t_rcv - Receive normal data or expedited data on a connection
#include <xti.h>
int t_rcv(
int fd,
char *buf,
unsigned nbytes,
int *flags );
XTI Library (libxti.a)
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.
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: This is a meaningful parameter. This is
not a meaningful parameter. The content of the object
pointed to by y is meaningful. Specifies a file descriptor
returned by the t_open() function that identifies the
local transport endpoint where an active connection
exists. Points to the receive data buffer where returned
data is to be written. Specifies the length in bytes of
the received-data buffer pointed to by the buf parameter.
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.
-----------------------------------------------------------------------
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.
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.
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.
If the t_rcv() function fails, t_errno is set to one of
the following values: The specified file descriptor does
not refer to a valid transport endpoint. Asynchronous
mode is indicated because O_NONBLOCK was set, but no data
is currently available from the transport provider. An
asynchronous event has occurred on this transport endpoint
and requires immediate attention (refer to t_look() function).
The t_look() function was issued in the wrong
sequence on the transport endpoint referenced by the fd
parameter. A system error occurred during execution of
t_look(). This function is not supported by the underlying
transport provider. 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).
The t_rcv() function can only be called in the T_DATAXFER
and T_OUTREL transport provider states.
Functions: fcntl(2), t_getinfo(3), t_look(3), t_open(3),
t_snd(3).
Standards: standards(5).
Network Programmer's Guide
t_rcv(3)
[ Back ] | 