Provided by: umview_0.6-1_amd64 bug

NAME

       msocket - create an endpoint for communication in a multi-stack environment

SYNOPSIS

       #include <sys/types.h>          /* See NOTES */
       #include <msocket.h>

       int msocket(char * path, int domain, int type, int protocol);

DESCRIPTION

       msocket()  creates an endpoint for communication and returns a descriptor in a multi-stack
       environment or defines the default stack.

       The path parameter selects the stack used for the call. The path must  refer  to  a  stack
       special  file (S_IFSTACK).  When path is NULL, the default stack gets used. It is possible
       to specify a default network stack for each domain (see SOCK_DEFAULT below).

       The domain parameter specifies a communication domain; this selects  the  protocol  family
       which  will be used for communication.  These families are defined in <sys/socket.h>.  The
       currently understood formats include:

       Name                Purpose                          Man page
       PF_UNIX, PF_LOCAL   Local communication              unix(7)
       PF_INET             IPv4 Internet protocols          ip(7)
       PF_INET6            IPv6 Internet protocols          ipv6(7)
       PF_IPX              IPX - Novell protocols
       PF_NETLINK          Kernel user interface device     netlink(7)
       PF_X25              ITU-T X.25 / ISO-8208 protocol   x25(7)
       PF_AX25             Amateur radio AX.25 protocol
       PF_ATMPVC           Access to raw ATM PVCs
       PF_APPLETALK        Appletalk                        ddp(7)
       PF_PACKET           Low level packet interface       packet(7)

       The socket has  the  indicated  type,  which  specifies  the  communication  semantics  or
       SOCK_DEFAULT  to define the standard stack for the specified domain(s).  Currently defined
       types are:

       SOCK_STREAM
              Provides sequenced, reliable, two-way, connection-based byte streams.   An  out-of-
              band data transmission mechanism may be supported.

       SOCK_DGRAM
              Supports datagrams (connectionless, unreliable messages of a fixed maximum length).

       SOCK_SEQPACKET
              Provides a sequenced, reliable, two-way connection-based data transmission path for
              datagrams of fixed maximum length; a consumer is required to read an entire  packet
              with each input system call.

       SOCK_RAW
              Provides raw network protocol access.

       SOCK_RDM
              Provides a reliable datagram layer that does not guarantee ordering.

       SOCK_PACKET
              Obsolete and should not be used in new programs; see packet(7).

       Some  socket  types  may  not  be  implemented  by  all  protocol  families;  for example,
       SOCK_SEQPACKET is not implemented for AF_INET.

       When type is SOCK_DEFAULT msocket does not define any communication endpoint,  instead  it
       defines the stack that will be used for the following msocket calls with NULL path, or for
       the following obsolete socket(2) calls.  Default  stacks  get  inherited  through  process
       creation  fork(2)  and  execution  execve(2).   When  type  is  SOCK_DEFAULT and domain is
       PF_UNSPEC the named stack becames the default stack for all the protocols it supports.

       The protocol specifies a particular protocol to be used with the socket.  Normally only  a
       single protocol exists to support a particular socket type within a given protocol family,
       in which case protocol can be specified as 0.  However, it is possible that many protocols
       may  exist,  in  which  case  a particular protocol must be specified in this manner.  The
       protocol number to use is specific to the “communication domain” in which communication is
       to  take  place; see protocols(5).  See getprotoent(3) on how to map protocol name strings
       to protocol numbers.

       Sockets of type SOCK_STREAM are full-duplex byte streams, similar to pipes.  They  do  not
       preserve  record boundaries.  A stream socket must be in a connected state before any data
       may be sent or received on  it.   A  connection  to  another  socket  is  created  with  a
       connect(2) call.  Once connected, data may be transferred using read(2) and write(2) calls
       or some variant of the send(2) and recv(2) calls.  When a session  has  been  completed  a
       close(2)  may  be  performed.   Out-of-band  data  may also be transmitted as described in
       send(2) and received as described in recv(2).

       The communications protocols which implement a SOCK_STREAM ensure that data is not lost or
       duplicated.   If  a  piece  of data for which the peer protocol has buffer space cannot be
       successfully transmitted within a reasonable  length  of  time,  then  the  connection  is
       considered  to be dead.  When SO_KEEPALIVE is enabled on the socket the protocol checks in
       a protocol-specific manner if the other end is still alive.  A SIGPIPE signal is raised if
       a  process sends or receives on a broken stream; this causes naive processes, which do not
       handle the signal, to exit.  SOCK_SEQPACKET  sockets  employ  the  same  system  calls  as
       SOCK_STREAM  sockets.   The  only  difference  is  that read(2) calls will return only the
       amount of data requested, and any data remaining in the arriving packet will be discarded.
       Also all message boundaries in incoming datagrams are preserved.

