SYNOPSIS
       #include <sys/socket.h>

       ssize_t recv(int socket, void *buffer, size_t length, int flags);


DESCRIPTION
       The  recv()  function shall receive a message from a connection-mode or
       connectionless-mode socket. It is normally used with connected  sockets
       because  it  does  not  permit  the  application to retrieve the source
       address of received data.

       The recv() function takes the following arguments:

       socket Specifies the socket file descriptor.

       buffer Points to a buffer where the message should be stored.

       length Specifies the length in bytes of the buffer pointed  to  by  the
              buffer argument.

       flags  Specifies the type of message reception. Values of this argument
              are formed by logically OR'ing zero or  more  of  the  following
              values:

       MSG_PEEK
              Peeks  at an incoming message. The data is treated as unread and
              the next recv() or similar  function  shall  still  return  this
              data.

       MSG_OOB
              Requests  out-of-band  data.  The  significance and semantics of
              out-of-band data are protocol-specific.

       MSG_WAITALL
              On SOCK_STREAM sockets this requests  that  the  function  block
              until  the full amount of data can be returned. The function may
              return the smaller amount of data if the socket  is  a  message-
              based socket, if a signal is caught, if the connection is termi-
              nated, if MSG_PEEK was specified, or if an error is pending  for
              the socket.



       The  recv()  function shall return the length of the message written to
       the buffer pointed to by the buffer argument. For  message-based  sock-
       ets, such as SOCK_DGRAM and SOCK_SEQPACKET, the entire message shall be
       read in a single operation.  If a message is too long  to  fit  in  the
       supplied  buffer,  and  MSG_PEEK  is not set in the flags argument, the
       excess bytes shall be discarded.  For  stream-based  sockets,  such  as
       SOCK_STREAM,  message  boundaries  shall be ignored. In this case, data
       shall be returned to the user as soon as it becomes available,  and  no
       data shall be discarded.
       sage in bytes. If no messages are available to be received and the peer
       has performed an orderly shutdown, recv() shall return 0. Otherwise, -1
       shall be returned and errno set to indicate the error.

ERRORS
       The recv() function shall fail if:

       EAGAIN or EWOULDBLOCK

              The socket's file descriptor is marked O_NONBLOCK and no data is
              waiting to be received; or MSG_OOB is  set  and  no  out-of-band
              data  is  available  and  either the socket's file descriptor is
              marked O_NONBLOCK or the socket does  not  support  blocking  to
              await out-of-band data.

       EBADF  The socket argument is not a valid file descriptor.

       ECONNRESET
              A connection was forcibly closed by a peer.

       EINTR  The recv() function was interrupted by a signal that was caught,
              before any data was available.

       EINVAL The MSG_OOB flag is set and no out-of-band data is available.

       ENOTCONN
              A receive is attempted on a connection-mode socket that  is  not
              connected.

       ENOTSOCK
              The socket argument does not refer to a socket.

       EOPNOTSUPP
              The  specified  flags  are not supported for this socket type or
              protocol.

       ETIMEDOUT
              The connection timed out during connection establishment, or due
              to a transmission timeout on active connection.


       The recv() function may fail if:

       EIO    An  I/O error occurred while reading from or writing to the file
              system.

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

       ENOMEM Insufficient memory was available to fulfill the request.


       The following sections are informative.
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       poll()  ,  read()  ,  recvmsg()  ,  recvfrom()  ,  select()  , send() ,
       sendmsg() , sendto() , shutdown() , socket() , write() , the Base Defi-
       nitions volume of IEEE Std 1003.1-2001, <sys/socket.h>

COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  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 .