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

SYNOPSIS
  #include <xti.h>

  int t_rcv(
	  int fd,
	  char *buf,
	  unsigned nbytes,
	  int *flags );

LIBRARY
  XTI Library (libxti.a)

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

  t_rcv():  XNS4.0, XNS5.0

  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 option 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 option 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 option 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 option bit and the T_MORE option 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 option bits set on return.  When the
				final piece of the ETSDU is received, the
				T_MORE option 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.
      ______________________________________________________________________

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 option 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).

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

SEE ALSO
  Functions: fcntl(2), t_getinfo(3), t_look(3), t_open(3), t_snd(3).

  Standards: standards(5).

  Network Programmer's Guide

Index for Section 3

Alphabetical listing for T

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