       SOCK_DGRAM  and  SOCK_RAW  sockets  allow  sending of datagrams to correspondents named in
       sendto(2) calls.  Datagrams are generally received with  recvfrom(2),  which  returns  the
       next datagram along with the address of its sender.

       SOCK_PACKET  is  an  obsolete  socket type to receive raw packets directly from the device
       driver.  Use packet(7) instead.

       An fcntl(2) F_SETOWN operation can be used to  specify  a  process  or  process  group  to
       receive  a  SIGURG  signal  when  the  out-of-band  data  arrives or SIGPIPE signal when a
       SOCK_STREAM connection breaks unexpectedly.  This operation may also be used  to  set  the
       process or process group that receives the I/O and asynchronous notification of I/O events
       via SIGIO.  Using F_SETOWN is equivalent  to  an  ioctl(2)  call  with  the  FIOSETOWN  or
       SIOCSPGRP argument.

       When  the  network  signals  an error condition to the protocol module (e.g., using a ICMP
       message for IP) the pending error flag is set for the socket.  The next operation on  this
       socket will return the error code of the pending error.  For some protocols it is possible
       to enable a per-socket error queue to retrieve detailed information about the  error;  see
       IP_RECVERR in ip(7).

       The operation of sockets is controlled by socket level options.  These options are defined
       in <sys/socket.h>.  The functions setsockopt(2) and getsockopt(2) are used to set and  get
       options, respectively.

RETURN VALUE

       On  success,  a  file  descriptor  for  the  new  socket  is  returned except when type is
       SOCK_DEFAULT.  In this latter case 0 is returned on success.  On error,  -1  is  returned,
       and errno is set appropriately.

ERRORS

       EACCES Permission to create a socket of the specified type and/or protocol is denied.

       EAFNOSUPPORT
              The implementation does not support the specified address family.

       EINVAL Unknown protocol, or protocol family not available.

       EMFILE Process file table overflow.

       ENFILE The system limit on the total number of open files has been reached.

       ENOBUFS or ENOMEM
              Insufficient  memory  is  available.  The socket cannot be created until sufficient
              resources are freed.

       EPROTONOSUPPORT
              The protocol type or the specified protocol is not supported within this domain.

       Other errors may be generated by the underlying protocol modules.

CONFORMING TO

       This is a system call defined for View-OS. It extends socket(),  appeared  in  4.2BSD  and
       conforming to 4.4BSD, POSIX.1-2001.  System providing msocket() do provide also a socket()
       call for backward compatibility.  In fact: socket(domain,type,protocol) is  equivalent  to
       msocket(NULL,domain,type,protocol)

       In  this way it is generally portable to/from non-BSD systems supporting clones of the BSD
       socket layer (including System V variants).

NOTES

       POSIX.1-2001 does not require the inclusion of <sys/types.h>, and this header file is  not
       required  on  Linux.   However, some historical (BSD) implementations required this header
       file, and portable applications are probably wise to include it.

       The manifest constants used under 4.x BSD for  protocol  families  are  PF_UNIX,  PF_INET,
       etc., while AF_UNIX etc. are used for address families.  However, already the BSD man page
       promises: "The protocol  family  generally  is  the  same  as  the  address  family",  and
       subsequent standards use AF_* everywhere.

       The  header file <sys/types.h> is only required for libc4 or earlier.  Some packages, like
       util-linux, claim portability to all Linux versions and libraries.   They  certainly  need
       this header file.

BUGS

       SOCK_UUCP is not implemented yet.

SEE ALSO

       socket(2),  accept(2),  bind(2),  connect(2),  fcntl(2),  getpeername(2),  getsockname(2),
       getsockopt(2), ioctl(2), listen(2), read(2),  recv(2),  select(2),  send(2),  shutdown(2),
       socketpair(2), write(2), getprotoent(3), ip(7), socket(7), tcp(7), udp(7), unix(7)

COLOPHON

       This  page  has  been  modified  from socket(2) page of release 2.79 of the Linux. In fact
       msocket(2) is an extension of  this  call.   man-pages  project.   A  description  of  the
       project,     and    information    about    reporting    bugs,    can    be    found    at
       http://www.kernel.org/doc/man-pages/.

       View-OS is a project of the Computer Science Department, University  of  Bologna.  Project
       Leader: Renzo Davoli.
       <http://www.sourceforge.net/projects/view-os>

       Howto's and further information can be found on the project wiki
       <wiki.virtualsquare.org>.