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t_rcv(3)
NAME
  t_rcv - Receives normal data or expedited data on a connection

LIBRARY
  XTI Library (libxti.a)

SYNOPSIS
  #include <xti.h>
  int t_rcv(
      int fd,
      char *buf,
      unsigned nbytes,
      int *flags) ;

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  t_rcv():  XNS4.0

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  The following table summarizes the relevance of input and output parameters
  before and after t_rcv() is called:

		     Parameters	  Before Call	After Call
		     _____________________________________
		     fd		       y	    n
		     buf	       y	   (y)
		     nbytes	       y	    n
		     flags	       n	    y
  Notes to Table:
  y    This is a meaningful parameter.
  n    This is not a meaningful parameter.
  (y)  The content of the object pointed to by y is meaningful.

  fd   Specifies a file descriptor returned by the t_open() function that
       identifies the local transport endpoint where an active connection
       exists.

  buf  Points to the receive data buffer where returned data is to be
       written.

  nbytes
       Specifies the length in bytes of the received-data buffer pointed to
       by the buf parameter.







  flags
       Points to an unsigned integer (least significant bit rightmost) whose
       bits are flags that specify the action that must be taken by the
       responding transport user when the t_rcv() function is processed.
       Corresponding values and symbolic names for the following flag bits
       are defined in the xti.h include file:
	   Bit	   Symbolic Name   Meaning
	   ______________________________________________________
	     0	   T_MORE

				   When set, this bit notifies
				   the transport user that
				   received data is a fragment of
				   a Transport Service Data Unit
				   (TSDU) or Expedited Transport
				   Service Data Unit (ETSDU), and
				   that more data is available.
				   The rest of the TSDU or ETSDU
				   can be received through
				   further t_rcv() function
				   calls. Each time this flag is
				   set on return, another t_rcv()
				   call can receive additional
				   pieces of the TSDU or ETSDU.
				   When the final TSDU or ETSDU
				   is received, this flag bit has
				   a value of 0 (zero) on return.
				   When the transport provider
				   does not support TSDU or ETSDU
				   data exchanges (refer to the
				   t_open() and t_getinfo()
				   functions), the state of this
				   flag bit should be ignored.
	     1	   T_EXPEDITED

				   When set, this bit notifies
				   the transport user that
				   received data is an ETSDU.
				   When the number of ETSDU data
				   bytes exceeds the value
				   specified by the nbytes
				   parameter, this flag bit and
				   the T_MORE flag bit are set on
				   return of the initial t_rcv()
				   call. Subsequent t_rcv() calls
				   issued to retrieve the rest of
				   the ETSDU have both these flag
				   bits set on return. When the
				   final piece of the ETSDU is
				   received, the T_MORE flag bit
				   has a value of 0 (zero) on
				   return.


				   When an ETSDU is received
				   during reception of a TSDU, no
				   remaining pieces of the TSDU
				   may be received until the
				   current ETSDU has been
				   completely received.






VALID STATES
  The t_rcv() function can only be called in the T_DATAXFER and T_OUTREL
  transport provider states.

DESCRIPTION
  The t_rcv() function is an XTI connection-oriented service function that is
  used to receive normal or expedited data. The transport endpoint through
  which data arrives is specified by a file descriptor previously returned by
  the t_open() function. By default, t_rcv() executes in the synchronous
  operating mode. In synchronous mode t_rcv() waits for data to arrive even
  when none is currently available before returning control to the calling
  transport user.

  When the transport endpoint, specified by the fd parameter, has been opened
  with the O_NONBLOCK flag set in the t_open() or fcntl() functions, the
  t_rcv() function executes in asynchronous mode. In asynchronous mode, when
  no data is available, this function fails.

NOTES
  In synchronous mode, the only way for a transport user to be notified of
  the arrival of normal or expedited data is to call the t_rcv() function or
  to check for states T_DATA or T_EXDATA using the t_look() function.

RETURN VALUES
  Upon successful completion, the t_rcv() function returns the number of
  bytes of data received. Otherwise, the value -1 is returned and t_errno is
  set to indicate the error.

ERRORS
  If the t_rcv() function fails, t_errno is set to one of the following
  values:

  [TBADF]   The specified file descriptor does not refer to a valid transport
	    endpoint.

  [TNODATA] Asynchronous mode is indicated because O_NONBLOCK was set, but no
	    data is currently available from the transport provider.

  [TLOOK]   An asynchronous event has occurred on this transport endpoint and
	    requires immediate attention (refer to t_look() function).

  [TOUTSTATE]
	    The t_look() function was issued in the wrong sequence on the
	    transport endpoint referenced by the fd parameter.

  [TSYSERR] A system error occurred during execution of t_look().

  [TNOTSUPPORT]
	    This function is not supported by the underlying transport
	    provider.

  [TPROTO]  This error indicates that a communication problem has been
	    detected between XTI and the transport provider for which there
	    is no other suitable XTI(t_errno).

RELATED INFORMATION
  Functions: fcntl(2), t_getinfo(3), t_look(3), t_open(3), t_snd(3).


  Standards: standards(5).

Index for Section 3

Alphabetical listing for T

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