SOCKETPAIR(3)              POSIX Programmer's Manual             SOCKETPAIR(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
       socketpair -- create a pair of connected sockets

SSYYNNOOPPSSIISS
       #include <sys/socket.h>

       int socketpair(int _d_o_m_a_i_n, int _t_y_p_e, int _p_r_o_t_o_c_o_l,
           int _s_o_c_k_e_t___v_e_c_t_o_r[2]);

DDEESSCCRRIIPPTTIIOONN
       The _s_o_c_k_e_t_p_a_i_r() function shall create an unbound pair of connected
       sockets in a specified _d_o_m_a_i_n, of a specified _t_y_p_e, under the protocol
       optionally specified by the _p_r_o_t_o_c_o_l argument. The two sockets shall be
       identical. The file descriptors used in referencing the created sockets
       shall be returned in _s_o_c_k_e_t___v_e_c_t_o_r[0] and _s_o_c_k_e_t___v_e_c_t_o_r[1].  The file
       descriptors shall be allocated as described in _S_e_c_t_i_o_n _2_._1_4, _F_i_l_e
       _D_e_s_c_r_i_p_t_o_r _A_l_l_o_c_a_t_i_o_n.

       The _s_o_c_k_e_t_p_a_i_r() function takes the following arguments:

       _d_o_m_a_i_n      Specifies the communications domain in which the sockets
                   are to be created.

       _t_y_p_e        Specifies the type of sockets to be created.

       _p_r_o_t_o_c_o_l    Specifies a particular protocol to be used with the
                   sockets.  Specifying a _p_r_o_t_o_c_o_l of 0 causes _s_o_c_k_e_t_p_a_i_r() to
                   use an unspecified default protocol appropriate for the
                   requested socket type.

       _s_o_c_k_e_t___v_e_c_t_o_r
                   Specifies a 2-integer array to hold the file descriptors of
                   the created socket pair.

       The _t_y_p_e argument specifies the socket type, which determines the
       semantics of communications over the socket. The following socket types
       are defined; implementations may specify additional socket types:

       SOCK_STREAM   Provides sequenced, reliable, bidirectional, connection-
                     mode byte streams, and may provide a transmission
                     mechanism for out-of-band data.

       SOCK_DGRAM    Provides datagrams, which are connectionless-mode,
                     unreliable messages of fixed maximum length.

       SOCK_SEQPACKET
                     Provides sequenced, reliable, bidirectional, connection-
                     mode transmission paths for records. A record can be sent
                     using one or more output operations and received using
                     one or more input operations, but a single operation
                     never transfers part of more than one record. Record
                     boundaries are visible to the receiver via the MSG_EOR
                     flag.

       If the _p_r_o_t_o_c_o_l argument is non-zero, it shall specify a protocol that
       is supported by the address family. If the _p_r_o_t_o_c_o_l argument is zero,
       the default protocol for this address family and type shall be used.
       The protocols supported by the system are implementation-defined.

       The process may need to have appropriate privileges to use the
       _s_o_c_k_e_t_p_a_i_r() function or to create some sockets.

RREETTUURRNN VVAALLUUEE
       Upon successful completion, this function shall return 0; otherwise, -1
       shall be returned and _e_r_r_n_o set to indicate the error, no file
       descriptors shall be allocated, and the contents of _s_o_c_k_e_t___v_e_c_t_o_r shall
       be left unmodified.

EERRRROORRSS
       The _s_o_c_k_e_t_p_a_i_r() function shall fail if:

       EEAAFFNNOOSSUUPPPPOORRTT
              The implementation does not support the specified address
              family.

       EEMMFFIILLEE All, or all but one, of the file descriptors available to the
              process are currently open.

       EENNFFIILLEE No more file descriptors are available for the system.

       EEOOPPNNOOTTSSUUPPPP
              The specified protocol does not permit creation of socket pairs.

       EEPPRROOTTOONNOOSSUUPPPPOORRTT
              The protocol is not supported by the address family, or the
              protocol is not supported by the implementation.

       EEPPRROOTTOOTTYYPPEE
              The socket type is not supported by the protocol.

       The _s_o_c_k_e_t_p_a_i_r() function may fail if:

       EEAACCCCEESS The process does not have appropriate privileges.

       EENNOOBBUUFFSS
              Insufficient resources were available in the system to perform
              the operation.

       EENNOOMMEEMM Insufficient memory was available to fulfill the request.

       _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
       The documentation for specific address families specifies which
       protocols each address family supports. The documentation for specific
       protocols specifies which socket types each protocol supports.

       The _s_o_c_k_e_t_p_a_i_r() function is used primarily with UNIX domain sockets
       and need not be supported for other domains.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _S_e_c_t_i_o_n _2_._1_4, _F_i_l_e _D_e_s_c_r_i_p_t_o_r _A_l_l_o_c_a_t_i_o_n, _s_o_c_k_e_t()

       The Base Definitions volume of POSIX.1-2017, <<ssyyss__ssoocckkeett..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                        SOCKETPAIR(3)
