_o_t_o_*() functions), and the implementation
       may maintain an open file descriptor for the database.

       The _g_e_t_p_r_o_t_o_b_y_n_a_m_e() function shall search the database from the
       beginning and find the first entry for which the protocol name
       specified by _n_a_m_e matches the _p___n_a_m_e member, opening and closing a
       connection to the database as necessary.

       The _g_e_t_p_r_o_t_o_b_y_n_u_m_b_e_r() function shall search the database from the
       beginning and find the first entry for which the protocol number
       specified by _p_r_o_t_o matches the _p___p_r_o_t_o member, opening and closing a
       connection to the database as necessary.

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

       The _g_e_t_p_r_o_t_o_b_y_n_a_m_e(), _g_e_t_p_r_o_t_o_b_y_n_u_m_b_e_r(), and _g_e_t_p_r_o_t_o_e_n_t() functions
       shall each return a pointer to a pprroottooeenntt structure, the members of
       which shall contain the fields of an entry in the network protocol
       database.

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

       These functions need not be thread-safe.

RREETTUURRNN VVAALLUUEE
       Upon successful completion, _g_e_t_p_r_o_t_o_b_y_n_a_m_e(), _g_e_t_p_r_o_t_o_b_y_n_u_m_b_e_r(), and
       _g_e_t_p_r_o_t_o_e_n_t() return a pointer to a pprroottooeenntt 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 _g_e_t_p_r_o_t_o_b_y_n_a_m_e(),
       _g_e_t_p_r_o_t_o_b_y_n_u_m_b_e_r(), or _g_e_t_p_r_o_t_o_e_n_t().  The returned pointer, and
       pointers within the structure, might also be invalidated if the calling
       thread is terminated.

EERRRROORRSS
       No errors are defined.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       None.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       The Base Definitions volume of POSIX.1-2017, <<nneettddbb..hh>>

CCOOPPYYRRIIGGHHTT
       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                       ENDPROTOENT(3)
